000 FXUS66 KSEW 151603 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 903 AM PDT Sat Aug 15 2020 .SYNOPSIS...It will be quite warm the next few days with Sunday being the hottest day. Onshore flow will bring cooler weather for the latter part of next week. A weak disturbance will lead to a small chance of a thunderstorm near the Cascades late Sunday. && .SHORT TERM /TODAY THROUGH MONDAY/...An upper ridge will build over the area today with highs warming into the 80s for most locations. A few lower 90s are possible for the south interior. Sunday will be the hottest day for the interior with 90s common. There will be flow reversal at the coast with southerly winds developing which should cool temps a bit out there. There could also be some smoke coming up from the south on Sunday but confidence on how impactful that will be is low. There will be a marine push Sunday night with stratus developing at the coast and pushing partially inland Monday morning. A weak short wave in the southwest flow aloft could spark a few showers and thunderstorms Sunday night, mainly over the Cascades. There might also be some drizzle near the coast. Monday will be cooler under the influence of low level onshore flow. Low clouds will burn back to the coast with daytime heating. Highs will still be above normal - mostly in the 80s - but the impactful heat will be over. Schneider .LONG TERM /TUESDAY THROUGH FRIDAY/...Previous discussion...The upper level ridge axis responsible for this weekends rapid warmup will be off to the east. However, elevated mid-level heights will remain in place over the region with warm mid-level (H850 and H700) temperatures. Guidance is indicating a ribbon of mid-level dry air getting funneled over Western Washington during the Tuesday/Wednesday timeframe between the periphery of the ridge of high pressure and an advancing shortwave trough to the west. Highs in the 80s are expected across most inland locales on Tuesday, cooling slightly on Wednesday as the ridge begins breaking down. Increasing clouds and chances for showers will be on the increase late this week as an upper level low over the eastern Gulf of Alaska will eject a series of shortwave trough across the region. At this time, there is a fair amount of variance regarding how much moisture will be associated with this system across Western Washington. Nonetheless, temperatures will return to normal across the region with more cloud coverage expected. Pullin && .AVIATION...Southwesterly flow aloft with upper level ridge centered east of the area. In the low levels northerly flow today will turn weakly offshore tonight into Sunday morning. Low level flow turning back onshore Sunday afternoon. Clear skies through Sunday afternoon. KSEA...Clear skies. Northerly winds 6 to 10 knots increasing to 10 to 15 knots around 21z. Winds becoming northeast 6 to 10 knots after 05z. Felton && .MARINE...Low level northerly flow today will go briefly offshore tonight into Sunday morning before turning back onshore Sunday afternoon. Varying degrees of onshore flow will continue Monday through the middle of next week. Small craft advisory north to northwest winds in the inner coastal waters this afternoon and evening. KOLM-KBLI gradient already -1.5 mb with the gradient around -2.5 mb expected by late this afternoon. Small craft advisory northerly winds developing in Puget Sound and Hood Canal this afternoon will ease later this evening. Small craft advisory winds expected in the central and eastern Strait Sunday night with the marine push. Felton && .FIRE WEATHER...Critical fire conditions are expected to continue this weekend, due to dry and unstable conditions, with the Red Flag Warning remaining in effect for much of the area. Daytime relative humidities will reach critical values this afternoon, and with mid-level Haines 6 conditions expected both Saturday and Sunday. Additionally, a weak disturbance moving from the south to the east of the area late Sunday may bring enough instability and moisture to trigger a few thunderstorms. This chance remains rather small - only around 10 to 15 percent - but a few strikes near the Cascade crest cannot entirely be ruled out. Cullen && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed until then. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Red Flag Warning until 11 PM PDT Sunday for Black Hills and Southwest Interior Lowlands-Southeast Puget Sound Lowlands Generally Below 1500 Feet-West Slopes of the Central Cascades Generally above 1500 Feet-West Slopes of the North Cascades Generally above 1500 Feet. Heat Advisory from 7 AM Sunday to 2 AM PDT Monday for Bellevue and Vicinity-Bremerton and Vicinity-Everett and Vicinity- Hood Canal Area-Lower Chehalis Valley Area-Seattle and Vicinity-Southwest Interior-Tacoma Area-Western Skagit County-Western Whatcom County. Excessive Heat Warning from 7 AM Sunday to 2 AM PDT Monday for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and King Counties-Cascades of Whatcom and Skagit Counties- East Puget Sound Lowlands. Red Flag Warning from 11 AM to 11 PM PDT Sunday for Northeast Puget Sound Lowlands Generally Below 1500 Feet. PZ...Small Craft Advisory from 2 PM this afternoon to 11 PM PDT this evening for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-Puget Sound and Hood Canal. && $$ www.weather.gov/seattle

336 FXUS66 KPQR 151703 AAA AFDPQR Area Forecast Discussion National Weather Service Portland OR 1000 AM PDT Sat Aug 15 2020 Updated aviation discussion. .SYNOPSIS...Hot weather for the weekend as a large ridge of high pressure moves across the Pacific Northwest. Unstable air moves up out of the south late Sunday, bringing chances for thunderstorms to parts of the region Sunday afternoon and night. A little cooler air slowly seeps into the region early next week as the upper ridge moves east and a trough of low pressure approaches from the west. && .SHORT TERM...Today through Monday...Even a short loop of water vapor pictures early this morning makes apparent the strengthening of the upper ridge over the Pacific Northwest, as had been advertised by the models. Surface analysis showed a thermal induced trough extending north up the Oregon coast from the ORCA low this morning. Models in general have shown the trough shifting inland in the afternoon, turning coastal winds onshore for the afternoon hours. Models continue to show very warm temperatures at 850 mb this afternoon, now topping out at 25C or even slightly higher over the interior, which makes 100F in the Willamette Valley look increasingly likely. Coastal areas are likely to warm quickly this morning, before the switch to northwest onshore breezes puts the brakes on the heating in the afternoon. All indications are that the very warm air mass persists into Monday, so expect to see some of the warmest low temperatures of the summer over inland areas Sunday morning. Especially warm lows will be found in the Cascade foothills Sunday morning thanks to the warm mid levels above a shallow low elevation surface inversion. East flow through the Gorge, depending on the activity of the Mosier fire, may bring areas of smoke west through the Gorge and into the east Portland metro area. On Sunday as the upper ridge axis shifts east, models hinting at some shortwaves lifting north in an increasingly southerly flow aloft. With the shortwaves comes the potential for some mid and upper level instability and moisture, as suggested in both the NAM and GFS 00Z operational runs. This often results in chances for thunderstorms over the Cascades, but it is not out of the question that chances for thunderstorms could extend further west given the uncertainty in the track of any upper level disturbances. For now prefer to extend a slight chance out into the Willamette Valley for Sunday night especially given the qpf produced by GFS operational run. Will however for now, hold off on pops as far west as the Coast Range as the National Blend limits pops mainly to Cascades and Cascade Foothills. With the ridge shifting east, models show an increasing onshore flow during the day Sunday, beginning on the central Oregon coast and through the central coast with a southwest Range. This will likely bring cooling to the coast while the interior begins the day with a similarly very warm air mass as compared to Saturday. The strength and timing of the onshore gradients in the afternoon suggest some cooling may spread into the south end of the Willamette Valley Sunday afternoon for a slightly cooler day overall, while in the north Willamette Valley the onshore flow is likely too little too late to provide any real relief from the heat Sunday. A modest onshore flow continues into Monday as the warm upper ridge holds strong over the interior western U.S. Shallow marine air will hold sway along the coast, but do not expect much in the way of marine clouds to spread inland. While not as hot as the weekend, it is still likely to be rather warm Monday in the inland valleys. .LONG TERM...Monday night through Friday...Models show a ridge of high pressure over the western United States early in the coming week. The ridge is slowly weakened through the course of the week as a trough of low pressure over the east Pacific ejects a series of shortwaves into the Pacific Northwest. Through much of the week, the net result is a slow cooling down of the air mass through a lowering of heights aloft as well as a return to onshore low level flow. The onshore flow will also tend to increase marine clouds, mainly along parts of the coast. At the end of the week, will include slight chances for showers returning to the north coastal areas as suggested by the National Blend, as the main upper trough off the Pacific inches closer. && .FIRE WEATHER...Critical fire weather conditions are expected this afternoon and evening, which is covered by another red flag warning that begins at 11 AM. Minimum humidities are expected to decrease below 25 percent over much of the region for critically dry conditions that will persist into the evening. These dry conditions, combined with increased instability from the thermally induced surface trough will favor rapid fire growth. Any new or existing fires will have the potential