836 FXUS66 KSEW 280311 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 810 PM PDT Thu Aug 27 2026 .SYNOPSIS... An upper-trough will swing a couple of disturbances into the region through Saturday. Brief ridging is in the offing to begin next week but the pattern is forecast to reopen by Tuesday as additional troughing takes aim. A well-ogranized system looks to arrive around midweek with the potential for widespread rainfall. Cooler than average temperatures are favored throughout this time. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... Shower activity has mostly fizzled out from an already pretty scattered pattern over W WA earlier this afternoon...although the last vestiges can be found over the North Cascades. Inherited forecast remains on track and thusly, no evening updates are required. For additional forecast details, please refer to the Previous Discussion section below. 18 From Previous Discussion...The first of a series of upper-lows has swept through western Washington earlier today. Light shower activity has resulted along with breezy winds. Latest KATX/KLGX scans show shower coverage mainly over the coast, Olympic Peninsula and Cascade mountains along with a smattering over the southwest interior. 200-400 j/kg of surface based CAPE over the northern half of the CWA is being highlighted by HREF this afternoon. So with that, can`t rule out a strike of lightning or two before the evening. Tonight, conditions are slated to trend drier as we`ll be in between disturbances. Overnight lows are forecast to drop into the 50s. Quasi-zonal flow aloft on Friday as models have the next impending upper-low looming off the coast of British Columbia. Mostly dry conditions during the day on Friday (barring a few showers) however, guidance have 850 mb winds converging over Puget Sound Friday night. A PSCZ is favored to develop around this time across both King and Snohomish counties with measurable rainfall a probability into the early morning hours on Saturday. The aforementioned upper-low is slated to arrive on Saturday morning as well with more widespread rain showers across western Washington. A 10-20% chance of thunder is in the forecast across the CWA with the highest probabilities over the Cascades. Precipitation will gradually dry out Saturday night as subsidence provided via transient ridging builds in to start the new week. Highs throughout the short-term ranging between the lower 60s to lower 70s with overnight lows in the 50s but can`t rule out a few 40s in the southwest interior. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As mentioned, brief upper-ridging Sunday and Monday with drier conditions. Then, the next upper-trough will dig over the NE PAC and sit right off the PNW coast by Monday evening. Given latest guidance, it`s associated upper-low will track south of the area into Oregon but we could get side swiped with showers on Tuesday. Then, a more organized disturbance is slated to arrive Wednesday and lead into Thursday. This feature has the potential to bring widespread rainfall and well-below average temperatures as the region will begin to get a taste of fall. 41 && .AVIATION... West-southwest flow aloft continues through Friday with troughing over Western Washington. VFR cigs this evening with widespread mid level clouds. A few showers will linger into Friday, however most terminals will remain dry through Friday afternoon. Stratus will develop tonight into Friday morning for MVFR/IFR cigs for most terminals. Localized LIFR possible along the coast as well as across the Kitsap Peninsula. Cigs will slowly improve into the afternoon. South to southwest winds through Friday morning will become more northerly for a few sites from King CO northwards by Friday afternoon. KSEA...VFR cigs this evening with mid level clouds. Cigs will lower into MVFR between 10-12z and remain MVFR through midday before cigs slowly lift into VFR. There remains a 20 to 25% probability for IFR cigs Friday AM as well, mainly between 12 to 17z. South winds into Friday afternoon may briefly transition to N/NW Friday evening. JD && .MARINE... A weak frontal system will continue to move over the coastal waters today. Breezy south to southwesterly winds have picked up as a result, with localized gusts up to 30 kt in northern portions of the Hood Canal, producing wind waves up to 4 feet. As a result, a Small Craft Advisory has been issued through this afternoon. The strongest winds in this advisory will be in the Hood Canal area, though isolated SCA wind gusts elsewhere are possible through the afternoon. Weak systems will continue to move over the coastal waters through the weekend, maintaining onshore flow and periodic westerly pushes through the Strait of Juan De Fuca. The westerly push Friday looks to reach Small Craft strength The push on Friday is expected to reach Small Craft strength, and a Small Craft Advisory has been issued. Another weaker westerly push is expected Saturday evening before winds become generally benign over area waters through the remainder of the weekend. Seas will remain around 4 to 6 feet through the weekend. 15 && .FIRE WEATHER... Onshore flow, cooler temperatures, and increasing RHs will persist into next week. There still remains an isolated threat for thunderstorms this afternoon and Saturday afternoon. For today, the threat is primarily over the Northern Cascades. As for Saturday, the threat expands from the Northern Cascades into the Central Cascades. Shall a thunderstorm develop, wetting rains are unlikely and lightning may pose a hazard that could lead to new fire starts. Additionally, thunderstorms could produce erratic and gusty outflow winds over existing fires. A weather system towards the middle of next week may bring wetting rains to the area. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 2 PM to 11 PM PDT Friday for Central U.S. Waters Strait Of Juan De Fuca. && $$

