124 FXUS66 KSEW 211000 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 300 AM PDT Mon Sep 21 2026 .SYNOPSIS... Upper level ridge well to the east with an upper level trough offshore today. Weak system moving by to the north this afternoon. Convergence zone possible over the Central Puget Sound late tonight into Tuesday morning. Next system spinning out of the trough dissipating as it reaches the area Wednesday. Stronger system arriving Thursday night into Friday morning. Flat upper level ridge over Western Washington next weekend with a warm front dissipating off the coast Sunday. && .SHORT TERM /TODAY THROUGH WEDNESDAY/... Satellite imagery looks almost identical to early Sunday morning with low clouds and fog starting to form over the coast and most of the lowlands. Many locations are already down to the mid to upper 40s at 3 am/10Z with the remainder of the area in the lower to mid 50s. Like Sunday morning good set up for fog and low cloud development across the area this morning. Light flow in the lower levels combined with the longer nights and low level moisture will produce areas of low clouds and fog. Tops near or below 1000 feet with a late morning/midday breakout. Weak system moving by to the north spreading middle and high level clouds over the area this afternoon for partly sunny/mostly cloudy skies. Highs remaining a little below normal, in the 60s and lower 70s. Southwesterly flow aloft continuing tonight and Tuesday with an upper level trough offshore. Increasing low level onshore flow with a possible convergence zone late tonight into Tuesday morning over the Central Puget Sound producing some drizzle. The increase in the onshore flow will limit fog coverage late tonight but with plenty of low level moisture will still have low clouds developing in the overnight hours. Low clouds dissipating midday Tuesday with mostly sunny skies in the afternoon. Lows in the upper 40s to mid 50s. Highs in the 60s. Next system spinning out of the upper level trough offshore falling apart as it reaches the coast early Wednesday morning. What is left of the system moving through the Northwest Interior later in the morning for a slight chance of showers. A couple hundredths along the north coast will be the best this system can do rain wise. Middle and high level clouds with the system will make for a partly sunny/mostly cloudy day for the interior. Lows in the mid 40s to lower 50s. Highs in the 60s. Felton && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Models in good agreement with a consolidated front reaching the area late Thursday night/Friday morning. Rain out ahead of the front spreading over the area Thursday afternoon into Thursday evening. This system will have a little juice with it with a half to one inch of rain along the coast, Olympics and Central and Southern Cascades and a quarter to half inch over the interior. Right now the North Cascades looks to be the wettest location with one to one and a half inches of water. Snow levels lowering to 6000 to 6500 feet giving the higher elevations a few inches of snow. Upper level trough behind the front showing signs of digging south and becoming slightly negatively tilted Friday morning which could stall the system over the area into Friday afternoon. Upper level trough moving through Friday evening. Cool days Thursday and Friday with highs only in the lower to mid 60s. Lows in the mid 40s to lower 50s. Models continue to be in good agreement over the weekend with a flat upper level ridge over the area. Warm front dissipates before it reaches the coast Sunday. Post frontal onshore flow and the lack of much ridge building will keep temperatures cool. Highs remaining in the lower to mid 60s. Mornings will be on the cool side as well with the coldest locations dropping into the upper 30s. Lows in the 40s for most places. Just a note the autumnal equinox is at 5:05 pm Tuesday the 22nd. Felton && .AVIATION... Otherwise mostly clear skies and light to calm winds will promote continuing development of low stratus and fog this morning. It remains most prolific across southwest WA and along the coast, but will continue to develop across portions of the rest of the interior this morning through around 15Z. Compared to yesterday, the coverage of fog appears to be slightly less. Clouds will then begin to lift and scatter between 17-20Z this morning for VFR conditions through much of the remainder of the TAF period. Onshore flow will increase tonight, allowing for another round of stratus to build late tonight into early Tuesday, through primarily around or after 12Z Tuesday. The highest probabilities will be along the coast and through the central Puget Sound interior with convergence following the passage of a dry cold front late tonight. Mostly calm winds will be westerly 8 kt or less during the day, except up to 10-15 kt through the Strait of Juan de Fuca this evening. KSEA...VFR early this morning with clear skies. Fog will develop in the valleys near the terminal, through confidence is lower in it forming directly over the terminal later this morning. Model probabilities are in the 10-20% range for IFR or lower between 14- 17Z. VFR conditions then prevail with high clouds overhead. A dry cold front will move through tonight, and behind it, weak convergence will allow for MVFR cigs to develop overnight into Tuesday morning, after around 10-13Z Tuesday. Light N winds 4 kt or less will become more W/NW 4-6 kt after around 18Z. Winds become light again tonight. 62 && .MARINE... High pressure will weaken over the coastal waters this morning. A weak cold front will traverse the area waters this afternoon into early Tuesday, resulting in increased onshore flow. Winds will increase this afternoon through the Strait of Juan de Fuca and will reach Small Craft Advisory thresholds through late tonight. The advisory was extended slightly to account for the potential of some lingering gusts into early Tuesday morning. Another push of westerlies through the Strait of Juan de Fuca is forecast Tuesday evening, but guidance remains confident in the strongest winds remaining on the Canadian side of the strait.A weakening front then moves across the waters on Wednesday, with the potential for another weather system moving through late Thursday into Friday. Seas of 3 to 5 feet will build to 7 to 9 feet tonight as a longer period northwesterly swell arrives to the coastal waters. Ensemble guidance has backed off on the probability for seas greater than 9 ft (15-25% or less). Seas then subside to 6 to 8 feet Tuesday afternoon and remain like so through the remainder of the week. 62 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 2 PM this afternoon to 3 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca. && $$

