ZSE Aviation Forecast Discussions

832 FXUS66 KSEW 130958 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 258 AM PDT Wed Aug 13 2025 .SYNOPSIS...A cooler and wet pattern will take shape across western Washington today through early next week. A trough to the north will bring extra clouds today and a slight chance of showers throughout the region. A more organized system is expected to produce widespread rain regionwide Friday and Saturday, with potential for a few thunderstorms in the Cascades. A break in the rain is expected going into next week, though a few showers could linger into Sunday. && .SHORT TERM /TODAY THROUGH FRIDAY/...An upper level ridge (responsible for the hot conditions across the Pacific Northwest past few days) has begun to break down and slide to the east this morning. This will give way to a passing shortwave trough expected to dig southward into WA this morning and afternoon. Some areas of stratus/fog are possible this morning as temperatures drop into the low 60s (dew points still holding in the upper 50s to low 60s this morning for a slight muggy feel). While some clearing is possible this afternoon, clouds will largely fill back in with the trough passing through. There is enough moisture for this system to produce a few showers/sprinkles going into the afternoon/Thursday. The most organized area will be in the central Cascades (typically where a convergence zone would set up). Low level flow will become onshore again with this trough, so expect cooler temperatures today with highs in the interior only reaching the mid and upper 70s (coastal areas remain in the 60s). Interior temperatures will cool a few degrees for highs Thursday. Some smoke from the Bear Gulch and fire in Victoria may bring smoke to parts of the region - check local clean air agencies for the latest air quality information. Friday into Saturday is expected to be active (in terms of precipitation). An upper level low will start to become more negatively tilted along the B.C. and WA coast Friday into Saturday. This is expected to drive an organized frontal system into the region to finish off the week. The main message is that this system will likely bring a widespread steady rain across the entire coverage area. There remains some uncertainty in possible rain shadowing and exact amounts (when all set done), but given the cool air aloft, cannot rule out a few thunderstorms for portions of the area (especially over the Cascades). There may also be a period of gusty south winds of 20-30 mph Friday afternoon in the interior (especially close to Puget Sound and all interior waters). Highs will cool considerably into Friday with most interior spots below 70 degrees. .LONG TERM /SATURDAY THROUGH TUESDAY/...The previously mentioned frontal system is expected to continue to produce widespread rain into Saturday. While there remains a large spread in some of the model solutions for total rainfall, NBM 50th percentile paints the mountains and coast seeing roughly 1.5-2 inches (locally higher amounts are possible, especially with any convection), and lowland interior areas potentially seeing around 1 inch of rain. There again remains some uncertainty in the exact amounts (as with the amount of moisture available via low level flow). Nevertheless, persons planning to be outdoors in the mountains, or near area rivers should monitor the forecast for possible changes, and be prepared for steady rain, possible isolated thunder, and possible river rises. Shower activity is expected to taper back going into Monday and Tuesday next week as the trough moves north out of the area. The low will track inland and the flow aloft will become more northwesterly. Conditions will dry out with the sun coming out in spots, and temperatures will warm back up into the mid and upper 70s (for the interior) Sunday into the workweek. HPR && .AVIATION...Westerly flow will persist aloft today as an upper level trough swings across British Columbia. Conditions across the area terminals early this morning generally remain VFR, with satellite showing stratus quickly approaching the coast. Expect stratus to push inland throughout the morning hours as onshore flow strengthens in the low levels for overall BKN-OVC conditions across the region today. Areas along the coast and the Southwest Interior could see terminals dip down into MVFR/IFR in low stratus this morning, but expect terminals across the interior to largely remain VFR. Terminals that do drop to MVFR/IFR in stratus this morning will likely rebound towards VFR again by this afternoon- with the exception of terminals along the coast, which may stay MVFR through much of the day. Winds are generally light and variable across the area terminals overnight, but will ramp up to 8-12 kt and transition to the south through the morning hours. Winds along the coast will remain westerly, persisting at 8-12 kts. Winds may become breezy at times to 20 kt this afternoon. Smoke from wildfires may also result in localized diminished conditions in a few spots today. While smoke will largely remain aloft, some may mix down to the lower levels from wildfire activity in Mason county. Smoke from Canadian wildfires may also impact BLI at times. KSEA...VFR conditions early this morning. Stratus will move into the terminals this morning, likely between 13-16Z. There is a 25% chance of ceilings dropping to MVFR this morning. Should ceilings drop, expect improvement back towards VFR by this afternoon. Westerly winds at 6 kts will transition to the south and increase towards 8-12 kts by this afternoon. A few gusts to 20 kts will be possible this afternoon. 14 && .MARINE...High pressure will remain over the coastal waters today before weakening on Thursday as an strong frontal system for August approaches the region. Westerly winds along the Strait of Juan de Fuca will ease over the next few hours, however will increase again late this morning as onshore flow increases across the region. Occasional gusts to gale will be possible along portions of the central Strait this afternoon and evening, but expect the majority of the winds along the Strait to remain between 20-30 kt. A small craft advisory also remains in effect over the outer coastal waters for seas generally hovering around 10 ft at 10 seconds. Seas will subside through the day back towards 4-6 ft and will gradually become less steep. A strong frontal system will then move across the area waters Friday into Saturday and will allow for winds to switch back to the south. Southerly winds will become breezy across the coastal waters and interior waters of Puget Sound on Friday and may yield additional small craft headlines at times heading into the weekend. Winds will then ease again through the day Saturday and Sunday as high pressure starts to briefly build back into the region. Additional, weaker systems may move across the area waters early next week. Seas will increase towards 6-8 ft again by Friday and Saturday, before subsiding back down to 4-6 ft by Sunday. Seas look to continue to subside to around 3-5 ft by early next week. 14 && .FIRE WEATHER...Elevated fire weather conditions will come to an end this morning as an approaching trough leads to increasing onshore flow. This will result in a steep drop in temperatures today along with good relative humidity recoveries. Chances for rainfall then increase towards the end of the week. There is a high degree of confidence that a frontal system will produce wetting rains across the entirety of the region Friday into early Saturday. 27/HPR && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 5 AM PDT early this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 6 AM PDT Thursday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. && $$

