808 FXUS66 KSEW 212152 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 252 PM PDT Fri Aug 21 2026 .SYNOPSIS...Upper level low approaching from the southwest Friday will move into the coastal waters Saturday and into Southern British Columbia early Sunday morning. This system will bring cooler weather with a chance of showers and thunderstorms. Upper level ridge rebuilding Sunday will move east Monday for dry and mild weather. Upper low shifting inland on Wednesday with showers returning. && .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...High pressure over the region is bringing one more warm and dry day to western Washington today. Highs in the interior are in the 80s with pockets of Moderate HeatRisk (mainly east of I-5). Satellite does show some wildfire smoke over western Washington due to light east winds over the crest. Sensors are showing degraded air quality in portions of Whatcom County and King County (due to the Three Queens fire). The air quality should improve on Saturday as the wind flow changes directions. Our next system will move in late tonight and into Saturday and Sunday. This system will bring cooler weather along with increasing chances of thunderstorms. The highest chances of thunderstorms will be in the mountains, especially across the northern Cascades. The highest chances of wetting rains will be near the Canadian border. With the colder air mass in place, Saturday`s highs will be cooler and in the 60s to lower 70s across most areas. Showers will linger on Sunday (mainly north part) as the low tracks N/NE into B.C. 33 && .LONG TERM /MONDAY THROUGH FRIDAY/...High pressure returns early next week for more dry and mild weather. The flow remains onshore with temperatures close to average. The ridge will stall an upper low offshore that will eventually shift inland by midweek for another round of showers. The low and cooler air mass will result in below average temperatures in the 60s and lower/mid 70s. We`re under weak troughing through the end of the week with isolated mountain showers. 33 && .AVIATION...Southerly flow aloft will increase tonight into Saturday as an upper low offshore approaches Western Washington. VFR cigs for the majority of terminals this afternoon with increasing mid and high clouds. MVFR/IFR stratus continues along portions of the coast. Stratus will move inland into Puget Sound into Saturday morning, resulting in more widespread MVFR/IFR cigs. LIFR stratus will exist along portions of the coast tonight into Saturday as well. Showers and a few thunderstorms are expected to develop late tonight into Saturday. Probabilities for thunderstorms range to 10 to 20 percent for all terminals, with the higher probabilities from KPAE northwards. Cigs will improve to VFR for interior locations by the afternoon. W/NW winds this afternoon will transition more SW tonight and increase into Saturday. KSEA...VFR with mid and high clouds into tonight. Stratus will spread inland early Saturday, reaching the terminal around 12z. Predominantly low-end MVFR cigs are expected. There is a 20% probability of IFR cigs between 13 to 17z as well. Cigs will slowly improve to VFR into the afternoon, between 19 to 21z. Showers and a few thunderstorms are expected to develop early Saturday morning. Confidence remains lower in the exact location for precipitation, but there is a 10 to 15% probability for thunderstorms around the terminal Saturday, peaking between 12 to 20z. W/NW surface winds ranging 5 to 8 kts will transition SW after 00-01z. JD && .MARINE...Onshore flow will increase this evening resulting Small Craft westerly winds through the Strait of Juan de Fuca tonight. A weak surface low then moves into the coastal waters Saturday before the low dissipates Saturday night. Showers will develop late tonight into Saturday associated with the system. There is a also a slight chance (10-20%) for thunderstorms over both the coastal and interior waters on Saturday. South to southwest winds will also increase on Saturday, with gusts ranging 15 to 20 kts for portions of the interior waters and inner coastal waters. High pressure rebuilds Sunday and remains over the area into Tuesday. A cold front moves into the waters by midweek. Seas will mostly be in the 3 to 5 foot range into early next week. JD && .FIRE WEATHER...Dry and warm conditions continuing today. Critical RHs have been observed for locations above 2500 ft so far this afternoon. Increasing cloud coverage and continued low- level onshore flow this evening. Then, an upper-low offshore will track into the region late tonight into early Saturday with the potential for scattered showers and thunderstorms. As a result, a Red Flag Warning has been issued for the Cascade and Olympic Mountains late tonight into Saturday evening. The North Cascades are currently the most favorable for thunderstorms at this time with a 30-40% chance. Lightning may lead to new fire starts, as well as result in gusty and erratic winds. Low level onshore flow increases Saturday night into Sunday with varying degrees of onshore flow through the middle of next week. Good relative humidity recoveries each night will keep fire weather concerns at a minimum. Chance of showers and possible thunderstorms next Wednesday with an upper level trough moving into the area. 41 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Red Flag Warning from 5 AM to 8 PM PDT Saturday for West Slopes of the North Cascades Generally above 1500 Feet. Red Flag Warning from 1 AM to 5 PM PDT Saturday for East Portion of the Olympic Mountains-West Portion of the Olympic Mountains-West Slopes of the Central Cascades Generally above 1500 Feet. PZ...Small Craft Advisory from 6 PM this evening to 6 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca. && $$

838 FXUS66 KPQR 212131 AFDPQR Area Forecast Discussion National Weather Service Portland OR 231 PM PDT Fri Aug 21 2026 .SYNOPSIS...Low pressure brings chances for showers tonight and into Saturday across northwest Oregon and southwest Washington, with a 15-20% chance for thunderstorms over the Cascades and 5-10% chance elsewhere. Southerly winds tonight will become more west/southwest on Saturday and return to a west/northwest pattern Sunday. Seasonable weather returns Sunday through the middle of next week. && .DISCUSSION...Tonight through Thursday...An upper level trough over the northeast Pacific will continue to move eastward towards the PacNW through the overnight hours. This will support upper level cloud cover, a decrease in temps and a low chance for precipitation through Saturday. Hi-res models seem to be struggling with the development and progression of precipitation across the area as the low shifts over the area. The most up to date CAMs continue to show the potential for light precipitation starting this evening and continuing into the overnight hours. As winds shift more southwesterly, PWAT values are expected to increase to between 1.0-1.30 inches across NW OR and SW WA. The biggest question will be CAPE over the region. CAMs and high resolution models continue to show surface based CAPE (SBCAPE) values 400-800 j/kg is possible over the Cascades but a strong capping inversion of 75-175 J/kg of CIN could stifle any development. Most unstable CAPE (MUCAPE) values are a bit higher in the 700-1100 J/kg range over the Cascades which supports elevated instability in the mid levels of the atmosphere, this lends credence to the Cascades maintaining the highest probability of thunderstorms through the overnight hours. It should also be noted that CIN values over the Cascades are around 100-200 J/kg and that could be enough to stifle any development for the Cascades as well. Therefore, will continue to maintain the slight chance PoPs and