525 FXUS66 KPQR 211201 AAA AFDPQR Area Forecast Discussion...UPDATE National Weather Service Portland OR 500 AM PDT Mon Sep 21 2026 Updated aviation discussion. .SYNOPSIS...Temperatures trend cooler through the workweek as broad upper-level troughing develops over the Gulf of Alaska. Dry weather with areas of morning fog and low clouds giving way to afternoon will continue through Wednesday. The broad upper-level trough over the Gulf of Alaska will deepen and progress towards western Washington and Oregon late Thursday into Friday, bringing increasing chances for widespread rain. Trending dry over the weekend in the wake of this trough. && .SHORT TERM...Now through Wednesday night...The short term forecast is highlighted by continued dry weather, near normal to slightly below normal temperatures, and areas of morning fog and low clouds giving way to increasing afternoon sun. Expect daily high temperatures in the low to mid 70s over inland valleys and 60s at the coast. Morning lows will generally range anywhere from the mid 40s to mid 50s, warmest over urban areas and coolest over rural areas. In regards to the large scale weather pattern, model ensemble guidance remains in good agreement for increasing southwest flow aloft ahead of broad upper level troughing over the Gulf of Alaska. This trough will generally not be amplified enough yet to bring rain back into northwest Oregon or southwest Washington through Wednesday night, as the main weather system associated with this trough will be impacting the British Columbia coast. The only potential exception to that is Tuesday night through Wednesday morning along the south Washington and far north Oregon coast when there is a very low chance (5-10%) for light rain with an initial weak wave and attendant decaying surface front. Despite the lack of precipitation, 500 mb heights and temperatures aloft will be on a gradual decrease as the trough begins to deepen towards the middle of the week. This will allow temperatures to cool slightly each day Monday through Wednesday, however only by a degree or two each day. -23 .LONG TERM...Thursday through Sunday night...Troughing over the Gulf of Alaska will approach the region in earnest late Thursday into Friday as the trough becomes more amplified and progresses eastward towards Washington and Oregon. As such, the 24-hour probability for precipitation remains fairly high during that time, ranging between 55-65%. The main reason probabilities are not higher than that is due to a subset of ensemble guidance that remains dry, mainly with the GEPS as this ensemble system shows a higher likelihood of the trough deamplifying after moving inland with the bulk of the precipitation falling farther to the north over northwest Washington. While this is not the most likely outcome, it is worth mentioning as it is still within the realm of possibilities. Those with outdoor plans late Thursday or Friday should monitor the forecast over the coming days to see if rain chances trend up or down. If rain does fall, do not expect any flooding impacts as rain amounts would most likely range somewhere between 0.1-0.6 inches, highest in the mountains and lowest over the Willamette Valley. The wettest model solutions produce 0.5-1.2 inches of rain, however chances for rain amounts this high are only at 10% as suggested by the NBM 90th percentile. Even these rain amounts would not be enough to produce flooding given the extended duration. Upper-level heights look to rebound quickly in the wake of the shortwave trough, with high confidence for dry weather and slightly warmer temperatures on Saturday given chances for rain fall below 10%. However, high pressure building in behind this trough Friday night into the weekend will bring clearing skies and calm winds during the overnight hours. This will bring an ideal set-up for radiational cooling and chillier overnight low temperatures. Aside from the high Cascades, overnight lows will be coldest in the Upper Hood River Valley where frost development is possible Friday night, Saturday night, and Sunday night. The NBM is showing a 30-50% chance for morning lows below 36-37 degrees Friday night and Saturday night near Parkdale and a 5-10% chance near Odell. Those with outdoor vegetation that is susceptible to frost damage should monitor the forecast over the coming days. -23 && .AVIATION...Through 12Z Tuesday...As of 12Z Monday, low marine stratus remained in place along the coast with ceilings ranging between 900-1500 ft. Areas of fog and low stratus continue to expand over the Willamette Valley, bringing increasing chances for LIFR to IFR flight conditions at all TAF sites. Similar to previous mornings, expect areas of fog and low stratus to continue expanding in coverage through sunrise with fog and low clouds clearing by 18-20Z Monday. Current observations suggest all TAF sites will be most likely be impacted by fog and/or low clouds to some degree by sunrise, with a potential exception at KHIO where conditions are favored to remain VFR the vast majority of the time this morning. KPDX AND APPROACHES...At 12Z Monday, a low stratus deck with ceilings around 700-900 ft was rapidly expanding southwestward onto the Columbia River and over the KPDX terminal. Expect low stratus to continue through this morning with ceilings ranging anywhere between 300-1000 ft. VFR conditions will return sometime between 18-20Z Monday as skies clear back out. -23 && .MARINE...High pressure will maintain predominately northerly winds across the waters through Thursday. An exception would be Tuesday afternoon to Wednesday morning, when winds may turn more westerly for the waters north of Cape Falcon with the passage of a weak front. Winds become more northwesterly and increase slightly in strength over all of the coastal waters Thursday night into Friday with the passage of another front. This front will be relatively stronger than the frontal passage earlier in the week, with widespread rain likely. Wind gusts should generally stay under 20 kt through Friday, even with the two frontal passages. Seas are expected to increase to 6 to 8 ft Monday evening into Monday night with the arrival of a long period west-northwestwerly swell. Seas then remain near that range through Friday, but are not expected to be particularly steep at any point in time due to the dominant wave periods of 10 to 13 seconds. -23 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