850 FXUS66 KPQR 280526 AFDPQR Area Forecast Discussion National Weather Service Portland OR 1026 PM PDT Thu Aug 27 2026 Updated aviation discussion. && .SYNOPSIS...A cool and somewhat unsettled pattern will persist through the weekend as upper-level troughing remains over the Pacific Northwest. Periodic marine pushes will continue to bring morning cloud cover inland, while weak disturbances may produce occasional light precipitation along the coast and at higher terrain. Forecast uncertainty increases into early next week as ensemble solutions diverge on the pattern. && .DISCUSSION...Now through Wednesday...Upper-level troughing remains the dominant feature over the northeast Pacific, maintaining a cool air mass and persistent onshore flow across the region. Another push of marine stratus is expected tonight into Friday morning, with clouds likely reaching well into the interior lowlands. Despite the cloud cover, precipitation chances remain low, with most locations staying dry. Temperatures Friday should remain in the upper 70s across the interior and 60s along the coast. The broader trough will remain in place through Saturday, although another weak disturbance may enhance precipitation chances, particularly north of a line from McMinnville and Mollala. Ensemble guidance currently gives a 20-60% chance of measurable rainfall across these areas. Any precipitation that develops is expected to be light, with the coast, Coast Range, and Cascade foothills favored for the highest chances. Continued onshore flow will also maintain the potential for morning marine stratus across the interior. By Sunday, the upper-level low shifts east and a shortwave ridge forms, allowing temperatures to increase 1 to 3 degrees into the upper 70s across interior. Looking into early next week, ensemble guidance continues to favor a cooler and potentially wetter pattern, but confidence remains limited. An increasing number of ensemble members support measurable precipitation across a larger portion of the forecast area, though there remains substantial spread in the timing, amplitude, and eventual position of the upper-level trough. Further refinement will be possible as the pattern becomes better resolved. Lastly, to give a rough approximation of expected precipitation early next week, probabilistic guidance suggests chances for at least 0.01 inches of rain over 48 hours from early Tuesday to late Wednesday ranges from 70-90%. As for chances of higher amounts of rain, there is a 40-70% chance for 0.25 inches, 25-50% chance for 0.50 inches, and a 5-30% chance for 1 inch. ~12 && .AVIATION...Through 06z Saturday...An upper-level trough extending over the Pacific Northwest will support continued onshore flow and increased nighttime chances for restricted cigs as marine stratus pushes inland. Cloud coverage will increase initially along the coast, with high confidence in MVFR cigs, but only moderate chances for IFR, highest along the central Oregon coast (70% at KONP) and decreasing to the north (30% at KAST). Inland, chances for MVFR cigs increase through the night, reaching 50-70% at KTTD and KEUG by 11-13z Fri and 30-50% at other inland terminals. Low clouds will erode through the morning, with a return to VFR conditions by 16-18z Fri inland and 18-21z Fri along the coast. North to northwest winds of 3 kt or less tonight will build to 5-10 kt inland and 8-12 kt along the coast by midday Friday. KPDX AND APPROACHES...VFR conditions expected to prevail throughout the period, with moderate chances, 40-50%, for MVFR cigs from 13-17z Fri as marine stratus pushes inland. Low clouds will then tend to erode by midday Friday. Northwest winds ease to 3-5 kt tonight, then build to 5-8 kt by Friday afternoon. -36 && .MARINE...As low pressure near Vancouver Island weakens, high pressure continues to build in across the NE Pacific. Light southerly winds veer westerly later this afternoon, becoming north-northwesterly by early Friday. Winds are expected to remain around 10-15 kt or less. A weak front drops into the northern coastal waters late Friday into Saturday with little to no impact expected. Northerlies persist through the weekend while predominately wind driven seas remain at around 3 to 5 ft. The pattern may become a bit more active early to the middle of next week as there is potential for multiple frontal systems to move into the coastal waters. /DH && .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

452 FXUS66 KMFR 280525 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1025 PM PDT Thu Aug 27 2026 .DISCUSSION...Updated aviation discussion for 06Z TAFs. && .AVIATION...28/06Z TAFs...Areas of IFR/LIFR stratus and fog will impact the coast from Cape Blanco northward, including North Bend, and also from around Gold Beach southward, tonight into Friday morning. Then, conditions improve to VFR before lowering again Friday evening. There should be enough moisture to cause MVFR ceilings to develop in the Umpqua Basin, around Roseburg, for several hours late tonight into Friday morning before clearing to VFR in the afternoon. Patchy clouds could develop in parts of the Illinois Valley or near Grants Pass as well, but it should remain VFR in Medford. While Klamath Falls will have some high clouds at times tonight/Friday, VFR will prevail there. Coastal areas will have gusty N breezes (~20-25 kt) Friday afternoon/evening, while areas east of the Cascades and in NE California have gusty S-SW afternoon winds (20-30 kt). Isolated showers/thunderstorms could graze far SE sections of the area Friday afternoon/evening, especially out around the Warner Mtns of Modoc/southern Lake counties. -Spilde && .PREV DISCUSSION... /Issued 446 PM PDT Thu Aug 27 2026/ DISCUSSION...Updated aviation discussion for 00Z TAFs. AVIATION...28/00Z TAFs...Areas of IFR/LIFR stratus and fog will develop and impact the coast from Cape Blanco northward, including North Bend, tonight into Friday morning. Patchy IFR/LIFR ceilings/fog could also develop along the coast south of there this evening; these will become more widespread south of Pistol River overnight into Friday morning. Once again, there should be enough moisture to cause MVFR ceilings to develop in the Umpqua Basin, around Roseburg, for at least several hours late tonight into Friday morning before clearing to VFR in the afternoon. It should remain VFR in the Rogue Valley, including Medford and while Klamath Falls will have some high clouds at times, VFR will prevail there as well. Coastal areas will have gusty N breezes (~25 kt) Friday afternoon, while areas east of the Cascades and in NE California have gusty S-SW afternoon winds (20-30 kt). Isolated showers/thunderstorms could graze far SE sections of the area Friday afternoon/evening, especially out around the Warner Mtns of Modoc/southern Lake counties. -Spilde PREV DISCUSSION... /Issued 239 PM PDT Thu Aug 27 2026/ KEY MESSAGES... * Today: Critical fire weather conditions continue for eastside areas, including areas of Klamath and Lake counties in Oregon and parts of Modoc County in northern California. * Tomorrow: Chance (15-30%) for thunderstorms over far eastern Modoc County and southeast Lake County with lightning being the main threat. * Temperatures are mostly seasonable through Monday (Saturday is a bit cooler), but next week is shaping up to have below normal temperatures through much of the week as a system passes through. * System next week could bring rainfall in addition to the cooler temperatures. Rainfall chances increasing midweek and continuing through later parts of next week, especially westside areas. DISCUSSION... A closed upper level low off the coast