ZSE Aviation Forecast Discussions

000 FXUS66 KSEW 191619 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 920 AM PDT Tue Jun 19 2018 .SYNOPSIS...An upper ridge will move inland today and east of the Cascades tonight and Wednesday. Western Washington will be sunny with near record highs, but there`s a chance of thunderstorms over the Cascades. Onshore flow will bring cooler marine air inland Thursday and Friday. High pressure aloft will cross the region Saturday, followed by an upper trough early next week. && .SHORT TERM...Low temperatures this morning over W WA pretty much ranged throughout the 50s with locations along the Canadian border only cooling to around 60. Looking at current observations at the time of this writing...temps over much of the area appear to be hovering right around that 60 mark...whether it is the upper 50s along the coast to right at 60 in the SW interior and south Sound region to low 60s in the Seattle Metro. Switching over to satellite for a moment...we can see marine stratus set up over much of the Olympic peninsula...coinciding with the cooler temperatures. While current trends show no hints at their receding just yet...should see these clouds withdraw to the coastal waters by late this morning or noon today. Getting north of Everett...temps are already in the lower to mid 60s with obs around Bellingham and north reaching near 70. That all being said...current obs are about in line with what was observed 24 hours ago for the most part and as such...certainly a good indicator that W WA is on its way to another warm day. Current models appear to support that as upper level ridging makes its way inland today...with the resultant sunny skies and continued warm temps. However...high level moisture wrapping around the north side of the upper low exiting Idaho and entering into Montana, along with weak upper instability, could produce afternoon and evening showers over the mountains and possibly thunderstorms near the Cascade crest. The ridge axis exits the area during the overnight hours allowing for a shortwave feature to set up over the Cascades and help enhance the chances for showers/thunderstorms there Wed afternoon. For the remainder of W WA however...this may result in an upward nudge in RH values...adding a little mugginess to the continued heat expected Wed. This leads to the main forecast problem...as the continued heat with this little influx of moisture manages to pose some possible heat related health impacts and with that being the case...a heat advisory might be warranted...mainly for the Seattle Metro and the SW interior. Will take a look at 12Z model data as it comes in and will have a better feel for the situation in time for afternoon discussion. The good news is that more moderate conditions are on the way as stronger onshore flow will develop Wednesday evening, as the leading edge of an offshore upper trough moves into the Pac NW. A cool, moist marine layer should push inland Wed night and W WA will probably be more or less covered by marine stratus Thursday morning, which should give way to sun breaks in the afternoon. Highs across the interior lowlands should be back into the upper 60s and 70s, with mid 60s at the coast. SMR/McDonnal .LONG TERM...From Previous Discussion...Low level onshore flow will continue Friday as an upper shortwave moves across the area, which should produce a few showers and maybe a Puget Sound convergence zone. Then an upper ridge will build as it moves inland Saturday and east of the Cascades Sunday, for more sunshine and somewhat warmer weather. There is less agreement in the models for Monday, but most likely an upper trough will begin to pass by to our north. McDonnal && .AVIATION...Wrn WA will be sandwiched btwn upper level ridges centered over British Columbia and off the nrn Baja CA coast, and upper level lows centered offshore and over MT. The flow aloft will be light and variable. Weak low level sly flow flow will become light onshore or wly this afternoon. Meanwhile, areas of mainly MVFR CIGs blanketed much of the lowlands from the Olympic peninsula wwd at this time. Expect the low clouds to scatter out or retreat to the coastline by 2100 UTC. KSEA...VFR. Light southerly winds will become light westerly this afternoon. Winds tonight will be light and variable, becoming light southerly or southwest Wednesday morning. && .MARINE... Light southerly flow this morning will become weak onshore or westerly this afternoon. Expect onshore flow of varying strength tonight through the end of the week. Gale force winds are possible again over parts of the Strait of Juan de Fuca Wednesday and Thursday nights. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Gale Watch from Wednesday evening through late Wednesday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory from 5 PM this afternoon to 1 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca. && $$ www.weather.gov/seattle

000 FXUS66 KPQR 191637 AAA AFDPQR Area Forecast Discussion...UPDATE National Weather Service Portland OR 836 AM PDT Tue Jun 19 2018 Updated Aviation section .SYNOPSIS...A few warm days on tap for the region today and Wednesday. An upper level disturbance will approach from the southwest Wednesday, with increasing threat of showers and thunderstorms Wednesday afternoon and evening. Then increased onshore flow with more in way of marine stratus and cooler temperatures. Back to warmer conditions over the weekend. && .SHORT TERM...Today through Thursday...Low clouds along the coast will gradually break up and retreat farther offshore today. Still variable high clouds this morning over the interior, thanks to the circulation around the low over Idaho. But, will be warmer today. The 850mb temps and 1000/500mb thickness values rising, with support of afternoon highs well into the mid and upper 80s inland, with a few spots closer to 90. This warmer temperatures will contribute to some midlevel instability over the Cascades. So, will maintain a slight chance of afternoon/evening thunderstorms over the south Washington Cascades, and north Oregon Cascades as well. Flow aloft such that these will not move much away from the Cascades crest. Another warm day on tap for the region on Wed, with temperatures reaching into the lower to middle 90s inland. Models