thunder (both 10-25%) over the area with the Cascades remaining most likely for any precipitation initially then shifting north of the OR/WA border as a weak cold front moves onshore late tonight into Saturday morning. Any showers or storms will be isolated with most locations likely remaining dry. The upper level trough will continue to progress northeast through the weekend. The weak cold front moving through the area early Saturday will support daytime highs in the upper 70s to low 80s for inland valleys as well as highs in the 60s along the coast and 70s for the Cascades. Southerly winds which developed today will become more west/southwest tonight and into Saturday. Winds through west- east aligned mountain gaps could be gusty, especially through the western Columbia River Gorge. Gusts around 30 mph are expected with a 30-50% chance for isolated gusts approaching 40 mph Saturday afternoon. Zonal flow aloft develops Sunday as the upper level trough continues to trek northeast away from the region. Seasonable highs in the upper 70s to low 80s are expected across the interior lowlands. Looking ahead into early next week, ensemble clusters favor ridging over the central CONUS and the PacNW. Model spread for high temperatures on Monday increases with the 10th-90th percentiles ranging from the upper 70s to low 90s for the interior lowlands. Confidence increases Tuesday and Wednesday with highs likely in the mid 70s to mid 80s. Clusters indicate another trough influencing the region by the middle of the week but exact timing and upper level pattern are uncertain but onshore flow and more seasonable temperatures would be favored. /42-19 && .AVIATION...Through 00Z Sunday...Marine stratus remains along portions of the coast, maintaining LIFR/IFR CIGs at KONP and MVFR CIGs at KAST. While conditions may continue to improve at these terminals, some coastal terminals will once again deteriorate back to LIFR/IFR conditions by 00-02Z Sat as marine stratus pushes back into the coast. While guidance suggests a 30% chance of LIFR and 50-70% chance of IFR CIGS at KONP by 02Z Sat, guidance has trended to only 30% chance of IFR CIGs at KAST. As for inland terminals, expect VFR conditions and mid to high clouds through at least 12Z Sat, then a 20-40% chance of MVFR CIGs between 12-18Z Sat. Otherwise, expect mostly south to southwesterly winds between 5-10 kt through the TAF period, with the exception of 10-15 kt with gusts up to 25 kt at coastal terminals beginning around 16-18Z Sat. KPDX AND APPROACHES...Expect VFR conditions and mid to high clouds through at least 12Z Sat, then a 20-40% chance of MVFR CIGs between 12-18Z Sat. Winds will be light and variable through most of the period, although generally southerly and increasing to around 6-8 kt by 10-12Z Sat. ~12 && .MARINE...South to southwest winds continue today as a low pressure system moves over the northeast Pacific. A cold front moves through Saturday, bringing a 50-80% chance for maximum wind gusts to exceed 21 kt for the inner waters, including the Columbia River Bar. As a result, a Small Craft Advisory has been issued for the inner waters from 5 AM to 5 PM Saturday and for the Columbia River Bar from 11 AM to 5 PM Saturday. For the outer waters, chances are 20-50% with the highest values of that range between 10 and 30 NM. High pressure and northerly winds return by Sunday, with a 40-70% chance for northerly wind gusts to exceed 21 kts in the evening and continuing into Monday. Seas of 4-6 ft persist through the period.~12 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 11 AM to 5 PM PDT Saturday for PZZ210. Small Craft Advisory from 5 AM to 5 PM PDT Saturday for PZZ251>253. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

497 FXUS66 KMFR 220016 AFDMFR Area Forecast Discussion National Weather Service Medford OR 516 PM PDT Fri Aug 21 2026 ...Updated the Aviation and Marine Sections... .AVIATION...22/00Z TAFs...Marine stratus will persist tonight through Saturday night with mainly IFR along the coast and over the marine waters. Patches of LIFR will be at maximum coverage late tonight into early Saturday morning. Also, drizzle is possible along and west of the coastal ranges. Inland, VFR conditions will prevail. High clouds from the Cascades eastward will gradually shift north-northeastward, out of the area by late Saturday morning. Gusty winds will linger early this evening, and return for Saturday afternoon and evening. The strongest winds will be east of the Cascades and in the Shasta Valley, with south to west gusts today and southwest to northwest gusts on Saturday at 20 to 40 kt. Winds will ease after sunset. && .MARINE...Updated 830 PM PDT Friday, August 21, 2026...Light winds and low seas will persist into Sunday morning. Southerly winds will shift to westerly Saturday as a weak front dissipates over the waters. A thermal trough will develop Sunday with increasing northerly winds. These winds will likely be hazardous to small craft south of Cape Blanco late Sunday morning through Monday morning. The area of stronger winds is likely to shift offshore, beyond the inner waters, during Monday. Winds are then likely to diminish again later Monday night through Tuesday into Wednesday. && .PREV DISCUSSION... /Issued 252 PM PDT Fri Aug 21 2026/ KEY MESSAGES... * While marine stratus persists over coastal areas and clouds stream to the north inland, activity is unlikely this afternoon and evening. * A Red Flag Warning is in place for the Shasta Valley as well as Klamath and eastern Lake counties this afternoon and evening for gusty winds and low relative humidities (RHs). For Saturday afternoon and evening, a Red Flag Warning is in place across Klamath and Lake counties. * Winds ease on Sunday, with a generally unimpactful pattern expected for next week. DISCUSSION...A cutoff low passing to the west will guide area weather today and through much of the weekend. While marine stratus lingers along the Oregon coast and clouds are streaming from south to north over more inland areas, activity is not expected today (although virga may bring some hopes up). Radar returns show a line of higher returns over the Cascades and moving eastward, so a few stray showers are possible into parts of Klamath County. But with cloud cover limiting daytime heating, convective instability will be limited. Thunderstorms aren`t entirely out of the question, but chances have trended downward for this afternoon and evening (5- 10%). With gusty winds and dry surface air being observed, a Red Flag Warning is in place for the Shasta Valley as well as across Klamath and eastern Lake counties. The low stats to swing inland over Washington state on Saturday. With drier air aloft, precipitation is not expected. Gusty southerly winds will move eastward, which will take the Shasta Valley out and put the rest of Lake County in a Red Flag Warning for Saturday afternoon and evening. Areas under marine stratus will see cooler temperatures while inland areas will be at seasonable temperatures. The cutoff low is expected to be to the northeast by Sunday, bringing a southwest flow pattern that will generally persist through the week ahead. A shortwave ridge is currently expected to bring temperatures 5-10 degrees above normal for Monday and Tuesday. An upper trough passing to the north will bring temperatures back down on Wednesday and Thursday, with elevated westerly winds over Lake and Modoc county terrain possible depending on its position. Deterministic models start to diverge into Friday and beyond, but meteograms show agreement that the rest of August looks to stay dry. -TAD FIRE WEATHER...Updated 130 PM PDT Friday, August 21, 2026...An upper level trough will pass through the region today into Saturday, bringing