335 FXUS66 KPQR 131103 AFDPQR Area Forecast Discussion National Weather Service Portland OR 403 AM PDT Wed Aug 13 2025 .SYNOPSIS...Marine stratus and fog may reduce visibility along the coast this morning. Today and Thursday will see a relative cool down as high pressure breaks down and onshore flow increases. A low pressure system in the northeast Pacific will bring widespread rain by the end of the week with cooler temperatures across the region. Drier conditions return heading into early next week. && .SHORT TERM...Now through Thursday Night...A relative cool down begins today as high pressure breaks down due to an upper-level trough descending from western Canada. This will strengthen onshore flow, shifting winds more west-northwesterly and bringing a deeper marine layer to the coast. A Dense Fog Advisory remains in effect along the coast through 11 AM this morning. Fog and low stratus will be patchy along the north Oregon and south Washington coasts, but if it does form, it will be dense. The highest concentration of dense fog will be from Lincoln City southward towards Florence. Areas from Cannon Beach north will see fog burn off the quickest in the morning. Visibility should improve above one quarter of a mile by late morning (10-11 AM), but marine clouds will be persist throughout the day. Onshore flow doesn`t appear to be strong enough to filter marine stratus into the Willamette Valley, so expect mostly sunny skies today inland. Afternoon highs are forecast about 10 to 15 degrees cooler than yesterday - mid to upper 80s across interior valleys. The most noticeable cooldown will be felt the further north you go. HeatRisk will decrease to a "Minor" level throughout the region, and overnight lows will become more comfortable, generally in the upper 50s to low 60s. By Thursday, the initial trough will continue its eastward movement, while a new upper-level trough originating from the Gulf of Alaska begins moving into the Pacific Northwest. This will maintain strong onshore flow with winds turning more westerly. Afternoon highs on Thursday are forecast near or slightly below seasonal averages, reaching the upper 70s to low 80s inland and the 60s along the coast. Most locations remain dry on Thursday, however rain chances return Thursday evening. The north Oregon and south Washington coasts may end the calendar day with 0.10-0.20" (20-30% chance of exceeding 0.20"), with the highest totals north of Astoria. -Alviz && .LONG TERM...Friday through Tuesday...Rain chances increase early Friday into Saturday as the upper level trough from the Gulf of Alaska continues to progress southward, centering just offshore of British Columbia. The surface warm front associated with this system will bring rain on Friday with the trailing cold front pushing through Friday night into Saturday morning. This frontal passage will shift winds more southerly to southwesterly, and last through Saturday. Temperatures Friday and Saturday will also cool below-normal, with afternoon highs forecast in the mid to upper 70s across interior valleys. While there is high confidence that we`ll see widespread measurable rain across the region, there is still some uncertainty with exactly how much rain we will receive by the end of this system. Chances for 0.50" of rain or greater from 5 AM Friday to 5 AM Sunday are around 70-90% from Lincoln City and Salem northward, and 40-60% south of Lincoln City and Salem as you head towards Lane County. However, there is still about a difference of 0.60-0.80" between the 25th and 75th percentile 48-hour QPF across northwest Oregon and southwest Washington. It will all depend on how far south the trough drops down as well as the magnitude. While this kind of pattern is not the most favorable for thunderstorms, it can`t be completely ruled out. Once the cold front pushes through on Saturday, will see lingering showers and potential for some cloud breaks. This could increase afternoon instability and thus, lead to thunderstorm development. However, confidence in thunderstorms is low at this time and remain around a 15-20% chance across the Cascades Saturday afternoon. Sunday to Tuesday, the trough will weaken and return drier and warmer temperatures. However, broad troughing remains in place during this time, maintaining onshore flow. -Alviz && .AVIATION...Satellite imagery as of early Wednesday morning depicts marine stratus and fog moving northward along the Oregon coast, bringing LIFR CIGs and VIS at KONP. Expect more predominately IFR/MVFR CIGs and VIS at KAST by 13-14z Wed. These lowered CIGs continue throughout the day along the coast, but fog should lift by 18-19z Wed, improving visibility back to VFR. VFR conditions with mostly clear skies continue across the Willamette Valley today, with low stratus developing tonight as low level moisture increases. Winds generally west-northwesterly across the area around 5-10 kt, strongest in the afternoon with gusts up to 20 kt in the Willamette Valley. PDX AND APPROACHES...VFR conditions with mostly clear skies today. Increasing low clouds tonight, with a 30-40% chance of MVFR CIGs after 09z Thursday. Variable winds around 5 kt or less through this morning, becoming northwesterly around 8-12 kt with gusts up to 20 kt this afternoon after 20-21z Thu. -Alviz && .MARINE...Dense fog will reduce visibilities to 1 NM or less across the inner waters and Columbia River Bar this morning, with the most dense fog is expected south of Cape Falcon. Fog should lift after 1000-1200 Wednesday, improving visibility above 1 NM. High pressure will maintain northwesterly winds across the waters through tonight with gusts around 10-15 kt or less. Seas around 7-9 ft at 8-9 seconds today will gradually fall to 5-6 ft at 7-8 seconds tonight. Given the choppy seas, the Small Craft Advisory remains in effect through 1400 Wednesday. Thursday begins a pattern change as a low pressure system in the northeast Pacific shifts winds more southwesterly. The latest NBM guidance projects a 50-70% chance for Small Craft conditions during the frontal passage on Friday, with the highest chances across the inner waters north of Cape Foulweather and Columbia River Bar. Winds weaken heading into the weekend but there is some uncertainty with the direction. Some models like the ECMWF/Canadian want to keep low pressure in the northeast Pacific and maintain southerly winds, while the GFS suggests surface high pressure re- building over the waters and returning northerly winds. -Alviz && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Dense Fog Advisory until 11 AM PDT this morning for ORZ101>103. WA...Dense Fog Advisory until 11 AM PDT this morning for WAZ201. PZ...Dense Fog Advisory until 11 AM PDT this morning for PZZ210- 251>253. Small Craft Advisory until 2 PM PDT this afternoon for PZZ271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