continue to show southwest flow aloft over region Wed, with another upper level disturbance in the flow lifting up and across the region later in the afternoon and evening. This should destabilize the air mass enough for afternoon showers to pop up, mainly over Willamette Valley and eastward. Will also keep chance of thunderstorms over the Cascades and foothills, with highest chance being over the Oregon Cascades, where will go with isolated thunderstorms. As disturbance passes in the evening, will see increasing onshore flow. Will boost marine stratus along the coast Wed night, spreading inland later Wed night and Thu am. As layer deepens, will see spotty drizzle along the coast and into the coastal mtns at that time. Generally, much cooler on Thu, with inland highs down about 15 to 20 deg over what will see on Wed. Clouds will break up, but still would expect partly cloudy skies at best inland. Rockey. && .LONG TERM...Thursday night through Monday. The models are slowly starting to deliver the same message for the end of the week, both are showing an underdeveloped ridge entering into the area Thu night, followed by a shortwave trough through Fri. The passing of the shortwave looks to increase precip chances from Fri afternoon through early Sat morning. Sat there is a slight difference showing between the 12z GFS and the 12z Euro. They are in agreement of a ridge developing from Sat afternoon and that looks to dominate for the remainder of the weekend. However, the GFS has a more amplified ridge compared to the Euro, developing through Sun night. The GFS and Euro agree that a new trough will become the controlling feature for the start of the week. This will result in near seasonal temperatures thanks to onshore flow. This also means more cloud cover than sun. /42 && .AVIATION...VFR conditions prevail across the interior today under mostly clear skies. Expect passing high clouds across the region at times, but no impact to operations. Some cumulus build-ups over the Cascades likely this afternoon and still cannot rule out a few thunderstorms. However, if any do develop, they should not drift west into the lowlands. Marine stratus remains along the coast this morning, but will slowly improve through the day. Local statistical tool suggests breakout at KONP around 18z per latest PIREP, and this looks about right given latest satellite trends. However, expect a return to IFR stratus along the coast by 03z. Confidence is lower in any lower cigs developing inland tonight, but chances look highest south of KSLE and possible in the northern Willamette Valley if residual clouds build back west from the Cascades/foothills. KPDX AND APPROACHES...VFR continues through the next 24 hours under mostly clear skies today. Light wind this morning, becoming northwesterly and increasing a bit this afternoon (6-8 kts) as onshore gradient increases. Cullen && .MARINE...Weak low pressure will remain over the coastal waters through tonight. This will result in weak pressure gradients and fairly light winds. High pressure will then restrengthen on Wed, with thermal low pressure building into northern California. This pattern will likely continue through the upcoming weekend. Winds look to remain less than 20 kt through Fri, but may become a bit gustier over the weekend. Seas will continue to gradually subside to around 5 ft today. Expect seas to remain below 5 ft through the week. Seas over the southern waters will build to around 7 to 8 ft this weekend and may become choppy at times as the northerly winds increase. /64 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the CWA or forecast area.

728 FXUS66 KMFR 192134 AFDMFR Area Forecast Discussion National Weather Service Medford OR 234 PM PDT Tue Jun 19 2018 .DISCUSSION...Dry weather is expected through tonight. The latest satellite image shows a upper trough located near 32 north and 132 west. While this looks innocent at the moment, it`s this feature that will bring the threat for strong and possibly severe thunderstorms Wednesday afternoon and evening. Were already starting to see the effects from the shortwave with building cumulus over the mountains. Meanwhile, marine stratus is eroding along the coast, but this may be short lived and is expected to return again this evening. Everything is still coming into play for a thunderstorm outbreak Wednesday afternoon into Wednesday evening. The one thing that has changed is the timing. The models are bringing the shortwave trough a bit earlier than last night or even yesterday. However, this is not expected to change the forecast by that much. If anything the threat for thunderstorms could begin a bit earlier in the day and decrease earlier in the evening. One thing of note: Due to the expected earlier arrival of the shortwave, there`s a chance we could have a cloud sheild could move into our area Wednesday morning which could slow down the amount of warming and instability, but confidence on this is low, but something we`ll have to keep a close watch on. All of the ingredients are still there for an outbreak of thunderstorms, some of which could be strong to severe Wednesday afternoon into at least Wednesday evening. The key ingredients needed for thunderstorms are: Moisture, trigger (shortwave) and instability. We`ll have of these and the parameters for all three are significant. Each of these will be discussed below. Trigger: A shortwave trough will approach the Oregon Coast Wednesday afternoon and will become negatively tilted with plenty of strong shortwaves (trigger) out ahead of it as it approaches. A negatively tilted trough is an indicator of a system strengthening. Moisture: This will be in abundance on Wednesday. Models are showing precipitable water values around .75 of an inch Wednesday morning, increasing to around 1.25 inches, especially along and west of the Cascades Wednesday afternoon. Instability: Plenty of this exist, especially in the afternoon. The general consensus is for very unstable conditions Wednesday afternoon and evening. For example, the GFS shows Li`s between -3 and -5 C. The NAM is through the roof with even lower with values between -5 and almost -8 C. In addition CAPE values well over 1000 J/kg. All of this will be coming during near or max heating of the day which will only add