a period of increased winds and critical fire weather conditions. Afternoon winds increase today as the trough and associated dry cold front approach the region (gusts 25-35 mph), but daytime humidities will also trend somewhat higher compared to yesterday. Despite the uptick in humidities, it`s close enough with the higher confidence on more widespread higher winds on Friday to warrant maintaining a Red Flag Warning for FWZs 281, 284, 285 and 624. Sustained winds won`t quite reach criteria for FWZ 625 today, but by Saturday, however, 700 mb winds will peak in strength east of the Cascades and more widespread sustained winds of 15 to 20 mph are expected as the dry front passes. Additionally, daytime RHs will trend lower again, so another day of critical fire weather conditions is expected on Saturday. The Fire Weather Watch has been upgraded to a Red Flag Warning for FWZs 284/285/624/625 for gusty winds and low RH for Saturday afternoon/evening. In addition to wind/RH concerns for today and Saturday, there is the potential for isolated showers and very isolated thunderstorms today. Ample cloud cover so far is expected to limit daytime heating and instability, which should keep the lightning potential minimal today. There are some returns on radar this afternoon, but very little, if any, precipitation is making it to the ground. By Saturday, the mid-levels dry out and thunderstorm threat will shift well north of the forecast area into northern Oregon/Washington. More typical summer conditions return Sunday and persist into early next week. There are some signals for thunderstorm chances across eastern 285/625 on Monday, but much will depend on how far west the Four Corners High retrogrades behind this trough passage. Otherwise, another trough drops southward from the Gulf of Alaska and lingers off the BC coast through early next week. There will likely be additional shortwaves/troughs to swing through the region early next week, bringing periods of enhanced winds. Stay tuned for updates. /BR-y && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 9 PM PDT this evening for ORZ624-625. CA...Red Flag Warning until 9 PM PDT this evening for CAZ281-284-285. PACIFIC COASTAL WATERS...None. && $$

464 FXUS66 KEKA 212252 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 352 PM PDT Fri Aug 21 2026 .KEY MESSAGES... * A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures this weekend. && .SYNOPSIS...A deep marine layer and cooler temperatures aloft will combine to bring near to slightly below normal temperatures through the weekend. The coast may finally see more clearing over the weekend. Some warming is expected Sunday and Monday before another trough brings cooler temperatures next week. && .DISCUSSION...An upper level-open wave trough crowds into the PACNW coastline over the few days. This pacific low is a part of a larger pattern, Omega block, which has high pressure ridging set up in the interior with peak amplitude extending into Canada. The positive tilt of the pacific area trough has kept the potential for convection and consequently lightning probabilities low. That and the sourced tropical moisture being pulled into the area via elongated troughing motion has also paired with the deepening marine layer to quell high temperatures inland and rebound overnight recovery RH values, further suppressing fire weather behavior. Saturday the upper level low starts to move out of the area with high pressure filling in behind it. This will bring cooler temperatures aloft which will keep the inland areas mainly in the 80s with 70s closer to the coast. This may finally bring some clearing and breezy afternoon winds. The cooler temperatures aloft will weaken the marine inversion. Saturday night into Sunday morning there is some offshore flow and this may help clear skies out more quickly during the day. It doesn`t look strong enough to keep skies clear overnight. Monday through the middle of the week a trough starts to approach the area bringing cooler temperatures and deeper marine layer again. This will come more from the west, thunderstorms look unlikely. && .AVIATION...The deepening marine layer has lifted the cloud base and kept ceilings 1300-1500ft at the coastal terminals, locking flight categories into MVFR with periods of VFR as skies scatter out and fill back in with offshore stratus persisting. Satellite products in the visible spectrum confirm what models are also predicting for this evening, IFR conditions with ceilings coming down below 1000ft. The marine layer will hold the cloud base around 700ft or so for KACV and KCEC with a few periods of sub 500ft ceilings at KCEC being signaled for a few hours. That said, offshore winds at KACV could help keep visibility improved overnight as well. Mostly prevailing VFR conditions at KUKI overnight with gusty northerlies late Saturday afternoon. /EYS && .MARINE...Calm seas and light to gentle breezes are expected through early Saturday. Moderate northerly winds return to the outer waters Saturday afternoon and increase through Sunday with localized gusts near Gale, south of Cape Mendocino and fanning out into the southern outer waters. A small craft advisory has been hoisted for the southern waters late Saturday night/early Sunday morning as well as the northern outer waters which start Sunday evening. && .FIRE WEATHER...Marine influence has will continue to increase through the end of the weekend. High clouds will aid in the warmest interior temperatures pulling back closer to 90 with RH closer to 25 percent. Mid and upper slope recoveries will also improve though remain poor on higher peaks. Warmer, near average conditions will return Sunday and into early next week. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ 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

121 FXUS66 KMTR 212208 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 308 PM PDT Fri Aug 21 2026 ...New SHORT TERM, LONG TERM, MARINE... .KEY MESSAGES... Updated at 308 PM PDT Fri Aug 21 2026 - Temperatures will be close to or below normal into the beginning of next week - Warm and dry conditions above 1000ft persist into the weekend && .SHORT TERM... Issued at 308 PM PDT Fri Aug 21 2026 (This evening through Saturday night) The forecast is on repeat today. Satellite imagery shows high clouds streaming overhead and the stratus a bit more dispersed along the coast. Expect these conditions to continue this afternoon, with the marine layer making a return later this evening and overnight. Guidance shows the marine layer should be around 1000-1500ft across our service area, which should lead to another night and morning of cloudy skies for the majority of the valleys. Low clouds continue to clear by mid to late morning, with a few high clouds potentially lingering into Saturday. With stratus clearing potentially a bit earlier and less high clouds, highs should be similar to Thursday, perhaps a few degrees warmer. && .LONG TERM... Issued at 308 PM PDT Fri Aug 21 2026 (Sunday through next Thursday) The extended forecast looks similar, as we remain caught in the quasi-zonal to weak troughing while high pressure holds to the east. Temperatures should cool a few degrees on Sunday and then moderate into early next week. Models and ensembles show ridging trying to build slightly to the west, which would lead to warming for mid to late next week. Some caveats to what might happen will be the Pacific. The Tropical Weather Outlook from the National Hurricane Center shows three potential disturbances well south of Baja. Could influence how the high behaves. && .AVIATION... (18Z TAFS) Issued at 1125 AM PDT Fri Aug 21 2026 Currently have a mix of IFR to VFR ceilings due to patchy stratus across our region. VFR