313 FXUS66 KMFR 131121 AFDMFR Area Forecast Discussion National Weather Service Medford OR 421 AM PDT Wed Aug 13 2025 .DISCUSSION...Satellite image shows marine stratus along the coast, coastal valleys, and inland over the Coquille Basin. The marine stratus will remain confined to these areas through daybreak, then will gradually burn off inland away from the coast. Elsewhere, it will remain clear and dry. Afternoon temperatures will be cooler than yesterday, but still above normal for this time of the year. The typical afternoon and early evening breezes are likely again for the interior westside valleys and portions of the eastside. Dry weather will continue through Thursday. Onshore flow will increase allowing the marine stratus to push farther inland into the Umpqua Basin and possibly right up to the Umpqua Divide. Upper troughing will set up over the area Friday into the weekend. The net result will be further cooling with temperatures below normal for the interior. A cold front will slowly move south into the northwest part of the area. As usual the NBM is too high, and too far south and east the extent and probability of precipitation. Most likely scenario will be intermittent light rain in Coos, northwest Douglas county, and northern Cascades Friday afternoon. Even then precip amounts may only end up bring 0.01-0.05 of an inch. The upper trough will deepen some (500mb heights lowering) Friday night into Saturday morning which will allow the front to move south. The best chance for precipitation will be along the coast, coastal mountains, north ofthe Umpqua Divide, and northern Cascades. The NBM solution is once again too far south and inland with the extent of the precipitation and the forecast has been adjusted to keep the best chance of rain to the above mentioned areas. Saturday afternoon, the front will move inland and precipitation will become showery in that it will be convective in nature. Guidance shows instability will be marginal at best in the northern Cascades, and northern Klamath and Lake County and have a slight chance of thunderstorms confined to these areas. Meanwhile, convective showers are possible along and west of the Cascades. Sunday into early next week, the parent upper low from the Gulf of Alaska will remain parked just south of the Alaska Panhandle with a broad southwest flow aloft over our area. Instability Sunday afternoon is marginal along with weak shortwaves moving through, therefore isolated storms are possible again for portions of the eastside and Cascades. It will be more stable the first half of next week, with no threat for thunderstorms. Temperatures will be on a slow rebound, with values near seasonal norms. -Petrucelli && .AVIATION...13/12Z TAFs...Along the coast and just offshore. Marine stratus will result in IFR and local LIFR conditions that will likely last for most of the TAF period. It`s possible for ceilings to improve for a brief period of time late this afternoon, but confidence is not high enough to include improving conditions for the North Bend TAF. Inland, marine stratus will remain confined to the Coquille Basin, with clouds burning off late in the morning (17-18z) with clear skies in the afternoon. Elsewhere, VFR conditions will continue through the TAF period with gusty afternoon and early evening breezes. -Petrucelli && .MARINE...Updated 200 AM PDT Wednesday, August 13, 2025...The thermal trough rebuilds today into Thursday, with moderate to occasionally strong winds in the southern waters. Winds will be strongest from about 2 nm from shore out to 20 nm from shore and south of Port Orford. Broad upper level troughing arrives late in the week, disrupting the thermal trough pattern and allowing conditions to become relatively calm through the weekend. -Petrucelli && .FIRE WEATHER...Updated 200 AM PDT Tuesday, August 12, 2025...Dry weather will continue through Thursday. Afternoon temperatures for the interior will be cooler than yesterday. However. relative humidities will be low and we still expect gusty afternoon and early evening breezes for the Rogue, portions ofthe Illinois Valley and portions of Fire zone 624. Thus a Red Flag Warning remains in effect for winds and low relative humidity. Upper troughing remains in place Thursday with further cooling. We`ll still have the typical afternoon and early evening breezes east of the Cascades and interior westside valleys, but relative humidities will be higher, therefore critical conditions are unlikely to be met. An upper low from the Gulf of Alaska will drop south toward western B.C. in the Gulf of Alaska Friday. The leading edge of a cold front will approach the area during the day Friday and will bring intermittent light rain to portions of Fire zones 615 and 616. Since the front is nearly parallel to the upper flow, it will be slow to move into the area. The front will continue to move south Friday night into Saturday morning and could increase the chance of very light rain to the rest of the coast, coastal mountains and Douglas County. Saturday, the front will move farther inland with convective showers pushing inland. Instability parameters are marginal at best Saturday afternoon and a few isolated thunderstorms are possible in northern Fire zones 624 and 625, and portions of northern California, southern Cascades and Siskiyous. Sunday, a broad upper low will set up north of the area with a southwesterly flow along with week shortwaves moving through. Guidance suggest marginal instability east of the Cascades, and it`s in these areas where it could be unstable enough for isolated thunderstorms. It`s still a ways out there and details could change, so it`s something we`ll have to continue to watch closely. Stay tuned. Upper troughing remains in place for the start of next week, but it expected to remain dry with temperatures near seasonal norms. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning from 2 PM this afternoon to 8 PM PDT this evening for ORZ620-622. Red Flag Warning from 2 PM this afternoon to 8 PM PDT this evening for ORZ624. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT Thursday for PZZ356-376. && $$

188 FXUS66 KEKA 130723 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1223 AM PDT Wed Aug 13 2025 .SYNOPSIS...Hot and dry weather will continue to slowly ease through midweek with shallow marine air along the shore. Gusty northwest wind will accompany building marine influence late in the week. && .DISCUSSION...High pressure will succumb to a trough lobe, elongating from the upper wave pattern overnight into Wednesday and lasting a few days as temperatures ease and the possibility of drizzle or light accumulation arise for adjacent coastal areas of the CWA. No definite signs of uplifting air/instability with this shortwave as trough dynamics lack vorticity and shear. It is more likely that there will be stratiform precipitation and mostly offshore with some near shore accumulation. High resolution model soundings show saturated boundary layer with a warm air mass aloft, indicative of a drizzle event. Around Friday, a proper, deep wave trough will sweep across the Pacific Northwest and help deepen and lift marine influenced air inland. Highs will bottom out this weekend in the low 90s for the interior alongside wispy mid and high level clouds. Gusty northwest winds will accompany a diffuse surface cold front as the cooler air sweeps inland as soon as Thursday afternoon but especially on Friday. Gusts on exposed ridges and in channeled valleys could easily reach 30 mph or more each afternoon, especially in Lake and Mendocino Counties. A relatively troughy pattern will most likely persist through next week, maintaining cooler and more moist conditions. Such conditions may bring a slight chance of thunderstorms early next week but that threat is currently very uncertain. /JHW /EYS && .AVIATION...