000 FXUS66 KSEW 231733 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 1033 AM PDT Mon Sep 23 2019 .SYNOPSIS...A weak ridge will build over the area today with a frontal system moving down from the northwest dissipating tonight over Western Washington. Another system arriving Wednesday night into Thursday will bring considerably cooler conditions. && .SHORT TERM /TODAY THROUGH WEDNESDAY/...Satellite imagery shows cloudy skies to the north with some clearing over the southern portion of the area this morning. Doppler radar has precipitation echoes from about Quillayute to Mount Vernon but most of the precipitation is aloft at this point. Temperatures were in the mid 50s to lower 60s. Upper level ridge trying to build over the area today with a warm front moving through the top of the ridge into the northern portion of Western Washington this afternoon. Rain aloft on the radar will begin making it to the surface this afternoon. Will update the forecast to increase the pops for the Northwest Interior this afternoon with a chance of rain over most of the remainder of the area. Highs will be in the lower to mid 60s. Warm front dissipating over Western Washington tonight keeping at least a chance of rain in the forecast. With the cloudy skies lows will be in the 50s. Tuesday looking a little drier on the 12z model runs. Plenty of low level moisture combined with light onshore flow will keep the lower levels of the air mass moist so even with a drier forecast there will still be cloud cover in the area. Highs a couple of degrees warmer, in the mid and upper 60s. First look at the 12z models has the next system arriving into the area a little slower than previous runs. If this trend continues with all of the model runs in will cut back on the pops for Wednesday afternoon. For now only changes to the forecasts will be the increasing pops this afternoon. Felton .LONG TERM /THURSDAY THROUGH SUNDAY/...Previous discussion follows. This initial system will move through the area at a good clip...pushing out Thursday afternoon. The GFS is a little faster ejecting it...but maybe a little too fast. ECMWF solution remains pretty consistent with prior runs and feel like favoring that a bit more. Models remain in agreement that late Thursday morning/early Thursday afternoon still look like a another bit of a break. Current solutions have sufficient moisture behind for PoPs Thursday evening into early Friday morning...but this is a bit of a deviation from prior solutions...as such...have trimmed inherited pops slightly to take this new solution into account and as such might be a bit too wet if this drier solution becomes more consistent. Models a little bit more consistent with an upper level low impacting W WA Friday evening but once again...track and precip amounts vary. Ejecting the system also a point of contention...as the GFS wants to dry things up for Sunday while the ECMWF will have precip linger. Given this low confidence in the extended....have opted for minor tweaks to what was inherited until a solid consensus can emerge. SMR && .AVIATION...Moist northwest flow aloft will continue today and tonight. At the surface, onshore flow will ease today and become moderate southerly tonight. A weak front will approach from the northwest today and dissipate over the area tonight. The air mass is moist and stable over the northwest part of the area, with a large mostly clear area over the southeast part. Ceilings are generally VFR except for some MVFR in a convergence zone in Snohomish County. Conditions will slowly deteriorate, with more widespread MVFR around the dissipating front tonight. KSEA...Mostly VFR with southerly wind 10-15 kt. Ceilings likely to fall to MVFR after 09Z. CHB && .MARINE...A weak front will approach from the northwest today and dissipate over the area tonight. Onshore flow will ease this morning, then southerly small craft advisory strength winds will develop over most waters this afternoon and continue tonight. Onshore flow will resume Tuesday, with advisory strength west winds likely in the strait Tuesday night. Another front will approach from the northwest Wednesday and move through Thursday. CHB && .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...None. PZ...Small Craft Advisory until 8 PM PDT this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. Small Craft Advisory from 2 PM this afternoon to 10 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. Small Craft Advisory until 11 AM PDT this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory from 6 PM this evening to 2 AM PDT Tuesday for Northern Inland Waters Including The San Juan Islands. Small Craft Advisory until 5 AM PDT Tuesday for Puget Sound and Hood Canal. && $$ www.weather.gov/seattle

000 FXUS66 KPQR 231747 AFDPQR Area Forecast Discussion National Weather Service Portland OR 1046 AM PDT Mon Sep 23 2019 Updated the aviation discussion .SYNOPSIS...Skies are beginning to clear early this morning, except near the Cascades where clouds and a few showers linger. Where the skies clear, expect areas of valley fog to develop this morning, and any fog may be locally dense. Otherwise generally dry and seasonable weather is expected today, though still a touch on the cool side. Clouds and rain chances increase from the north tonight as a warm front approaches. Rain chances will linger into Tuesday, mainly north of Salem. Strong but flat upper level ridging will build into the region Tuesday and Wednesday, allowing mild to warm afternoon temperatures. This ridge breaks down for much cooler and showery weather later this week into the weekend, with the first hint of snow possible all the way down to the Cascade passes. && .SHORT TERM...Today through Wednesday...Drier air is gradually moving into the forecast area early this morning, as satellite fog product reveals areas of clearing moving into the Willamette Valley. Suspect any wind-sheltered valleys that fully clear will quickly fog in this morning, with fog becoming locally dense. Clouds and isolated showers linger in the Cascades, as shown by weak echoes lingering on KRTX Doppler Radar and occasional tips of 0.01" on rain gauges for some of the RAWS stations in the Cascades. As high pressure and drier air moves into the Cascades, expect any lingering showers to taper off this morning. Morning low clouds or fog are expected to clear for partly to mostly sunny skies this afternoon, as model soundings