708 FXUS66 KMFR 211130 AFDMFR Area Forecast Discussion National Weather Service Medford OR 430 AM PDT Mon Sep 21 2026 .KEY MESSAGES... * Seasonable temperatures and dry conditions will prevail most of the upcoming week but temperatures trend below normal end of week * Rain chances increase Thurs/Fri (20%-60%) with isolated thunderstorm possible (10%-20%) && .DISCUSSION... A closed low is passing south of the forecast area today. As we reach peak heating today, there is a very small chance for some cumulus buildups, and this means we have about a 5%-10% chance of one or two becoming a shower/thunderstorm over northern California where some lift will be possible. Most likely there wont be much activity today, and it may end up being cumulus scattered across the area. High clouds will likely limit destabilization as well, so this is an extremely low chance for lightning today but worth mentioning. As the low exits to the east, we will experience mostly zonal flow over the forecast area which will lead to generally quiet weather with very little impacts/hazards for the following couple days. That said, by Thursday the upper flow becomes more southwesterly as a trough develops over the Pacific. Deterministic models differ in the trough axis timing coming over the west coast and the forecast area, so confidence is low for timing/coverage of potential rain and isolated thunderstorms, but generally looking at increasing chances for both starting Thursday and continuing through Friday. Activity at this time appears to stay mostly over westside areas. Currently, instability is very meager, so not expecting much in the realm of thunderstorm chances, but we could see light rainfall across westside areas. Thereafter, temperatures drop as the trough pushes eastward. For example, Medford may only reach the upper 60s for a high on Friday with temperatures struggling to reach the lower 70s through the weekend. In other words, expecting a cool down later in the week to below normal temperatures in the wake of the upper trough across the region. && .AVIATION (12Z TAFs)... Along and near the coast a marine layer has brought low ceilings (IFR) which is impacting KOTH and will likely continue through the remainder of the cycle with ceilings around 1000 ft. While close to KRBG, current thinking is these low ceilings wont make it into Roseburg albeit very close. This means inland TAF sites should remain in VFR through this cycle with only high clouds expanding across the area from the south where a low pressure system is passing. && .MARINE...Updated 330 AM PDT Monday, September 21, 2026...Gusty north winds will maintain steep seas south of Cape Arago through this evening with very steep seas over the inner and partial outer waters south of Brookings starting this afternoon as winds increase. Winds ease some on Tuesday and conditions will improve north of Cape Blanco as seas become less steep and transition to swell dominated. However, steep to very steep seas likely persist south of Cape Blanco through Tuesday evening. Conditions gradually improve Wednesday into Thursday. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Tuesday for PZZ356-376. Hazardous Seas Warning from 2 PM this afternoon to 11 PM PDT Tuesday for PZZ356-376. Small Craft Advisory until 2 PM PDT this afternoon for PZZ350- 370. && $$

922 FXUS66 KEKA 210812 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 112 AM PDT Mon Sep 21 2026 .KEY MESSAGES... * Warm and dry conditions for interior areas through Wednesday. * A shallow but strong marine layer along shore will weaken over the next couple of days with some clearing possible by Tuesday. * Cold front Thursday into Friday with a 20% chance of light wetting rain along the North Coast. && .SYNOPSIS...Warm and dry conditions will persist across the interior through Wednesday. The coastal marine layer will begin to weaken today with better clearing expected by Tuesday. A cold front may bring some light rain to Humboldt and Del Norte counties on Thursday or Friday. && .DISCUSSION...Low pressure moving into the Central California Coast will help to ease high pressure over the next couple of days. Dry and warm conditions will persist through Wednesday across the interior with varying levels of high level cloudiness across the region. Ensemble models have started to show better clarity for the forecast by late weak. Most show a quickly passing area of high pressure on Thursday to be followed by a cold front Thursday night into Friday, helping to drop interior highs into the low and mid 70s for next weekend. The front will also disrupt and lift any marine layer that manages to reform on Thursday. Most models still show the front mostly dry, but now about 20% show very light wetting rain focused along the North Coast. Weak high pressure is most likely to quickly rebuild behind the front. Despite the cooler air, there is little potential (20% or less even for the coldest valleys) for frost behind the front. && .AVIATION...A strong marine inversion continues to hold coastal clouds along the coast with IFR to LIFR conditions expected overnight into Monday morning. Patchy areas of drizzle are possible in the morning hours. As an area of low pressure spins over California, light offshore flow on the north side of this low will likely start to weaken the inversion and bring increasing clearing, but this may not occur until Tuesday in northern areas at CEC and ACV. IFR to low end MVFR is likely to persist Monday the two primary coastal terminals. Farther inland any morning near coast valley clouds will dissipate in the monring hours leaving VFR through the day. && .MARINE...Moderate to isolated strong north winds have now built throughout the outer waters, though condition remain calmer closer to shore, especially north of Cape Mendocino. Short period seas have built in response to the winds with waves over 8 feet in the outer waters and some steep seas up to 6 feet migrating into the inner waters. Similar winds will persist for the next several days and even strengthen in the southern outer waters with some near gale conditions by Tuesday morning. Winds will gradually weaken form north to south mid to late week as a cold front approaches. Short period wind waves will continue to dominate the environment alongside a very minor southwest swell. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT Wednesday for PZZ455. Small Craft Advisory until 9 AM PDT Wednesday for PZZ470. Small Craft Advisory until 9 AM PDT Thursday for PZZ475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. 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