(06Z TAFs) Overnight into Wednesday: A weak shortwave approaches from the southwest, further deepening the marine layer. This creates a high probability (70-100%) of LIFR (Low Instrument Flight Rules) conditions persisting at the coast. While the duration of fog is uncertain, temporary bouts are expected through early morning as the shortwave trough passes and the marine layer deepens. This should also weaken the inversion, potentially leading to better clearing by Wednesday. Crescent City (KCEC): - SKY COVER: Mean sky cover remains near 100 percent until 16Z, then slowly decreases to 50 percent by 01Z before increasing to 80% by 06Z Wed evening. - Ceiling Level: Mean ceiling level remains between 100 and 300 feet for the entire forecast. There`s up to 80% chance of ceilings below 500 feet, peaking near 13Z Wednesday. - Winds: Near calm until 17Z Wednesday, then gradually increasing and peaking around 00Z Thursday with mean sustained values of 8 KTS and gusts to 12 KTS from around 270 degrees. - Visibility: Deterministic visibility down to 1/4SM until it improves around 15Z Wednesday, peaking at 4SM by 21Z, then worsening afterward. The greatest probability (around 50%) of visibility less than one mile is near 12-13Z, indicating lower confidence in visibility compared to ceiling forecasts. Arcata (KACV): - Sky Cover: Mean sky cover remains 80-100% until 18Z Wednesday, decreasing to about 50% by 00Z Thursday before increasing again Wednesday evening. - Ceilings: Deterministic ceilings remain between 100 and 500 feet for the entire forecast, peaking between 20Z and 23Z Wednesday. - Winds: Mean sustained wind speeds are forecast to remain 6 KTS or less throughout the forecast period, peaking at 6 KTS with gusts to 7 KTS around 23Z Wednesday. - Visibility: Deterministic forecasts show 1/4 SM visibility until 15Z Wednesday with some improvement peaking at 2.5 SM between 19Z and 23Z Wednesday. The chance of visibility below 1SM peaks at 40% near 13Z, reflecting lower confidence in low visibility values compared to higher confidence in lower ceilings. Ukiah (UKI): - Sky Cover: Mean sky cover remains 20% or lower for the entire forecast period. - Ceilings: Mean ceilings do not drop below 20K feet. Despite deterministic ceilings, there`s a 40% chance of ceilings below 2K feet. - Winds: Mean winds remain light, with an increase in the afternoon, peaking at 6KTS with gusts to 14KTS from around 290 degrees around 23Z. - Visibility: The chance of visibility less than 5SM remains below 20-% for the entire forecast period./MH && .MARINE...Winds are forecast to strengthen from Wednesday, peaking on Thursday with sustained speeds of 20-25 KTS and isolated gusts up to 30 KTS. Gale-force gust potential exists around Cape Mendocino. Short-period seas are expected to build up to 9 feet over the outer waters from Wednesday evening through Thursday night. Winds and seas will diminish on Friday and are likely to remain low through the weekend. /MH && .FIRE WEATHER...Persistent hot and dry weather has helped increase fire danger all across the area with ERC forecast for near record values over the next couple of days. Thankfully, conditions will generally quickly ease over the next couple of days with highs dropping back into the 90s and and RH back around 25 percent. RH recoveries will especially improve with recoveries generally back above 70 percent tonight. There remains a very low chance of isolated thunderstorms as low pressure builds along the coast (less than 5%) tonight into Wednesday evening. All that said, conditions will still be generally warm and dry and fuels will be slow to respond. Strong northwest winds will build in during the afternoons Thursday and Friday ahead of a onshore marine push. Gusts in excess of 30 mph are most likely on ridges exposed to the northwest and in channeled valleys, especially along the Russian River and around Clear Lake. Cooler and more moist conditions will persist into this weekend with a very slight chance of thunderstorms early next week. /JHW && .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

596 FXUS66 KMTR 131159 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 459 AM PDT Wed Aug 13 2025 ...New UPDATE... .KEY MESSAGES... Updated at 1200 AM PDT Wed Aug 13 2025 - A pattern change will bring a more robust marine layer, cooler temperatures, and some morning drizzle today. - Strong NW winds will arrive to the coast Thursday and spread inland Friday. - Temperatures will climb slightly through Friday before cooling again this weekend. && .UPDATE... Issued at 454 AM PDT Wed Aug 13 2025 As the weather balloon rises this morning the marine layer was revealed to be around 2,100 feet. While some expansion was expected, this is admittedly deeper than anticipated. As a result, the stratus expansion is much further inland than yesterday and and drizzle is now being reported across San Francisco and along the Peninsula coast. The southern Monterey Bay has also recorded some measurable drizzle early this morning. && .SHORT TERM... Issued at 1200 AM PDT Wed Aug 13 2025 (Today and tonight) Let`s talk about moisture first. Tropical Storm Ivo dissipated early Monday in the tropical Eastern Pacific and most of the moisture is being reabsorbed by the monsoon trough. Despite this, a long loop of water vapor imagery shows that a small band of this moisture split off and pushed north towards the Bay Area. This moisture is now manifesting as upper level clouds currently streaming across the Bay Area (well above the marine layer stratus). These clouds are somewhere between 20,000 and 25,000 feet based on a comparison between IR imagery cloud top temperatures (-11C) and the latest vertical sounding (temperature vs. height). Outside of these high clouds, this moisture is too high and thin to have any other effect on the weather at the ground. The vertically integrated precipitable water is only 0.61". That puts us in the 25th percentile for this time of year. So the overall moisture is still well below normal. The reason for this is very dry air between the marine layer and these high clouds. The PGE 2km WRF cross section across the Bay Area is highlighting RH around 10% above 3,000 feet. This dry air is being dragged to lower elevations east of the Diablo Range due to mountain wave activity. As a result, a few inland stations are reporting red flag conditions with RH still in the teens at midnight and moderate westerly winds around 15 mph. Otherwise the short term forecast will bring a pattern change. A 500 mb trough is slowly approaching from the west. This will bring a deeper marine layer, higher humidity, and lower temperatures. Bottom line: temperatures will be about 5 degrees cooler than yesterday with similar moderate