show much drier air pushing down below 850 mb, effectively eroding the current low clouds from the top. Afternoon sunshine may be filtered by increasing high clouds as a Pacific warm front begins to approach the Pac NW. Temperatures this afternoon will still be a little below normal for late September. Just how much cooler than normal will depend largely on how fast fog/low clouds clear today, and the above-mentioned high clouds may delay clearing of the lower clouds. NAM-based MOS guidance suggests a chilly day with a high of only 60 degrees at Hillsboro this afternoon. However the NAM appears to be a little too fast with the high clouds, so we opted for warmer temperatures closer to the National Blend of Models output. Most models were 5-10 deg F warmer than NAM-based MOS guidance, so highs in the mid 60s to lower 70s appear reasonable for our lowlands. Models are in decent agreement the next weak and occluding front will drop southeastward and likely bring rain to our northern coastal zones this evening. The evening shift expanded mentionable rain chances as far south as the Portland metro this evening, which seems reasonable given the warm advection and saturation occurring in the 850-700mb layer in model soundings. Rain chances will slowly drop southward overnight, but it still looks like rain will likely struggle our southern counties including much of Lane, Benton and Linn Counties. Chances for light rain will linger into early Tuesday, mainly for the northern half of the forecast area. Some clearing is likely Tuesday afternoon, especially south of a Portland-Tillamook line as flow aloft turns more north-northwesterly. With 850 mb temps rising to near +10 deg C for the Willamette Valley, 70s are a good bet there Tuesday afternoon...especially for our southern zones where there will be more sunshine. Little change is expected in the overall pattern Tuesday night/Wednesday, though clearer skies Tue night may lead to more fog and stronger inversions Tue night/early Wed. MOS guidance has been suggesting a little cooling Wednesday, but given a warming air mass aloft and at least a partly sunny afternoon, high temps Wednesday afternoon will probably be similar to Tuesday. Weagle/Neuman .LONG TERM...Wednesday night through Sunday...Models show good agreement that the flat upper level ridge over the NE Pacific and much of the U.S. West Coast will begin to buckle and retrograde out into the Pacific Wednesday night, allowing an Alaskan cold front to push down toward the Pac NW. This will be the beginning of a major pattern shift back toward colder and showery weather for the end of the week and the upcoming weekend. The details regarding which days will be wetter versus which days will be drier remain up for debate between models, but the best chance for significant rainfall appears to be Friday night into Saturday as the main upper trough axis swings onshore. There is good agreement on this between 00z ECMWF/GEFS ensembles. Still, some models/ensemble members, such as the 00z GEM, are drier due to limited overwater trajectory. Will need to start thinking about snow in the Cascades, as the 00z ECMWF pushes 850 mb temps down to near deg C in the Cascades...likely cool enough for snow down to Government Camp and the Cascade passes. At this point, it appears doubtful the combination of moisture and cold will exist to necessitate Winter Weather Advisories, but anyone with plans to head to the Cascades Fri-Sun should be aware that snowy weather will be possible above 4000 feet or so in elevation. Elsewhere, temperatures will also be well below normal for the season, and there remains a possibility that a day or two may fail to reach 60 degrees, even in the lowlands. Any overnight clearing this weekend will bring the potential for patchy frost...especially in higher elevation valleys such as middle to upper portions of the Hood River Valley. Weagle && .AVIATION...VFR this morning with increasing high clouds into the area. Observations are hinting at low clouds trying to form in the Willamette Valley but do not think IFR CIGS will materialize. Mid and high level clouds will increase this afternoon and evening with the next front. Expect MVFR CIGS for the coast with light rain or drizzle this evening with possibly IFR late tonight (after midnight). Rain and MVFR conditions will be most likely for the coast, coastal mountains, and the Cascade Foothills spreading NW to SE from late this afternoon through tonight. Otherwise expect VFR with a CIGS around 5000 ft. Although could see MVFR stratus in the Willamette Valley behind the front early Tuesday morning with CIGS around 2500 feet. KPDX AND APPROACHES...VFR conditions with high clouds filling in this morning. Ceilings around 5000 feet expected later this afternoon and evening as a front nears. Do not expect much rain or MVFR conditions with the front, but MVFR conditions is possible with stratus filling in behind the front early Tuesday morning. Stratus early Tuesday may result in ceilings around 2000 feet. Light winds will make it difficult to see a clear wind shift with the front. ~TJ && .MARINE...Seas remain quite steep this morning with buoys reporting seas 9-10 ft with period of 9 to 10 seconds. Have extended the Small Craft Advisory through 9 AM. Seas will be a bit less steep, but still remain choppy. A ridge of high pressure extending southwest off the central and south Oregon coast will continue through tonight. To the north of the ridge a weakening front will push across the waters later today and tonight. Expecting a few hours of advisory gusts to 25 kt over the northern outer waters as the front brushes by. High pressure rebuilds across the waters Tuesday and could bring some northerly advisory gusts to the central waters Tuesday afternoon/evening. Another front is then expected Thursday appears a little weaker than previously so have eased winds a little for this forecast. A persistent west to northwesterly swell will generally keep seas in the 6 to 9 ft range through the first half of the week, with seas building again on Thursday. Have cut back on wave heights since it appears the system generating the swell is expected to be weaker. /mh /64 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 4 PM this afternoon to 11 PM PDT this evening for coastal waters from Cape Shoalwater WA to Cascade Head OR out 60 NM. && $$ 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 forecast area.