to become plume dominated. The elongated ORCA low, aka the thermal low of southwest Oregon, will sit over the Coast Range through tonight supporting mid-level haines 6 values most of today. An upper level short wave moving up out of southwest Oregon Sunday afternoon may trigger thunderstorms, most likely over the Cascades. Models are forecasting steepening lapse rates and potentially some mid and upper level moisture with this feature to support the possibility for thunderstorms. This moisture however is not deep, and the thunderstorms will likely be elevated, suggesting any storms that develop may produce little to no rain. Any lightning could be problematic, but at this point will be limiting LAL values to 3 or less. && .AVIATION...VFR the next 24 hours with mostly clear skies. A surface thermal trough along and just off shore of the Oregon coast will gradually shift inland today, likely keeping any coastal clouds at bay. Through the afternoon, high pressure over the area will cause winds to become easterly which will keep the area dry and very hot. With the offshore winds there is a slight chance for some of the smoke from fires in the Columbia River Gorge to migrate into the area. Likely will be patchy and should have little to no influence on visibility to KTTD or other nearby sites. Around 03Z Sun, low pressure along the California coast will migrate northward causing winds to shift to a southerly flow overnight. METAR note: KTTD ASOS has several missing elements and is currently being worked on. KPDX and APPROACHES...VFR SKC through Sat evening. East wind gusts 15-20 kt develop at the west end of the Columbia Gorge Sat morning, but weaken by early evening. Very hot conditions with temps near 100 degrees expected Sat afternoon. There is a very slight chance for some smoke to filter in near the terminal due to nearby fires. However, confidence is very low and even if it does move into the area, should have little impact on vis. Decided to leave out of the TAF. -Hartsock/Muessle && .MARINE...High pressure remains anchored over the area with a thermally induced low pressure trough along the waters stretching from California to southern Washington. This thermal trough is the main reason for the gusty northerly winds. Small craft winds 15 to 20 kt with gusts to 25 kt are likely over all of the waters through Sat afternoon. The inner waters are expected to dissipate first, followed by the central outer waters, and finally the northern waters Sat night. During the morning hours today can expect periods of lulled winds, reaching their peak gusts in the afternoon. Seas during this time are expected to be northwesterly at 4 to 6 ft with localized seas up to 8 ft south of Newport. Late Sat/early Sun, weak low pressure, stemming from the eastern Pacific, will advance northward causing a southerly wind shift. The southerly winds with gusts up to 15 kt will persist through Mon. As high pressure once again builds across the Pacific NW on Tue, winds will become northerly. Northwesterly seas during this time will likely remain around 4 to 6 ft with a 10 second period. -Muessle && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning until 9 PM PDT Sunday for Cascade Foothills in Lane County-Central Columbia River Gorge- Central Willamette Valley-Greater Portland Metro Area- Northern Oregon Cascade Foothills-South Willamette Valley- Upper Hood River Valley-Western Columbia River Gorge. Red Flag Warning until 11 PM PDT Sunday for Central Oregon Cascade Foothills-Mt. Hood National Forest West of Cascade Crest-North Oregon Cascade Foothills-Willamette National Forest-Willamette Valley. Heat Advisory until 9 PM PDT Sunday for Cascades in Lane County- Central Coast Range of Western Oregon-Coast Range of Northwest Oregon-Lower Columbia-Northern Oregon Cascades. Red Flag Warning until 11 PM PDT this evening for Central Oregon Coast-East Slopes of the Central Oregon Coast Range- North Oregon Coast-North Oregon Coast Range. WA...Excessive Heat Warning until 9 PM PDT Sunday for Central Columbia River Gorge-Greater Vancouver Area-Western Columbia River Gorge. Red Flag Warning until 11 PM PDT Sunday for Clark County Lowlands-Eastern Gifford Pinchot National Forest Mt Adams Ranger District-Extreme South Washington Cascades and Foothills. Heat Advisory until 9 PM PDT Sunday for I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-South Washington Cascades. Red Flag Warning until 11 PM PDT this evening for East Willapa Hills-South Washington Coast and West Willapa Hills. PZ...Small Craft Advisory until 9 PM PDT this evening for Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM. Small Craft Advisory until 7 PM PDT this evening for Waters from Cascade Head to Florence OR from 10 to 60 NM. Small Craft Advisory until noon PDT today for coastal waters from Cape Shoalwater WA to Florence OR out 10 NM. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland

000 FXUS66 KMFR 151629 AFDMFR Area Forecast Discussion National Weather Service Medford OR 929 AM PDT Sat Aug 15 2020 .UPDATE... Updates to the forecast this morning were to adjust the smoke, haze, and fog in the forecast for areas west of the Cascades for today. Smoke and haze from the Red Salmon Fire is pushing northward along the coast. This will continue today and some of it will also spread across the inland west side as the afternoon and evening winds bring it eastward. Also, wording for thunderstorms today was adjusted from isolated to slight chance as little, if any, are expected to occur. && .DISCUSSION... It will be heating up this afternoon through this evening to near record levels for this calendar date. There continues to be a slight chance of thunderstorms across the inland west side, portions of NorCal, and portions of the east side this afternoon and evening. However, the majority of the model guidance continues to show nothing to very little happening today in terms of thunderstorms, so removed the isolated wording and went with slight chance instead. Numerical models suggest that the greatest threat, albeit small, for thunderstorms today is from the Marble Mountains to western edge of the Shasta Valley northward over the Siskiyous and into Jackson County to north and northeast of Crater Lake NP, with a lesser threat across northern Klamath County, Lake, and Modoc counties. If a storm does form, it will produce little or no rainfall. Sunday and Monday the thunderstorm threat increases across the area. Based on the preceding dryness, heat, gusty wind potential, and the threat of isolated to scattered thunderstorms, fire weather watches are in effect for most areas east of Interstate 5 for Sunday afternoon and evening. ~BTL && .AVIATION...For the 15/12Z TAFs...Clear skies are expected to continue for most areas through the TAF period. One exception is smoke from the Red Salmon Fire, which will reduce visibilities in much of western siskiyou County, with haze potentially spreading to the north and northeast. There may be some patchy IFR/MVFR conditions that develop in the Coquille Basin and near KOTH early this morning. If anything does develop, it will be short lived with conditions improving to VFR by 16-17z today. Additionally tonight, expect areas of IFR/LIFR conditions to affect the coast as a southerly surge brings low clouds and patchy fog to coastal areas. -CC && .MARINE...Updated 300 AM PDT Saturday 15 August 2020...Winds and seas will gradually subside today as the thermal trough gradually moves inland. Steep seas are expected to linger across the waters this morning with some very steep seas through early morning for the outer waters south of Gold Beach. Steep seas persist across the outer waters through the afternoon then seas will diminish below small craft advisory levels. A southerly wind surge is expected late today into tonight. This is expected to bring some low clouds and patchy fog to the waters by tonight. Southerly winds continue through Sunday as a disturbance moves up from the south. Any precipitation with showers or thunderstorms associated with this disturbance is expected to remain inland though. Relatively light winds and seas will then continue through Tuesday. A thermal trough is expected to return Wednesday and Thursday. Of note, models have trended weaker with this thermal trough. Steep seas are possible during this period, mainly south of Cape Blanco. -CC && .FIRE WEATHER...Updated 1015 PM PDT Friday 14 August 2020... A strong upper ridge will build into the area this weekend and persist into next week bringing the hottest stretch of weather this summer thus far. It will be very hot across inland areas with high temperatures challenging or exceeding record levels. Humidities will remain rather low as well, but the upper level trough off the West Coast will allow deep southerly flow to bring mid-level moisture northward into the area Saturday. This will bring an isolated threat of lightning to portions of the area during the afternoon and evening. Moisture, forcing and instability aren`t overly robust, but models support isolated thunderstorm development. Mid-level flow is shown to be around 15 kt or so and this motion should allow any storm that is able to develop to move northward up over the Siskiyous into Jackson and eastern Josephine Counties over to the Cascades. There could also be a couple of isolated storms from Modoc County up into Lake and northern Klamath County. It should be noted that while we think coverage of storms won`t be sufficient for a Red Flag Warning, any lightning at all will bring with it the threat of new fire starts. We`ll continue to headline the Fire Weather Planning Forecast. By Sunday, we`ll be on the western periphery of an upper high over the Great Basin. A closed low out around 130W will open up and eject northeastward offshore. Mid-level flow ahead of this system is expected to increase to around 35-45 kt around 600 mb. This should lead to some gusty winds due to strong diurnal mixing and downward transport of momentum during the afternoon/evening. We have issued a Fire Weather Watch for the increased winds along with low humidity for the Shasta Valley to NW Modoc and some areas east of the Cascades. See RFWMFR for the specific details. In