onshore winds. && .LONG TERM... Issued at 1200 AM PDT Wed Aug 13 2025 (Thursday through Tuesday) By Thursday afternoon the 500 mb trough axis should be over the Bay Area and will stall. This will generally bring cooler temperatures, a deeper marine layer, and higher humidity. At the surface, however, a narrow ridge of high pressure will move over far northern California/southern Oregon Thu-Fri. The Eureka-SFO pressure gradient will increase from 0.5 mb tonight to 4-6 mb by early Friday morning. This will increase northerly winds, causing a brief period of offshore winds in the North Bay. These winds will bring slightly higher temps Friday, when the North Bay will be about 5 degrees warmer than normal. Outside of the North Bay, wind direction should remain onshore, and this gradient will be felt more in the wind strength. The MTR WRF is showing large areas of 20+ mph gusts across the region Friday afternoon, with stronger winds expected along the coast and in higher elevations. At this time we do not expect to reach wind advisory criteria, but this breeze will be noticeable. As the N-S gradient relaxes over the weekend, the wind will decrease and temperatures fall back below normal across the cwa. The forecast then looks fairly stable as the 500 mb trough pattern remains in place. Looking ahead, 500 mb ensemble cluster analysis reveals a switch back to ridging is likely by the 21st, though there is significant uncertainty regarding the intensity at the moment. && .AVIATION... (12Z TAFS) Issued at 419 AM PDT Wed Aug 13 2025 Currently a mixed bag of LIFR-MVFR at the terminals with a marine layer of 1,800 feet. With the exception of HAF, high confidence in at least brief VFR being achieved by this afternoon. It is likely (60% chance) that sub-VFR ceilings return to all terminals tonight with the pattern changing very little through the TAF period. Vicinity of SFO...Currently MVFR with westerly flow. High (80%) confidence in VFR by the afternoon with high (70%) confidence on a sub-VFR ceiling likely on the cusp of MVFR/IFR returning to the terminal tonight. Westerly winds will prevail through the TAF period. SFO Bridge Approach...10% probability that OAK does not achieve VFR and that low stratus clouds linger through the TAF period. Monterey Bay Terminals...Currently LIFR with westerly flow at MRY and LIFR with northwesterly flow at SNS. Brief VFR will be achieved this afternoon with low stratus clouds sticking close to the coast. Ceilings on the cusp of LIFR/IFR will return to both terminals tonight. && .MARINE... (Today through Monday) Issued at 419 AM PDT Wed Aug 13 2025 Moderate northwesterly breezes today will increase to become fresh to strong tomorrow. Widespread hazardous conditions will be present tomorrow with gale force gusts across the outer waters and along the coastal jet region of Point Reyes and near-gale force gusts across the rest of the inner waters. Moderate seas will increase to become rough for the inner waters and outer waters through Friday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 1 PM this afternoon to 3 AM PDT Thursday for SF Bay N of Bay Bridge. Small Craft Advisory from 9 AM to 3 PM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm. Gale Warning from 3 PM Thursday to 3 AM PDT Friday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory from 3 PM Thursday to 3 AM PDT Friday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM to 9 PM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 3 AM PDT Friday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 9 PM this evening to 3 PM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory from 9 AM to 9 PM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM. Gale Warning from 9 PM Thursday to 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...Sarment MARINE...Sarment Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea

544 FXUS66 KOTX 131037 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 337 AM PDT Wed Aug 13 2025 .KEY MESSAGES... - Critical fire weather conditions Wednesday due to windy and dry conditions - Cooling trend Thursday through end of week with showers for the weekend. && .SYNOPSIS... A cold front passage on Wednesday will bring windy conditions across the Inland Northwest. Low relative humidity with gusty winds will result in critical fire weather conditions across much of eastern Washington. Showers are expected to return for the weekend along with cooler temperatures. && .DISCUSSION... Wednesday: A shortwave, evident on water vapor satellite imagery this evening, is approaching the northwest coast as an upper-level trough slides south over British Columbia. This shortwave will deliver a stronger push of onshore flow and cooler air into western Washington on Wednesday, increasing the thermal and pressure gradients across the Cascades. Deterministic models indicate a +9 to +12 mb sea level pressure difference between PDX and GEG by Wednesday afternoon. Winds will increase across much of the region by morning, peaking in the afternoon with the greatest boundary layer mixing. Nearly all moisture associated with this system will be wrung out over the Cascades, leaving dry conditions east of the crest. While temperatures will cool slightly from Tuesday, highs will still warm into the 90s with continued low relative humidity across the Inland Northwest. Afternoon relative humidity values in the teens to low 20s, combined with stronger winds, will create critical fire weather conditions for much of the region. The strongest winds are expected in the lee of the Cascades, through the Waterville Plateau, Upper Columbia Basin, West Plains, and Snake River area, where the NBM shows a 90% chance of sustained winds exceeding 25 mph. A Red Flag Warning is in effect from noon to 9 PM Wednesday. Any new fires will spread rapidly. Use extreme caution with any activities that could produce sparks. Thursday through Monday: A transition to a cooler, showery pattern is expected late in the week as a deep upper-level low develops over the Gulf of Alaska and digs southeastward. Models are in good agreement for a cold front, enhanced by an unseasonably juicy moisture plume (PWATs >200% of normal), to move onshore Friday, then spread into eastern Washington and north Idaho Friday night into Saturday morning. The best rainfall potential will be over the Cascades, far northeast Washington, and north Idaho, where there is a >70% probability of at least 0.10 inches of rain. Along the Canadian border in far northeast Washington and north Idaho, there is a 35% chance of exceeding one inch. For the Spokane and Coeur dAlene areas, probabilities are around 50% for at least 0.10 inches. Areas in the lee of the Cascades, the lower Columbia Basin, and the Palouse have a 20-40% chance of at least 0.10 inches. Some instability may support embedded convection, which could produce localized heavier amounts beneath stronger cores. Uncertainty remains regarding how long the showery pattern will persist, with some models keeping showers over the Inland Northwest into Sunday depending on the exact location of shortwaves rotating around the base of the offshore low. Temperatures will trend warmer early next week as troughing lingers over the northeastern Pacific and an upper-level ridge builds over the southwest. /vmt && .AVIATION... 