to the instability. Additionally, a significant southerly wind field yields 0-6km bulk shear of 40kt, and upper level deformation is high. If all this comes to pass, severe thunderstorms are possible with the primary threat being damaging winds. Also, a strong jet will be moving into the area and we`ll be on the left exit region of this jet which could aid in the development of moderate to severe storms. There`s still some uncertainty with the details, but there`s fairly good agreement most of the action could be centered from western and central Siksyou County north along the Cascades and portions of the westside, this would include the Rogue Valley. The axis of the shortwave trough will swing northeast and centered east of the Cascades later Wednesday evening. The best chance for thunderstorms will also begin to shift east as the steering winds become westerly and best dynamics are confined to northern Klamath and Lake county. Due to the earlier arrival and exit time of the shortwave, it`s possible most if not all of the action is north of our area late Wednesday evening and the forecast has been adjusted to reflect this thinking. Slight cooling is expected Thursday and Friday with a weak west to northwest flow and light to moderate onshore flow. We`ll stay dry with be above normal temperatures in the afternoon inland away from the coast. Saturday remains dry. The models differ on the strength and timing of the the upper trough moving through Washington State and Eastern Oregon which could determine how warm it will get. For example, the GFS solution digs the upper low further west resulting in cooler afternoon temperatures than whats in the forecast. The ECMWF is weaker and slower with the upper trough and would result in higher afternoon temperatures. We`ll heat up some Sunday as ridging builds over the area. This won`t last long as an upper trough approaches the area Monday and over us on Tuesday with increasing onshore flow. -Petrucelli && .AVIATION...For the 19/18Z TAFs...The LIFR cigs/vsbys associated with the marine layer is receding back to the coast. Brief periods of clearing expected along the coast this afternoon before returning tonight. In the Umpqua basin, the MVFR CIGS could spread into KRBG. Elsewhere, VFR conditions prevail and will do so throughout the TAF period. -Schaaf && .MARINE...Updated 200 PM PDT Tuesday 19 June 2018...Relatively calm conditions will continue through Thursday. Seas will be a mix of longer period west swell and shorter period northwest swell through this evening, with the northwest swell diminishing tonight. The thermal trough redevelops Friday. Small craft conditions with steep wind driven seas are expected to return by Friday night and continue into the weekend. Gale conditions could be possible over the weekend, but confidence is still low since it`s still a few days out. -Schaaf/BR-y && .FIRE WEATHER...Clear skies inland with low clouds along the coast will continue tonight. On Wednesday, a strong upper level disturbance will move up from the southwest and across the area in the afternoon and evening. Scattered to isolated thunderstorms are expected to develop over inland areas early in the afternoon and increase in coverage in the late afternoon and evening. Storms are likely to initiate over the mountains in the Southern Oregon Cascades, Siskiyous and western Siskiyou County early Wednesday afternoon then spread north and northeast in the late afternoon and evening. Frequent lightning, locally heavy downpours as well as hail and gusty winds are possible with these storms. In addition, there is a marginal 5 percent risk for severe thunderstorms with damaging hail and winds possible. The marginal risk for severe thunderstorms extends primarily from Siskiyou Summit and areas east of Medford northward and northeastward across the Southern Oregon Cascades and Klamath County. Thunderstorms are expected to diminish late Wednesday evening. Then, expect warm and dry weather Thursday and Friday with areas of low clouds along the coast and into the Umpqua basin. On the weekend, an upper level ridge will build into the area and expect drying humidities and warming temperatures. Temperatures will peak Sunday the ridge slides inland. Moderate recoveries are expected on area ridges over the weekend as well. Early next week, expect a cooling trend with the ridge shifting east and an upper trough approaching the region from the northwest. -CC && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...None. $$

797 FXUS66 KEKA 191107 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 407 AM PDT Tue Jun 19 2018 .SYNOPSIS...A warming is expected through the end of the week, with peak temperatures expected Friday through Sunday. Coastal clouds will remain prevalent through at least Thursday and possibly Friday as well. A brief thunderstorm will be possible Wednesday afternoon in far northeast Trinity County. && .DISCUSSION...A prolonged period of above normal interior temperatures can be expected across inland areas for much of the next week, thanks to building high pressure along the west coast overall. While temperatures will certainly be warm today through Thursday, likely reaching the upper 80s to mid 90s outside of the marine layer, the hottest temperatures are expected Friday through the end of the weekend. Over these three days, the hottest temperatures yet this season are likely to be observed, with values likely to reach the upper 90s to near 100. While these temperatures are not particularly out of the ordinary for this area, the prolonged nature of these hot temperatures may result in a moderate risk for health effects for heat sensitive groups. As for precipitation, very little can be expected for the foreseeable future, aside from perhaps some drizzle along the coast (more on that later) and perhaps a brief thunderstorm across far northeast Trinity County Wednesday afternoon. In fact, the combination of strong winds aloft and strong instability may yield a relatively substantial risk for strong thunderstorms north of Trinity County and into southern Oregon. However, any storms that can manage to develop in the far northeast tip of Trinity County will likely not be able to strengthen much before moving quickly to the north and out of the region. A few