881 FXUS66 KMTR 211130 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 430 AM PDT Mon Sep 21 2026 ...New AVIATION, MARINE, FIRE WEATHER... .KEY MESSAGES... Updated at 1201 AM PDT Mon Sep 21 2026 - Cool conditions today - Warming trend resumes Tuesday, cooler again Friday into the weekend && .SHORT TERM... Issued at 1201 AM PDT Mon Sep 21 2026 (Today and tonight) The local weather pattern remains dominated by a cut-off low with a broad rotation centered to the west of Monterey and San Luis Obispo Counties. The satellite imagery reveals scattered to broken high clouds associated with the low pressure system, some low clouds developing across the inland valleys, and some convective activity south of the Monterey County coast that has been potent enough to show up on the radar returns. One of those cells even lit up LightningCast (long story short, a satellite based algorithm for lightning probability) with a 50% probability of lightning but fell apart before reaching the southern Monterey County shore. However, most of them haven`t corresponded to any rainfall at the surface, as the 00Z (5 PM PDT) sounding from Oakland revealed that the lower layers remain very dry. But could we still see a high based thunderstorm through the night? It`s unlikely, even if the HRRR continues to hold on to K-Index values up to 22C, which would correspond to isolated thunderstorms, and some lightning flash signals near the Santa Lucia range around 4 AM to 8 AM. CAPE values are still the limiting factor; the 00Z OAK sounding continued to show a conditionally unstable layer with lapse rates around 8.5 C/km, but this layer was still below the moist air. This is supported by the reflectivity values at -10 C and -20 C, which remain below the values that would be necessary to support the ice particles that would be necessary for thunderstorm development. We will continue to monitor the cells as they develop, because while the risk of lightning is very small, the chance that it would be accompanied by wetting rains (at least 0.1" of rain) are zero, thus posing an obvious concern for dry lightning-induced fire starts. As the low moves onshore later this morning and passes through to our south, cool conditions will continue with highs ranging from the middle 70s to lower 80s in the inland valleys, the middle 60s to the middle 70s near the Bays, and the upper 50s to middle 60s along the Pacific coast. Typical diurnal onshore winds develop this afternoon and evening with gusts reaching 20 to 30 miles per hour through gaps and passes, and within the northern Salinas Valley. && .LONG TERM... Issued at 1201 AM PDT Mon Sep 21 2026 (Tuesday through Sunday) The cut-off low will continue to move to the east and will be out of our area by Tuesday morning, degrading into a shortwave trough as it moves into the Great Basin. This will allow more zonal flow to develop over the region and start a warming trend through Wednesday and Thursday. The word "ridge" might be a little strong for what the models are expecting, but there is definitely a northward bump in the flow that develops by Wednesday. Temperatures on Wednesday and Thursday will range from the middle 80s to middle 90s in the inland valleys to the middle 70s to middle 80s near the Bays, and the middle 60s to lower 70s along the Pacific coast. There are some pockets of Moderate HeatRisk (moderate risk for heat-related illness among sensitive populations) possible on those two days in favored interior locations, but widespread heat impacts are not expected. As the previous forecaster noted, Heat Advisories in late September typically happen with offshore flows and longer duration events. By Friday, another trough arrives from the eastern Pacific and reverses the warming trend, with temperatures closer to seasonal averages into the weekend. Longer-range outlooks show a slight lean towards temperatures warmer than seasonal averages and precipitation totals above seasonal averages for the last few days of September into the first few days of October. && .AVIATION... (12Z TAFS) Issued at 423 AM PDT Mon Sep 21 2026 Currently LIFR-MVFR. An upper-level low is bringing high clouds and elevated rain showers with a low probability for any thunderstorms to our area. Stratus on the cusp of IFR/MVFR will persist through late-morning before retreating to the coast. Reasonable worst case scenario is bayshore (OAK and SFO) and coastal (HAF and MRY) terminals remain MVFR all day due to an increase in onshore flow this afternoon as stratus would be retreating. Drizzle will be possible through the morning, especially at HAF and MRY, which would lead to further reduced ceilings/visibilities. Diurnal winds will prevail. Vicinity of SFO...Currently MVFR with westerly flow. Moderate confidence in the overall forecast and 12Z TAF. Reasonable worst case scenario is MVFR stratus lingers through the TAF period with increasing onshore winds this afternoon. The best chances for VFR will be this afternoon (19Z-00Z) with an early return of MVFR stratus likely. Diurnal winds will prevail. SFO Bridge Approach...The San Mateo Bridge Approach will likely be MVFR through at least late-morning, improving before the terminal. Monterey Bay Terminals...Currently MVFR with southwesterly flow at MRY and VFR with westerly flow at SNS. High confidence in MVFR stratus through late-morning. As it retreats to the coast this afternoon, MRY will likely remain MVFR with an increase in onshore flow. Nonetheless, another early return of IFR-MVFR