713 FXUS66 KMFR 231618 AFDMFR Area Forecast Discussion National Weather Service Medford OR 918 AM PDT Mon Sep 23 2019 .UPDATE... Updates have been made to the forecast for today. These updates have primarily been for this morning to provide more detail/update the fog and low cloud forecast. This has included issuance of a Dense Fog Advisory for portions of the valley areas of Jackson, Josephine, and Douglas counties valid through 10 AM PST. && .DISCUSSION... After less than a half inch of rain yesterday (most areas got 0.10" to 0.30") and partial clearing overnight, we`ve got some low clouds and fog this morning. This fog has been dense in some areas, enough that a Dense Fog Advisory was issued for portions of Jackson, Josephine, and Douglas counties. This advisory will be allowed to expire at 10 AM PDT as observations across the area suggest that most areas have improved to above a quarter of a mile visibility at this time. A light to moderate east wind across the ridges will serve to dry out the air mass this afternoon leading to a sunny afternoon and evening for most of us. We`re looking at a warming trend through mid-week and then a cooling trend beginning Thursday into Friday, followed by another round of much cooler weather this weekend. Please see the previous discussion, below, for further details. BTL && .AVIATION...For the 23/12Z TAFs...Expect areas of MVFR/IFR in low ceilings/fog with mountain obscurations this morning. Conditions will gradually improve during the day with the lower ceilings lingering longest at the coast and in the Umpqua Valley. Expect low clouds and fog to return to the coast and Umpqua Valley tonight. Patchy fog may form again near Klamath Falls. -Spilde && .MARINE...Updated 245 AM PDT Monday 23 September 2019...Seas will build tonight as higher northwest swell arrives. The thermal trough will quickly redevelop early Monday and strengthen into mid-week. Gusty northerly winds will produce steep wind driven seas south of Port Orford early Monday morning through Tuesday. The continued strengthening is likely to produce very steep seas with gales possible south of Cape Blanco Wednesday into Thursday with conditions hazardous to small craft spreading north of Cape Blanco. The first in a series of disturbances is expected around Thursday, but winds are likely to remain gusty and northerly into next weekend. -Spilde/DW && .PREV DISCUSSION... /Issued 411 AM PDT Mon Sep 23 2019/ DISCUSSION... Still a few lingering showers this morning along the west facing slopes of the Cascades. However, those will diminish as we move closer to sunrise this morning. In addition, patchy fog is covering some of the valleys this morning. We could still see it build into the Rogue Valley before sunrise if there is enough clearing. High pressure will begin to build later today and temperatures will trend higher as a result. Even with the warm up, high temperatures will still be cooler than normal for late September. The high will build a little bit more Tuesday through Wednesday and temperatures will respond by warming to their respective climatological normals. We`ll see a thermal trough build along the coast Tuesday. The Chetco effect will be on full display as highs warm into the upper 70`s along the southern Oregon coast Tuesday and Wednesday. The overall weather pattern will gradually begin to change on Thursday as some of the models are predicting some weak disturbances riding around the large area of high pressure. There is moderate to low confidence on how all the details will play out on Thursday. As the forecast stands right now, there is a slight chance for rain showers over sections of the coast and in northern California. The forecast Friday into Saturday still is uncertain in some respects. We have high confidence that we will see cooler temperatures move in during the weekend in addition to a high probability that it will rain and snow at higher elevations at some point this weekend. However, the finer details on the exact timing when all of this will happen is still unclear. The low could move in a little quicker on Friday or could be more delayed and move in earlier on Saturday morning. The message still remains that higher elevations will likely see some accumulating snow during next weekend as snow levels are around 4500 to 5500 feet for most of the weekend. -Smith && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Dense Fog Advisory until 10 AM PDT this morning for ORZ023>028. CA...None. Pacific Coastal Waters... - Gale Watch from late Tuesday night through late Wednesday night for PZZ356-376. - Small Craft Advisory until 5 AM PDT Thursday for PZZ356. - Hazardous Seas Watch from Tuesday afternoon through late Wednesday night for PZZ356-376. - Small Craft Advisory from 5 PM Tuesday to 5 AM PDT Thursday for PZZ350-370. - Hazardous Seas Watch from late Tuesday night through late Wednesday night for PZZ350-370. - Small Craft Advisory until 5 AM PDT Wednesday for PZZ376. $$ BTL/CZS/MAS

157 FXUS66 KEKA 231129 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 429 AM PDT Mon Sep 23 2019 .SYNOPSIS...Warm and dry conditions will occur across the region through Wednesday. Thereafter, cooler and potentially showery weather will spread across the area this Friday through the weekend. && .DISCUSSION...Large-scale subsidence is occurring across the region as an upper trough departs east across the Great Basin, and a ridge builds eastward from the NERN PAC. A moist antecedent airmass at the surface due to recent rainfall was aiding in patchy fog along the coast Monday morning, but clear skies will occur across all of NWRN CA by this afternoon as a warm dry airmass spreads southeast with the development of offshore winds. Abundant sunshine and warm offshore winds will aid in high temperatures in the 80s to near 90 across the interior today...with further warming into 90s to near 100 on Tuesday and Wednesday. Much cooler weather is forecast to spread south across NRN CA Friday into the weekend as a large upper trough digs over the WRN CONUS. Interior highs are forecast to cool into the 60s by Saturday, and overnight lows near freezing will be possible across wind sheltered valleys in Trinity County Sunday night and Monday night. In addition to the cooler weather...light showers are expected to develop across the region Saturday and Sunday. However, impacts associated with shower activity will likely be minimal. JMG && .AVIATION...Sky conditions have improved overnight as high pressure rapidly builds behind yesterdays weak weather system. Widespread VFR conditions are expected to continue throughout the day and even over the next few days as some drier offshore flow moves through the area. Afternoon NW winds develop along the coast and become quite gusty on Tuesday and Wednesday. && .MARINE...A fresh round of headlines