addition, PWs increase to 1.00 inch or greater as subtropical moisture works its way northward. Moisture, instability and forcing will be greatest along and east of the Cascades, so that is the area where isolated thunderstorms are most likely, but a slight chance of storms exists just about everywhere from I-5 eastward in Oregon and east of the Red Salmon complex in NorCal. Latest data suggests a tick upward in thunderstorm chances but also suggests lots of midlevel and high cloud cover, which tends to limit the amount of lightning our area sees. Given the sharp change in model output this evening and the questions surrounding cloud cover, we are choosing to not issue a Fire Weather Watch at this time, but we wanted to communicate this change in the Fire Weather Discussion. We`ll remain in S-SW flow aloft through at least Tuesday, so the hot weather looks to continue, albeit not quite as hot as over the weekend. Isolated thunder chances continue in north Cascades and over far eastern sections both Monday and Tuesday afternoons. -Spilde/Keene && .PREV DISCUSSION... /Issued 417 AM PDT Sat Aug 15 2020/ DISCUSSION...Satellite imagery is showing a relatively thin band of cirrus clouds moving from south to north very slowly across southern Oregon and northern California with clear skies elsewhere. This has indicated our shift into deep southerly flow (winds from the south) which will in turn, advance a much warmer air mass into our area than yesterday. The forecast continues to call for dangerously hot temperatures today, reaching up to 110 degrees in some parts of the west side valleys, including at Medford and Happy Camp. The last time we`ve reached temperatures this hot was 2017. Even Roseburg is forecast to reach 106 today which as noted by the previous shift is 20 degrees above normal-- which is already the hottest part of the year, and should shatter the previous daily record high temperature of 98 degrees set in 1933 and then tied in 2002 and 2012. Temperatures on Sunday will be a few degrees cooler than Saturday, but overall, expect the hot weather to continue through at least Tuesday. Additionally, overnight low temperatures are forecast to be rather warm. This will prevent significant relief from occurring. Here are some tips to help keep yourself and your loved ones safe during this heat. Please check our website at weather.gov/medford for more heat safety tips. A host of Excessive Heat Warnings and Heat Advisories continue through Sunday evening, highlighting the hottest period of this heatwave. Please see the NPWMFR for more details. * Check in on older adults, young children and those who are not feeling well. * Take plenty of rest breaks in shade or air conditioning. * Drink water before, during and after activities. * Some area rivers are dangerously cold and have strong currents. Wear a life jacket if swimming. For those who may decide to recreate today in the Mountains, streams, or lakes; please be aware that the pattern will lead to the possibility of thunderstorms today. The trigger looks really weak, and guidance has backed off somewhat today, but still think a storm or two could occur across Western Siskiyou County move up through the Siskiyous into Jackson and eastern Josephine Counties into the southern Oregon Cascades and portions of the East Side as well as for Modoc County. Any storm could produce some gusty winds and some occasional lightning. Have a plan to reach the safety of a building or car as soon as you hear thunder. * Have a plan and be on the look out for building thunderstorm clouds. * You should make your way to your designated safe spot (a building, or a car) if you hear thunder. * When thunder roars, go indoors. The main threat for thunderstorms will occur on Sunday. Confidence is increasing that something will happen as the convection allowing models are split between two modes: scattered thunderstorms and a more stratiform rain scenario. There are a few nuances with this. If we start the day with a thick and widespread cirrus shield, this could limit the thunderstorm potential. However, even in this scenario, the hot temperatures could create a leading edge of thunderstorms moving up from central California ahead of the stratiform rain. The other scenario, and at this point equally as probable is that this system brings some elevated (and thus dry) storms to northern California early Sunday morning (6 AM) and spread them into areas west of the Cascades in southern Oregon before 10 AM. Then the thunderstorm chances increase in the afternoon with more rainfall associated with the storms. The problem with this is that the steering flow is 30 knots, so these storms will be moving quickly, limiting the wetting rain potential. Since confidence is increasing that something is going to happen, have issued a fire weather watch for much of the area for this threat. More information will be available in the fire weather discussion below. The forecast for Monday will continue to show isolated storms inland from the coast range as well as another round of hot temperatures. Tuesday will continue the hot temperature trend (still not as hot as Saturday). Then, the flow shifts to be more westerly (from the Pacific Ocean) moderating temperatures around the area to be closer to normal for this time of year. Precipitation chances also decrease in the latter half of next week. -Schaaf && .MFR WATCHES/WARNINGS/ADVISORIES... OR... Fire Weather Watch from Sunday morning through Sunday evening for ORZ624-625. Heat Advisory until 11 PM PDT Sunday for ORZ027>029. Excessive Heat Warning until 11 PM PDT Sunday for ORZ024-026. Heat Advisory until 11 PM PDT this evening for ORZ021-022. Excessive Heat Warning until 11 PM PDT Sunday for ORZ023-025. Fire Weather Watch from Sunday morning through Sunday evening for ORZ617-622-623. Fire Weather Watch from Sunday morning through Sunday evening for ORZ621. CA...Heat Advisory until 11 PM PDT Sunday for CAZ082>084. Excessive Heat Warning until 11 PM PDT Sunday for CAZ080-081. Fire Weather Watch from Sunday morning through Sunday evening for CAZ285. Fire Weather Watch from Sunday morning through Sunday evening for CAZ280>282-284. Pacific Coastal Waters...Small Craft Advisory until 11 AM PDT this morning for PZZ350-356-370-376. $$ BTL/BMS/BMS

000 FXUS66 KEKA 151237 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 537 AM PDT Sat Aug 15 2020 .SYNOPSIS...Some of the hottest temperatures of the summer are expected for interior northwest California today, and it will remain hot into the middle of next week. While coastal areas will not be as hot, it will be unusually warm again today, accompanied by sunny skies. Isolated thunderstorms are expected over the Trinty mountains this afternoon, with more storm activity expected late tonight and Sunday. && .DISCUSSION...Strong upper level ridging centered over the Desert SW will continue to build northwestward into the Pacific NW today. Triple digit heat is expected for much of interior NW California again today, with highs peaking around 105-110F degrees in the hottest valleys. An excessive heat warning and a heat advisory remains in effect. Coastal areas will be quite warm today, and feeling hot again, due to the higher humidities. NBM continues to indicate high probabilities for temperatures in the mid 70s for coastal areas. Some sites may even peak in the lower to mid 80s, though the offshore flow is not supportive for this to occur. Probabilities of lower 90s are near 25% for places like Fortuna and other sites in the Northern Humboldt Coast Zone that are farther inland away from the ocean breezes. Models continues to point toward possible terrain driven thunderstorms this afternoon over the Trinity mountains. Another surge of mid/upper level moisture with PWAT over 1 inch will bring a potential for more thunderstorms late tonight and Sunday. The atmospheric forcing is weak, though mid level lapse rates are steep with sufficient CAPE. HREF continues to indicate increasing probabilities for storms on Sunday which appears to be the most active day for storms. NAM-nest and HRRR indicate convection developing late tonight and early Sunday morning, primarily over Lake, Mendocino and east/southeast Trinity Counties. With extremely parched conditions, the greatest impact from storms will be cloud-to-ground lightning strikes and fire starts. Per coordination with neighboring offices, a fire weather watch for dry storms with abundant lightning activity has been hoisted. Models indicate another surge of moist air and possible convection and light showers Sunday night and Monday. For now will not hit this very hard, due to the very dry and stable conditions over the area at this time and the fact that there has not been any strikes detected to our south. The models could be way out of whack with the advection of tropical moisture over the area and hence the convection. The highest chances for storms on Monday appear to be over NE Trinity County again per the SREF. Triple digit heat is expected to persist through mid week. The 850mb temperature anomaly will wane toward the latter portion of the week as an upstream trough gradually knocks down the hot Desert SW ridge. Temperatures in the interior will most likely remain slightly above normal (lower to mid 90s), however. The high PWAT anomaly over the area will also diminish by mid week, and the threat for thunderstorms will decrease as well. NBM continues to indicate non-zero probabilities around 5-10% over the mountain sites as a trough approaches the West coast late in the week and next weekend. There is still a great deal a variance amongst the ensemble members with how fast this trough will progress eastward and how much it will knock down the ridge. It is August, one of the hottest months of the year for Northwest California, and any rain from this trough does not appear very likely at this time. && .AVIATION...Through the early morning hours, the entire California coast was void of coastal stratus. Moreover, the nearest identifiable stratus feature could only be identified along the northern tip of coastal Washington. Some higher clouds will continue to stream in from the south. Today, southerly flow will begin to moisten