12Z TAFS: VFR conditions will prevail. A cold front will sweep across on Wednesday. Westerly winds will increase across the Inland Northwest through Wednesday morning and become gusty into the afternoon. Widespread wind gusts of 25-30 kts will be common across the exposed areas of the Columbia Basin impacting all airports, including from Wenatchee (EAT) to Spokane/Coeur d`Alene (GEG/SFF/COE) to Pullman/Lewiston (PUW/LWS). FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions. JW ----------------------- 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:/weather.gov/otx/avndashboard && .FIRE WEATHER... A Red Flag Warning is in effect from noon Wednesday through 9 PM for much of the Inland Northwest due to the combination of strong sustained winds and relative humidity values in the upper teens to low 20s. While the onshore push of marine air looks to marginally increase relative humidity values into the 20-25% range for the lee of the Cascades, sustained winds 25-35 mph would overcome the marginal relative humidity values if a new fire ignites. The highest confidence for relative humidity values in the teens and sustained winds over 20 mph will be for Fire Weather Zone 708 and the eastern portion of Fire Weather Zone 709 where the NBM indicates a 70-90% chance of these conditions occurring. Additionally, the Hot, Dry, Windy Index is painting these areas, including Fire Weather Zones 706 and 707, with a 90+ percent chance to exceed its 95th percentile. Any new fires that ignite tomorrow will have a high potential to rapidly spread under these conditions. Use caution with any ignition sources. && .Preliminary Point Temps/PoPs... Spokane 92 59 83 59 79 61 / 0 0 0 0 10 30 Coeur d`Alene 93 60 83 58 78 62 / 0 0 0 0 10 30 Pullman 89 55 79 53 78 57 / 0 0 0 0 10 20 Lewiston 99 65 89 63 87 67 / 0 0 0 0 10 10 Colville 92 51 84 51 74 51 / 0 0 0 0 30 60 Sandpoint 90 55 82 54 74 58 / 0 0 0 0 20 40 Kellogg 88 60 79 58 76 62 / 0 0 0 0 10 20 Moses Lake 94 59 86 61 83 61 / 0 0 0 0 10 30 Wenatchee 91 64 86 67 80 66 / 0 0 0 10 40 60 Omak 95 60 88 62 79 62 / 0 0 0 10 30 60 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...Red Flag Warning from noon today to 9 PM PDT this evening 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)-Methow Valley (Zone 704)-Okanogan Valley (Zone 703)- Waterville Plateau (Zone 706)-Western Columbia Basin (Zone 707). ID...None. && $$

892 FXUS66 KPDT 130552 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1052 PM PDT Tue Aug 12 2025 .AVIATION...06Z TAFs...VFR conditions comprised of mostly clear skies and P6SM VSBYS are forecast through the valid period for all sites. Predominantly light, diurnally and terrain-driven winds of 10 kts or less are forecast for all sites overnight. Later Wednesday morning through Wednesday evening, a weather system passing over southern Canada and northern Washington will induce not-so-light, synoptically driven winds of 15-25 kts with gusts of 20-35 kts for all sites. Plunkett/86 && .PREV DISCUSSION... /issued 258 PM PDT Tue Aug 12 2025/ DISCUSSION...All is calm in the region currently. Satellite shows some cumulus forming near the John Day Basin through the Eastern Mountains. Slight chance (10-20% chance) that a stray dry thunder storm could develop going through the later afternoon/early evening hours. Some CAM guidance has trended downward for T-Storm potential, but some confidence is left to put them in the grids for the southern parts of Wallowa and Union counties. This will be our only precip/convection chances until late Thursday/early Friday morning as the ridge continues to push out of the region and a shortwave moves into the PacNW region. This will allow for temperatures to cool going forward the next couple of days, relieving us of the triple digit temperatures of today and yesterday. High temps will be about 10-15 degrees cooler by the time we start the weekend. Pressure gradients will get tighter as the shortwave drops further south/southeast, enabling potential Wind Advisory criteria gusts around the Kittitas Valley for Wednesday afternoon. Breezy to windy conditions accompanied by low relative humidity will persist Wednesday and Thursday for much of the forecast area. Fire Weather Watches were upgraded to Red Flag Warnings for Wednesday. Fire weather conditions will be less elevated as we head into the weekend as the shortwave will bring widespread precipitation into the region Friday through the weekend. Chances for some wetting rain across the Cascade Crests and portions of the Blue Mountains are medium-high (40-80% chance). Highest QPF in the Blues will be up to 0.25", while portions of the Basin will see 0.05 to 0.15 inches. Heading into the weekend, the trough will bring a sharp SW flow aloft into the region, allowing for more moisture advection, along with increased thunderstorm chances across large portions of the region Saturday. Some of the stronger storms will develop between 2PM-7PM with daytime heating adding instability, with an accompanied cold front providing lifting Saturday. Thunderstorm coverage shifts to Central OR, Southern Blues, and Eastern Mountains going into Sunday as the cold front pushes to the east. && .PRELIMINARY POINT TEMPS/POPS... PDT 69 94 59 83 / 0 0 0 0 ALW 73 95 63 84 / 0 0 0 0 PSC 68 98 59 87 / 0 0 0 0 YKM 67 93 58 86 / 0 0 0 0 HRI 71 96 61 86 / 0 0 0 0 ELN 66 87 57 79 / 0 0 0 0 RDM 55 92 50 83 / 0 0 0 0 LGD 62 92 56 84 / 0 0 0 0 GCD 60 93 55 86 / 0 0 0 0 DLS 71 89 63 81 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning from noon to 9 PM PDT Wednesday for ORZ691-693- 701-702. Red Flag Warning until 11 PM PDT Wednesday for ORZ696-698-700- 703>705. WA...Red Flag Warning from noon to 9 PM PDT Wednesday for WAZ690>694. Wind Advisory from 2 PM to 8 PM PDT Wednesday for WAZ026. && $$ SHORT TERM...95 LONG TERM....95 AVIATION...86

996 FXUS65 KREV 130753 AFDREV Area Forecast Discussion National Weather Service Reno NV 1253 AM PDT Wed Aug 13 2025 .KEY MESSAGES... * Winds increase this afternoon with elevated fire weather conditions and minor impacts for recreation and aviation, with continued breezy afternoons expected through the weekend. * Shower and thunderstorm chances shift south and east to Mono County and west central NV south of Highway 50 this afternoon. * A gradual cooling trend will begin today with temperatures dipping to below average by the weekend. && .DISCUSSION... The peak of the heat has passed with many valley sites in the advisory area seeing triple digit heat yesterday, including a tied record high of 102 degrees at Reno airport for the date. Slow overnight cooling and light winds will keep lingering effects in some areas for the next few hours, so we`ll let the heat advisory run its course. Today we`ll see a highs touching 100 degrees near and east of US-95 in west central NV, but overall a cooling trend will start to take place. Highs will dip below average by this weekend, with upper 80s-lower 90s for most lower elevations and mid 70s-near 80 for Sierra communities. Thunderstorm activity today will shift to the south and east this afternoon as drier southwest flow advances into more of the region due to a trough reaching the west coast, while the high pressure ridge retreats to the Four Corners region. The best chances (20-40%) favor Mono, Mineral, southern