is poised to go into effect across the coastal waters as winds and seas quickly ramp up today behind the departing trough. Small Craft Advisory conditions will develop across the outer waters and continue to increase to gales later today. Gale warnings are in effect for the outer waters while hard sca`s are in effect for the inner waters. The Gales look to persist across the outer waters through Thursday, which will allow short period seas to build into the 15 to 18 foot range by the middle of the week. Although the strongest winds are generally expected to remain farther offshore, the steeper seas being generated beyond 10NM will spread into the nearshore zones and produce potentially hazardous seas in the 12-15 foot range during the middle of the week. A Haz Seas watch is in effect to reflect the potential for the rough sea state. && .FIRE WEATHER...Surface high pressure is forecast to build south from Oregon into Nevada through Wednesday. North-northeast ridgetop winds will strengthen in response to the high, with gusts from 20 to 30 mph possible Monday night and Tuesday night. The gusty winds combined with afternoon RH values in the teens followed by poor overnight recovery will aid in locally critical fire weather conditions over portions of Mendocino, Lake, and extreme southern Trinity Counties. JMG && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning from 9 PM this evening to 11 AM PDT Wednesday for CAZ276-277. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 PM PDT this afternoon for PZZ470. Gale Warning from 3 PM this afternoon to 2 PM PDT Thursday for PZZ470. Small Craft Advisory from 9 AM this morning to 5 PM PDT Thursday for PZZ450-455. Hazardous Seas Watch from Tuesday afternoon through Thursday afternoon for PZZ450-455. Small Craft Advisory until 9 AM PDT this morning for PZZ475. Gale Warning from 9 AM this morning to 5 PM PDT Thursday for PZZ475. && $$ 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 232055 AFDMTR Area Forecast Discussion National Weather Service San Francisco Bay Area 155 PM PDT Mon Sep 23 2019 .SYNOPSIS...Dry offshore flow and gusty winds will result in critical fire weather concerns for the North and East Bay Mountains/Hills through Wednesday morning. A robust warming trend is also on tap for Tuesday and Wednesday with hot temperatures expected across inland valleys and very warm conditions even near the coast. Temperatures will trend sharply cooler late in the week and into the upcoming weekend with the potential for unsettled weather conditions as an upper level trough deepens over the West Coast. && .DISCUSSION...as of 1:55 PM PDT Monday...Under sunny skies, afternoon temperatures are warmer than yesterday at this time by as many as 10 degrees with readings ranging from the 60s at the coast to the upper 80s inland. Surface pressure gradients are starting to tighten in the offshore and northerly directions with WMC- SFO now at 4.7 mb and ACV-SFO at 6.2 mb. The offshore gradient will continue to tighten overnight and winds will become gusty over the North Bay Mountains and East Bay Hills. This, along with lowering RH values overnight will maintain critical fire weather risk through Wednesday morning, and a Red Flag Warning remains in effect (See Fire Weather portion below for more info.) Building high pressure will bring a robust warming and drying trend to the area for Tuesday and Wednesday. Widespread high temps in the 90s to around 102 can be expected across inland areas both Tuesday and Wednesday, with coastal areas in the 80s. Overnight temperatures will also be warm, especially in the hills tonight and again Tuesday night. This will exacerbate the heat impacts across many areas. Thus, a Heat Advisory has been issued for Tuesday and Wednesday for all inland valleys, the near shore zones, and some coastal and mountain locations. The Heat Advisory includes...but is not limited to...the cities of San Francisco, San Jose, Santa Rosa, Santa Cruz and Monterey. The heat wave will be short-lived, thankfully, as an upper level trough approaches the coast after midweek. This will bring onshore flow and much cooler temperatures to near-coastal areas on Thursday. By Friday widespread cooling is expected as the trough deepens over the western states. Latest model runs are showing decreased rain chances for our area with this trough, but cool and unsettled conditions are still expected through the weekend. Another offshore wind event could be in store by early next week. && .AVIATION...As of 10:38 AM PDT Monday...for 18Z TAFs. Satellite imagery shows stratus dissipating inland leaving VFR conditions at all sites this morning. VFR prevailing through the period. Dry offshore flow to develop overnight bringing LLWS concerns to some taf sites (STS, OAK, SFO, SJC, LVK). Winds aloft should ease by early tomorrow morning. Generally light winds at the surface today with locally breezy onshore winds in the afternoon near the coast. Vicinity of KSFO...VFR through the period. NE winds this morning to increase and turn onshore by the afternoon (~20-21z). Increasing NE winds aloft tonight into early tomorrow morning creating some LLWS. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR to prevail through the period. Dry offshore winds overnight are expected to limit redevelopment of stratus. Light winds through the period, locally breezy down the Salinas Valley this afternoon. && .FIRE WEATHER...as of 03:02 AM PDT Monday...Very dry conditions and breezy to gusty north/northeast winds will develop over the region beginning late tonight. The strongest offshore winds are forecast to occur in the higher elevations of Napa and Sonoma Counties as well as the East Bay Hills where offshore winds will gust to 30 to 35 mph at times from late tonight through Wednesday morning. Some of the highest peaks and ridges could see gusts up to 40 mph in the aforementioned locations. Along with these stronger winds, minimum relative humidity values are forecast to drop into the teens and lower 20s with overnight recoveries reaching only to between 30 to 50 percent. Thus, a Red Flag Warning remains in effect for the locations mentioned above (Fire Weather Zones 507 and 511) from 9 PM this evening through early Wednesday morning. && .MARINE...as of 8:44 AM PDT Monday...North to northwest winds will increase across the coastal waters today. The strongest winds will be over the northern outer waters where gale force gusts are possible. Locally breezy winds will also develop at the typical coastal jet spots south of Point Sur, western Santa Cruz county, and south of Point Arena along the Sonoma coast. Short period wind generated waves will return with periods of 5 to 6 seconds. Mixed seas will also continue with a northwest swell at 8 to 10 seconds and a light longer period southerly swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...Red Flag Warning...CAZ507-511 SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM GLW...