up the column and return chances for low clouds overnight at the coastal terminals. Isolated thunderstorms will also be possible for inland areas this afternoon and evening. Winds will be surging southerly around the cape today, potentially advecting any existing stratus south of the cape up the coast in the evening hours. There is not a strong signal for a robust stratus surge early in the evening at this time. However, the potential for LIFR cigs will increase into early morning hours of Sunday for KACV and KCEC. Winds will be generally light through the period, while KUKI stays VFR. && .MARINE...Northerly winds and steep seas have continued to ease overnight. By midday, winds will have turned southerly in the waters. Winds be locally accelerated around Cape Mendocino, where gusts up to 20kts will be possible through the afternoon. A mid period swell will move into the waters on Sunday around 4 feet at 10 seconds. Winds will transition northerly overnight Sunday and through Monday, focused more in the southern waters where some steeper seas will eventually develop. && .FIRE WEATHER...Upper level moisture from the subtropics will spread over the area late tonight and Sunday, bringing a threat for dry thunderstorms and abundant lightning. Storms will be relatively fast moving with very little or no rain totals. Low humidities and dry fuels will favor new fire starts due to lightning. Hot dry weather is expected to continue through the middle of next week. Also, locally breezy south and southwest winds will also be possible Sunday afternoon across the region resulting in locally critical fire weather conditions. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Fire Weather Watch from this evening through Sunday evening for CAZ264-276-277. Heat Advisory until 7 PM PDT this evening for CAZ102-104>108. Fire Weather Watch from Sunday morning through Sunday evening for CAZ204-211-212-283. Excessive Heat Warning until 7 PM PDT this evening for CAZ110>115. NORTHWEST CALIFORNIA COASTAL WATERS...None. && $$ Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png

000 FXUS66 KMTR 151906 AFDMTR Area Forecast Discussion National Weather Service San Francisco Bay Area 1206 PM PDT Sat Aug 15 2020 .SYNOPSIS...Dangerously hot temperatures with Excessive Heat Warnings inland and Heat Advisories around the Bay with record or near record heat possible again today. Little relief along the coast as the marine layer will be very shallow with only light onshore breezes. Isolated dry lightning is also possible across the region late today into early Sunday. The ridge responsible for the hot weather will stay in place through next week. && .DISCUSSION...as of 12:06 PM PDT Saturday...Fire Wx Watches have been upgraded to Red Flag Warnings for dry lightning. Activity started firing around 7:30 am in San Luis Obispo. First batch of storms is now into southern Monterey county. Several new starts already reported in Santa Barbara and San Luis Obispo with new starts now being reported in southern Monterey county. More activity expected to reform later this afternoon and evening, first for Monterey/San Benito then eventually the Bay Area later this evening and overnight. Due to heat wave fuels are incredibly receptive and even wet storms appear to be starting new ignitions. Several historic fires have started through the years in similar patterns. Heat products remain on track with hot weather again today. Heat Warnings inland and Heat Advisories around the Bay. && .PREV DISCUSSION...as of 3:45 AM PDT Saturday...An oppressive, prolonged heatwave is now underway not only for our local area but across much of the western CONUS. Widespread record breaking temperatures were observed yesterday regionwide and afternoon temperatures easily exceeded triple digits readings across the interior with pockets of mid 90s to around 100 even near the coast. Forecast model data has struggled to keep up with this oppressive heat along the coastal interface and as a result the forecast will constantly be reevaluated and action taken as necessary. An afternoon sea breeze did eventually pick up along the immediate coast mid to late yesterday afternoon which helped to bring some limiting cooling, however, many areas away from the coast or at higher elevations are still struggling to cool overnight. This lack of overnight cooling relief can lead to accumulating heat stress and should be taken seriously during prolonged heat events such as this one. At the synoptic scale, there are two primary weather systems that will play a role in our weather through the weekend. The first and most prominent is the 597dm 500mb high pressure system centered roughly over Arizona which is slowly expanding into California from the southeast. Hot stagnant air trapped beneath this dome of high pressure first encroached on the region Thursday night which then set the stage for Fridays historic heat which broke temperature records across the region. This high pressure system will gradually strengthen to 600dm at 500mb as it retrogrades towards Vegas and further builds into the local area through next week, resulting in continued oppressive heat, especially across the interior through next week. To the west, a 579dm 500mb low pressure system is colliding with the northwestern perimeter of the oppressive high pressure ridge. This low pressure system will bring about a brief cooling trend between Friday and Saturday and again on Saturday on Sunday as it nudges the perimeter of the hot dry air under the ridge farther eastward, likely making Sunday the coolest day throughout the entirety of the prolonged heatwave. However, as this occurs, a surge of moisture at 700-500mb aloft will be advected in from the south in the southerly flow between these features later today, tonight, and into Sunday morning. Elevated convective parameters meet critical thresholds to spark the potential for fast moving, high based convection of which some isolated thunderstorms may develop and move across the area from south to north. Given the dry fuels and hot, drying air mass in place, any isolated lightning strikes could lead to new wildfire starts. In addition, due to both the high based and fast northward progression, little if any precipitation will accompany lightning strikes at the surface, suggesting that isolated dry lightning will be the main outcome of any elevated convection through the coming days. As a result, in coordination with the neighboring offices, a fire weather watch has been issued for the potential of isolated dry lightning Saturday PM to Sunday AM. Those paying close attention may notice that there are two fire weather watches for our area, which have been segmented by GACC coverage (regional fire offices) and likely timing of arrival of highest MUCAPE/Modified Total Totals/PWAT values. Lightning risk aside, heat risk will be the broader societal impact again on Saturday. The excessive heat watches across the interior (including the urban areas of the East and South Bay valleys) continue to remain in effect through the prolonged heatwave with expected peak temperature for today again in the low to mid 100s, locally in the upper 100s. In addition to the excessive heat warning across the interior, we plan to issue targeted daily heat advisories for the nearshore and coastal zones as needed. Friday showed how oppressive this heatwave can be and even the highest ensemble members of the hottest forecast models struggled to encapsulate the full extent of yesterdays record breaking heat along the coastal to inland interface. Given this experience and the warm overnight temperatures in place to start the day today, made several passes on the forecast temperatures and nudged nearly all of Saturday`s forecast temperatures higher in the coastally influenced sites that may have been too cool. Noticeably warmer temperatures are now in place for today along the San Francisco Bayshore and for the city itself, however, Saturday is not expected to be nearly as hot as Friday by a margin of a few to several degrees, though not many days are capable of such heat. As such, heat advisories are in place for today for all of the same locations they were in place by the last update around lunchtime yesterday. This includes, the North Bay valleys including Santa Rosa and Napa, the San Francisco Bayshore, including Oakland and Silicon Valley, San Francisco itself, the Santa Cruz mountains including Scotts Valley, the northern Monterey Bay including Santa Cruz and Watsonville, and the southern Monterey Bay including Big Sur. Some locations in today`s heat advisory may not fall within criteria of the heat advisory however other portions of a zone will, ie Big Sur Station will likely be much warmer than Pacific Grove. Likewise, the higher hills and east to southeastern portion of San Francisco are much warmer than the west side of town. Overall, these temperatures are 10 to 25 degrees above seasonal normals, depending on the location. The most important weather shift to watch for today will be subtle shifts in wind direction as afternoon sea breezes are expected to develop once again this afternoon. As with many previous heat events, coastally influenced communities may hit their maximum daytime temperature as early as 1130am before winds shift onshore and cooler air from the nearshore waters advects in and begins to counterbalance the warmer air inland. This occurred yesterday at Carmel, for example, which peaked in the mid 90s before noon when the wind shifted. For today, watching for wind shifts towards the west will be key in determining maximum temperatures for the day and is one key reason days like yesterday are difficult to nail both for the models and human forecasters, as even the slightest of onshore breezes result in significant temperature shifts over the course of an hour or two. Looking ahead, the upper low off the coast weakens and is ejected out of the area late Sunday into early Monday which allows the high pressure system to further strengthen and recenter itself north of Vegas over the Great Basin. Consequently, high pressure will be in total control of the weather pattern and hot stagnant air will result in increasing temperatures from Monday