lightning strikes, small hail and gusty winds will be possible over a very limited area in the worst case scenario. Along the coast, marine layer clouds will continue to be very persistent through at least Thursday, and possibly Friday, before stronger northerly winds develop and help to clear some of them out. Until then, coastal areas can expect overcast skies to roughly 2000 to 2500 feet from late in the afternoon, through the night, and well into the mid to late morning hours the next day, with some afternoon clearing. Drizzle appears to be particularly likely overnight tonight through Wednesday morning, and only limited sky clearing is expected Wednesday afternoon. /BRC && .AVIATION...Stratus is impacting both ACV and CEC this morning with IFR to LIFR ceilings. Visibilities have been gradually improving this morning however some brief periods of reduced visibilities are still possible through late this morning. Most models indicate that the stratus will not dissipate this afternoon and evening as it has the past few days so expect IFR to MVFR ceilings to prevail at CEC and ACV through this TAF cycle. UKI will remain VFR through this period. /WCI && .MARINE...Latest ASCAT pass this morning still shows very light winds in place across the waters. High pressure will begin to build across the area today which will cause northerly winds to slightly strengthen especially south of Cape Mendocino. Seas will continue to gradually subside for the next few days as a westerly and northerly swell move through the waters. Winds will really begin to strengthen Thursday through the weekend when gale force conditions are possible across the waters. These strong winds will lead to steep and hazardous seas this weekend. /WCI && .FIRE WEATHER...A prolonged period of above normal temperatures and dry conditions is expected for much of the next week, particularly Friday through Sunday. While critical fire weather conditions are not expected, these prolonged temperatures will likely speed up the drying of local fuels. Meanwhile, winds will remain mostly light and terrain driven through Thursday, but some breezier north winds can be expected Friday and beyond, particularly near the coast. A brief thunderstorm will be possible across far northeast Trinity County Wednesday afternoon, but much better chances for thunderstorms, some strong, are expected from Siskiyou county northward. /BRC .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...None. && $$ Visit us at http://www.weather.gov/eureka Follow us on Facebook and Twitter at: http://www.facebook.com/NWSEureka http://www.twitter.com/nwseureka For forecast zone information see the forecast zone map online: http://www.weather.gov/eureka/zonemap.png

052 FXUS66 KMTR 192047 AFDMTR Area Forecast Discussion National Weather Service San Francisco Bay Area 147 PM PDT Tue Jun 19 2018 .SYNOPSIS...Temperatures will warm throughout the interior this afternoon as high pressure begins to build over the southwestern United States. Little day-to-day change in highs are expected from Tuesday to Wednesday as high pressure flattens. A noted warming trend develops late in the week and into the weekend with hot temperatures forecast for inland areas. && .DISCUSSION...as of 01:44 PM PDT Tuesday...Inland stratus was slow to clear today and coastal locations are still hanging onto coastal stratus. Interior locations are actually running a few degrees above yesterday at this time with ample sunshine. The coast is a different story where lingering coastal clouds are actually keeping temperatures cooler. It is possible that a few coastal locations may fall short of their max temp forecast for today. No major changes during the short term forecast. The longwave pattern aloft denotes a ridge of high pressure centered over the Bay Area. The ridge is forecast to drift slowly eastward over the next 24 hours. Therefore, night and morning low clouds will be common again with little day to day change at the coast. However, away from the coast temperatures are likely to warm a few more degrees tomorrow. By Thursday the ridge becomes flattened as an upper level trough passes to the north of the Bay Area. The pattern trough will help to moderate weather conditions from Wednesday to Thursday - night/morning clouds continue. Still the biggest weather impact to the region will be in the long term forecast. High pressure will rebuild in earnest Friday and Saturday leading to possibly one of the hottest "heat events" so far this year. Synoptically speaking high pressure builds over the region Friday and Saturday with 500mb heights eclipsing 590 DAM and 850mb temps approaching 28C. A fully mixed atmosphere with 850mb temps near 28C would yield max temps near 105 degrees. FWIW some ensemble guidance envelop puts San Jose and Santa Rosa over 100. Not totally buying off on that yet. Therefore, based on airmass potential and MOS/ensemble guidance high temperatures on Friday/Saturday will be well into the 90s and up to lower 100s across the interior. Did bump up previous forecast just a few degrees. Overnight lows will be rather mild as well, especially in the hills with lows in the 60s and 70s. The combination of hot daytime temps and mild overnight lows will increase the risk of heat related illnesses for sensitive group. The latest experimental heat risk guidance puts much of the interior North/East Bay, N San Benito in a moderate risk with a few pockets of high risk. Still kind of far out to issue any heat products now, but as the event draws near a heat advisory may be needed at a minimum. For now, issued a hazardous weather outlook highlighting potential for hot weather. As typical with heat events in the Bay Area the battle ground will be toward the coast - how hot will it get? Latest models guidance continues to indicate a little bit of onshore flow keeping the coast much cooler than the interior. However, did raise temperatures a little with highs in 60s to lower 80s. Temperatures will cool a little on Sunday as the ridge begins to shift eastward. Interior locations will still remain above normal and in the 90s to near 100. More widespread cooling is expected on Monday and Tuesday as another broad upper trough begins to impact the West Coast. && .AVIATION...As of 10:51 AM PDT Tuesday...For 18z tafs. Marine