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Arena to Pt Reyes 0-10 nm until 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM && $$ PUBLIC FORECAST: Sims AVIATION: AS MARINE: AS FIRE WEATHER: RGass 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 231933 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1233 PM PDT Mon Sep 23 2019 .SYNOPSIS... A few showers are possible through Tuesday, otherwise drier weather is expected with occasional breezy winds. Much cooler and unsettled weather is likely late this week and into the weekend. Mountain snow, non accumulating valley snow, and frost or freeze conditions will be possible. && .DISCUSSION... Today through Tuesday: A few showers persist across portions of the Idaho Panhandle early this morning as what remains of yesterday`s shortwave trough passes through the region. Elsewhere, increasing subsidence across central and eastern Washington is bringing mostly clear skies. The best chance for valley fog formation this morning will be across the Idaho Panhandle and the Methow Valley, though midlevel clouds will likely limit its coverage. Expect increasing cloudiness through the course of today as a quick- moving northwesterly shortwave passes through the region. The Cascades, northern mountains, and Idaho Panhandle will have the best chance of measureable rainfall with this system. However, hi-res models have consistently shown the potential for sprinkles or light showers this afternoon and evening as far south as I-90 or the Palouse. The other tricky part of this forecast period will be gusty winds as these weather systems pass through. Look for west to southwest wind gusts of 20 to 30 mph this afternoon and early evening across the Columbia Basin, West Plains, and into the Palouse. Winds increase a bit more on Tuesday as an upper level jet streak noses into the region. Look for high temperatures to generally be in the 60s to 70s today and Tuesday, which is around to slightly cooler than normal. Dang Tuesday night and Wednesday...Models are in pretty good agreement in depicting a fast northwest zonal flow through the region for this period. The polar jet axis will reside just north of the region and a sustained westerly surface pressure gradient will promote breezy conditions across the region. This flow regime suggests conditions will be dry with most of the area except for the high Cascades benefiting from a downslope rain shadow. Wednesday is the last confidently forecast dry day for most of the region. Wednesday night and Thursday...There is consistency with the GFS and ECMWF deterministic models in plowing a deep and juicy fetch of Pacific moisture into the region as zonal flow continues...but with a short wave embedded in this flow scheduled to arrive late Wednesday night and Thursday. In addition to continued breezy conditions on Thursday...this moisture feed will be favorable for light rain and some high mountain snow across much of the area on Thursday with the eastern Washington mountains and the Idaho Panhandle high terrain subject to picking up a quarter to a half of an inch of rain. Rain amounts in the eastern basin will be on the order of a few hundredths of an inch...with the deep basin holding onto a narrower rain shadow in the Cascades lee. Friday through Sunday...Transitioning from deterministic model interpretation to ensemble guidance evaluation in these far periods suggests a big change is afoot for the end of the week and into next weekend. Models still are rather insistent in carving a deep trough into the northwestern US out of Canada drawing drier but colder Canadian continental air into the region with it. There will still be some ambient moisture available...and in this colder air mass not as much moisture will be necessary to generate mountain snow showers and in the valleys and even the eastern basin it is possible that snow levels will drop to the surface during the overnight and early morning hours before retreating to the higher terrain during the daytime. No appreciable accumulation is expected in the lower elevations and in this trough cusp actual showers will probably be spotty and hit-and-miss through the weekend. This pattern will however bring a strong likelihood of pockets or even areas of frost to threaten ripening vegetables each morning beginning Friday morning through the weekend with daytime highs topping out well below normal for late September. /Fugazzi && .AVIATION... 18Z TAFS: A weather system will spread more clouds into the region into this evening. CIGS are expected to be primarily VFR at the TAF sites except for a lingering MVFR cloud deck around the KGEG/KSFF/KCOE TAF sites through 20z. There is a chance of light rain with this feature as well but with the best chances over the mountains of NE Washington and the N Idaho Panhandle. Behind this wave the boundary layer moistens again late tonight over the Idaho Panhandle and extreme Eastern WA with upslope winds with KCOE having the best threat of MVFR conditions developing Tuesday morning. JW && .PRELIMINARY POINT TEMPS/POPS... Spokane 66 48 70 43 66 48 / 20 10 0 0 0 40 Coeur d`Alene 64 46 69 41 65 47 / 20 10 0 0 0 50 Pullman 66 46 69 41 66 46 / 10 0 0 0 0 40 Lewiston 74 56 77 51 73 56 / 10 0 0 0 0 40 Colville 69 39 73 36 71 42 / 40 30 0 0 10 50 Sandpoint 62 45 67 40 64 46 / 30 20 10 0 10 70 Kellogg 62 49 64 44 62 48 / 30 10 20 0 0 70 Moses Lake 72 49 77 45 74 50 / 10 10 0 0 0 20 Wenatchee 68 54 72 51 71 53 / 20 10 0 0 0 30 Omak 67 48 72 46 69 49 / 30 10 0 0 10 40 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$

000 FXUS66 KPDT 231730 AAA AFDPDT Area Forecast Discussion...Updated National Weather Service Pendleton OR 1030 AM PDT Mon Sep 23 2019 Updated aviation discussion .SHORT TERM...No major weather concerns today as the area lies under a relatively dry northwest flow aloft. Doppler Radar near SEA is showing increasing showers along the Olympic Peninsula associated with a front that will remain stationary over western WA through Tuesday, and this front will bring showers to the east slopes of the WA Cascades north of Trout Lake this afternoon and evening. The front will also enhance surface winds due to a tightening cross-Cascade gradient, and the eastern valleys of the Cascades from the Kittitas Valley down to the eastern Columbia River Gorge will have breezy winds today with gusts 30-40 mph this afternoon and evening. Yesterday`s cold front spread cooler air, and today`s highs will be a tad cooler--60s to mid 70s. Only update to the forecast was to increase cloud cover this morning in a few zones. Otherwise, no changes. Wister && .AVIATION...18Z TAFs...VFR conditions should prevail through the next 24 hours. Broken mid and higher level clouds are