of British Columbia will meander over this general area for the next several days. This will result in continued southwesterly flow aloft that will keep the forecast area generally dry as this trough pattern maintains (small exception for tomorrow). This pattern will maintain gusty winds and low RH today, but improvement in fire weather conditions look to develop Friday and continue through the weekend. On Friday, an upper jet streak looks to develop between the aforementioned low and an area of high pressure over the Desert Southwest. This could help trigger a couple thunderstorms through peak heating as convective temperatures will be reached. While we have increased moisture, PWATs are not overly impressive, so not expecting a lot of rain. Main threat will be lightning, but if a storm or two can maintain in our area, we could have isolated gusty winds as well. Overall, the limited instability may only lead to isolated chances with better chances east of our area. By Sunday, it does appear this upper trough pattern will shift east and we will briefly transition to a zonal pattern, but another trough pattern looks to quickly form over the west coast by Monday. In fact, It looks like a couple discernible troughs will transition the PacNW next week. There is some uncertainty in some of these cases where deterministic models vary on the timing, orientation, and strength of the upper pattern, but the overall pattern does appear to favor a trough. The increased rainfall chances do make sense given this pattern, but some of the finer details are a little hazy at this time given the model differences. It does also look like westside areas will be favor under this pattern. It should also be noted this doesn`t appear to much rainfall for any of our locations. Westside areas will be favored, but the highest probability for any 24hr time period is only 60% for 0.05" of rainfall for Wed/Thurs. Coastal areas would be the higher probability for this rainfall, especially Coos County and western Douglas County. Instability looks very feeble across our forecast area, so not expecting much--if any--thunderstorms under this pattern next week. All that said, given uncertainty in the upper levels, it is advisable to check back as the forecast may change for both rainfall amounts and thunderstorm possibilities. If nothing else, increased cloud cover and cooler temperatures is looking very favorable Tuesday through middle/later parts of next week. AVIATION...27/18Z TAFs...Fair weather cumulus will continue this afternoon along the coast with mainly clear VFR skies farther eastwards. We`ll see another round of IFR stratus and visibilities along the coast. Fog down to 1/4 is possible at times, especially closer to Brookings. -Smith MARINE...Updated 100 PM PDT Thursday, August 27, 2026...Relatively calm conditions with light winds switching to the north this afternoon and low seas are expected through tomorrow morning. North winds increase tomorrow afternoon with steep seas developing south of Cape Blanco. These steep seas and gusty winds will persist through the weekend. Winds will be strongest each afternoon and early evening Friday through Sunday. Conditions are likely to improve Monday afternoon. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory from 2 PM Friday to 5 AM PDT Monday for PZZ356-376. && $$ MAS

761 FXUS66 KEKA 272011 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 111 PM PDT Thu Aug 27 2026 .KEY MESSAGES... * Tropical moisture arrives today and may bring a few showers to Mendocino & Lake Counties this evening through early Friday afternoon. * Interior areas continue to see near to slightly below normal temperatures through this weekend. * Coastal areas continue to see overnight stratus with afternoon clearing. && .SYNOPSIS...Tropical moisture arrives today, bringing slight chances for showers to Mendocino & Lake Counties through Friday. Generally mild, seasonable weather continues across the area with slightly below normal interior temperatures and coastal areas seeing overnight stratus. && .DISCUSSION...Tropical moisture from the remnants of Tropical Storm Iselle starts to stream into the area this afternoon and evening. This will primarily affect the southern portions of the area (Lake and southern Mendocino Counties). Some rain may reach the ground with precipitable water values approaching 1 inch, but dry low levels will limit precipitation to a few sprinkles. The first chances for showers would be late this afternoon and early evening. CAMs are not in agreement if these will form, however CAPE of around 100-200 J/kg, while limited, may allow for a few showers to tap into the moisture and a stray lightning strike cannot be completely ruled out. Overnight into early Friday, moisture continues to surge into the southern half of the area, though most models show instability declining to near zero. This will limit any impacts to virga or a stray shower through early Friday afternoon. Moisture moves east Friday afternoon. It should be noted the chances of either showers or thunderstorms are very slim (15% for any rain and less than 5% for thunderstorms), but this is being watched closely as conditions change. Interior temperatures will be moderated somewhat by this moisture push and the associated mid and high cloud cover. Most interior areas are likely to see high 80s to low 90s. The continuation of the troughing pattern will support a deeper marine layer near the coast while additional moisture will support drizzle overnight along the coast. Stratus is likely to clear, at least partially, in the afternoons through the weekend as breezy northwest winds develop in the afternoons and the marine inversion remains elevated and weak. Coastal high temperatures are likely to remain in the low 60s through the weekend and into early next week as this pattern continues. Model guidance is showing a trough dropping far south off the coast of the Pacific Northwest and possibly forming a cutoff low right off the northern California Coast by Tuesday. This is several days out, so this has time to change, but this could give the northern half of the area some light rain. NBM is showing around a 20% chance for the North Coast to see a tenth of an inch of rain while chances in Del Norte are around 40%. Should this trough move northward, there is also the potential for a return of tropical moisture early to mid next week. Stay tuned! /JB && .AVIATION...(18Z TAFs)...Stratus has retreated to the immediate coastline, but has continued to bring occasional IFR ceilings and visibility impacts into the early afternoon. This is likely to continue though the afternoon until rebuilding this evening, returning more consistent IFR to LIFR stratus impacts. Drizzle will result in lowered visibilities and support fog formation at times through the night. /JB && .MARINE...Northerly winds increase today, especially south of Cape Mendocino where widespread gusts of 20 to 30 kts are likely in the lee of the Cape. Winds increase further this weekend over the outer waters with near-gale force gusts possible by Saturday night. Nearshore winds remain lighter with peak gusts of 10 to 20 mph, with locally higher winds in the lee of Cape Mendocino. Steep seas will be associated with these winds and will likely occasionally bring propagate into the inner waters, especially south of Cape Mendocino. The northerly winds will decrease quickly early next week as another trough approaches the area. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 AM Friday to 9 PM PDT Saturday for PZZ455. Small Craft Advisory from 3 PM Saturday to 3 PM PDT Sunday for PZZ470. Small Craft Advisory until 3 PM PDT Sunday 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