conditions are expected to prevail this afternoon into the early evening hours. HAF is an exception as they may have a couple hours of VFR scattered cloud decks in the early afternoon before shifting back to IFR ceilings. Moderate to fresh onshore breezes around 10 to 15 kt expected through the day and ease overnight. The marine layer returns this evening impacting coastal sites first before filling in over inland terminals. Low to medium confidence on the exact stratus arrival as it is dependent on where the upper level low sets up during the day. Currently, all TAF sites are expected to develop IFR to MVFR ceilings, with coastal sites having a high chance of dropping to LIFR in the overnight hours. Vicinity of SFO...Stratus is beginning to mix out of the SF Bay as moderate onshore breezes increase. VFR through the afternoon with occasional gusts around 20-25 kt possible. Winds remain around 10 kt overnight. Medium confidence on the timing of IFR ceilings as they may arrive as early as sunset. The marine stratus is expected to linger until late Saturday morning. SFO Bridge Approach...Ceilings that develop may not be as low as SFO and clear before SFO does. Otherwise, similar to SFO. Monterey Bay Terminals...Stratus is receding to the coastline resulting in VFR conditions through the afternoon. Onshore winds will be diurnally driven this TAF period. The marine layer holds on strong as it returns with IFR ceilings this evening around 6-7 PM PDT. Medium confidence that ceilings will drop to LIFR overnight (OVC003-004), but there is still uncertainty regarding the exact timing and duration of LIFR conditions. If LIFR ceilings develop, they are likely to impact visibility and linger at the terminals through mid Saturday morning. && .MARINE... (Tonight through next Wednesday) Issued at 308 PM PDT Fri Aug 21 2026 Widespread moderate to fresh northwest breezes prevail through the weekend with slight to moderate seas. Locally strong breezes with occasional near gale force gusts are expected in the coastal jet regions of Point Sur and Point Reyes. Hazardous conditions for small crafts are expected this afternoon for the bay waters and immediate coastal waters. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-SF Bay N of Bay Bridge. Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 2 PM Saturday to 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...KR LONG TERM....KR AVIATION...Navarrete MARINE...Navarrete 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

361 FXUS66 KOTX 220003 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 503 PM PDT Fri Aug 21 2026 .KEY MESSAGES... - A Heat Advisory has been issued through Friday evening due to very warm temperatures and widespread Major HeatRisk. - Saturday system brings increased chances for showers, thunderstorms, and gusty winds. This will lead to critical fire weather conditions across the Inland Northwest. - Patchy blowing dust is possible Saturday in the Western Columbia Basin. && .SYNOPSIS... Temperatures will be very warm Friday with widespread Major HeatRisk. A pattern change Friday night into Saturday will bring unsettled conditions with chances for showers, thunderstorms, and gusty winds. Sunday will remain breezy and dry, but cooler. Temperatures will warm again at the start of next week with breezy conditions returning by the middle of next week. && .DISCUSSION... Friday through Sunday: An incoming cold front will bring gusty winds and isolated to scattered thunderstorms to the region Saturday into Sunday. Today, ahead of the cold front passage on Saturday, temperatures have warmed into the high 90s with triple digits possible in the lower Basin. This has led to widespread Major HeatRisk values, so anyone without adequate cooling and hydration as well as health systems and industries could see impacts. A Heat Advisory is valid through much of the Inland Northwest through 10 PM this evening and low temperatures into tomorrow will be in the 60s and 70s and provide little overnight relief. Tonight into Saturday, moisture advection ahead of the frontal passage will raise PWATs to 125 to 150 percent of normal, around 0.75 to 1 inch. The arrival of the cold front on Saturday accompanied by a 40-50kt 500mb jet and warm overnight and daytime temperatures will create a favorable environment for isolated to scattered thunderstorms across the Cascades and northern mountains. While these showers will initially start out as isolated in nature, as daytime warming increases, thunderstorms become more scattered in nature, especially into Saturday afternoon and evening. With PWATs near 1 inch and DCAPE values 500 J/kg and higher, main impacts look to be isolated heavy rainfall rates, gusty outflow winds up to 50 mph, and lightning induced fire starts. Steep terrain and burn scars will need to be monitored for any heavy rainfall rates. This threat will move eastward across the forecast area through the day, and Saturday night into Sunday morning the ID Panhandle sees isolated to scattered thunderstorms. To reflect these critical fire weather conditions, Red Flag Warnings have been issued. For the Cascades and northern mountains, the Red Flag Warning is valid from Saturday morning through Sunday morning. For the ID Panhandle, the Red Flag Warning is valid from Saturday afternoon through Sunday morning. Another impact from this cold front will be gusty winds leading to critical fire weather concerns across the Basin and Spokane area. There is a 40 percent chance and higher for most locations in the region to see wind gusts higher than 30 mph on Saturday night. Areas that will see the highest gusts include the Lewiston, Moses Lake, Wenatchee, and Waterville Plateau areas. A Red Flag Warning for the basin, Palouse, and Spokane areas is valid from Saturday afternoon through Saturday evening. Potential impacts from these winds include rapid spreading of wildfires alongside blowing objects and difficulties driving, especially for high profile vehicles. While models initially had the low moving out of the area quicker, there is now better agreement that the low lingers over the state of Washington through Sunday before moving out of the area Sunday night into Monday. Impacts will continue to be seen into Sunday afternoon with residual winds and isolated to scattered thunderstorms in the northern Idaho Panhandle. One thing to keep a close eye on is the extent of the thunderstorms post cold frontal passage on Sunday morning. As high-res models pick up the end of the event Sunday morning, they are showing enough lingering instability throughout fire zone 708 (Eastern Columbia Basin/Palouse/Spokane area) that it may need to be added into the Red Flag Warning. Wind gusts around 15- 20 mph will linger throughout the Cascade gaps, Okanogan Valley, Waterville Plateau, Columbia Basin, Spokane/CdA, and Palouse areas through late Sunday afternoon, bringing continued elevated fire weather conditions. A significant cooldown due to the cold front will be observed Saturday into Sunday, with high temperatures dropping around ten or more degrees. Temperatures will end up being a couple degrees below normal on Sunday. Apart from the northern mountains and Cascades, precipitation chances drop down to near zero. Monday through Wednesday: With high confidence (80 percent of clusters) indicating a strengthening ridge building over the area early next week, the temperature drop will be short lived. By Tuesday, temperatures will again warm into the high 80s to low 90s. Clusters show a 50 percent chance of another trough approaching the PNW coast, though timing and track are uncertain. This could lead to a return of gusty winds and thunderstorm chances. Overall chances for precipitation remain low, with PoPs 15 percent and lower expected Monday through Wednesday. /AS && .AVIATION... 