stratus is on tap tonight. Diurnal winds will prevail. && .MARINE... (Today through Saturday) Issued at 423 AM PDT Mon Sep 21 2026 Moderate to fresh northwesterly breezes will prevail Monday. Locally strong breezes across the northern waters will generate hazardous conditions for small craft. Northwesterly breezes increase Tuesday to become fresh to strong, bringing hazardous conditions for small craft across the coastal waters. Conditions begin to improve Wednesday with strong gusts likely through Friday. Moderate seas Monday will build to become rough Tuesday and Wednesday before subsiding to become moderate Thursday. && .FIRE WEATHER... Issued at 423 AM PDT Mon Sep 21 2026 An upper-level low will support near to slightly below normal temperatures, increased diurnal winds, a deep marine layer, and a chance for drizzle today. It is also bringing elevated rain showers, fortunately there is a low probability for thunderstorms as little to no rainfall is expected to reach the ground. Warming and drying trend kicks off Tuesday with temperatures up to 10 degrees above normal and areas of moderate HeatRisk Wednesday and Thursday. The marine layer will compress below 1,000 feet during this warm-up with nocturnal drying expected above it. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 3 PM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory until 3 PM PDT Tuesday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...DialH LONG TERM....DialH AVIATION...Sarment MARINE...Sarment Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea

164 FXUS66 KOTX 210832 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 132 AM PDT Mon Sep 21 2026 .KEY MESSAGES... - Warm temperatures through Tuesday with afternoon highs in the high 70s to mid 80s. - Temperatures begin cooling midweek, with an increasing risk for showers and high elevation snow Friday into Saturday. - Breezy Tuesday into Wednesday. Potential for stronger winds Friday with a cold front passage. && .SYNOPSIS... Expect warm and dry conditions through Tuesday, with high temperatures in the high 70s to mid 80s. Wednesday through Friday will see temperatures cool to around normal and breezy afternoons. A stronger cold frontal passage on Friday will result in gusty winds, chances for showers, and high elevation snow. && .DISCUSSION... Monday-Tuesday: The upper-level ridge will begin to slowly flatten today and Tuesday as a broad upper-level crosses over 130W and shortwaves begin ejecting into British Columbia. Bands of high clouds will pass through the region at times over the next few days but conditions will remain dry. Monday will remain mild with temperatures within 1-2 degrees of Sunday then cool 5-10 degrees heading into Tuesday with the arrival of a weak cool front. Winds for much of the region will remain light today. There will be a noticeable increase in afternoon and evening breezes across the Okanogan Valley and through the Cascade river valleys starting off from the south/southeast then shifting to the west and northwest in the evening. Winds for Tuesday will become a bit more breezy region-wide as cooler air begins to bleed into the region. West to southwest winds will increase closer to 10-15 mph with gusts 20-25 mph and locally stronger through the windier Cascade gaps. Wednesday-weekend: A broad upper-level trough will become established over the Eastern Pacific and Northwest by Wednesday with temperatures cooling further and residual breeziness. A reinforcing shot of cooler air and shortwave dropping into the offshore trough on Thursday will dig into the base of the trough allowing flow to buckle slightly over the Inland NW. This has potential to warm temperatures another 1-5 degrees from Wednesday but largely unrealized in Central WA and most noticeable in far southeastern WA and the lower Idaho Panhandle including the L-C Valley where highs will rebound closer to 80F. Confidence continues to increase for a more robust trough and cold front Friday. There remains considerable timing differences still varying from Thursday night to Friday afternoon dialing int the frontal passage timing. Confidence is high for increased winds with this system due to a 8C cooling of the air mass but impacts and precise speeds will heavily depend on if this front passes through during peak heating or overnight as well as how quickly the system passes through. A scenario with a slower passage and overnight would deliver the lighter side of the wind outcomes with gusts mainly 15-25 mph. A scenario with an afternoon passage and swift progression of the front would be a windy outcome with gusts 25-35 mph and local gusts around 40 mph. The latest probabilities from the NBM come with a 60-80% chance for wind gusts at least 20 mph, 20-50% for 30 mph, and 10-15% chance for 40 mph. The windier solution would also suggest sustained winds of 15-25 mph for our windier areas from the East Slopes to the Palouse. This is something we will need to monitor closely in the coming days. The system will also deliver cooler temperatures with highs cooling from the 70s Wednesday and Thursday then into the 60s Friday into the weekend. Some mountain valleys may be flirting with freezing over temperatures heading into the weekend. As for precipitation, ensembles are indicating a 50-60% chance for at least 0.10" along the Cascade Crest and mountains of NE WA and N ID. The potential outcomes for these areas are as high as 0.50 inches or more. This could equate to several inches of snow for some of the highest peaks. Confidence is much lower for rainfall amounts outside of these areas and will depend on the speed of the trough Friday-Saturday. There has been an increase in probabilities for at least some rainfall region- wide and this seems logical given the strong forcing expected along this frontal boundary. Additional precipitation chances could come in the post frontal air mass with convective showers under the cool pool. Latest guidance has increased the chance for a tenth of rain toward 20-40% for locations like Lewiston, Pullman, Spokane, Kellogg, Colville, and Omak. Outlooks are not as favorable in the lee of the Cascades with probabilities less than 20% for locations like Ephrata and Moses Lake. Wenatchee and Chelan are closer to 20%. There is a slight chance for isolated thunderstorms Friday with the frontal passage but this comes with very low confidence. Snow levels in the Cascades will dip toward 6500 feet Friday and 5500 feet Friday night into Saturday morning. Those venturing into the high country should be prepared for cooler temperatures and wet conditions. At this time, snow accumulations look light but a few of the highest peaks near the immediate Cascade crest could pick up several inches. /sb && .AVIATION... 