611 FXUS66 KMTR 280724 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1224 AM PDT Fri Aug 28 2026 ...New SHORT TERM, LONG TERM, FIRE WEATHER... .KEY MESSAGES... Updated at 1041 PM PDT Thu Aug 27 2026 - Slight chance of rain showers and thunderstorms through Friday afternoon focused on the Central Coast. - Cooling trend begins Friday && .SHORT TERM... Issued at 1041 PM PDT Thu Aug 27 2026 (Tonight through Saturday) As the remnant moisture from Tropical Storm Iselle moves over the region we must analyze the risk for high-based thunderstorms. This type of thunderstorm forms high in the atmosphere above a dry layer of air. Most of the rain evaporates in the dry layer, but lightning has no trouble getting to the ground. This dry lightning is a well-known wildfire ignition source, so let`s take a close look. The 00Z sounding measured a PWAT of 1.24", with 307 J/kg of MUCAPE. The best lapse rate was 850-500 mb at 7.6 C/km, with the moisture all above 700 mb. As this moisture gradually moves lower in the atmosphere, the instability will increase. That, combined with subtle lift from the trough and terrain could trigger some thunderstorms today. Models are not doing a good job analyzing the (307 J/kg of MUCAPE) instability measured on the 00Z weather balloon sounding. For example the 00Z ECMWF model initialization at OAK has 0 MUCAPE. The lapse rates and precipitable water are in the ballpark, but not lined up as well as reality. It`s the same story with the HRRR and NAM. Specifically the models aren`t resolving the moisture at the base of the unstable layer. As such, we`ve increased the probability of thunderstorms to 15% across the Santa Cruz Mountains and most of Monterey County from 5AM to 2PM. The two big questions are will this instability be realized, and will the rain reach the ground. The instability piece looks better as the night goes on. Now that the balloon data is getting into the models, they are gradually getting more interesting. The 06Z HRRR is just starting to come in and the lightning flash density has trended up. It`s now showing a potential peak of 1 flash every 5 mins across parts of Monterey County, with more scattered activity across the rest of the Bay Area. The 00Z ECMWF has a similar trend across the Central Coast, but still doesn`t show much in the Bay Area. One factor working against convection is the timing. While the upper level support peaks in the mid to late morning, peak surface heating will lag behind by several hours. If these lined up, there would be some more help from surface based instability. On the other hand, if the storms preform well in the morning, the increasing surface temperatures may continue to support convection that keeps some activity going longer into the afternoon than currently expected. As the 500 mb trough axis approaches Saturday it will usher in a much drier air mass. This will end the threat of thunderstorms, while ushering in some gusty onshore winds and cooler temperatures this weekend. && .LONG TERM... Issued at 1041 PM PDT Thu Aug 27 2026 (Saturday night through next Thursday) The marine layer will gradually reform and deepen through the weekend. An active pattern will bring several short waves into the Pacific Northwest this week, keeping the Bay Area on the cool and breezy side. There is even a chance for some light rain midweek. && .AVIATION... (06Z TAFS) Issued at 925 PM PDT Thu Aug 27 2026 It`s VFR with widespread mid and high level clouds over much of the forecast area. High based showers have decreased in coverage. A few light showers/sprinkles reached the ground over the north Central Coast based on earlier webcam and spotter reports. Increased cloud cover i.e. water vapor will interfere with and decrease radiative cooling; coastal stratus and fog will be limited tonight and Friday. Vicinity of SFO...VFR. A few showers are possible tonight and/or Friday. Currently, the 06z TAF advertises vicinity showers (VCSH) 11z-20z Friday. West to northwest wind 8 to 14 knots. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR. Vicinity showers (VCSH) tonight, with tempo showers 10z-15z Friday morning and low confidence if showers will continue during late Friday morning. Winds will be a mix of west to northwest 5 to 15 knots and light and variable. && .MARINE... (Tonight through next Wednesday) Issued at 918 PM PDT Thu Aug 27 2026 Northwest breezes gradually diminish to moderate by Monday. Moderate wind driven seas prevail into next week. A long period southerly swell impacts our coastal waters by Friday and persists into the weekend. && .FIRE WEATHER... Issued at 1041 PM PDT Thu Aug 27 2026 A Red Flag Warning is in effect from 5 AM through 3 PM for dry lightning potential across the Santa Cruz Mountains and Central Coast. Refer to the Short Term section for more details. By Saturday a cooling trend will kick off as the marine layer gradually deepens. && .FIRE WEATHER... Issued at 125 PM PDT Thu Aug 27 2026 One more day of near-critical fire weather conditions above 1000 feet, especially across the Central Coast, as warm and dry conditions continue above the marine layer inversion and overnight humidity recoveries remain poor into Friday morning. There still is a non-zero chance for thunderstorms across the Central Coast today through tonight. By tomorrow, with the increasing potential for lightning, we have issued a Red Flag Warning for much of the Central Coast including the Santa Cruz Mountains from 5 AM to 3 PM Friday given the low confidence for wetting rains to develop. By Friday night and into the weekend, the cooling trend will continue and bring cooler temperatures and likely a deeper marine layer, bringing progressively more relief to some of the higher elevations. RGass && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning from 5 AM to 3 PM PDT Friday for CAZ512-516-517- 528>530. PZ...Small Craft Advisory until 9 AM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...Canepa MARINE...Canepa 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