moving into the area from the northwest and will continue to do so through this evening generally above 5K feet AGL. Clouds will begin to clear after 06Z though this may allow some scattered lower clouds to develop at 3K-5K feet after 07Z at KRDM, KBDN, KALW and KPDT. Winds are increasing and should reach 10 to 20 kts with higher gusts at KDLS, KPDT, KALW and KPSC through 03Z this evening. Otherwise winds will remain below 12 kts for the next 24 hours. Perry && .PREV DISCUSSION... /issued 248 AM PDT Mon Sep 23 2019/ SHORT TERM... Today through Wednesday Night... Mainly dry conditions have developed in the wake of yesterdays storm system with scattered to widespread cloudiness persisting. This will likely continue through the morning hours as weak lift continues along the northern periphery of a closed low now digging into the Desert Southwest. As this feature departs, upper ridging will build in across southern Oregon and northern California into tonight. This ridge will ultimately be shunned southward, however, by a series of shortwaves moving through rather fast west/northwest flow across the Pacific Northwest. Each of these waves will bring bouts of increased mid and high cloud cover, and chances for showers mainly in the Washington Cascades and their east slopes. This pattern will support rather breezy conditions both today and tomorrow, with a tightening pressure gradient and rather strong winds just off the surface. The typically windier locations of the Columbia Gorge and lower Columbia Basin will likely see wind gusts in the 25 to 35 mph range, which is shy of advisory criteria, but it will certainly be noticeable for those traveling. Temperatures to remain rather mild each afternoon with highs generally in the 60s and 70s and lows in the 40s and 50s. 79/Austin LONG TERM... Thursday through Sunday... A frontal system will be pushing through eastern Washington and Oregon on Thursday with some light precipitation and breezy to locally windy conditions. Cooler air arrives behind the front with snow levels lowering to 5000-6000 feet by Friday morning with some lingering showers. Overall pattern from Friday through the weekend shows an upper level low in southern Canada by Friday night that drops south into eastern Washington and Oregon through the weekend, but models continue to show varying amounts of moisture and differences with timing. Scattered showers can be expected through the period with some mix of rain and snow during the overnight hours for the mountains. This pattern will allow for some of the coldest air so far this fall with frost and some freezing temperatures possible beginning Friday morning through the weekend with daytime highs topping out well below normal for late September. 93 && .PRELIMINARY POINT TEMPS/POPS... PDT 69 51 74 45 / 0 0 0 0 ALW 73 55 77 50 / 0 0 0 0 PSC 74 55 79 51 / 0 0 0 0 YKM 72 49 76 45 / 10 10 0 0 HRI 74 53 79 48 / 0 0 0 0 ELN 66 50 70 47 / 10 10 10 0 RDM 69 46 74 43 / 0 0 0 0 LGD 69 50 72 45 / 0 0 10 0 GCD 71 48 76 45 / 0 0 0 0 DLS 72 56 77 53 / 0 10 10 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 85/83

547 FXUS65 KREV 231002 AFDREV Area Forecast Discussion National Weather Service Reno NV 302 AM PDT Mon Sep 23 2019 .SYNOPSIS... For today, expect tranquil weather conditions with a light northeast wind and cooler temperatures as a cold front makes its way out of the region. A warmup will then occur Tuesday and Wednesday before another, stronger weather system brings gusty winds late week along with much colder temperatures and shower chances Friday through the weekend. && .SHORT TERM... Light rain showers in northern Washoe and Pershing/Churchill counties are still visible on radar early this morning due to the unstable atmospheric conditions under the current short wave trough. Embedded lightning flashes were even detected suggesting deeper convection than earlier anticipated. Any remaining showers should move out of the region this morning as the trough shifts towards the southeast and into southern Nevada and Arizona. A clear sky and light north-northeasterly winds will be leftover for this afternoon keeping temperatures on the cooler side, below climo. Expect temps to peak in the mid 70s for western Nevada and upper 60s for the Sierra valleys. For Tuesday and Wednesday of this week, the light northeast flow and a clear sky will persist with a warming trend forecast as the eastern edge of a high pressure system, centered roughly 800 miles off the California coast into the Pacific, noses in over the region. High temperatures for both days are expected to be at or just above normal for early fall with upper 70s/low 80s for western Nevada and mid 70s for the Sierra. Low temperatures overnight will also be on the warmer side forecast to be a few degrees above climo. Northwest winds and cloud cover increases by Thursday morning as the active weather pattern returns to the west. -LaGuardia .LONG TERM...Thursday through Sunday... As is sometimes the case...the medium range deterministic model solutions can change rather substantially over a 12 to 24 hour period. Such is the case now...and that lowers confidence in the forecast for the end of the week and the upcoming weekend; confidence is actually higher for the Saturday/Sunday time frame than either Thursday or Friday. Because there is more deviation in the operational model guidance than we previously saw...and the ensemble members have less spread...we have opted not to change much with the inherited forecast. Subsequent shifts will need to reevaluate as we may need to make some substantial changes early in the extended period over the day or so. First let us say the ensemble members are still in good agreement that a much colder and wetter system will drop into the region for the weekend. It is getting to the weekend that becomes a bit more problematic. Both the ECMWF and GFS operational solutions have slowed and weakened the initial shortwave trough for Thursday and early Friday. This delay in timing could mean less wind each day and slightly warmer temperatures along with a lack of showers. We left some mention of showers near the Oregon border as a nod to previous solutions Thursday afternoon and let that spread south overnight into Friday. This is at odds with the operational solutions...but more closely aligns with the ensemble guidance. The operational model solutions bring the main longwave trough and cold front south into the area Saturday and Sunday. Based on current projections Sunday might be the coolest day...but the model guidance is quite a bit warmer than we saw 24 hours ago. We are hewing a bit more closely to the ensemble guidance which would result in cooler temperatures and lower snow levels both days. POPs and QPF were not altered much. This does not look to be a huge precipitation event during any one