Lyon and southeast Churchill counties mainly between 2-7 PM, with potential impacts including outflow wind gusts of 45+ mph, short bursts of heavy rain and small hail, and lightning strikes that could ignite new fires. A few showers and storms could return in eastern parts of Mineral-Mono counties Thursday afternoon, but these chances drop to 10-20%. Otherwise, dry conditions should prevail through the upcoming week, although there`s a minimal (5-10%) chance for a few afternoon showers near the OR border this weekend. The other effect of this cooling and drying trend will be increasing winds this afternoon. Current projections still show potential for wind gusts of 30-35 mph overlapping with RH between 10-15% in parts of western NV for a couple of hours. This will lead to elevated fire weather concerns, especially in areas receiving lightning but little rain yesterday. More typical afternoon breezes are then expected for the remainder of the week and the weekend. However, the location of the trough near the west coast could edge a bit closer and bring increased wind gusts similar to today for Saturday and/or Sunday. MJD && .AVIATION... Shower and thunderstorm chances shift mainly to Mono-Mineral counties this afternoon, with 10-20% chance of a storm near KMMH between 20-23Z, but better storm chances are likely to remain farther east. For the other main terminals, no storms are expected but west winds will increase with gusts 25-30 kt mainly between 21-04Z, except starting and ending a couple hours earlier for KTRK-KTVL. These winds will likely produce low-end turbulence and LLWS impacts today for flights in/out of the main terminals. VFR conditions with afternoon wind gusts of 20-25 kt are then expected for the reminder of this week at the main terminals. MJD && .REV Watches/Warnings/Advisories... NV...Heat Advisory until 9 AM PDT Wednesday NVZ001-003>005. CA...Heat Advisory until 9 AM PDT Wednesday CAZ070-071. && $$

006 FXUS66 KSTO 122018 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 118 PM PDT Tue Aug 12 2025 .DISCUSSION... .SYNOPSIS... Areas of Moderate HeatRisk with triple digit highs in the Northern Sac. Valley this afternoon ahead of a cooling trend for the remainder of the week. Non-zero chance of isolated mountain showers and thunderstorms this afternoon, south of Interstate 80. && .KEY MESSAGES... *Today: - Areas of Moderate HeatRisk today over the Northern/Central Sacramento Valley and adjacent foothills;Cooling trend elsewhere - Probability of high temperatures > 100F: -Northern Sacramento Valley: 70-95% - Afternoon highs in the mid 90s to mid 100s with dry conditions over the Northern Sac Valley (Min RHs - 15-25%) - Non-zero chance of isolated mountain thunderstorms mainly south of Interstate 80 if anything does develop *Wednesday-Friday: - The East Pacific ridge axis aloft weakens as an upper trough from western Canada drops down bringing increased onshore flow, cooler temperatures, and higher relative humidity - The increased Delta breeze will give noticeable relief for the Delta and southern Sacramento Valley by Wednesday morning - Afternoon highs cooling to upper 80s to upper 90s this week *Weekend: - Near to below average temperatures then continue later this week and into the weekend with rising relative humidity - Periodically breezy onshore flow is forecast at times, strongest in the Delta vicinity and over the Sierra Crest - Low confidence in isolated thunderstorm potential along the higher elevations in the mountains this weekend (10-15% chance), dry weather elsewhere .Changes from previous forecast... - No significant changes to the forecast at this time. && .AVIATION... VFR conditions continue the next 24 hours over interior NorCal. Surface winds generally below 12 knots, with a brief period from around 22z today through 16z Wednesday with west-southwest surface winds gusting up to 30 knots in the Delta and southern Sacramento Valley. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

647 FXUS65 KMSO 130700 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 100 AM MDT Wed Aug 13 2025 .DISCUSSION... KEY MESSAGES: - Gusty winds and low humidity today with increased fire weather concerns - Cooler Thursday into the coming weekend - Beneficial rain for northwest Montana Friday night into Saturday A few early-morning showers and thunderstorms have been observed from southern Idaho County into Lemhi County and southwest Montana, driven by a weak disturbance and elevated instability. While rainfall will be minimal, occasional lightning strikes are expected. A dry cold front will move through the Northern Rockies this afternoon into tonight. Its primary impact will be strengthening westerly winds (gusts of 30-40 mph) across the region. The combination of gusty winds and low relative humidity will create critical fire weather conditions, with the highest concern over grasslands and sagebrush areas. These winds will also generate choppy conditions on area lakes, particularly Flathead Lake, where a Lake Wind Advisory is in effect. Any isolated showers or thunderstorms with this front will be confined to the Canadian border and southwest Montana this afternoon and evening. Westerly upper-level flow will persist Thursday and Friday, keeping temperatures near seasonal norms and supporting typical afternoon and evening breezes. Model guidance indicates another disturbance moving through the Northern Rockies Friday night into Saturday, shifting the flow to southwesterly. About half of the ensemble solutions show beneficial rainfall from Clearwater County, Idaho, into northwest Montana by Saturday evening. Current consensus suggests 24-hour precipitation totals of 0.10" to 0.50", with the heaviest amounts likely in the Troy/Yaak region. A warming and drying trend is expected early next week as southwesterly flow remains in place. This pattern may still bring subtle disturbances capable of producing showers and thunderstorms, but their timing and intensity remain uncertain. && .AVIATION...VFR conditions will persist through Thursday under westerly flow aloft. Early this morning, a few showers and thunderstorms have been observed from southern Idaho County into Lemhi County and southwest Montana, associated with a weak disturbance and elevated instability. While rainfall will be minimal, occasional lightning strikes are expected. A weak cold front will move through this afternoon into the overnight hours, bringing an increase in westerly winds with gusts of 25-35 kts. Winds will diminish around sunset at terminal sites. Aside from a few showers or thunderstorms in southwest Montana and along the Canadian border, conditions will remain dry. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Red Flag Warning from 1 PM this afternoon to 9 PM MDT this evening for Flathead Reservation. Lake Wind Advisory from noon today to 9 PM MDT this evening for Flathead/Mission Valleys. Red Flag Warning from noon today to 8 PM MDT this evening for Deerlodge/West Beaverhead...East Beaverhead. Fire Weather Watch from Thursday afternoon through Thursday evening for East Beaverhead. ID...Red Flag Warning from noon to 9 PM PDT Wednesday for Palouse/Hells Canyon. && $$