900 FXUS66 KOTX 280834 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 134 AM PDT Fri Aug 28 2026 .KEY MESSAGES... - Cooler temperatures and potential for mountain showers and thunderstorms on Saturday. - Temperatures warm briefly Monday and Tuesday, then return to below seasonal normals by the middle of next week. - Elevated chances of wetter than normal conditions middle to end of next week && .SYNOPSIS... A weather system passing through the region on Saturday will bring breezy winds, cooler temperatures, and chances for mountain showers and thunderstorms. Temperatures will cool into the 70s for the weekend. After a brief warm up on Monday and Tuesday, another upper level low will bring cooler temperatures and returning chances of rain. && .DISCUSSION... Friday: An upper level trough over the area alongside colder air moving in will lower high temperatures 4-6 degrees than seen on Thursday. Winds in the afternoon will be breezy, with gusts up to 20 mph expected, especially in the deeper Basin, Waterville Plateau, Cascade gaps, and Okanogan Valley. The air moving in remains dry, with PWATs 80-90% of normal at around 0.5 inches, so no precipitation is expected through the day. Saturday through Sunday: A deep low pressure system will swing down into the area late Friday into Saturday, bringing a more appreciable chance for precipitation alongside a significant drop in temperatures. Temperatures will further drop between Friday and Saturday, with highs expected in the low to mid 70s for much of the area. An important thing to keep an eye on will be sheltered valleys in the Idaho Panhandle and northern mountains. Models are indicating low temperatures dropping into the mid-30s, which could lead to some frost formation. Additionally, fog in these sheltered valleys is possible as well, with RHs remaining high due to that colder air staying in the valleys. This cold front will also bring a chance for rain across the mountains, with the northern mountains, highest elevations of the Cascades, and the far southeastern portion of the ID Panhandle having a 20 percent chance and above at seeing 0.10 inches. There is a 15 to 25 percent chance of thunderstorms in these same areas. With DCAPE values 500 J/kg or more throughout the areas, expect main threats to be lightning and gusty outflow winds near 30 mph. Ahead of and with the cold frontal passage, winds will increase across the region. Expect wind gusts 25-30 mph through much of the Basin, Palouse, Spokane/CdA, Waterville Plateau, and Wenatchee areas. Monday through Friday: As the low moves away from the area, slight ridging will lead to an increase in temperatures and drier conditions for Monday and Tuesday. However, there is universal agreement in the clusters that another low pressure system will drop down into the PNW coast Tuesday evening and remain there through the end of next work week. Mid and long term models are showing better chances of more widespread precipitation, so stay tuned. The 6-10 and 8-14 Day Outlooks are also show that we have higher chances for lower than normal temperatures and higher than normal precipitation, so expect a major pattern change over the weekend and next week. && .AVIATION... 06Z TAFs: Gusty winds have mostly relaxed and conditions have cleared. Winds will pick up again for most places tomorrow around 18Z, but will not be as strong as today with wind gusts 15-20kts expected. VFR conditions are mostly forecast for all terminals but could temporarily drop to MVFR due to smoke, particularly for GEG, SFF, COE, and MWH. High-res smoke models indicate GEG, SFF, and COE will all see smoke move through the area in the early hours of the morning. Timing is very uncertain, with earlier models showing the smoke arriving much earlier. Current timing has smoke impacts beginning at 8Z for GEG. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate confidence in timing of winds. Low confidence regarding timing for smoke and also visibilities at GEG, SFF, COE, and MWH from wildfire smoke. Most impactful alternate scenario would require amendments due to smoke arrival timing or when visibilities drop. /AS ----------------------- 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 79 51 72 45 72 45 / 0 0 0 0 0 0 Coeur d`Alene 80 51 72 46 71 45 / 0 0 0 10 10 0 Pullman 77 44 69 37 69 38 / 0 20 0 10 0 0 Lewiston 84 57 77 51 76 50 / 0 10 10 10 0 0 Colville 79 41 71 35 72 37 / 0 0 30 30 10 0 Sandpoint 77 44 70 39 67 40 / 0 0 10 20 20 0 Kellogg 78 50 70 44 66 43 / 0 20 10 20 10 0 Moses Lake 82 49 75 44 76 45 / 0 0 0 0 0 0 Wenatchee 82 58 73 53 76 55 / 0 0 0 0 0 0 Omak 82 51 72 46 76 49 / 0 0 60 30 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...Air Quality Alert until further notice Okanogan, Chelan, Douglas counties. ID...None. && $$

967 FXUS66 KPDT 280527 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1027 PM PDT Thu Aug 27 2026 .KEY MESSAGES... - Slight chances (10-15%) of thunderstorms in the Cascade and Eastern Mountains. - Cooling trend through the weekend with high temperatures dropping to the mid to upper 70s by Saturday. - Diurnal winds with periods of breezy winds across the region through the next several days. && .DISCUSSION... Satellite and radar depict dry and mostly clear conditions through the area with high to mid clouds prevail across the eastern mountains. Not expecting any showers or thunderstorms with this system as NBM guidance keeps chances <5% through tonight. Weather overall remains mostly fair and benign as a weak shortwave pushes through the area. Lifting will bring slight chances of showers and thunderstorms across the eastern mountains (up to 10% chance). REF`s develop 100-250 J/kg of MUCAPE both late morning to early evening Friday & Saturday. Parts of the Foothills of the Blues through Central Oregon have greater development on Friday than Saturday, thus giving each area up to 10% chances of storms developing. PWATs are dry with less than 0.8 inches through the development period, so I would suspect that the majority of storms that will develop through the weekend to be mostly dry with an occasional strong, wet storm. Not expecting abundant lightning with this system, but some storms can still bring lightning and possibly small pea size hail in some of the strongest developing storms across the Eastern Mountains. As the shortwave passes through, we`ll see elevated fire weather conditions prevail through Saturday as breezy winds develop overlapping with dry air in the region. Not expecting criteria to hit over a wide area, but could see some isolated areas of critical conditions developing in parts of the Basin. At the same time, temperatures cool off through the weekend, with high temperatures dropping down to the mid to upper 70s by Saturday (70-90% confidence) that will improve fire weather conditions as we head through the weekend. Elevated fire weather conditions will prevail through parts of the region, but not expecting a wide critical set-up through the shortwave passage. Guidance is in agreement that our next set-up for a wide precip event will be sometime mid next-week with a trough digging down, bringing southwesterly flow aloft increasing PoP`s across the board. Plenty of time to monitor for impacts as impacts look to be a week out with no anticipated severe weather set-up at this time. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Light winds under 10 knots are expected across the Columbia Basin with more winds coming though the gaps, hence DLS will remain breezy to gusty (20 kts Tonight, and closer to 26 knots in the afternoon Friday). Low confidence exists in the the chances for brief IFR vsby from nearby smoke between about 12 and 15z at RDM which as been a trend the last few nights. VFR category is expected at all terminals outside of the small brief chances for vsby restrictions at RDM. && .Preliminary Point Temps/PoPs... PDT 47 82 47 73 / 0 0 0 0 ALW 54 84 54 75 / 0 0 10 0 PSC 52 85 51 78 / 0 0 0 0 YKM 55 85 53 76 / 0 0 0 0 HRI 54 85 52 76 / 0 0 0 0 ELN 48 77 47 69 / 0 0 0 0 RDM 42 82 39 72 / 0 0 0 0 LGD 49 86 47 75 / 0 0 0 0 GCD 52 89 49 77 / 0 0 0 0 DLS 57 82 56 74 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...Air Quality Alert until noon PDT Friday for WAZ026-522-523. OR...Air Quality Alert until noon PDT Friday for ORZ041-505-506- 509>511. && $$ DISCUSSION...95 AVIATION...71

475 FXUS65 KREV 272036 AFDREV Area Forecast Discussion National Weather Service Reno NV 136 PM PDT Thu Aug 27 2026 .KEY MESSAGES... * Gusty winds and near critical fire weather conditions continue through the afternoon. * Low chances of showers and isolated thunderstorms this afternoon along and south of Interstate 80. * Shower and isolated thunderstorm chances become more widespread Friday, along with much cooler temperatures. && .DISCUSSION... Persistent eastern Pacific troughing will encourage another dry and breezy afternoon today for areas north of the I-80 corridor. W/SW gusts of 30-35 mph (40-45 mph for wind prone locales) will be common between 12 PM and 8 PM PDT, renewing elevated fire concerns from the OR border south along the Sierra Front this afternoon (more details in the Fire Weather section below). Lakes may also be a bit more choppy in the afternoon. Increasing moisture aloft and daytime heating will support a 20-40% chance of light rain showers through the evening along and south of I-80. Thunderstorm chances today are only 10-15% and confined to Mono, Mineral, Lyon, and Churchill counties, but any storm that does develop will be capable of strong outflow gusts (45+ mph), brief heavy rain, and occasional lightning. Light rain showers may linger overnight tonight (10-20% probability), then chances increase to 50-80% from the Sierra crest far western Nevada. Abundant cloud cover and limited instability makes thunderstorm potential a bit more uncertain, but blended guidance shows a 20-30% chance of storms from Alpine-Mono County into Lyon, Mineral, Churchill counties Friday afternoon. Elsewhere, thunderstorm chances are 15% or less. Faster storm motions suggest that new lightning fires will be more of a concern compared to flooding, but flash flooding will still be possible (at least a 5% chance) where storms train -- especially if they do so over vulnerable burn scars and/or steep terrain. Friday will also be noticeably cooler as temperatures fall ~10 degrees from today. A drying trend will reduce shower and thunderstorm coverage/chances on Saturday with dry weather favored Sunday and Monday. Chances begin to increase after Monday, but confidence is low. Afternoon winds may also become a tad stronger than our typical zephyr breeze Monday and Tuesday, which would pose fire weather concerns once again next week. Otherwise, next week`s temperatures are leaning towards being mild and cooler than normal. -Salas && .AVIATION... TAF sites look to see mostly VFR conditions today and tonight. Area winds will gust up to around 20-25 kts between 27/20Z-28/04Z, with portions closer to the OR border seeing gusts up to around 30 kts. Forecast guidance shows around a 10-40% chance for showers between 27/20Z-28/06Z in W NV and the Sierra, with the higher end chances in Mono County/KMMH. In addition, there is a 10% chance for an isolated thunderstorm at KMMH. On Friday, a cooler weather system moves through the region, bringing increased cloud cover and a more widespread showers (50-75% chance) and thunderstorms. -078/Salas && .FIRE WEATHER... A 2-5 hour overlap of W/SW gusts of 30-35 mph (40-45 mph on exposed ridges) and RH reductions to 10-15% will unfold this afternoon across far NE California and NW Nevada -- including the S-1 Vya, S- 3, and Hawk fires. Nighttime recoveries will be poor to moderate in this area as RH struggles to exceed 40%, extending burn periods into the overnight hours. Increasing moisture and abundant cloud cover arrives on Friday, introducing much cooler temperatures, higher humidity, and moderate to high chances (50-80%) of rain showers to much of the region. A warmer and drier pattern returns Saturday into early next week with increased breezes possible Monday and Tuesday. -Salas && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

951 FXUS66 KSTO 271922 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1222 PM PDT Thu Aug 27 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Seasonably warm high temperatures continue today with a cooling trend from Friday onward. - Elevated Fire Weather conditions from dry conditions and breezy winds through this evening for portions of the Valley and foothills. - Shower and isolated thunderstorm chances arrive late today into Friday, generally from Interstate 80 southward. - There is high uncertainty in exact details, but unsettled weather and precipitation chances look to return by mid to late next week. && .DISCUSSION... Today-Friday... Despite clear to partly cloudy skies early today, a plume of subtropical moisture is beginning to edge into interior NorCal early this afternoon. While cloud cover is expected to become more prevalent through the afternoon and evening hours, seasonably warm temperatures and dry conditions look to persist for much of the region north of Interstate 80 today. Resultant high temperatures in the mid to upper 90s at low elevations and 80s at higher elevations persist again this afternoon with breezy onshore winds remaining strongest