particular 6 hour period...but rain could fall off and on for a couple of days. That might produce over an inch of liquid in some locations. Snow accumulations are likely in the higher elevations as snow levels drop to near 5000 feet in northeast California and down to around 6500 feet in the Sierra. Accumulations could be a few inches above 7000 feet. Most road surfaces are not likely to see a significant accumulation as the ground and road surfaces should still be rather warm. The highest passes...above 8000 feet...have the best chance for accumulation late Saturday night and early Sunday. Again we must reiterate...the model solutions for the latter part of the work week into the weekend are proving to be quite changeable. While confidence is not as high in any particular solution this morning compared to previous days...we are confident there will be substantial change to the weather by the weekend. && .AVIATION... Isolated showers north of Interstate 80 and east of Highway 95 should slowly decrease in coverage early this morning. Brief periods of lowered visibility and ceiling near those showers should give way to VFR conditions for the remainder of the day. There is a roughly 40 percent chance of fog around KTRK this morning...but any that develops should lift by 16 UTC. A building ridge should keep conditions mainly VFR for Tuesday and Wednesday with relatively light winds. Increasing winds aloft are likely by late Thursday as another are of low pressure begins to drop south out of the Pacific Northwest. Timing is a bit uncertain with this system. Some light rain showers could develop in the vicinity of most terminals by early Friday...but the better chance for inclement weather is next weekend. We are likely to have prolonged periods of IFR/MVFR conditions by the weekend with snow possible in the Sierra and higher elevations of northeast California. Gusty winds and turbulence along with mountain obscurations would also be likely. $$ .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit... http://weather.gov/reno

000 FXUS66 KSTO 231022 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 322 AM PDT Mon Sep 23 2019 .SYNOPSIS... Hot and dry weather with breezy northerly winds will lead to elevated fire weather concerns early this week. Significant cool down with a chance of showers late in the week. && .DISCUSSION... Satellite imagery indicates the upper trough is over western Nevada early this morning and is in the process of closing off as a strong vort drops southeastward near Lake Tahoe. Skies have cleared behind the vort, other than some lingering low clouds over eastern Shasta County and northern Plumas County, but remain partly cloudy over the southern part of the forecast area. Current temperatures are milder compared to 24 hours ago and generally range from the upper 30s and lower 40s in the mountain valleys, to the upper 60s across milder portions of the Central Valley. Northerly surface gradients have already begun to tighten (KMFR-KSAC over 8 mbs at 09Z) resulting in local wind gusts in the teens to lower 20 mph range over the northern Sacramento Valley and surrounding foothills. The low will move south to near Yuma early Tuesday, and into northern Baja by early Wednesday, allowing ridging from the eastern Pacific to build into NorCal in its wake. Along with dry conditions and hotter temperatures, breezy to locally windy northerly flow will develop elevating fire weather concerns into mid-week. The strongest northerly winds for the Sacramento Valley will occur during each afternoon and evening thru Wednesday where gusts of 25-35 mph will be possible, but the strongest winds will retreat to the western edge of the valley each night. Locally gusty east winds will also be likely each night across the Sierra Nevada and foothills. Temperatures will only warm a few degrees today compared to Sunday, but hotter weather is expected Tuesday and Wednesday when highs warm to 5-10 degrees above average with warmest valley readings around 100. Some cooling will be possible by Thursday as short-waves moving through the PacNW flatten the ridge and induce a return of onshore flow. && .EXTENDED DISCUSSION (Friday THROUGH Monday)... Anomalously deep troughing will settle over the western U.S. late this week into early next week, bringing significantly cooler temperatures and precipitation chances across interior NorCal. The highly amplified setup over North America has been rather well advertised as a powerful ridge across the Gulf of Alaska forces a deep trough to position itself over the West. During the Fri-Sun timeframe, forecast highs could drop 15 to 25 degrees below seasonal normals. Valley locations should see temperatures in the upper 60s to low 70s, while 30s and 40s would be more commonplace across the mountains. At this point, precipitation coverage and amounts remain uncertain, but it appears best chances will be over higher terrain. Snow levels could lower to around 5,500 to 6,500 foot over the weekend, so cannot rule out the potential for some snow over the higher elevations. && .AVIATION... VFR conditions are expected over the next 24 hours. Northerly wind gusts increase to 20-30 kts across the Sacramento Valley by 15Z-18Z Monday. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 PM this evening to 11 AM PDT Wednesday for 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-Lake County Portion of Lake-Napa-Sonoma Unit-Northern Motherlode From 1000 to 3000 Ft. Includes portions of Nevada- Yuba-Placer-Amador and ElDorado Units-Northern Sacramento Valley to Southern Tehama County Line 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)-Northern Sierra Including the Tahoe and ElDorado NF/S West of the Sierra Crest-Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-Glenn Unit- Southern Motherlode From 1000 to 3000 Ft. Includes portions of Calaveras-Tuolumne Unit-Southern Sacramento Valley in Yolo- Sacramento Far Western Placer, southern Sutter and Solano County Below 1000 Ft-Stanislaus NF West of the Sierra Crest. && $$