00Z TAFs: VFR conditions are expected to continue through the TAF period except KEAT. There will be elevated showers that move through the region late this evening and overnight. There is a small chance (10-15% chance) of sprinkles) from 06-15Z for most TAF sites as a vort max moves through. Chance of TS out of these is very low (5%) but cannot be ruled out. Bands of convection will form in the Cascades in the very late morning to early afternoon and eventually SE WA and southern ID Panhandle around 23-00z. Confidence is too low for TS in the TAF but there is a 10-20% chance around 00z for KLWS-KPUW-KEAT. Vsbys at KEAT will degrade this evening around 07-08z as northwest winds bring in smoke from the Little Giant Fire. South to southwest winds will increase in the Columbia Basin, Palouse, and Spokane area in the late morning to early afternoon. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Low confidence for TS impacts before 0Z for KEAT-KLWS-KPUW. ----------------------- 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 68 94 59 82 54 87 / 10 10 20 0 0 0 Coeur d`Alene 68 95 60 81 53 86 / 10 10 40 0 0 0 Pullman 62 91 51 78 46 86 / 10 10 30 0 0 0 Lewiston 72 98 62 87 59 92 / 10 10 40 0 0 0 Colville 60 95 52 81 45 87 / 10 10 40 10 0 0 Sandpoint 62 93 56 77 47 83 / 10 20 40 10 0 0 Kellogg 63 92 55 77 52 84 / 10 10 40 0 0 0 Moses Lake 69 95 56 85 54 89 / 10 10 0 0 0 0 Wenatchee 76 94 63 83 62 88 / 20 20 0 0 0 0 Omak 71 96 56 85 56 88 / 10 20 20 10 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...Heat Advisory until 10 PM PDT this evening for Central Chelan County-Lower Garfield and Asotin Counties-Moses Lake Area- Northeast Blue Mountains-Northeast Mountains-Okanogan Highlands-Okanogan Valley-Spokane Area-Upper Columbia Basin-Washington Palouse-Waterville Plateau-Wenatchee Area-Western Okanogan County. Red Flag Warning from 4 PM Saturday to 11 AM PDT Sunday for Selkirk Mountains of Northeast Washington (Zone 700). Red Flag Warning from noon to 10 PM PDT Saturday for Colville Reservation (Zone 702)-Eastern Columbia Basin -Palouse - Spokane Area (Zone 708)-Foothills of Central Washington Cascades (Zone 705)-Foothills of Northeast Washington (Zone 701)-Lower Palouse -Snake River (Zone 709)- Waterville Plateau (Zone 706)-Western Columbia Basin (Zone 707). Air Quality Alert until 2 PM PDT Monday for Central Chelan County-Okanogan Highlands-Okanogan Valley-Upper Columbia Basin-Waterville Plateau-Wenatchee Area-Western Chelan County-Western Okanogan County. Red Flag Warning from 11 AM Saturday to 8 AM PDT Sunday for East Portion of North Cascades National Park/Lake Chelan National Recreation Area (Zone 697)-East Washington Central Cascades (Zone 696)-East Washington North Cascades (Zone 698)-Methow Valley (Zone 704)-Okanogan Highlands and Kettle Mountains (Zone 699)-Okanogan Valley (Zone 703). ID...Heat Advisory until 10 PM PDT this evening for Central Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse- Lewis and Southern Nez Perce Counties-Lewiston Area- Northern Panhandle. Red Flag Warning from 4 PM Saturday to 11 AM PDT Sunday for Northern and Central Idaho Panhandle (Zone 101). && $$

072 FXUS66 KPDT 212255 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 355 PM PDT Fri Aug 21 2026 .KEY MESSAGES... - Heat Advisories remain in effect through 10 PM. - Very low to slight chance (5-20 percent) of high-based showers and thunderstorms today and Saturday. Red Flag Warnings in effect for several fire weather zones. - Widespread breezy to windy westerly winds coupled with low relative humidity Saturday. Red Flag Warnings in effect for numerous fire weather zones. Wind Advisories in effect. && .DISCUSSION... Water vapor imagery shows a large, closed low offshore in the Pacific, just west of the OR/CA border. Meanwhile, an upper- level ridge of high pressure extends from the Four Corners into the Pacific Northwest. The interaction of these two synoptic- scale features will drive the bulk of our weather over the next couple days. Under the ridge, widespread hot conditions are in place with afternoon high temperatures already in the 90s to lower 100s this afternoon. Temperatures are expected to continue climbing in areas bereft of significant mid/high cloud. Clouds draped over the western half of our forecast area will suppress daytime highs relative to yesterday. Heat Advisories remain in effect through 10 PM this evening due to widespread Moderate (level 2 of 4) to Major (level 3 of 4) HeatRisk. This level of heat affects anyone without cooling/hydration. Ensemble NWP guidance is in concensus that the upper low will slowly track north-northeast through the day, remaining just offshore. This places the forecast area under southerly to southwesterly flow aloft. Synoptic-scale forcing coupled with increasing mid-level moisture may facilitate some high-based showers and thunderstorms this afternoon, tonight, and into Saturday morning, but probabilities are quite low (5-15 percent), highest for the Cascades. The low is then expected (95 percent confidence) to track inland across northern Oregon and Washington during the day Saturday, morphing into an open-wave trough as it moves inland. Its attendant cold frontal passage during the day will help drive breezy to windy westerly winds through the Cascade gaps as well as across the Columbia Basin and portions of the Blue Mountains. Wind Advisories were issued for many public forecast zones across north-central Oregon and south-central Washington, and may be expanded should confidence increase in windy conditions extending farther east across the Columbia Basin and Blue Mountain foothills. While confidence was "only" medium-high (50-90%) in reaching rh thresholds across fire weather zones, due to the magnitude of the forecast winds (10-25 mph with gusts of 25-40 mph, locally higher through especially wind-prone areas), have issued Red Flag Warnings for wind and low relative humidity for the majority of our non-mountain fire weather zones for later Saturday morning (OR/WA693) or Saturday afternoon (WA690, WA691, OR691, OR696, OR698, OR700, and OR703). In addition to Red Flag Warnings for wind/rh, the potential for abundant lightning and gusty outflow winds prompted Red Flag Warnings for WA695 (tonight through Saturday morning) and OR/WA692 (late Saturday morning through Saturday evening). Some breezy conditions are forecast to linger Sunday as the trough exits to the east. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... VFR conditions prevail with lingering smoke in the region. Elevated smoke may make its way down to the surface overnight, bringing a slight chance (5 to 15 percent) of MVFR conditions developing effective for all TAF sites. Breezy to locally windy conditions will develop in the morning to afternoon hours. Some sites will develop winds up to 25 to 35 knots of gusts during the strongest period. && .Preliminary Point Temps/PoPs... PDT 63 91 50 84 / 10 0 0 0 ALW 70 94 59 85 / 10 0 0 0 PSC 67 96 58 87 / 10 10 0 0 YKM 71 95 58 87 / 10 20 0 0 HRI 69 93 58 86 / 10 10 0 0 ELN 66 88 54 79 / 10 20 0 0 RDM 55 89 45 85 / 10 0 0 0 LGD 65 95 52 87 / 10 20 10 0 GCD 64 95 54 89 / 10 0 0 0 DLS 67 86 60 85 / 10 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...Heat Advisory until 10 PM PDT this evening for WAZ024-026>030- 521-523. Air Quality Alert until noon PDT Monday for WAZ026-522-523. Wind Advisory from 11 AM to 11 PM PDT Saturday for WAZ024-521. Red Flag Warning from noon to 10 PM PDT Saturday for WAZ690- 691. Red Flag Warning from 11 AM to 11 PM PDT Saturday for WAZ692. Red Flag Warning from 10 AM to 8 PM PDT Saturday for WAZ693. Wind Advisory from 2 PM to 10 PM PDT Saturday for WAZ026. Red Flag Warning from 11 PM this evening to noon PDT Saturday for WAZ695. OR...Heat Advisory until 10 PM PDT this evening for ORZ041-044-049- 050-502-503-505>508-510-511. Air Quality Alert until noon PDT Monday for ORZ041-044-049-050- 502-503-505>507-509>511. Wind Advisory from 11 AM to 11 PM PDT Saturday for ORZ041-044- 508-510. Red Flag Warning from noon to 10 PM PDT Saturday for ORZ691- 696-698-700-703. Red Flag Warning from 11 AM to 11 PM PDT Saturday for ORZ692. Red Flag Warning from 10 AM to 8 PM PDT Saturday for ORZ693. && $$ DISCUSSION...86 AVIATION...95