across the northern Sacramento Valley/Burney Basin/northeast foothills this afternoon and evening. As a result, Elevated Fire Weather conditions continue for these locations through today. As longwave troughing becomes a mainstay offshore of NorCal through the end of the week, the aforementioned moisture plume will have a direct conveyor toward the region today and Friday. Given the broader nature of the forcing aloft today, primarily showery activity is anticipated south of the I-80 corridor this afternoon and evening, with likely little to no accumulating precipitation. Available instability will remain the biggest uncertainty with this event. Despite limited model agreement, with clearing this morning and the advancing moisture plume aloft, a few lightning strikes cannot be entirely ruled out in the northern San Joaquin Valley and adjacent terrain later today. Heading into Friday, the areal extent of subtropical moisture is expected to become more widespread across interior NorCal. While the primary shortwave feature is expected to track across the Pac NW through the end of the week, a weaker, secondary midlevel trough is on track to build into interior NorCal early Friday. Available instability will likely be limited due to broader cloud cover over the region, however, the presence of more appreciable forcing aloft paired with more robust moisture may offset the instability downturn. As a result, another day of showers and isolated thunderstorms remains forecast for Friday. Highest potential overall is still anticipated from I-80 southward with best chances for thunderstorms (15-30%) remaining along the Sierra. Similarly, probabilities for precipitation greater than 0.1" sit around 10-15% for the southern Sacramento and northern San Joaquin Valleys with probabilities jumping to 40-70% for the Sierra and adjacent upper foothills. The Weekend Into Next Week... As the moisture plume pushes eastward by the weekend, a trend toward drier weather is anticipated area wide Sunday into early next week. While chances are expected to be notably lower on Saturday, there may be enough overlap of lingering moisture and troughing aloft for additional shower/thunderstorm potential along the Sierra south of Highway 50. At this time, probabilities of showers and isolate thunderstorms sit around 10-15%, although highest potential will likely be from the Sierra crest eastward. Despite the broader drying trend that is on track late weekend into early next week, the presence of a troughing aloft and low heights will keep temperatures seasonable through the weekend. By early next week, ensemble guidance is in general agreement on a longwave trough deepening offshore of the Pac NW toward NorCal. The immediate impacts of this developing pattern look to be even further cooling to below normal temperatures alongside breezier onshore winds. Heading toward the middle of next week, there are some indications within ensemble guidance for a return to unsettled and active weather. These indications are predicated upon the potential for remnant tropical moisture to become swept up in the deepening trough and yield additional shower/thunderstorm chances to the region. There are stark discrepancies regarding the timing and location of this additional moisture plume though leading to notably high uncertainty toward the end of the extended forecast period at this time. && .AVIATION... VFR conditions prevail across interior NorCal with surface winds generally below 12 kts. A weather system will arrive later tonight, introducing VCSH to northern San Joaquin TAF sites around 02z Friday through 10z. If any shower develops, MVFR conditions will be possible. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

527 FXUS65 KMSO 280819 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 219 AM MDT Fri Aug 28 2026 .DISCUSSION... KEY MESSAGES: - Isolated thunderstorms across southwest Montana and Lemhi County through this evening, with outflow wind gusts to 40 mph and lightning being the primary storm threats - Cooler temperatures today through the weekend with widespread precipitation Saturday and Sunday - Temperatures rebound early next week Southwesterly flow aloft ahead of an approaching Pacific Northwest trough of low pressure will allow isolated to scattered showers and thunderstorms to develop during the afternoon and evening hours today. The most favorable moisture and instability will be over southwest Montana and Lemhi County. Model soundings depict a dry lower atmosphere conducive to gusty outflow winds of about 40 mph with thunderstorms that are able to form. Frequent lightning will also accompany thunderstorms. Rainfall will remain scarce. Expect daytime high temperatures today to be a few degrees cooler than the past few days. The Pacific low remains on track to move across the Pacific Northwest into the Northern Rockies by late Saturday into Sunday. Daytime high temperatures will drop 15-20F by Sunday. Showers and thunderstorm coverage increases Saturday as the low moves further inland. As far as precipitation goes, chances for wetting rains (more than 0.10 in) reaches 80-90% for west-central and southwest Montana, as well as Lemhi County. Confidence for wetting rain decreases across northwest Montana, as probabilities for wetting rains drop below 30 percent. Temperatures rebound early next week towards seasonal normals, while ensemble solutions are indicating more unsettled weather later in the week. && .AVIATION...Showers and thunderstorms will again be a concern for KSMN and KBTM this afternoon and evening. Storms will be capable of gusty winds to about 35-40 knots and frequent lightning. The remainder of the Northern Rockies will see mostly VFR conditions with westerly or southwesterly gusts to about 20 knots in the afternoon ahead of an approaching trough of low pressure. Expect increasing clouds overnight with widespread rain starting on Saturday morning. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