layer hovering around 1500 feet. Low clouds are clearing back to the coastline most areas but still stuck inside sf bay. Expect clearing by ~19z for sfo/oak. Increasing onshore flow with established marine layer should bring stratus back to the coast early this evening and spreading into the bay before midnight. Vicinity of KSFO...Clearing expected around 1930z but could linger just over or west of the terminal for much of today. Low confidence. Stratus could return earlier this evening than current taf shows. SFO Bridge Approach...San Mateo bridge reporting clear already. Should hold onto visuals through 04z this evening at the bridge. Monterey Bay Terminals...Stratus may linger near or just west of kmry for much of today while ksns has already cleared. Expect low cloud deck to spread back inland by 01-02z this evening. && .MARINE...as of 1:44 PM PDT Tuesday...Light to moderate northwesterly winds will persist across the coastal waters through mid week before winds increase. Gusty winds are expected this afternoon for the near shore waters as well as the San Francisco and Monterey Bays. Seas will remain relatively light with a mixed northwest and southerly swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Mry Bay until 9 PM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...SF Bay until 9 PM && $$ PUBLIC FORECAST: MM AVIATION: RWW MARINE: CW 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

000 FXUS66 KOTX 192126 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 226 PM PDT Tue Jun 19 2018 .SYNOPSIS... Showers and thunderstorms will develop Wednesday afternoon. A weather disturbance will move into the region during the evening hours and keep the threat of thunder going for portions of WA and ID through the night and into Thursday morning. Thursday is the best day to see scattered showers and thunderstorms. All storms will have the potential to produce very heavy rain. Friday and Saturday remains unsettled, mainly in the mountains. The beginning of next week currently looks dry. && .DISCUSSION... Tonight through Wednesday: The upper level low pressure system that has brought cooler temperatures to extreme eastern WA and north ID continues to move east of the Continental Divide. Meanwhile central WA is seeing above average temperatures. Through Thursday night we will be under the influence of very high precipitable water values and weak winds. There is instability available this afternoon and evening for showers or thunderstorms to develop. However, with no real kicker to get things going, think it will be pretty isolated. Have lowered our chance of precipitation for this evening. Wednesday looks much of the same, but no convective inhibition and perhaps more dynamic support. The best shower and thunderstorm potential exists along the Cascades and into the Okanogan mountains, but have mention of thunder along the US/Canadian border across NE WA and N ID. Models are also showing some thunder potential in the Blue Mountains. Any thunderstorms that develop will bring very heavy rainfall with it and perhaps some small hail. Wednesday will be our warmest day with valley temperatures in the 80s to around 90. Wednesday Night through Thursday: The exciting weather comes Wednesday night into Thursday. A trough will push into northern CA with strong weather disturbances moving north through Oregon during the day on Wednesday. By Wednesday evening the disturbances are in northern Oregon and headed into central WA and the southern ID Panhandle through the evening and overnight hours. With the high precipitable water values and elevated instability continuing through the night, there will be a chance of thunderstorms through the night. Through the evening the thunder will mainly remain in the Cascades and Okanogan mountains, but the potential exists for thunder to roll off the mountains and into the Waterville Plateau and upper Columbia Basin (north of I90). By late evening and overnight as the wave moves up the chance of thunder move away from the Cascades and will be more focused across the Columbia Basin/Spokane/Palouse and into the Camas Prairie. By morning the threat will be most of extreme eastern WA and all of north ID. In the afternoon as we transition to surface based instability it will expand across all of northern WA as well. The main threat with these storms will be very heavy rainfall, as they will be slow moving with lots of moisture to tap into. Have also kept the mention of small hail during the afternoon and evening hours, but do not at think at this time we will see large hail. Temperatures across extreme E WA and north ID will cool several degrees, but the central part of the state will see similar temps to Wed. If you do escape showers or thunderstorms Thursday, it will still feel quite muggy by Pac NW standards. Dew points in the mid 50s to lower 60s is expected for eastern WA and north ID. By the aftn we will be back in our typical southwest or westerly flow across the region. Winds will increase through the Cascade gaps into portions of the Waterville Plateau and Columbia Basin through the evening. Our chance of thunder will decrease through the evening as the trough quickly exits the area. Showers are possible through the night for the ID Panhandle. /Nisbet Friday through Tuesday: Shower and thunderstorm chances linger into Saturday, before comparatively drier weather develops next week but it will be occasionally breezy. Between Friday another shortwave enters from the Pacific, before tracking southeast toward the Great Basin Friday night into Saturday. Models disagree over how it evolves in this latter time frame, with some runs taking it south through the central WA/OR border and others bringing it toward Idaho before it moves south. This has temperature and some shower confidence implications. So some details will need fine-tuning. For now look for shower chances around the north and eastern mountains Friday, expanding into the portions of the eastern basin late Friday into Saturday morning before the threat retreats to mainly the eastern mountains Saturday afternoon, before waning through the evening. However should the low track more toward Idaho it will hold PoPs higher over the eastern third of WA longer into Saturday afternoon and the forecast continues to hold onto this risk. The main thunderstorm threat will be found Friday afternoon/early evening over the northern mountains, but I cannot rule out some slipping off the mountains. Saturday and Sunday also look breezy. Sunday into Tuesday a ridge builds in before a couple shortwave disturbances slip by in the southwest flow. Limited moisture or convective instability at this time will keep only a limited shower threat within the northern mountains. Otherwise look for some occasional cloud cover and period breezy conditions. Temperatures will be near to slightly above normal. /J. Cote` && .AVIATION... 