into mid week next week, likely the next peak in the prolonged heat wave. This forecast shift nudged up the forecast maximum temperatures somewhat for the Tuesday to Wednesday timeframe however expect further increases as we near this time frame. Medium to long term models suggest a potential for this high pressure to remain the primary weather driver across the western CONUS through next weekend. We will continue to closely monitor both the heat and fire weather risk over the coming week and add or update any watches, warnings, and advisories as the data requires it. Generally after a few days of extreme heat, we see hints of a southerly wind reversal and return of a shallow but vigorous marine layer first over the Central Coast and then into Bay Area, however, still nothing of that sort expected in the nearterm. && .AVIATION....as of 10:28 AM PDT Saturday...for 18Z TAFs. VFR conditions through the period with increasing mid to high level clouds as monsoonal moisture moves over the region. There is a slight chance of high based thunderstorms around 10,000 to 15,000 ft AGL beginning this afternoon through tomorrow afternoon from south to north as the moisture progresses northward. Satellite and lightning detection already show ample convective activity over southern California. Left VCTS out of the tafs for now, as coverage and activity is highly uncertain at this time. However, will be closely monitoring conditions and may be adding thunderstorms to the tafs as needed. Typical onshore afternoon breezes. Vicinity of KSFO...VFR with increasing mid to high level clouds. Light winds this morning turning onshore this afternoon 15 to 20 kt. Slight chance of thunderstorms around the area this evening and tomorrow morning. Confidence is low enough that VCTS has been left out of the tafs for now. May be added later if deemed necessary. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR with increasing mid to high level clouds. As mentioned above, there is a slight chance of high based thunderstorms beginning this afternoon through tomorrow morning. Confidence is low, and VCTS has been left out for now. Conditions will be monitored and tafs will be updated as needed. Light winds this morning turning onshore this afternoon. There is also a slight chance of some patchy low clouds over the Peninsula early tomorrow morning, but confidence is low. && .CLIMATE... Record High Temperatures with the upcoming heat event. August 15 August 16 ------------------------------------------------------ Santa Rosa103 in 2019 100 in 2019 Kentfield101 in 2019 101 in 2015 Napa102 in 1906 104 in 2015 Richmond 91 in 2019 94 in 2015 Livermore108 in 1967 105 in 1951 San Francisco 87 in 1950 90 in 2015 SFO 94 in 2019 90 in 2015 Redwood City100 in 2019 101 in 2015 Half Moon Bay 71 in 1984 72 in 2015 Oakland Dtown 93 in 2015 92 in 2015 San Jose 99 in 2019 97 in 2015 Gilroy104 in 2019 107 in 2019 Santa Cruz101 in 2015 94 in 1983 Salinas 93 in 2015 94 in 1933 Monterey 90 in 2015 83 in 2015 King City104 in 1950 103 in 2015 && .MARINE...as of 9:00 AM PDT Saturday...Light west to northwest winds will prevail across the coastal waters this morning. Locally breezy afternoon and evening winds are expected along coastal gaps, particularly near Santa Cruz and along the Big Sur Coast south of Point Sur. There will be a slight chance of scattered thunderstorms tonight and tomorrow over the waters, mainly for the southern waters. Winds will increase slightly early next week as high pressure builds off the coast. Mixed seas will continue with a short period northwest swell and a couple of longer period southerly swells. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...Excessive Heat Warning...CAZ507-510-511-513-516>518 Red Flag Warning...CAZ516>518-528-530 Heat Advisory...CAZ006-506-508-512-528>530 SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 PM && $$ PUBLIC FORECAST: RWW AVIATION: AS MARINE: AS Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea

877 FXUS66 KOTX 151739 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1039 AM PDT Sat Aug 15 2020 .SYNOPSIS...The Inland Northwest can expect to see a steady warming trend over the next few days due to a rapidly building ridge of high pressure. By Sunday the Inland Northwest is expected to have temperatures well into the 90s to around 105. The heat will likely persist into Monday and Tuesday before temperatures cool a bit toward the middle of next week. Although most locations will be dry there will be a small chance of thunderstorms between Sunday night and Tuesday night as weak disturbances track into the region from the south. && .DISCUSSION... Today through Monday night...Big changes are expected to begin in earnest today as a highly anomalous ridge steadily builds over the Inland NW. We are already seeing signs of it on the latest water vapor imagery with drier air building over the north Cascades and pushing toward SE BC. This trend will continue through the day with the main consequence being a substantial warming of the lower atmosphere. 850 mb temps are forecast to rise into the 22-23C range this afternoon...which is around 3-5C warmer than yesterday afternoon and equates to warming of anywhere from 7-12F. That places most valley temperatures squarely into the 90s. Another change will result from the mid-atmospheric winds backing to more of a southwesterly orientation which will slowly pull more moisture northward. Surface dewpoints will begin to climb as a result which keep overnight most of the low temperatures in the 50s to lower 60s vs the pockets of upper 30s and 40s weve seen for the past few mornings. ...VERY HOT TEMPERATURES EXPECTED FROM SUNDAY THROUGH TUESDAY... By Sunday and Sunday night we begin to see even more changes as the very strong ridge axis shifts to the ID/MT border with 500 mb heights reaching an impressive 594DM or greater over the SE corner of WA. Meanwhile a meandering low off the central CA coast will interact with a deepening trough over the Gulf of Alaska and move rapidly northward overnight. Before it arrives we expect to see even more warming at 850 mbs with temps climbing into the 27-28C range...or roughly 5C warmer than today. These values are on par with what the region saw on 7/31 and suggests a strong possibility of 100F or warmer conditions over a large portion of the Inland Northwest. Some record or near record heat is still expected with Lewiston, Pullman, and Spokane coming within a degree of current records. The current records for Spokane and Pullman are 100 and 99 respectively both set in 1967. The record for Lewiston is an impressively old one of 106 set in 1897. There is a little fly in the ointment revolving around the California low as it could bring some high clouds across the OR/WA border late in the day possibly reducing the insolation. Where the forecast becomes particularly interesting will be overnight Sunday. Model confidence is good the California low will ride northeast brushing the WA coast overnight and steadily weakening as it heads toward SW BC. Ascent from this feature will likely trigger some convection over central Oregon during the afternoon, and then push up the Cascades into the evening, but just how widespread and how far east it will occur is questionable. The SREF keeps the best chance of thunderstorms locked over the Cascades, but the Nested NAM places the convection farther east over the Columbia Basin at least through the evening. Model soundings show very high cloud bases with a a deep and dry sub- cloud layer so any convection which forms wont likely produce much rainfall. But a few dry lightning strikes are certainly possible resulting in a fire risk. The Nested NAM is also showing a broad area of strong outflow winds pushing across the Basin and southern Cascades, but it erroneously did this during our last event with a similar scenario. It will be nice to get some more resolution from the HREF before biting off on this notion. While our confidence in widespread lightning and strong wind gusts is low there is a greater possibility of widespread cloud cover and a very mild night across the region. By Monday morning...we could very well see low temperatures in the 60s to mid 70s which will provide little relief from the daytime heat. By Monday the ridge continues to migrate slowly eastward with some 600 dm heights noted along the UT/NV border. Meanwhile the aforementioned upper level disturbance weakens over southern BC with the main impact of pushing the best instability axis into the far SE corner of WA into NC ID. 850 mb temps might cool a degree or two while there will be a greater chance of cloud cover which could further temper the afternoon highs just a bit. Nonetheless we are still looking at highs in the mid 90s to lower 100s. The threat of thunderstorms will mainly be restricted to the instability axis but there will likely be little if any forcing to initiate anything other than convergent flow over the Blues or the Camas Prairie. The current batch of heat headlines look appropriate and will continue. fx Tuesday to Friday: The extreme hot weather will continue for one more day, before the ridge starts to break down. Tuesday the ridge axis linger over the northern Rockies, with the region in a southwesterly flow. This will help push temperatures again into the mid-90s to lower 100s. Additionally a modest PWAT fetch is directed over the SE CWA in that flow, with values around 0.85 to 1.10 inches (or 120-180% of normal). With the hot temperatures, decent CAPE and mid-level front pushing in later in the day, this will carry some threat of thunderstorms over the SE CWA. The threat starts around the Blues and Camas Prairie in the later afternoon and expands northeast onto the Palouse. Spokane/CdA area and central Panhandle in the evening. Away from the lower Panhandle, models are not generating significant amounts of precipitation, meaning a threat of dry thunderstorms. This would bring a threat of fire starts from lightning, though confidence in coverage is limited and it may only be isolated. However this will monitored. The other feature of the incoming front will be the increased winds. The increased onshore flow on the backside of the ridge and cross-Cascade gradient will lead to the breeziest conditions near the just east of the Cascades. The current forecast indicated sustained speeds of 10-15 mph with gusts of 20-25 mph. Other breezy winds are possible further east, with gusts around 15-20 mph. Then from Wednesday to Friday additional shortwave disturbances press inland. Timing and intensity of these have some model disagreement, but overall they continue to break down the ridge. Limited shower chances will linger around the mountains Wednesday, the retreat to primarily the Cascades Thursday and Friday. Breezy conditions continue Wednesday from the Cascades across the Columbia Basin toward the ID border. At this time models suggest sustained winds around 10-20 mph, highest with gusts around 20-30 mph will be possible, highest near the Cascades gaps. Temperatures start to cool, relatively speaking, toward the upper 80s and lower 90s. This is still above normal. /Cote` && .AVIATION... 