268 FXUS65 KBOI 280856 AFDBOI Area Forecast Discussion National Weather Service Boise ID 256 AM MDT Fri Aug 28 2026 .KEY MESSAGES... - Scattered showers and isolated thunderstorms Friday and Saturday. Stronger storms possible in SE Oregon on Friday and SW Idaho on Saturday. - Notable temperature swings from Sunday through next week with Monday and and Tuesday being the warmest days. - A deeper low pressure system expected later next week for cold and wetter conditions. && .SHORT TERM /Through Sunday Night/... An upper level trough situated off the Pacific Northwest coast continues to stream elevated moisture into the region. Mainly virga has been seen thus far across southwest Idaho and southeast Oregon this morning as the boundary layer remains quite dry still. Clouds cover should limit surface based instability this afternoon. The exception will be where mid level moisture will overlap with surface warming to support localized thunderstorm development, especially over southern Harney and Malheur counties as well as higher terrain in southwest Idaho. Inverted V atmospheric profiles will promote erratic, gusty outflow winds with any robust cell that develops. Rainfall becomes more likely by sunset as the PWs across the area approach the 95th percentile. Precipitation chances exit southeast Oregon Friday night as moisture shifts eastward into southeast Idaho. On Saturday, the main upper level trough moves closer to the region, providing stronger synoptic forcing. A relatively well mixed boundary layer with enhanced instability and a strong upper level jet aloft should support scattered thunderstorm development and bring the potential for stronger downdrafts, leading to gusty outflow winds up to 45 to 55 mph with the strongest storms. Brief heavy rain is also possible given the high PWs though storms will be moving quite fast given the flow aloft lowering the risk of flash flooding. The best potential for thunderstorms is forecast across south-central Idaho Saturday afternoon. A cold front pushes through the forecast area late Saturday evening, bringing drier air and ending convective activity overnight. Temperatures on Sunday will drop significantly behind the front, cooling to around 10 degrees below seasonal normals under breezy westerly winds. && .LONG TERM /Monday through Friday/... Temperatures rebound closer to seasonal averages on Monday as shortwave ridging briefly takes hold. By Monday evening, the next trough begins moving inland from the coast and may pull monsoon moisture northward, supporting shower and thunderstorm chances primarily across south central Idaho. This trough will move across the Pacific Northwest Tuesday into Wednesday bringing a threat for showers and thunderstorms across the higher terrain. This feature will track ahead of a deeper low pressure system set to move into the Pacific Northwest coast late in the week. Consequently, expect enhanced cloud cover, intermittent shower and thunderstorm potential over higher terrain, and a tightening surface pressure gradient. Stronger, breezy surface winds are likely heading into Thursday and Friday along with another cooling trend. Ensemble spread remains slightly elevated regarding exact timing, but the overall signal favors a cool, windy, and unsettled end to the extended period. && .AVIATION /06Z Friday through Saturday/... Issued 1220 AM MDT FRI AUG 28 2026 Mainly VFR. Light rain and virga will increase overnight into Friday across S Idaho and far SE Oregon. Isolated embedded thunderstorms will also develop with gusty erratic winds 25-45 kt possible Friday afternoon and evening. Local reductions in visibility from wildfire smoke. Surface winds: SW-NW 5-15 kt, gusts to 25 kt Friday afternoon. Winds aloft at 10kft MSL: SW 15-25 kt. KBOI...VFR. Increasing mid to high clouds with light showers or virga in the vicinity overnight into Friday. Surface winds variable less than 10 kt overnight, then SE 5-15 kt developing by Friday afternoon. Weekend Outlook...Mainly VFR. Patchy morning fog in the west central Idaho mountains and scattered showers on Saturday through the day in Idaho, mainly in the mountains. Slight chance of thunderstorms in the afternoon. SW-NW surface winds 5-15 kt with gusts to around 25 kt. Breezy W-NW winds and dry on Sunday. && .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 SHORT TERM...JDS LONG TERM....JDS AVIATION.....ST

862 FXUS65 KLKN 271947 AFDLKN Area Forecast Discussion National Weather Service Elko NV 1247 PM PDT Thu Aug 27 2026 .KEY MESSAGES... * Lingering isolated dry storms continue this afternoon * Vegetation remains dry enough that any cloud to ground lightning strikes could produce fire starts that could spread rapidly * Shower and thunderstorm activity is expected to increase in coverage for Friday and into the weekend. Isolated strong thunderstorms are possible on Saturday * Temperatures will begin cooling tomorrow and Saturday with readings below to near normal && .DISCUSSION... (This evening through next Wednesday) WEATHER PATTERN OVERVIEW: The high pressure system to the east continues to feed monsoonal moisture into eastern Nevada, with storms already ongoing in White Pine and southeastern Elko county. These storms are expected to spread into northeastern Elko county this afternoon before dying out around sunset. Hazardous fire behavior from thunderstorm winds continues to be a threat today, as well as new ignitions from lightning. Monsoonal moisture continues in eastern Nevada through the weekend but beginning tomorrow its joined by an influx of Pacific moisture from the remnants of Tropical Storm Iselle. This additional moisture is expected to result in widespread showers and thunderstorms across the forecast area. Additionally, a level 1 Marginal risk of excessive rainfall is in place for much of the forecast area tomorrow and Saturday. Storms may also pose a debris flow threat to recent fires and fresh burn scars. Overcast skies and rain cooled air will also decrease high temperatures below normal values. The tropical moisture dissipates by Sunday but some monsoonal moisture will still be capable of spawning isolated thunderstorms through midweek as the high pressure center looks to take its time in breaking down. FORECAST CONFIDENCE & DEVIATIONS: High confidence in thunderstorm activity through Saturday. SST and SerpISC were again used to better represent thunderstorm probabilities in eastern NV between 18Z today and 03Z tomorrow. && .AVIATION...Thunderstorms continue to have intermittent impacts at KELY and KENV this afternoon. Additionally, more widespread showers and thunderstorms are expected to affect all sites starting tomorrow, although the extent of impacts was too low for TAF inclusion at some sites for the 18Z forecast. All sites except KENV will experience gusty winds up to 25KT this afternoon, and gusts up to 40KT are possible near thunderstorms. No sustained visibility or ceiling impacts are expected, although brief decreased visibility is possible with direct thunderstorm impacts. && .FIRE WEATHER...Isolated storm activity will impact eastern NV through Thursday evening including FWZ 425/469/470. Hazards will continue to be gusty erratic winds leading to extreme fire behavior and dangerous lightning. Friday evening into Saturday potential increases for heavy rainfall introducing the hazard of debris flows especially over fresh burn scars. This increase in rainfall will impact all fire weather zones except for western portions of FWZ437. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...94 AVIATION...94 FIRE WEATHER...99