12Z TAFS: VFR conditions are expected through the forecast period. Mostly clear, but increasing and thickening high clouds from the west this afternoon into tonight. Winds generally less than 10kts, except some winds up 15kts near KPUW 15-18Z. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. /Solveig ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .Preliminary Point Temps/PoPs... Spokane 84 53 77 49 72 48 / 0 0 0 0 0 0 Coeur d`Alene 82 53 76 49 71 48 / 0 0 0 0 0 0 Pullman 82 50 74 45 70 45 / 0 0 0 0 0 0 Lewiston 86 57 81 52 76 53 / 0 0 0 0 0 0 Colville 82 46 79 42 73 42 / 0 0 0 0 0 0 Sandpoint 78 49 74 46 70 45 / 0 0 0 0 0 0 Kellogg 81 52 75 48 70 49 / 0 0 0 0 0 0 Moses Lake 84 51 79 46 73 48 / 0 0 0 0 0 0 Wenatchee 83 56 77 51 72 53 / 0 0 0 0 0 0 Omak 83 52 79 47 73 48 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

898 FXUS66 KPDT 211127 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 427 AM PDT Mon Sep 21 2026 .KEY MESSAGES... - Temperatures continue to warm further today with highs reaching the low to mid 80s by the late afternoon hours. - Cooler pattern with possible rain chances, especially along the mountains later this week. - Diurnal winds with general breezy winds developing Tuesday and Friday, especially near the Cascade gaps. && .DISCUSSION... Radar and satellite imagery continues to display dry conditions with clear to mostly clear skies thanks to the upper level ridge of high pressure continuing to effect the area. This will allow temperatures to continue warming a few more degrees through today, with temperatures in most of the lower elevation areas to rise in the low to mid 80s. The upper level ridge will continue bringing warm southwest flow before another system enters the area by Tuesday. On the fire weather side, winds remain light and variable today, but will pick-up Tuesday afternoon with breezy winds developing across the Columbia Basin, Kittitas Valley, and Cascade gaps. Minimum relative humidities will continue to drop into the 20 to 30 percent range, with locally lower values down to 15 to 20 percent near Central Oregon. By Tuesday, guidance is in good agreement we`ll see our next system push through as a trough offshore will move in British Columbia and push through the rest of the week (>90% chance). What`s a bit tricky is how the trough will set-up with timing and strength determining the amount of precip we`ll get. For example, the cluster analysis by Friday afternoon has 52% of the clusters having the trough strong enough to bring some precip across our region. Of that 52%, only 22% have widespread precipitation across the CWA while the Cascade mountain region encompasses all 52% of the members. The remaining 48% has a drier set-up with a weaker trough axis across the PacNW, resulting in none, if not very little, QPF`s. Chances of rain remain higher in the Cascade mountains at 50 to 70 percent. Meanwhile, chances for widespread QPF`s across the Blues, Basin and other lower-elevation sites, chances of rain for those areas remain lower at around 15 to 25 percent through Friday. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... VFR conditions prevail through the period with the exception of YKM experiencing some temporary MVFR conditions due to passing haze. Will see this lifting in the later morning hours as atmospheric mixing improves by 14Z. Otherwise, not expecting any other CIG or VIS conditions with winds generally light to moderate. && .Preliminary Point Temps/PoPs... PDT 84 52 76 48 / 0 0 0 0 ALW 85 57 77 53 / 0 0 0 0 PSC 86 54 80 49 / 0 0 0 0 YKM 85 54 79 48 / 0 0 0 0 HRI 85 55 78 49 / 0 0 0 0 ELN 80 50 70 44 / 0 0 0 0 RDM 83 44 75 38 / 0 0 0 0 LGD 84 52 79 46 / 0 0 0 0 GCD 85 51 80 46 / 0 0 0 0 DLS 86 56 77 51 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...95 AVIATION...95

907 FXUS65 KREV 210714 AFDREV Area Forecast Discussion National Weather Service Reno NV 1214 AM PDT Mon Sep 21 2026 .KEY MESSAGES... * Precipitation potential returns today, especially for the Sierra and south of US-50. * Warming up and generally dry conditions are expected mid-week with temperatures 5 to 10 degrees above average. * Increased winds and cooler temperatures return towards the end of the work week. && .DISCUSSION... Upper level low observed in satellite imagery just off the West Coast is expected to move towards the Great Basin today. This system brings a 20-40% chance for showers mainly in areas south of US-50 and the Sierra, especially over Mono and Mineral counties this afternoon per the HREF and RRFS. The ECMWF, GFS and NAM show marginal instability with MUCAPEs up to 500 J/kg near the Tahoe Basin along the Sierra crest. This could lead to a few isolated thunderstorms this afternoon, but thunderstorm chances remain at or below 10%. Very few ensemble members indicate the possibility for high elevation mountain snow mainly above 10500 ft. If there is any snow, it could be a trace up to 0.2 inches based on ensemble data for areas near Mammoth Lakes. Precipitation chances continue through Tuesday, but up to 15% mainly over Lassen and northern Washoe as the upper low continues its northeastward track. For mid-week, temperatures start to increase as weak ridging develops over the West Coast. Temps will increase to 5 to 10 degrees above average with afternoon highs in the mid to upper 90s for western NV, northeast CA and southern Mono valleys, and mid to upper 70s for Sierra communities. Towards the end of the work week, an upper level trough moves towards the PacNW. This will tighten the surface pressure gradient resulting in slightly stronger winds compared to earlier in the week. Gusts are potentially going to be in the 25-40 mph range with a 20-40% chance of gusts greater than 35 mph for wind prone areas along the Sierra Front both on Thursday and Friday. Temperatures are also expected to start cooling off again as this trough brings another generally dry cold front by around Friday. Precipitation chances are very uncertain at the moment, maybe late week into the weekend, but chances are currently below 5%. -HC && .AVIATION... Mostly VFR conditions are expected through the next 24 hrs. Exceptions near SHRA/-TSRA where CIGs and VIS could drop to MVFR, and IFR with the strongest activity near KMMH and KHTH between 18Z-03Z today. There is a 20-40% of showers for the Sierra and areas south of US-50. Mountain obscurations are also possible through tomorrow. Winds will be generally light and VRB overnight and in the morning, then become from the west and southwest with gusts up to 20kts for KMMH/KTVL/KTRK, and from the east and southeast for western NV sites. -HC && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