18Z TAFS: No aviation concerns due to a very strong ridge of high pressure. Expect clear skies and VFR conditions to prevail. Winds will generally be light and variable. VMT && .PRELIMINARY POINT TEMPS/POPS... Spokane 91 60 100 67 98 65 / 0 0 0 10 10 10 Coeur d`Alene 88 57 97 66 96 65 / 0 0 0 10 0 10 Pullman 89 54 98 64 94 64 / 0 0 0 20 10 10 Lewiston 97 64 105 73 101 72 / 0 0 0 20 10 10 Colville 92 54 100 60 98 56 / 0 0 0 10 10 10 Sandpoint 86 50 94 62 93 61 / 0 0 0 10 10 10 Kellogg 86 52 95 68 93 68 / 0 0 0 10 10 10 Moses Lake 94 55 102 70 100 66 / 0 0 0 20 10 10 Wenatchee 95 63 101 75 99 71 / 0 0 0 20 10 10 Omak 94 63 102 70 100 65 / 0 0 0 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Heat Advisory from noon Sunday to 8 PM PDT Tuesday for Central Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse- Northern Panhandle. Excessive Heat Warning from noon Sunday to 8 PM PDT Tuesday for Lewis and Southern Nez Perce Counties-Lewiston Area. WA...Heat Advisory from noon Sunday to 8 PM PDT Tuesday for East Slopes Northern Cascades-Northeast Blue Mountains-Northeast Mountains-Okanogan Highlands. Excessive Heat Warning from noon Sunday to 8 PM PDT Tuesday for Lower Garfield and Asotin Counties-Moses Lake Area-Okanogan Valley-Spokane Area-Upper Columbia Basin-Washington Palouse- Waterville Plateau-Wenatchee Area. && $$

000 FXUS66 KPDT 151741 AAB AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1040 AM PDT Sat Aug 15 2020 .UPDATE... The main update this morning centered on the issuance of a fire weather watch for lightning late Sunday-early Sunday night for fire weather zones 610, 611, 640, 642, and 644 covering eastern slopes of the Central OR Cascades out into Central OR, the central Blues, and Strawberry mountains. Latest hi-res guidance and HREF are coming in line with current thinking. Specifically storms developing and evolving north and east in time late Sunday starting in south central/central OR. A decent southerly push of lower tropospheric moisture is expected Sunday coinciding with an advancing weak disturbance aloft and a modest belt of mid-level winds. The large scale forcing for ascent should help aid the development of isolated-widely scattered storms during this Sunday time frame. Some concern given its somewhat of a weakly forced event w.r.t. CI and the forecast instability but thinking orographic lift/boundaries and moisture will be sufficient. While storms are expected to be primarily dry in nature given their storm motion and theorem profiles however, some light wetting rain cannot be ruled out given precipitable waters forecast to be 0.75-1.0" (exceeding 150% of normal). Highest confidence in storms materializing across central OR to the Central OR Cascades, again isolated to widely scattered coverage. Hot and dry conditions are expected Sunday too and these conditions will prevail again then Monday that could promote additional concerns with any new fire starts or holdovers. && AVIATION...00Z Tafs. VFR conditions through the period. A mainly dry cold front will be crossing the area tonight with clouds few-sct 080- 100kft. Main impact for aviation will be strong winds 15-20kt by 21z and 20-30kt from 00-06z. Winds will decrease to 10-20kts after 06z and continue through the day on Sunday with high level cirrus clouds. 93 && FIRE WEATHER...A fire weather watch was issued for the eastern slopes of the central OR into Central OR to the central Blue mountains and Strawberry mountains (fire weather zones 610, 611, 640, 642, and 644) late Sunday-early Sunday night for abundant lightning. Increased confidence in storms developing in central OR cascades/south central OR Sunday afternoon moving northeastward in time. LALs 3 anticipated with any storms and LAL 4 possible in a storm or two. Meantime, any storms that develop should be characterized as somewhat dry, though light wetting rain cannot be completely ruled out given moisture profiles. Highest confidence in storms occurring and greatest coverage (widely scattered) is across central OR and near/along the Central OR Cascades. Otherwise, dry and dangerously hot conditions start Sunday and continue into Tuesday, though will be starting to lessen in central OR then. This could heightened concerns for any new fires or holdovers. Winds appear as a limiting factor Sunday and Monday with modest southwest/south breezes Sunday becoming more westerly on Monday. && .PREV DISCUSSION... /issued 232 AM PDT Sat Aug 15 2020/ SHORT TERM...Today through Monday night. Upper ridge building into the Pacific northwest this weekend with a significant warming trend. High temperatures will be 90-105 the next few days. For today satellite showing clear skies so another sunny day with light winds. Scattered cumulus developing late afternoon over central Oregon. By Sunday deep southwesterly flow will be established over the region. Instability and moisture increasing. A short wave and jet moving through late in the day will result in scattered thunderstorms. Expect storms to develop in the afternoon over central Oregon and spread north through the evening and overnight. Little change to the pattern for Monday. Appears another short wave will move through with additional storms late. LONG TERM...Tuesday through Saturday...Ridge axis that had brought triple digit heat across much of the region begins to shift eastward and flatten a bit on Tuesday. Region will still be under warm southwest flow aloft and it will still be fairly hot across the region, but a few degrees cooler than Monday. Could be lingering activity in the morning from Monday`s convection, but this should dissipate quickly. The convective debris could help keeps temps a few degrees cooler if it lingers into the afternoon. Models are hinting at more mid-level moisture and weak wave riding north along the western periphery of the ridge into eastern OR/WA. This will likely lead to more high based showers/storms, mainly over the eastern higher terrain as the western CWA will see a bit of push of drier/stabler air. Winds will begin to increase through the Cascade gaps into western Basin as the temp/pressure gradient tightens. This could lead to elevated fire concerns with low RH values expected, esp with the Mosier fire near Dalles. Ridge continues to weaken its grip over the region Wednesday into Thursday as the offshore trough/low creep towards the coast. Surface front expected to push across Wed. This could help fire off more showers/storms over Wallowa county. It will also bring a cooler temps with a nice onshore push (highs in the mid 80s to mid 90s). RH levels will still be low which could lead to fire weather concerns as winds will become breezy behind the front. Thursday should still be cooler but with lighter winds (highs mid 80s to lower 90s). Models differ beyond Thursday, but general trend is for CWA to be under dry southwest flow in between ridging to our east and troughing offshore. Expect continued temps in the mid 80s to mid 90s, possibly cooler Saturday as some guidance suggests another dry frontal passage. Also expect typical afternoon breezy conditions through the Cascade gaps into the Basin. && .PRELIMINARY POINT TEMPS/POPS... PDT 96 60 101 68 / 0 0 10 20 ALW 97 63 102 72 / 0 0 10 20 PSC 99 57 102 70 / 0 0 10 20 YKM 99 60 101 67 / 0 0 10 20 HRI 98 59 103 69 / 0 0 10 20 ELN 97 58 100 66 / 0 0 10 20 RDM 98 54 99 59 / 0 10 20 30 LGD 93 55 98 62 / 0 0 10 30 GCD 96 60 98 63 / 0 0 20 30 DLS 100 64 102 69 / 0 0 10 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning from 11 AM Sunday to 9 PM PDT Tuesday for ORZ041-044-505-507-508. Heat Advisory from 11 AM Sunday to 9 PM PDT Tuesday for ORZ049- 050-502-503-510-511. Fire Weather Watch from Sunday afternoon through Sunday evening for ORZ610-611-640-642-644. WA...Excessive Heat Warning from 11 AM Sunday to 9 PM PDT Tuesday for WAZ024-026>029-521. Heat Advisory from 11 AM Sunday to 9 PM PDT Tuesday for WAZ030- 520. && $$ SHORT TERM...94 LONG TERM....84 AVIATION...93 FIRE WEATHER...80 UPDATE...80