18Z TAFs: Stratus is lifting at KPUW and should dissipate by 20Z. Cumulus will develop through the afternoon. Isolated thunderstorms will be possible over the Central Panhandle Mtns and over the northern Cascades. Any thunderstorms that develop are not expected to impact the TAF sites. && .PRELIMINARY POINT TEMPS/POPS... Spokane 61 83 62 78 57 80 / 0 0 20 60 40 10 Coeur d`Alene 59 83 59 75 56 78 / 0 0 10 60 40 10 Pullman 57 81 59 74 55 77 / 0 0 20 60 40 10 Lewiston 62 87 63 81 59 84 / 0 10 30 60 40 10 Colville 60 84 58 83 54 82 / 0 10 10 30 40 20 Sandpoint 56 81 57 75 55 76 / 0 10 10 50 50 20 Kellogg 54 79 57 72 54 74 / 10 10 10 60 60 20 Moses Lake 59 90 63 88 57 86 / 0 0 50 20 10 10 Wenatchee 66 87 65 86 60 83 / 0 10 20 10 10 10 Omak 65 87 61 88 57 85 / 0 20 40 20 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$

007 FXUS66 KPDT 191709 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1010 AM PDT Tue Jun 19 2018 Updated aviation discussion .UPDATE...Water vapor imagery shows an upper low over central Montana and another low along the central British Columbia coast. The low over Montana continues to circulate moisture into the eastern half of the area and partly to mostly cloudy skies continue over that portion of the area. Radar is not showing any showers this morning but expect isolated to scattered rain showers over the northern Blue Mountains and Wallowa county this afternoon and early evening. Models show weak instability so have not added any mention of thunderstorms there but an isolated lightning strike or two is possible. Heavy cloud cover will help limit the thunderstorm potential. Further west, a weak wave will move through Washington this afternoon and create a slight chance of showers and thunderstorms along the Washington Cascades this afternoon and early evening. The rest of the area will be dry with mostly sunny to partly cloudy skies. Winds will be light today and tonight. Temperatures will be much warmer today with much of the area 5 to 15 degrees warmer than yesterday. Forecast was generally in good shape. Made some minor adjustments to temperatures, pops and sky cover today and tonight. Forecast update already out. Perry .AVIATION...18Z TAFs...VFR conditions will prevail for the next 24 hours. FEW-SCT clouds at 060-100 kft today then becoming clear overnight. Winds will remain 10 KT or less. && .PREV DISCUSSION... /issued 158 AM PDT Tue Jun 19 2018/ SHORT TERM...Today through Thursday...An elongated upper level low in MT is circulating moisture and light rain westward into eastern OR/WA. The low will continue to drift east today. Light showers in the Columbia Basin are dissipating. A band of showers is moving into Wallowa County. These trends are reflected in latest HRRR model. I expect showers to be limited from northern Blue Mountains to eastern Grant County eastward to Wallowa County this morning. A weak wave will move into WA this afternoon/evening. This wave may trigger a few showers and thunderstorms along the WA Cascades. Convection will end overnight as an upper level ridge moves through eastern WA and OR Wednesday morning. Wednesday afternoon a short wave will move into southwest OR. This will trigger some convection late in the day...overnight and into Thursday. I expect thunderstorms during this period to impact the CWA with the potential for some strong storms, particularly Wednesday evening. Coonfield LONG TERM...Thursday night through Monday...The mid level shortwave will exit to the east Thursday night. Scattered showers and isolated thunderstorms from the Blue Mountain foothills eastward Thursday evening will end by the overnight hours. Low amplitude ridging will cross the area Friday for dry conditions area wide. GFS/ECMWF are in reasonable agreement for the weekend, bringing the next system across extreme northern WA/southern BC Saturday, digging south across the intermountain West Saturday night/Sunday. Deep layer moisture and dynamic support will remain north and east of the center of the low. Thus, mainly dry conditions will prevail Saturday, with perhaps a slight chance of showers along the immediate Cascade crest of WA. Another low amplitude ridge is progged to cross the region Sunday, exiting to the east Monday for a continuation of dry conditions. Warm conditions can be expected under the ridge for Friday, with a slight cooldown Saturday as the low brushes the area, warming once again to above normal Sunday and Monday. && .PRELIMINARY POINT TEMPS/POPS... PDT 83 59 90 64 / 10 10 10 50 ALW 84 60 92 66 / 10 10 10 30 PSC 86 60 93 67 / 10 0 10 30 YKM 86 62 88 66 / 10 10 20 20 HRI 87 60 94 68 / 10 0 10 40 ELN 86 62 89 63 / 10 10 20 30 RDM 84 54 88 56 / 0 0 20 50 LGD 76 51 83 59 / 20 20 20 40 GCD 75 54 85 59 / 10 10 10 50 DLS 90 65 93 68 / 10 10 10 30 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 83/80/80