854 FXUS65 KREV 212000 AFDREV Area Forecast Discussion National Weather Service Reno NV 100 PM PDT Fri Aug 21 2026 .KEY MESSAGES... * Gusty southwest winds will bring a period of critical fire weather conditions and lake recreation impacts to parts of northeast CA, northwest and far western NV Saturday. * Showers and isolated thunderstorms return this weekend across parts of the eastern Sierra and western NV, with the highest chances on Saturday. * Near seasonal temperatures prevail through next week with overall dry conditions and afternoon breezes, which may increase for a day or two around the middle of next week. && .DISCUSSION... A swath of mid-high level clouds continues to track northward across northern CA-western NV today, leading to a slight cooling compared to the past couple of days. Slight instability may lead to a few showers across west central NV east of US-95 through the rest of this afternoon, although the chance for lightning is 10% or less. Elsewhere, winds edge upward a bit with gusts 25-30 mph across parts of northeast CA and western NV through early this evening. For Saturday, we`ll see winds increase as an upper level trough associated with a low pressure off the Pacific NW coast passes across northeast CA/northwest NV. This will bring lake recreation impacts for northeast CA and far western NV, where Lake Wind Advisories have been issued, and increased fire concerns with further details in the Fire Weather section below. Meanwhile, an increase in instability from the eastern Sierra of Mono County northward across areas of western NV will lead to 15-35% chances of showers and isolated thunderstorms. The best chances in western NV favor Lyon, Mineral, Churchill and Pershing counties, but a few cells could build a bit farther west across eastern parts of Storey, Carson City and Douglas counties. This activity is projected to start as early as 1-2 PM, and linger until 8-9 pm for far eastern portions of the Basin and Range, with stronger storms producing outflow gusts up to 45 mph, brief heavy rainfall, small hail and several lightning strikes. By Sunday, the winds trend downward to more typical gusts to near 25 mph. Shower and thunderstorm coverage decreases compared to Saturday, although isolated showers with 10-15% chance of lightning remain for Sunday afternoon, mainly in west central NV and eastern Mono County. For next week, the ensemble guidance is trending to a drier scenario while temperatures remain near or slightly above late August averages, with highs mainly 90-95 for lower elevations and lower 80s for Sierra communities. Typical afternoon breezes are expected, although a weak shortwave brushing across the Pacific NW may kick winds up a bit around the Tuesday-Thursday time frame, depending on the timing of this system`s passage. MJD && .AVIATION... * VFR conditions prevail with widespread mid to high level clouds through much of this weekend. Shower/thunder chances return this weekend mainly on Saturday, but storms have a 10% or less chance of affecting the main terminals. * SW-W wind gusts 20-25 kts at the main terminals today through 02-04Z. SW winds increase Saturday with gusts near 30 kt at the main terminals, except a bit less at KTRK/KTVL. By Sunday, winds decrease to similar levels as today. MJD && .FIRE WEATHER... * Wind gusts of 25-30 mph this afternoon will bring isolated periods of elevated fire weather conditions across northeast CA and northwest NV, extending southward to near the Reno area. * The greater fire weather concerns arrive on Saturday from late morning through the evening, as an upper trough passage increases wind gusts to the 30-40 mph range across northeast CA, northwest NV, and the Northern Sierra Front. While humidity values aren`t exceedingly low (minimums 12-18%), most of these areas did not receive much rainfall last week, resulting in a greater extent of dry vegetation where fire could spread more quickly when the winds pick up. Therefore we have issued Red Flag Warnings for these areas, so be extra cautious and fire safe, avoiding outdoor recreation or work activities that could spark any fires. * From Sunday through next week, afternoon breezes continue but at lower speeds compared to Saturday. The next time period to watch could be as soon as next Tuesday or Wednesday, when winds potentially trend upward again, while afternoon humidity decreases as a dry air mass settles in. MJD && .REV Watches/Warnings/Advisories... NV...Red Flag Warning from 11 AM to 11 PM PDT Saturday NVZ420-458. Lake Wind Advisory from 11 AM to 11 PM PDT Saturday NVZ003. CA...Red Flag Warning from 11 AM to 11 PM PDT Saturday CAZ270-278. Lake Wind Advisory from 11 AM to 11 PM PDT Saturday CAZ071. && $$

361 FXUS66 KSTO 212001 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 101 PM PDT Fri Aug 21 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Elevated Fire Weather Conditions today through Saturday within the Burney Basin due to low RH and breezy westerly winds. - Dry and with seasonable high temperatures through the weekend into next week. && .DISCUSSION... Upper level trough continues to dig into the Pacific Northwest and Northwestern California today through late Saturday. Radar has light reflectivity within portions of northern California, however there is no instability and conditions are dry in the low and mid levels. This is resulting in just scattered to broken clouds, with virga at times. The lack of instability and forcing is helping to prevent isolated thunderstorm potential. The best chances lie over the crest and toward the east where instability and forcing are more favorable. Otherwise, satellite shows few clouds across most of the Sacramento Valley, adjacent terrain, and into the San Joaquin Valley this afternoon. Temperatures reach into the upper 80s to lower 90s today, with cooling conditions near the Delta later this evening. As the trough moves east through the region, breezy conditions are expected at times within the northeastern foothills and into the Burney Basin. Highest chance to see up to 30kt gusts will be within the Burney Basin. This combined with already low RH values in the teens to lower 20s creates Elevated Fire Weather Conditions today. There will be some overnight recovery in RH values tonight. Winds will continue to be breezy Saturday with RH values in the the teens to 20s continuing the Elevated Fire Weather Concerns for the Burney Basin. Breezy onshore flow will be likely within the Delta helping to cool temperatures during the late afternoon, evening and overnight hours. Cooler evening temperatures will be predominately around the Delta, southern Sacramento Valley and into the northern San Joaquin Valley. Otherwise, as we move past the weekend and into next week the pattern aloft looks to remain in place helping to keep seasonal temperatures with dry weather conditions. && .AVIATION... VFR conditions continue through the TAF period, with SCT clouds moving through the Sacramento sites and RBL/RDD. Conditions remain dry helping to evaporate precipitation before it reaches the surface near RDD today. Skies will clear out slowly this afternoon/evening. Otherwise, breezy conditions near the Delta this evening and overnight. A few gusts to 15kts for the Sacramento Sites, MOD, and SCK this evening. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