616 FXUS65 KREV 150939 AFDREV Area Forecast Discussion National Weather Service Reno NV 239 AM PDT Sat Aug 15 2020 .SYNOPSIS... Showers and thunderstorms can be expected each afternoon through the middle of next week. Hot temperatures are forecast for the weekend and next week. Heat impacts are likely for sensitive groups and those with limited cooling options for their homes. && .SHORT TERM... Lots to chat about early this morning with heat and thunderstorms the two big concerns this weekend. Showers and thunderstorm might be a bigger issue each day as instability builds through the weekend. There is a decent moisture feed from the south as the Sierra and western NV are stuck between the ridge over central/eastern NV and a trough off the California coast. In this pattern, thunderstorms should initially develop over the Sierra then push off into western NV with the light zephyr breezes each afternoon. Waves of energy may quickly pass with each moisture surge leaving the door open to the potential for strong thunderstorms and even some late night/early morning activity starting Sunday night. Bottom line here is to be prepared to change your outdoor plans. Strong storms will be able to produce winds gusts over 50 mph, hail and periods of heavy rain. Flash flooding and debris flow threat appears to be rather low due to a 10-15 mph storm motion, though any slower moving storms could easily drop a burst of heavy rain. Heat could also lead to some health impacts for sensitive groups and those with limited cooling options. If you have outdoor plans also be prepared for the heat, definitely carry extra water, if you are going to be outside for several hours. Afternoon highs will approach 100 degrees for the NV valleys, though cloud cover may keep temperatures below 100. Highs in the Sierra up near 90 are not of the question as well. Overnight lows in population centers may not dip much below 70, leaving little time to cool homes at night. Did go with a dense smoke advisory for this morning for the actively burning Loyalton Fire. Expect smoke to settle into the Sierra Valley around Chilcoot, Loyalton, Vinton this morning. Some smoke may drift into the Reno-North Valleys and perhaps as far west as Portola and Graeagle. Waiting on the early morning VIIRS pass to initialize the fire for the smoke dispersion models. Expect a bit more detailed smoke forecast later today. Brong .LONG TERM...Tuesday onward... No major changes were made to this forecast cycle. Our focus remains on how long the heat will stick around our area as an anomalously strong ridge looks to remain over the Intermountain West through most of next week. * Heat: The major headline for the long term is how long the heat will endure for our region. Deterministic and ensemble model guidance is in consensus that Tuesday will be the hottest day across the Sierra and western Nevada as the 597 decameter contour arrives overhead at the 500 hPa level. Afternoon highs Tuesday through next Saturday will be in the upper 90s to low 100s for western Nevada valleys and upper 80s to around 90 in Sierra valleys. Radiational cooling will be limited Tuesday and Wednesday morning with the presence of subtropical moisture over our region. This prolonged period of well above normal daytime highs and overnight lows will create heat-health impacts for vulnerable populations and those outdoors for prolonged periods. Make sure to limit your outdoor exposure and understand the symptoms of heat- related illness. The good news is that a strong Gulf of Alaska trough looks to near the Pacific Northwest and Canadian Pacific coast next weekend, which may allow temperatures to cool back in the direction of normal. * Thunderstorms: Another persistent leitmotif in the forecast is the continued potential for thunderstorms each afternoon and evening through next Thursday mainly along the Sierra and Sierra Front. Minor changes in thunderstorm coverage could occur on one or more of these days as mesoscale vorticity maxima pivot around the periphery of the ridge allowing for cooling aloft and improved chances for convective initiation. Subtropical moisture will continue to stream into the region around the perimeter of the Intermountain West ridge through at least Thursday. Storms look to be of the hybrid variety with the increased PWAT; however, as we saw yesterday, lightning strikes outside of cores could start new fires, especially given the receptive nature of the very dry fuels. Report any new fires and smoke to local emergency personnel. As the center of the 500-hPa ridge begins to move south and east late next week, the associated influx of subtropical moisture will also move with it, causing thunderstorm chances to shift south and east by next weekend. Afternoon cumulus castellanus will still be possible over the High Sierra and White Mountains of southern Mono County Friday. * Winds: Expect typical zephyr breezes through next week with gusts to around 20-25 mph each afternoon. We will likely see intensified afternoon winds and heightened fire weather concerns depending on when the Gulf of Alaska trough moves into the Pacific Northwest region, which at this time looks to be next weekend. -Johnston && .AVIATION... Showers and thunderstorms to develop daily this weekend between 20z-04z. For Today thunderstorms should be limited to areas from roughly KRNO-KTRK southward to Mono/Lyon/Mineral Counties. Outflows 35-45 kts, small hail, and brief heavy rain are possible with the stronger storms. Thunderstorm chances for terminals today and tomorrow... KRNO: 25% - 30% KCXP: 25% - 35% KMEV: 30% - 35% KTRK: 20% - 30% KTVL: 25% - 30% KMMH: 30% - 35% Smoke and haze from the Loyalton Fire may limit visibility around the Sierra Valley, and Stead Airport today depending on fire activity. Brong && .FIRE WEATHER... The combination of heat and thunderstorms are the main concern this weekend. We`re stuck between a low off the California coast and High Pressure over eastern Nevada. This will allow moisture to continue to move into the region with a daily trend of showers and thunderstorms building over the Sierra by mid afternoon, then pushing into western NV as the light zephyr breezes kick in. Storm motion will be about 10-15 mph which will limit rainfall. Gusty outflows of 40 mph or more area also possible this weekend. One note for the Loyalton fire today, the heat, moisture, and instability are a very favorable set-up for pyrocumulus and perhaps pyrocumulonimbus development in the presence of active fire behavior. Simulations are starting to show some potential for overnight showers and thunderstorms this weekend as well. Overnight instability appears minimal tonight, so perhaps just some virga or very light showers. Sunday and Monday nights appear more favorable. Brong && .REV Watches/Warnings/Advisories... NV...None. CA...Dense Smoke Advisory until noon PDT today CAZ071. && $$ For more information from the National Weather Service visit... http://weather.gov/reno

936 FXUS66 KSTO 151030 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 330 AM PDT Sat Aug 15 2020 .SYNOPSIS... Prolonged heatwave will impact the region through the middle of next week. Daytime temperatures will be 10 to 20 degrees above normal with limited overnight relief. Slight chance of afternoon showers/thunderstorms over the mountains this weekend into Monday. && .DISCUSSION... Water vapor imagery this morning shows fairly dry conditions of northern CA as we remain trapped between high pressure over the desert southwest and a closed low over the Pacific. Guidance continues the same trend noted by the evening shift, where heights/thicknesses for tomorrow have increased by 1 to 2 degrees C at the 850mb level. Opted to start with yesterday`s temperatures and then nudged them up by a few degrees. Most climate sites have the chance to either tie or break records if the forecast pans out. Highs for the Valley are forecast to range from 105 to 112 degrees while the foothills range from 95 to 105. Not much more relief will be found in the higher elevations either as temps range from 85 to 95 degrees. In addition to the heat tomorrow, models continue to show elevated instability which could lead to a slight chance of afternoon showers or thunderstorms over the higher elevations of the Coastal Range and Sierra Nevada. Saturday night and into Sunday, the offshore closed low will move a touch closer to the north coast. Models are hinting at height falls and short wave trough sliding coast. Temperatures will likely reflect Friday`s forecast, but there`s some concern about potential cloud cover. Guidance from the CAMs suggest the chance for showers and thunderstorms; spreading from south to north Sunday morning and into the afternoon. PWATs are around an 1 inch, but the moisture is found in the upper levels. Should convection occur, isolated dry thunderstorms are not out the question for portions of interior NorCal. As a result, have issued a Fire Weather Watch for this threat as fires could rapidly grow given the heat, primed fuels, and unstable nature of the atmosphere. Beyond Sunday, there is a slight chance for thunderstorms over the Sierra and southern Cascades. If storms form they should stay confined to the terrain. Heights are forecast to rise Monday and Tuesday as high pressure builds over the Great Basin area. High temperatures will generally be in the 105 to 110 degree range for the Valley. Unfortunately, we won`t see much in terms of overnight relief as highs will span the 70s and 80s until midweek. As a reminder this is a significant and dangerous heat event. Heat related illness to humans and animals is likely with extended outdoor exposure. Heat is the number one weather-related killer in the U.S. Take necessary precautions to stay hydrated, cool, and safe during this prolonged heatwave. && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday)... Ensembles in general agreement weakening the center of strong high pressure, and shifting it eastward from southern Nevada back toward the Four Corners region later next week as a trough approaches the PacNW. The result is expected to be a gradual easing of temperatures across interior NorCal, back to only around 5 degrees above average by next weekend. Deeper moisture and instability is forecast to be east of the region. && .AVIATION... VFR conditions next 24 hrs. Isolated afternoon thunderstorms possible over higher elevations of the Coast Range and northern Sierra Nevada 21Z-03Z. Isolated high-based thunderstorms possible after 06Z Sunday. Surface wind generally below 10 kts. && .STO WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Sunday morning through Sunday evening for Burney Basin and Northeast Plateau in Shasta County Including Northwest Lassen NF north of Lassen NP-Carquinez Strait and Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below 1000 Ft-Eastern Mendocino NF-Eastern Portion of Shasta/Trinity NF-Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft- Northern San Joaquin Valley in San Joaquin and Stanislaus Counties Below 1000 ft-Northern Sierra Foothills from 1000 to 3000 Ft. Includes portions of Shasta-Trinity and Butte Units- Northern Sierra Including Lassen NP and Plumas and Lassen NF/S West of the Sierra Crest (West of Evans Peak-Grizzly Peak- Beckworth Peak)-Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-Glenn Unit-Southern Sacramento Valley in Yolo- Sacramento Far Western Placer, southern Sutter and Solano County Below 1000 Ft. Excessive Heat Warning until 9 PM PDT Wednesday for Carquinez Strait and Delta-Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Southern Sacramento Valley. && $$