283 FXUS65 KREV 191005 AFDREV Area Forecast Discussion National Weather Service Reno NV 305 AM PDT Tue Jun 19 2018 .SYNOPSIS... Much warmer and drier conditions will prevail for the rest of the week. Gusty afternoon winds with well above normal temperatures are projected for Wednesday and Thursday, with lighter winds on Friday. Thunderstorm risks remain quite low through at least next weekend. && .SHORT TERM... High pressure strengthens over northeast California and western Nevada through Wednesday, bringing 5 to 10 degrees of warming each day with highs reaching the 80s (Sierra valleys) and 90s (western NV valleys) by Wednesday. A weak wave moving by to the north Wednesday night will induce an increase in winds (gusts 25-30 mph, locally to 35 mph, out into far western NV) Wednesday afternoon and evening. This will bring heightened safety concerns for boaters on area lakes, especially west of Pyramid Lake and Lahontan Reservoir. Fire concerns will also rise somewhat in Basin areas with dried out grasses. Thursday, the warming trend will be halted as the weak wave moves by to the north, although highs will still top out a toasty 7-10 degrees above average. Breezy conditions are expected once again by the afternoon as the zephyr kicks in, although speeds will not be anything unusual. -Snyder .LONG TERM...Friday into early next week... The overall pattern will focus on the evolution of the subtropical ridge and any short waves passing by to the north. The ridge retrogrades off the coast briefly over the weekend as a short wave drops down the Front Range of the Rockies...then it moves east back over Arizona/New Mexico early next week as another trough moves into the Pacific Northwest. Overall, it doesn`t mean much for temperatures as they will remain above average for late June. Main effect will be on the winds with them being more from the north to northeast late Friday into the weekend, and they will be locally gusty overnight. Then, as the next short wave moves in, the zephyr returns and may be a bit stronger depending on the track of the trough. Concerns for fire weather may increase. X && .AVIATION... VFR conditions through Thursday with light NW to NE winds this afternoon and evening. FG for KTRK this morning looks minimal, and very shallow if it forms at all, chances about 25%. Winds will become locally gusty for the Sierra and adjacent east slopes Wed afternoon/evening with peak gusts to 25 kts from the SW-W. Some mtn wave turbulence can be expected, but it will be moderate at best. X && .FIRE WEATHER... Local critical conditions are possible Wednesday ahead of a wave moving into Oregon. The timing of the wave is not ideal for widespread critical conditions, but be best chances of seeing them would be along the Sierra Front and just on the east side of the Pine Nuts/Virginia Range. The winds Thursday look lighter now with a generic zephyr day expected, but that would still produce gusts to 25-30 mph in many areas along the 395 corridor. The airmass will become very dry beginning Wednesday night, with poor overnight recovery for many mid slope and ridge locations continuing into Friday. Afternoon humidity will also drop into the single digits during the afternoons. Of note with this pattern, the Tahoe Basin will see mid slope and ridge recoveries in the mid-evening, only to crater overnight into the single digits and teens. 24-hr min RH will be overnight for these locations, not fitting a typical diurnal trend. X .REV Watches/Warnings/Advisories... NV...Flood Watch until 10 AM PDT this morning NVZ003. CA...None. && $$ For more information from the National Weather Service visit... http://weather.gov/reno

000 FXUS66 KSTO 192121 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 221 PM PDT Tue Jun 19 2018 .SYNOPSIS... Hot and dry weather this week, peaking this weekend. && .DISCUSSION... An upper level ridge centered over Baja California has begun to build over the state as a broad area of circulation over the northern Rockies pulls eastward. The marine layer is running at around 1500 feet deep this morning with moderate onshore flow through the Delta. Temperatures across the interior are running upwards of 10 degrees warmer than yesterday, owing mostly to synoptic warming. Northern California will remain under a neutral weather pattern today and Wednesday, with high pressure to our south and a passing shortwave to our north. This will keep a light to medium Delta Breeze moderating temperatures in areas adjacent to the Delta. Look for high temperatures in the 90s across the Valley, with 70s to 80s over the mountains. These forecast temperatures are roughly 5 degrees warmer than normal for this time of year. Temperatures will continue to warm up later this week as the shortwave trough exits, and the upper ridge strengthens across the West Coast. By Friday we are likely looking at widespread triple digit temperatures across the Valley, and temperatures look to warm further into the weekend. Dang && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday) NorCal will be under a ridge of high pressure to start the extended period. The latest model runs have shifted the upper level trough over the Great Basin a bit further west and that has pushed the daytime highs just a bit cooler then what previous runs were saying. It will still be a hot one on Saturday though despite the model shift, valley highs 101 to 105, foothills 88 to 101 and 77 to 90 in the mountains. Breezy north winds can also be expected along with low RHs on Saturday. The ridge begins to push east on Sunday and we will see falling heights over CA. This will be the start of a gradual cooling trend into early next week. Not expecting any thunderstorms chances during the extended period. -CJM && .AVIATION... VFR conditions expected the next 24 hours. Winds generally under 10 knots. -CJM && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

000 FXUS65 KMSO 192033 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 233 PM MDT Tue Jun 19 2018 .DISCUSSION... The broad area of low pressure which has brought rainfall to much of the northern Rockies will continue to generate rain showers through this evening. Small streams and creeks will continue to run high through this evening as water begins to recede from the rainfall the last few days. Wednesday is expected to be dry and warm as the area of low pressure exits the area. A few patchy areas of fog will develop in valley locations Wednesday morning as clouds clear out overnight and residual moisture remains near the surface. Active weather returns Thursday as a weather disturbance moves from the Pacific Northwest into western Montana. In north-central Idaho, showers and thunderstorms will form during the morning hours, limiting day-time heating and instability. Therefore, weaker thunderstorms are expected across north-central Idaho. A few strong thunderstorms could develop across Lemhi, Granite, Deer Lodge, Powell, and Silver Bow counties. Instability and modest wind shear will help organize convection. Large hail and periods of heavy rainfall will be the primary storm threats. Further to the north and west in Missoula and