436 FXUS66 KSTO 201916 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1216 PM PDT Sun Sep 20 2026 .KEY MESSAGES... - Periodically breezy winds and warming temperatures this week, with areas of Moderate HeatRisk in the Valley on Thursday. - Isolated mountain shower and thunderstorm chances (less than 10%) in the Sierra south of Highway 50 on Monday. - Potential for unsettled weather and increased onshore winds Friday into the weekend as a system passes to our north. && .DISCUSSION... Today-Monday: Scattered high clouds are being observed over portions of Northern California this afternoon as a deepening offshore trough approaches the SoCal coast. As a result, periods of breezy onshore wind will develop today with west to southwest gusts 15 to 25 mph mainly through the Delta. Onshore flow increases on Monday with Delta gusts up to 30 mph and breezy winds up into the Sacramento Valley. Additionally, as this low tracks further onshore, it will bring chances for limited precipitation and isolated thunderstorms (less than 10%) Monday afternoon/evening. Highest potential exists south of US 50. Primary impacts from any thunderstorms that develop will be new fire starts from isolated lightning strikes and gusty outflow winds. Tuesday-Thursday: As the trough weakens and moves further into the Desert Southwest, Northern California will remain under split flow aloft as heights increase. As a result, onshore flow influence will weaken heading into midweek as temperatures trend warmer. The warmest temperatures of the week are currently expected on Thursday, with areas of Moderate HeatRisk in the Delta and southern Sacramento and northern San Joaquin valleys, however there is still some uncertainty regarding how warm temperatures will be. Relative humidities trend lower during this time as well. Friday-(next)Sunday: Heading toward the end of week/weekend period, offshore troughing is forecast to dig down from the Gulf of Alaska. This will induce stronger onshore winds through the Delta/Valley and enhanced gap flow through the Coast Range. This system will also bring the potential for unsettled weather in the form of light shower chances over Shasta County mountains on Friday. Temperatures are also forecast to trend cooler Friday into the weekend with Valley highs in the 80s. && .AVIATION... VFR conditions expected through 18z Monday. Winds at the TAF sites will be less than 12 kts, but west-southwest gusts to 15-20 kts are possible in the Delta after 23Z Sunday. Gusts then increase up to 25 kts after 06Z Monday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

112 FXUS65 KMSO 210800 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 200 AM MDT Mon Sep 21 2026 .DISCUSSION... KEY MESSAGES: - Chance for showers/thunderstorms in Lemhi County and southwest Montana on Tuesday - Warm, dry week ahead for the rest of the region. - Showers return late next week or early next weekend. Satellite imagery early this morning shows dry air under a ridge of high pressure over the northwestern U.S. including the Northern Rockies. A closed circulation of low pressure is spinning over central California and moving inland. The ridge of high pressure will keep the Northern Rockies dry today, with high temperatures about 10 degrees above normal. Patchy morning fog will affect some valleys of western Montana. Fog will remain in the forecast into midweek. The California low will track northeast today and on Tuesday. By Tuesday afternoon, moisture associated with that system will enter Lemhi County and southwest Montana, including Salmon and Butte, resulting in chances for showers and possibly thunderstorms in the late afternoon and evening. The moisture feed is short-lived, though, and dry conditions with above-normal temperatures will continue through Thursday. A shift towards more seasonable temperatures and chances for precipitation arrive on Friday. Most model ensemble members (about 75%) are in favor of a trough of low pressure digging along the Canadian coast and moving into the Pacific Northwest by Saturday. Details on this event are still unclear, as there is little agreement on timing and intensity of this system. Regardless of precipitation chances, expect a shift back towards seasonable temperatures on Friday lasting through next weekend. && .AVIATION...Keeping fog in the 21/0600Z TAFs for KGPI, KMSO, and KSMN this morning. Calm winds, clear skies, and dew point depressions almost identical to yesterday (Sunday) point towards a repeat of fog forcing IFR conditions for this morning, especially at KGPI. Beyond morning fog, high pressure will bring fair weather across the Northern Rockies airspace. Expect light and variable winds under mostly sunny skies today. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