013 FXUS65 KMSO 211913 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 113 PM MDT Fri Aug 21 2026 .DISCUSSION... KEY MESSAGES: - Marginal risk (5% chance for any given location) for severe thunderstorms capable of severe wind gusts (60 mph) on Saturday areawide. - Fire Weather Watches in effect Saturday into early Sunday morning across northwest Montana for dry lightning capable of new fire starts. - Fire Weather Watches in effect Sunday across southwest Montana (Fire Zones 110-111) for dry and windy conditions. A ridge of high pressure continues to bring hot and dry conditions to the area, with high temperature running 10-15F above normal today. Water vapor satellite imagery shows monsoon moisture streaming northward across the Great Basin into the Northern Rockies, with mid-high level cloud cover beginning to increase. High-resolution models and forecast soundings suggest atmospheric instability will begin to support high-based shower and isolated thunderstorm activity by this evening across central Idaho. Convection will move northward overnight, reaching western Montana after midnight. Little to any precipitation is expected as warm and dry air is present in the low levels. Isolated lightning activity (5-10% probability) can not be ruled out across north- central Idaho and southwest Montana this evening through early Saturday morning as this wave of showers and isolated convection moves northward. The risk for strong to isolated (5% probability) severe thunderstorms enters the picture Saturday afternoon and evening, with strong to damaging winds being the primary threat. An upper- level trough is still on track to lift out of the Pacific Northwest and phase with increasing monsoonal moisture providing plenty of moisture, lift, and instability for thunderstorm development. Widespread shower and thunderstorm activity will increase through the afternoon and evening hours across the region. A fire weather watch has been issued across the West Lolo and Kootenai National Forests and the Flathead Reservation as thunderstorms will bring an increased risk for dry lightning capable of starting new wildfires. PWATS are forecast to near and exceed 1.0 inches in southwest Montana and Lemhi County on Saturday, leading to a marginal threat for excessive rainfall, due to intense precipitation rates. Normally vulnerable spots such as burn scars, and areas of steep, rocky terrain will be monitored closely for excessive rainfall leading to debris flows and/or rock slides. A cold front crosses through, from the west, Saturday evening into Sunday lowering daytime high temperatures by 10-15 degrees; closer to seasonal normals. However, the post-frontal environment will also bring deep mixing, strong westerly winds, and a very dry airmass creating elevated to near-critical fire weather conditions especially considering the preceding risk of new lightning starts and holdovers from Friday and Saturday`s convection. A fire weather watch has been issued for Sunday across southwest Montana (Fire Weather Zones 110-111), where confidence is increasing for windy and dry conditions to bring critical fire weather. Ensemble model cluster analysis shows modest-high confidence (>80% agreement) for the Northern Rockies to be under the influence of southwesterly flow Monday through Wednesday next week. Model guidance suggests a ridge of high pressure centered over the Rockies, with a trough of low pressure near the Pacific Northwest coast. This pattern suggests mainly dry and warm conditions, with chances for showers and thunderstorms focused across Lemhi County, ID into southwest Montana. && .AVIATION...High pressure continues to bring hot conditions and elevated density altitudes across the regional airspace this afternoon. GOES Water Vapor imagery shows monsoon moisture moving into the mid-upper levels of the atmosphere south to north today. Elevated convection developing around and after 22/0000Z near KSMN and KBTM will spread northward into the overnight bringing the risks of localized erratic outflow wind gusts of 20-30 knots, inducing low-level turbulence, and LLWS near these high-based storm cores. Widespread shower and thunderstorm activity on Saturday poses threats for strong to severe wind gusts, hail, and temporary MVFR/IFR weather conditions across the region particularly during the afternoon hours. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Fire Weather Watch from Saturday afternoon through Sunday morning for Flathead Reservation...Kootenai...West Lolo. Fire Weather Watch from Sunday afternoon through Sunday evening for Deerlodge/West Beaverhead...East Beaverhead. ID...Heat Advisory until 8 PM PDT this evening for Lower Hells Canyon/Salmon River Region...Orofino/Grangeville Region. && $$

975 FXUS65 KBOI 212350 AFDBOI Area Forecast Discussion National Weather Service Boise ID 550 PM MDT Fri Aug 21 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Strong thunderstorm-outflow wind event moving northward through Idaho this evening. - Heat Advisory until 9 PM MDT in the Treasure Valley, western Magic Valley, and Upper Weiser River Valley. - Weak Pacific cold front will bring more thunderstorms to the area Saturday afternoon and evening. && .SHORT TERM /Through Sunday Night/... Issued 246 PM MDT FRI AUG 21 2026 The big issue early this evening will be strong thunderstorm-outflow winds entering southwest Idaho ahead of a northward surge of monsoon moisture currently in Nevada. HRRR is the most aggressive of all models but it tends to do well in these situations. HRRR has shown this outflow event consistently in hour-by-hour updates since last night, moving across the NV/ID border around 6 PM MDT this evening, through the Snake Basin 8-9 PM MDT, then weakening as it gets into the ID mountains around 9 PM but still holding together all the way past McCall around midnight MDT. A Wind Advisory has been issued for winds 20-35 mph with gusts to 55 mph, i.e., not as intense as HRRR as that model may have over-forecast it. The full force of the HRRR forecast would bring gusts 60 to 75 mph through the Snake Basin, likely causing damage, not to mention blowing dust and severely restricted visibility. Even so, areas of blowing dust and reduced visibility are expected. Strongest winds should last less than one hour at any given location. The timing of the event looks more definite, though, with the event entirely north of the Snake Basin by 10 PM MDT as it continues to move north while steadily weakening. By the time it gets to McCall, max gusts should be less than 40 mph. As stated earlier, these winds are due to outflow ahead of thunderstorms in a northward surge of monsoon moisture, so that after the winds die down there will be scattered showers and thunderstorms, but with little rain reaching the ground tonight. Meanwhile, we still have a Heat Advisory in effect through 9 PM MDT this evening. Saturday should be 5 to 10 degrees cooler than today as a Pacific cold front moves inland and through our area. The front will bring gusty west winds to Oregon and breezy northwest winds to western Idaho. With monsoon moisture still present on the Idaho side, the approaching front will help develop more showers and storms Saturday afternoon and Saturday night, with a better chance of rain than tonight`s storms. Sunday will be slightly cooler again, with another chance of late-day showers and storms on the Idaho side. Nighttime temps will be warm tonight and Saturday night, then cooler Sunday night. && .LONG TERM /Monday through Friday/... Issued 246 PM MDT FRI AUG 21 2026 Southwest