Ravalli counties, weak storm motions and deeper moisture will support storms capable of producing heavy rainfall. The Lolo Peak and Roaring Lion burn scars could be at risk for flash flooding if a strong thunderstorm were to hit these areas directly. Other areas across western Montana are expected to see general showers and thunderstorms Thursday. Friday and Saturday...Another weather system will enter the region from British Columbia. Scattered showers will develop across much of Northwestern Montana Friday afternoon. These showers will continue through the night then increase in coverage Saturday to include all of western Montana and parts of northcentral Idaho. Sunday through the middle of next week we are looking pretty dry under weak high pressure. && .AVIATION...Expect scattered showers, and some peaks of sun, through the evening hours at KBTM, KMSO and KSMN. Skies will remain partly to mostly cloudy though GPI may have a few showers in the vicinity but will remain mostly dry. Ceilings are fairly low so expect mountain obscurations through early Wednesday morning. More sunshine and warmer conditions are anticipated Wednesday. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

000 FXUS65 KBOI 192058 AFDBOI Area Forecast Discussion National Weather Service Boise ID 258 PM MDT Tue Jun 19 2018 .SHORT TERM...Tonight through Thursday night...Scattered showers associated with a departing upper low will diminish this evening and end by midnight. An upper ridge will move into the area tonight and shift to our east by late Wednesday. Dry conditions and warmer temperatures (with above-normal highs) will accompany the ridge. A developing low pressure system push a cold front through southeast Oregon Wednesday evening and southwest Idaho (north of the Treasure Valley) late Wednesday night. Showers and a chance of thunderstorms will accompany the system. The low will slow down and track just to our north, with a chance of showers and a slight chance of thunderstorms from Baker County, Oregon to the West Central Mountains in Idaho. The front will result in slightly cooler temperatures in southeast Oregon on Thursday, but little change in southwest Idaho. Winds will be light, except for strong gusty winds with thunderstorms and locally breezy west-northwest winds Thursday afternoon. .LONG TERM...Friday night through Tuesday...Progressive pattern during the period with dry conditions dominating. Weak ridging Friday will be replaced by a weak trough on Saturday. Little moisture associated with the trough so just a small chance of showers and thunderstorms over the West-Central Mountains. Northwest winds will increase on Saturday with the trough passage. A warming trend for Sunday and Monday as a stronger ridge builds over the area. Temperatures climbing several degrees above normal on Monday. A slight downward trend in temperatures for Tuesday and continued dry as the ridge shifts east and a weak trough brushes northern Idaho. && .AVIATION...Local MVFR in isolated to scattered showers, mainly over the high terrain north of Interstate 84 through about 20/02Z. Isolated showers on the Idaho side near the Nevada border. Otherwise, VFR conditions will dominate. Surface winds will favor west to northwest 5-10 KTS becoming variable less then 10 KTS after sunset. Winds aloft near 10KFT MSL: west to northwest 10-15 KTS. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...BW LONG TERM....TL/TL AVIATION.....TL

000 FXUS65 KLKN 192110 AFDLKN Area Forecast Discussion National Weather Service Elko NV 210 PM PDT Tue Jun 19 2018 .SYNOPSIS...Dry with above normal temperatures through Friday, along with some breezy afternoon winds. Most locations will be a few degrees cooler over the weekend, especially across northern NV. Dry early next week with well above normal temperatures. && .SHORT TERM...Tonight through Thursday. Shortwave energy clipping northeastern NV this afternoon will exit to the east this evening with diminishing clouds. High pressure begins to build in from the south on Wednesday while at the same time shortwave energy moves through northern CA and NW Nevada. GFS model suggest the merging air masses will lead to some afternoon cumulus build-ups across and near Lander Eureka and northern Nye counties. Not expecting any TS or shower activity however. Temperatures will warm across the region on Wednesday as southwesterly flow aloft increases. The shortwave energy over NW NV Wednesday extends across all of northern NV on Thursday. There should be enough moisture and instability across northern Humboldt and Elko Counties on Thursday afternoon for cumulus build-ups. Held off on introducing isolated thunderstorms for this area at this time, with POPs limited to around 5-10 percent. Although if TS did develop across the far north on Thursday afternoon storms would likely be dry. Temperatures will be above normal across the CWA Wednesday and Thursday. .LONG TERM...Thursday night through next Tuesday. Weak trough energy clipping northern Humboldt and Elko counties Thursday evening will exit east Thursday night. Slightly cooler on Friday mainly across northern NV as one weak trough exits to the east, and a second approaches from the NW. Dry conditions are expected although afternoon winds will again be breezy. A second, and slightly trough will drop in across northeastern NV on Saturday. Have introduced isolated thunderstorms across mainly the NE portion of Elko County. This trough exits into west-central UT Saturday evening and night with ridging building in behind the exiting system. Dry across the region early next week as high pressure rebuilds across the CWA sending high temperatures into the low to mid 90s for most valley locations. && .AVIATION....AVIATION...VFR conditions are expected at all terminals through Wednesday. && .FIRE WEATHER...Thursday there will be some instability across northern Humboldt and Elko Counties. For now it looks like enough moisture and instability for afternoon and evening clouds, but not thunderstorms. A stronger system on Saturday may bring a few lightning strikes to zone 470 and possibly far eastern portions of 469. Afternoon winds will be breezy Thursday through the weekend. In general, dry and warm over the coming week. && .LKN WATCHES/WARNINGS/ADVISORIES...None. && $$ 96/96/96/96