531 FXUS65 KBOI 211148 AFDBOI Area Forecast Discussion National Weather Service Boise ID 548 AM MDT Mon Sep 21 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Mostly dry with warming temperatures through Thursday. - Chance of showers and thunderstorms Tuesday, mostly across higher terrain of southwest Idaho. - Cooler temperatures heading into this weekend with a chance of precipitation across SE Oregon and portions of SW Idaho Friday. && .SHORT TERM /Through Wednesday Night/... Issued 245 AM MDT MON SEP 21 2026 Broad upper ridging will keep warm and dry conditions over the region on Monday. This morning, some mountain valley fog is possible in Central Idaho high terrain. But as the sun rises in clear skies temperatures reach 5-10 degrees above normal, or about 5 degrees warmer than Sunday. An eastward shift in the ridge axis on Tuesday will allow for a closed low to lift northeastward through the Great Basin. This will bring a 20-30% chance of showers and thunderstorms to higher terrain along the Idaho/Nevada border, the Central Idaho mountains and the mountains in Baker County Tuesday afternoon. Temperatures may be a degree or two cooler on Tuesday compared to Monday, but a general warming trend continues into Wednesday as the cut off low moves east, heights rise, and stronger warm southwesterly flow aloft moves in. && .LONG TERM /Thursday through Monday/... Issued 245 AM MDT MON SEP 21 2026 A ridge will remain over the area on Thursday. Thursday will be the hottest day in the 7-day period, with temperatures near 90 degrees in lower elevations and 80 degrees in higher elevations. A trough moves into the Pacific NW Friday/Saturday with cooler temperatures and increased chances (15 to 25 percent) of precipitation this weekend. Precipitation chances will be highest in Northeastern Oregon and West-Central Idaho, with generally dry conditions as one approaches the Nevada border. Temperatures fall to near normal on Friday, and 5 to 10 degrees below normal on Saturday and Sunday. The temperature drop may shift fully to Friday or Saturday as synoptic models come into better agreement on the cold front passage, causing a sharper cool off on Friday or prolonged warmness on Friday respectively. Cooler temperatures remain through the weekend into next Monday as a trough axis entrenches itself along the coast and the jet stream stays overhead. && .AVIATION /12Z Monday through Tuesday/... Issued 440 AM MDT MON SEP 21 2026 VFR. Sparse mountain valley fog in Central Idaho this morning quickly clears around sunrise. High clouds moving in this afternoon. Surface winds: mainly variable or S-SE 5-10kt. Winds aloft at 10kft MSL: S 5-10kt. KBOI...VFR with clear skies, high clouds move in this afternoon. Surface winds: SE 5-10kt, brief light NW this afternoon before shifting back to SE late this evening. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....JM SHORT TERM...JM LONG TERM....JM

184 FXUS65 KLKN 210957 AFDLKN Area Forecast Discussion National Weather Service Elko NV 257 AM PDT Mon Sep 21 2026 .KEY MESSAGES... * Rain showers and thunderstorms impact central and eastern Nevada today and tomorrow * Fair weather returns Wednesday though breezes will be present at the end of the week && .DISCUSSION... (Today through next Monday) WEATHER PATTERN OVERVIEW: A Pacific cut off low will continue to move inland and into SoCal this morning, and move into southern and central Nevada late this afternoon. Southwesterly flow ahead of the low will advect enough atmospheric moisture northward into Central Nevada from the south-southwest to produce rain showers and thunderstorms beginning around midday today. The upper low will continue to move northeastward thru the intermountain west with showers and thunderstorms moving into eastern Nevada, including White Pine and Elko Counties, this evening and Tuesday morning respectively. Activity looks to exit to the north- northeast Tuesday night. The primary thunderstorm hazards will be wind gusts near 50 mph and dangerous cloud to ground lightning strikes. Accumulating rainfall will be possible with the greatest accumulations expected in and near White Pine County. Accumulations between 0.10 and 0.25 inches are forecast with the higher end accumulation situated over the high terrain and particularly the Snake Range and Schell Creeks. Fair weather returns Wednesday under weak upper level flow. By Thursday afternoon, daytime high temperatures will be five to ten degrees warmer than normal for this time of year. Breezes are also expected to begin increasing Thursday in response to a deepening Pacific trof offshore of the PacNW. Trof progresses east thru the PacNW Friday with the associated surface frontal boundary skirting northern Nevada. This will cause west-southwesterly winds to peak Friday afternoon in and near Humboldt County with gusts around 35 to 40 mph. Winds remain relatively breezy thru the weekend as the upper wave pattern remains progressive. FORECAST CONFIDENCE & DEVIATIONS: High confidence in shower and thunderstorm activity today thru Tuesday with moderate confidence in regard to rainfall accumulations. High confidence in the forecast from mid week thru the end of the week. Again opted for a blend of various model guidance to produce a more accurate PoP and weather forecast than suggested by NBM thru the period. && .AVIATION...VFR conditions will persist thru this morning at all terminals. -SHRA and TS will move into central Nevada from the south-southwest mid day today, with affects beginning at KTPH around 21Z this afternoon. Activity spreads north and east this afternoon and thru Tuesday night with KELY, KENV, and KEKO also expected to observe -SHRA, VCSH, TS, and/or VCTS. Currently anticipating impacts to begin at KELY this evening and KENV and KEKO Tuesday morning. VFR will remain the primary flight category during this time though periods of MVFR will be possible under a heavier shower or thunderstorm due to reduction in VIS and lowered CIGs. Winds will be generally light though gusty and erratic winds should be expected in conjunction with any TS and gusts up to 45KT will be possible. && .FIRE WEATHER...Main concern within the next few days will be rain showers and thunderstorms that will move into central Nevada from the south- southwest around mid day today as an upper level low passes thru the region. Activity spreads into eastern Nevada tonight and Tuesday before exiting to the north- northeast Tuesday night. Showers and thunderstorms will affect zones 426, 427, 425, 469, and 470, as well as the southern and eastern fringes of zones 424 and 438. Wetting rains will be possible though the best opportunity will be within zone 425. Weather becomes fair Wednesday though west- southwesterly winds will become breezy at the end of the week. Winds peak Friday within zone 437 in response to a Pacific trof progressing thru the PacNW from the west. Gusts around 35 to 40 mph can be expected, though minimum afternoon RH is expected to remain greater than 15%, mitigating critical fire weather concerns. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...92 AVIATION...92 FIRE WEATHER...92