flow aloft will continue through the long term as the Desert Southwest upper-level ridge is tempered by semi-persistent troughing over the Pacific NW. Enough moisture will be in place to carry shower and thunderstorms chances through at least Tuesday night, primarily over southwest ID, with greater uncertainty Wednesday onward. Models show a potent shortwave trough moving over the area on Monday afternoon, with a 20 to 50 percent chance of showers and thunderstorms over southern ID. In far southeastern OR, there is a 15 to 30 percent chance Monday afternoon and evening as well. The upper-level low pressure system is forecast to move inland mid-to-late next week, causing dry, breezy, and slightly cooler temperatures Wednesday through Friday. Temperatures will be around 2-5 degrees above normal through the period. && .AVIATION /00Z Saturday through Sunday/... Issued 540 PM MDT FRI AUG 21 2026 Generally VFR. High density altitude from heat through evening. Areas of wildfire smoke. Scattered showers/thunderstorms from S to N through late tonight. Activity capable of erratic outflows to 40-55 kt, and blowing dust reducing vis. Surface winds outside of storms: variable 5-15 kt. Winds aloft at 10kft MSL: S 10-20 kt. KBOI...VFR. A 40% chance of showers and thunderstorms impacting KBOI terminal, this evening through 22/05Z. Moderate confidence of strong outflow wind gusts and blowing dust reducing vis at the terminal from nearby storms. Surface winds: variable 5-15 kt, gusty storm outflow winds 35-50 kt possible this evening from the southeast-southwest. Weekend Outlook...Generally VFR. Areas of wildfire smoke. Scattered showers and thunderstorms returning Saturday, especially far E Oregon and SW Idaho. Gusty outflow winds 35-55 kt and locally heavy rain from storms. High density altitude from heat Sat afternoon. Drier Sunday. Surface winds: Gusty SW winds Saturday afternoon. Breezy W-NW winds all areas on Sunday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning from noon Saturday to midnight MDT Saturday night for IDZ401>403-421-424-426. Heat Advisory until 9 PM MDT this evening for IDZ012-014-016- 033. Wind Advisory until 10 PM MDT this evening for IDZ012-014>016- 029-030. OR...Heat Advisory until 9 PM MDT /8 PM PDT/ this evening for ORZ064. Wind Advisory until 10 PM MDT /9 PM PDT/ this evening for ORZ064. Red Flag Warning from 11 AM to 8 PM PDT Saturday for ORZ670>672. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....SH SHORT TERM...LC LONG TERM....CH

262 FXUS65 KLKN 212226 AFDLKN Area Forecast Discussion National Weather Service Elko NV 326 PM PDT Fri Aug 21 2026 .KEY MESSAGES... * Subtropical moisture marks a return this afternoon and will continue into next week. This will help to fuel afternoon and evening thunderstorms * Some showers and thunderstorms could produce brief moderate to heavy rain with the main threat of debris flows on recently burned areas * Elevated fire weather conditions persist this afternoon with wind gusts of 20 to 25 mph and minimum relative humidity values of 10 to 15 percent across portions of fire zones 424 and 437 * Cooling trend begins today as mid-level moisture and increasing cloud cover continues its northward trajectory && .DISCUSSION... (This afternoon through next Friday) WEATHER PATTERN OVERVIEW: Current radar loop is showing showers and thunderstorms developing across central Nevada this afternoon. Some of these cells, especially those moving across White Pine county, are more wet than dry per radar estimation and the latest web cams looking over US Highways 6, 50, and 93. Additional cells are developing over portions of Lincoln and southern Nye counties and those are also moving north. These are all in response to subtropical moisture streaming northward throughout the day. A strong upper ridge is maintaining its position across the four corners region with an upper trough off the coast of the Pacific Northwest. The resulting southerly flow has allowed the precipitable water values to come up to at or above 0.75 inches in central Nevada. This moist air mass will make its way north during the evening and overnight hours. Look for the lows to be in the 50s and 60s. Little movement is expected concerning the main weather features for tomorrow. The upper ridge will shift slightly to the east while the upper trough will be moving to the northeast and impacting northwest Washington State. Moisture will remain rather higher than average with precipitable water values at or above 0.75 inches. Surface-based CAPE values will be around 250 to 700J/kg with lifted indices below 0C. This will translate into an expansion of showers and thunderstorms across northern and central Nevada. Some of these storms will be capable of brief moderate to heavy rain with any of these cells. There is a hydrologic concern due to the fairly robust moisture values and will need to carefully watch recent burn scars for possible debris flows. Wind gusts to 50 mph will also be possible along with dangerous cloud to ground lightning strikes. High temperatures will be slightly cooler with readings in the low to mid 90s. Look for storms to continue during the overnight with lows in the 50s. The upper level ridge will wobble slightly east across New Mexico and western Texas on Sunday and Monday. Southwest flow aloft will try to bring in drier air but it will be slow to push the moisture out. Expecting a continuation of showers and thunderstorms Sunday afternoon with more limited coverage to just northern Elko county on Monday. Highs will be cooling with readings in the 80s and 90s on both days with lows in the 50s. The upper ridge is forecast to gradually retrograde west from Tuesday through the end of the forecast period. The flow is expected to come from a more westerly direction as the ridge of forecast to be suppressed south by an upper trough to the north. This flow will help to keep a lid on any active weather during this period. Highs will be in the 80s and 90s through this time with lows in the 50s. FORECAST CONFIDENCE & DEVIATIONS: There is high confidence for the return of southerly flow and monsoonal moisture persisting through the weekend, bringing a daily 20% to 50% chance for isolated to scattered showers and thunderstorms for Nevada through Wednesday. There is low confidence of upper pattern evolution after Wednesday as models show either continued monsoon flow or a return of the upper level ridge and warmer temperatures. && .AVIATION...VFR conditions continue to be the primary flight conditions through Saturday. Winds will develop late tomorrow morning and afternoon, S-SW10-15G20-25KT. VCTS probabilities will generally be between 25% to 40% across the eastern terminals KEKO, KELY, and KENV with a probability of 10% to 20% for thunderstorms over KWMC, KBAM, and KTPH. Convective wind gusts to 45KT are possible with any storms, combined with brief moderate to heavy rain, reducing CIG/VSBY to MVFR at times. && .FIRE WEATHER... Subtropical moisture will continue to stream northward, allowing for afternoon showers and thunderstorms to develop. On Saturday afternoon there will be a 30% to 60% chance for showers and thunderstorms across much of northern and central Nevada. There is a low probability of ten to fifteen percent in the afternoon for Zones 424 and 437 where breezy conditions and low RH could combine with isolated dry thunderstorms. Outside of these two fire zones, the rest of the forecast area will see mainly wet storms with outflow wind gusts to 50 mph along with dangerous cloud to ground lightning. Sufficient moisture and instability will remain on Sunday for a continuation of showers and thunderstorms. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...86 AVIATION...86 FIRE WEATHER...86