000 FXUS65 KMSO 150913 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 313 AM MDT Sat Aug 15 2020 .DISCUSSION...Today begins a prolonged period of rising temperatures across north central Idaho and western Montana. With a large area of high pressure developing, temperatures are expected to rise by an average of 3 to 6 degrees each day, culminating in the low 100s and upper 90s Monday and Tuesday. Heat Advisories remain in effect for portions of central Idaho and western Montana as a result, though more areas may be added in time. One thing to note will be the chance for afternoon and evening thunderstorms to develop Tuesday and Wednesday. There is some discrepancy between models as to whether these storms will bring any rain with them, but moisture looks more promising Wednesday afternoon/evening. Storm development, strength, and whether or not they will be "wet" storms will definitely be something we`ll be watching in the coming days, particularly with wildfire activity in mind. Beyond Wednesday, high pressure rebounds across the western U.S. and the heat continues for us here in the Northern Rockies. If the current forecast holds, dry conditions are likely with little to no precipitation through at least August 23. && .AVIATION...High pressure will lead to stable conditions, clear skies, and warming temperatures the next 24 to 48 hours. An afternoon diurnal breeze is likely at KMSO and KBTM...otherwise, little else is expected at area terminals during this time. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Heat Advisory from 1 PM Sunday to 9 PM MDT Tuesday Flathead/Mission Valleys...Kootenai/Cabinet Region...Lower Clark Fork Region...Missoula/Bitterroot Valleys. ID...Heat Advisory from noon Sunday to 8 PM PDT Tuesday Lower Hells Canyon/Salmon River Region...Northern Clearwater Mountains...Orofino/Grangeville Region...Southern Clearwater Mountains. && $$

000 FXUS65 KBOI 151605 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1005 AM MDT Sat Aug 15 2020 .DISCUSSION...Ridge will continue to build over the region today with warmer temperatures expected. Monsoonal moisture will move north across NV today with increasing clouds and a slight chance of thunderstorms over southwest Harney County. The ridge will continue to strengthen on Sunday with record high temperatures possible. Monsoonal moisture will continue to increase on Sunday with thunderstorms possible over eastern Oregon. Thunderstorms on Sunday afternoon and evening will be capable of producing gusty outflow winds up to 60mph. No updates. && .AVIATION...VFR. Mostly clear skies with patchy smoke/haze. Slight chance of an evening thunderstorm south of KBNO. Surface winds: generally 10 kt or less. Winds aloft at 10kft MSL: W-NW 10-20 kt. Sunday Outlook...VFR. Light surface winds. Slight chance of thunderstorms in southeast Oregon Sunday afternoon, with gusty outflow winds possible. Hot temperatures Sunday into early next week will increase density altitude. && .PREV DISCUSSION... SHORT TERM...Today through Monday night...High pressure continues to build over the region today, with warmer temperatures expected. As the ridge amplifies on Sunday, temperatures across the region will become hot, with the Excessive Heat Watch still in place. Between Sunday and Monday, numerous locations could see record breaking high temperatures, and vulnerable audiences could be impacted by heat. Additional updates expected as timing and intensity continue to be refined. In addition to heat related impacts, the ridge will allow southwest flow over the area which will bring monsoonal moisture beginning this evening. This moisture is expected to aid in the production of showers and thunderstorms. Expect returning shower and thunderstorm activity for both Sunday and Monday afternoons, with gusty storm related wind possible. LONG TERM...Tuesday through Saturday...A persistent upper level ridge over the western U.S. will continue the exceptionally hot temperature streak into at least Tuesday. The near-record day temperatures combined with warm overnight temperatures will add heat stress to people and animals. The ridge will also support the arrival of monsoonal moisture into the area, which will initiate isolated showers and thunderstorms both Tuesday and Wednesday afternoon. Thereafter, expect hot and dry conditions to persist through the extended. Those with outdoor activities planned should take heat safety precautions. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Excessive Heat Watch from Sunday afternoon through Tuesday evening IDZ011>016-028>030-033. OR...Excessive Heat Watch from Sunday afternoon through Tuesday evening ORZ061>064. && $$ www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...KA AVIATION.....BW PREV SHORT TERM...KB PREV LONG TERM....SH

547 FXUS65 KLKN 150944 AFDLKN Area Forecast Discussion National Weather Service Elko NV 244 AM PDT Sat Aug 15 2020 .SYNOPSIS...Hot temperatures are expected this weekend and through next week, with some record high temperatures likely at times. Isolated mainly dry thunderstorms are possible in western counties this weekend, spreading eastward during the week. && .SHORT TERM...Today through Sunday afternoon The ridge building into the West amplifies considerably today and this will be the beginning of a heat event of long duration. The Excessive Heat Watch has been upgraded to a Heat Advisory for all counties for the Sunday through Tuesday period. Please see the Climate Section below for details. Highs are expected to soar to around 100 today and 103 to 104 degrees on Sunday in the warmest valleys. Winds will be lighter under the ridge. Lows will mainly be in the 60`s, with some mid to upper 50`s in southeast counties. The position of the ridge lends to tropical moisture being drawn up to the west of the CWA this weekend, with most thunderstorm activity over the Sierra. However, a bit of moisture may makes its way into our western counties and there could be some build ups with Virga or maybe even a few dry thunderstorms there on both Saturday and Sunday. There will be some scattered clouds in eastern Nevada today and then on Sunday, mid level moisture increases eastward and there will be more extensive cloud cover, though the area will be void of instability. .LONG TERM...Sunday night through Friday night. The anomalous strong high pressure system that intensified across the Great Basin and desert southwest will ensure that hot and dry conditions remain lock-in across the region through mid- week. The continuing heat risk conditions will undoubtedly be the topic of conversation going into next week as the upper high pumps heat into NV. Heat risk model guidance still highlights Monday and Tuesday as the hottest days during this abnormally hot period with expected highs in the upper 90s to low 100s. Some areas could see daytime highs reaching 15-18 degrees above normal when the average afternoon high for this time of year ranges from the mid 80s to low 90s. By mid-week temperatures will be on the down swing but still well above normal. The influx of upper moisture and intense surface heating will mix to enhance the risk for dry thunderstorms over central NV. Precipitable water values above 0.5 inch will cover much of the CWA through next week as modest mid-level moisture wraps around the high centered over western UT. A near continuous southerly tap of monsoonal-like tropical moisture will moisten the upper environment across central and northern NV and maintain the risk of late morning and afternoon isolated dry thunderstorms through at least mid-week. Little measurable precipitation is expected from the storms that do develop but strong storm outflows are possible and extended model guidance seems to hint at this. But this also carries the chance of a stray cloud to ground lightning strike over those region with active convection. Therefore, an enhanced fire weather condition will accompany the previous risk. But the general coverage of moisture over the eastern half of NV still brings some uncertainty into the mix as to the timing and coverage for any storms developing across the region. As the highs center gradually shifts southeastward into northern AZ, the predominate southwest upper flow will usher in more stable conditions across the region. A slight decrease in regional temperatures will follow shortly by the end of next week. && .AVIATION...VFR conditions are expected at KWMC KBAM KEKO KELY and KTPH through Sunday morning. && .FIRE WEATHER...Hot and dry conditions will prevail in all fire zones through at least next week with strong high pressure in place in the West. The temperatures will be well above normal and may approach or exceed record levels at times. Tropical moisture rounding the high should permeate into NV, which could lead to an isolated dry thunderstorm today in fire zones 426, 427, and western portions of 437, though will likely be just build ups with Virga. Isolated thunderstorms should expand in coverage a bit each day Sunday through at least Wednesday in northern and central Nevada, but is looking at this time to remain isolated in nature. && .CLIMATE... Much above normal temperatures are expected today through next week across all of Nevada. Hot daytime temperatures coupled with some relatively mild overnight lows are expected and a Heat Advisory is in effect for all counties due to the high risk of health related issues for those who are sensitive to heat and/or without effective indoor cooling. Keeping hydrated is highly recommended. Please prepare for this as it is a longer then normal duration heat event and some record temperatures from 101 to 104 degrees could be reached at times. && .LKN WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM Sunday to 11 PM PDT Tuesday for Humboldt County-Northeastern Nye County-Northern Elko County- Northern Lander County and Northern Eureka County-Northwestern Nye County-South Central Elko County-Southeastern Elko County- Southern Lander County and Southern Eureka County-Southwest Elko County-White Pine County. && $$ 90/97/92/90