000 FXUS65 KMSO 232004 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 204 PM MDT Mon Sep 23 2019 .DISCUSSION...Northwesterly flow will persist over the Northern Rockies through the end of the work week. A few subtle disturbances will be making their way through this flow pattern. The first feature will be a strong upper level jet streak will sag over the Northern Rockies on tomorrow. This jet streak will bring widespread gusty westerly winds to the region, as valleys could experience gusts up to 35 mph and the mountains experiencing gusts up to 60 mph by Tuesday afternoon. The second disturbance will be on Thursday which will bring precipitation to the area, especially across northwest Montana. Snow levels will be low enough that Logan and Marias passes could experience some light snow accumulations by Friday morning. Temperatures will be hovering around seasonal readings for the first part of the week, then cooling to around 5 to 10 degrees below average by Friday. A significant pattern change is still forecast for this weekend into next week. A deep low pressure system will settle over the Pacific Northwest, potentially causing significant impacts to the Northern Rockies. The first concern will be the extremely cold airmass for this time of year that will infiltrate the region. Temperatures will be 20 to 30 degrees below normal by Sunday. Widespread freezing conditions are expected throughout the Northern Rockies by Sunday and Monday morning. A few high valley locations could experience temperatures in the low 20s by Monday morning. This cold air will cause snow levels to crash to most valley locations throughout the region. Confidence is low to moderate on the placement of the wrap around precipitation associated with this low pressure system. The current solution indicates that the mountains along the Continental Divide could experience at least of foot of snow accumulation, with valleys along the divide (Butte/Georgetown/Seeley lake/Polebridge) could receive a few inches. The remainder of western Montana will experience at least a rain/snow mix at some point during this event. While the valleys of Idaho should remain all rain. Another concern will be the strong northeasterly winds on Saturday as the cold air gets ushered into the Northern Rockies. These winds could cause impacts on area lakes, especially Flathead. High confidence on the pattern change, but low to moderate confidence on the impacts during this weather change. && .AVIATION...Numerous clouds will impact all terminals the next 24 hours. There is a small chance for a few rain showers at all terminals through 24/1200z. The biggest impact for aviation concerns will be gusty westerly winds Tuesday afternoon. Gusts of 20-30 mph are anticipated Tuesday. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

958 FXUS65 KBOI 232101 AFDBOI Area Forecast Discussion National Weather Service Boise ID 301 PM MDT Mon Sep 23 2019 .SHORT TERM...Tonight through Wednesday...Northwest flow will persist over the region through the period. Moisture in the flow will bring periods of cloud cover tonight and Tuesday. Breezy conditions will develop each afternoon as winds aloft mix to the surface. Temperatures through the period are near normal. .LONG TERM...Wednesday night through Monday...Unsettled northwest flow continues mid-week as temperatures gradually cool down. A weak cold front on Friday will produce breezy conditions and cause temperatures to fall nearly 5 degrees. The cooling trend continues on Saturday as temperatures drop to roughly 15 degrees below normal. The timing of a deep upper level trough moving into the Intermountain West still holds some uncertainty among long range models, though widespread precipitation is expected to enter the region on Saturday. Snow levels will drop between 6000-7000 ft MSL for the onset of precip and will continue to fall as the trough deepens. Cool and unsettled conditions persist through Monday as the trough lingers over the Intermountain West. Snow levels will drop to between 4000 and 5500 ft for Sunday and Monday with temperatures remaining well below normal. && .AVIATION...VFR under scattered passing high clouds. Surface winds: generally W to NW 5-15 kts with local gusts up to 20 kts. Winds aloft at 10kft MSL: W to NW 15-25 kts. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...DG LONG TERM....AL AVIATION.....AL

226 FXUS65 KLKN 230918 AFDLKN Area Forecast Discussion National Weather Service Elko NV 218 AM PDT Mon Sep 23 2019 .SYNOPSIS...Low pressure will bring a few showers and thunderstorms to northern and central Nevada today. This system will quickly weaken as is moves through. High pressure will then bring a nice spell of weather for most of the week. A wet storm system is poised to bring valley rainfall and mountain snow next weekend. && .SHORT TERM...Today through Tuesday evening. Satellite imagery confirms model placement of the upper low center within the incoming trough, now moving north of the Sierra range. There is some diffluence aloft of most of the LKN CWFA currently however radar returns and thus showers are very light thus far. Lightning is hugging near the leading edge of the low circulation. Model agreement continues to be very good for the short term period, taking this low feature on a relatively unusual track over the next couple days. Today. The trough of low pressure will move very quickly southward through the Great Basin. The low center will track east of the spine of the Sierras to relocate just north of Las Vegas by day`s end. Thunderstorm potential seems more likely in the morning hours, focused near the center of the low. This system will not produce much precipitation. High temperatures will range from the 60s to around 70 degrees. Tonight through Tuesday evening. Low pressure will close off circulation and break from the mean trough, tracking from southern Nevada in a slight retrograde to move over Baja California by Tuesday evening. This will allow a fast spillover of very strong Pacific ridge into the Great Basin. Temperatures will quickly rebound in the drier regime. High temperatures will reach well into the 70s. Low temperatures will range from the mid 30s to the mid 40s. .LONG TERM...Tuesday night through next Sunday. Warm and dry across the CWA Tuesday night through at least Wednesday night with the region between systems. Models continue to show broad trough energy dropping down through the northwestern U.S. by Wednesday, reaching the Great Basin region by Thursday. Light precipitation is possible on Thursday over northern NV. While models continue to show cooler and much wetter conditions across the CWA Thursday night through next weekend, significant discrepancies remain between models with respect to timing and tracking of the system. As such run to run QPF amounts vary. Only minor adjustments to the previous forecast package at this time, with significant precipitation still expected over large portions of northeastern and central NV later this week. && .AVIATION...A low presssure system will quickly move through Nevada today. Light showers are most probable at KWMC and KEKO this morning. However VFR conditions are expected to continue at all sites today, and through Tuesday morning. && .FIRE WEATHER...Low pressure will move through Nevada today. Lightning strikes should be few and limited to fire zones 454 and 457. Precipitation will also be light from this quick-moving system. Dry conditions will resume tonight and last through Thursday. A very wet system is poised to drop into the Great Basin next weekend. && .LKN WATCHES/WARNINGS/ADVISORIES... None. && $$ 92/96/99/92