532 FXUS65 KBOI 130821 AFDBOI Area Forecast Discussion National Weather Service Boise ID 221 AM MDT Wed Aug 13 2025 .SHORT TERM...Today through Friday night...Not quite as hot as yesterday but still plenty hot again today especially in southern Idaho, as the surface thermal axis shifts gradually eastward. A Heat Advisory will continue in the Oregon Lower Treasure Valley through 9 PM MDT today, not only for the afternoon heat but also for the currently warm nighttime temperatures that provide only limited relief from the hot days. Latest water vapor imagery shows mid-level moisture still present over southern Idaho, originating from both the eastern Pacific subtropics and from the monsoon source in AZ, NM, and Mexico. This moisture will develop isolated showers and thunderstorms (15 to 25 percent coverage) late today and again late Thursday in southeast Owyhee and southern Twin Falls Counties. Thunderstorms should have outflow wind gusts up to 50 mph but little rain. Hi-res models show no other showers or storms in our CWA either today or Thursday, but they do suggest afternoon cloud buildups in the southern Boise Mountains. Satellite imagery also shows a weak north Pacific upper trough currently coming inland. Models take this trough eastward across our northern zones later today through Friday, but all parts of our CWA should cool to normal Thursday and Friday. .LONG TERM...Saturday through Wednesday...Deeper moisture from farther out in the north Pacific is forecast to come inland over WA and northern OR beginning Friday and reach Baker County Saturday, and most of eastern OR Saturday evening, with a 20 to 50 percent chance of showers and thunderstorms. This system looks like a winter-type frontal system, the first one since last spring. The storm`s cold front is forecast to weaken as it moves into and stalls over our CWA Saturday evening through Sunday, then retreats northward as a warm front Sunday night and Monday. Our forecast has a 15 to 30 percent chance of showers and thunderstorms near the frontal zone on those days. We also have a 15 to 20 percent chance of showers and thunderstorms near the NV/ID border Sunday afternoon and evening as a stronger southerly wind component aloft more effectively taps into monsoon moisture in the southern Rockies. Not all models agree on this, however, and later forecasts may change. && .AVIATION...VFR. Isolated thunderstorms south of KTWF 13/21Z through 14/03Z. High density altitude due to hot afternoon temperatures. Surface winds: Variable less than 10 kt through 13/18Z then NW 10-20 kt with gusts to 25 kt through 14/01Z. Winds aloft at 10kft MSL: SW 10-15 kt. KBOI...VFR. High density altitude in the afternoon. Surface winds: light and variable until 13/18Z, then NW 10-15 kt with gusts to 22 kt until 14/01Z. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...Heat Advisory until 9 PM MDT /8 PM PDT/ this evening ORZ064. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...LC LONG TERM....LC AVIATION.....LC

613 FXUS65 KLKN 130802 AFDLKN Area Forecast Discussion National Weather Service Elko NV Issued by National Weather Service Boise ID 102 AM PDT Wed Aug 13 2025 .KEY MESSAGES... Updated at 1135 PM PDT Tue Aug 12 2025 * Very warm daytime temperatures through Wednesday. * Elevated fire weather conditions continue due to warm temperatures, light to breezy winds, and low afternoon surface humidity levels. * Isolated dry thunderstorms for Wednesday afternoon and a mix of wet and dry thunderstorms Thursday and beyond across portions of central and eastern Nevada. && .DISCUSSION... (Tonight through next Tuesday) WEATHER PATTERN OVERVIEW: No major updates this afternoon with the Heat Advisory continuing through 1 am Thursday for Moderate to localized Major Heatrisk. Consider moving strenuous activities to the morning or late evening hours, if not post-poning altogether. High pressure continues to slowly move eastward, however today is expected to be very warm with temperatures in the 90s to 100s with overnight lows not cooling down far enough to allow adequate recovery from daytime heating with low temperatures in the 60s to 70s. Heat Advisory is still in effect for Elko, N Eureka, Humboldt, N Lander, and N Nye counties until 1 AM Thursday. An upper level trough will move into the Silver State from central California today, though weak, will still be strong enough to focus mid-level moisture to generate 10% to 20% chances for isolated thunderstorms this afternoon, with a 20% to 40% chance Thursday afternoon for scattered wet and dry thunderstorms across portions of central and northern Nevada. The trough is then likely to sit over Nevada as the upper flow stalls, keeping chances for isolated storms over the eastern half of the state, however these storms have a high probability of being dry thunderstorms. This pattern of upper level troughing over western U.S. and upper level ridging over central U.S. looks to persist through to the middle of next week, keeping Nevada under a southerly flow aloft. This southerly flow will aid in bringing in cooler temperatures after Thursday, ranging from the 80s to 90s across the region. Overnight lows also cooling into the 50s to 60s. FORECAST CONFIDENCE & DEVIATIONS: There is high confidence in the continuation of very warm temperatures through Thursday morning across the Great Basin. There is a 10% to 20% chance for isolated, mostly dry thunderstorms across portions of central and northern Nevada Wednesday afternoon. There is moderate confidence in the development of a low 20% to 40% chance of an isolated to scattered mix of dry and wet thunderstorms Thursday afternoon for portions of central and northern NV. These are the highest probabilities we have seen in nearly two weeks in the past dry spell. There is high confidence of elevated fire weather conditions, with warm temperatures and low afternoon surface humidity levels, across central and northern Nevada for the forecast period. There is moderate confidence for the development of a low 10% to 30% chances for isolated, mostly dry thunderstorms across eastern NV Friday, Saturday and Sunday afternoons. && .AVIATION... VFR conditions expected at all terminals over the next 24 hours. Afternoon breezes expected with gusts 20KT to 25KT. High based, isolated thunderstorms are also forecast this afternoon with coverage including all terminals except for KWMC. However, greatest confidence for any impacts on or near terminal will be at KEKO where VCTS has been included in the TAF. Gusty and erratic wind gusts of 45+KT will be associated with any thunderstorms and localized blowing dust may briefly reduce surface VIS. AMD NOT SKED at KBAM due to a communications issue. && .FIRE WEATHER... Mid-level moisture expected to increase over portions of central and eastern Nevada this afternoon. This will bring an increase to dry thunderstorms over all fire zones except for zone 437. Expect the storms to be a mix of wet and dry this afternoon and evening. Westerly winds this afternoon at 10-15 mph with gusts up to 20-25 mph. Winds up to 45 mph are possible from outflow winds of passing thunderstorms. Additional convective activity will continue into Thursday, Friday, and Saturday over portions of central and eastern parts of the district (20-40% Thursday, 15-20% Friday, 20-30% Saturday). Slight cooling trend as highs will be in the upper 80s to 90s with general winds at 10-15 mph gusts up to 25 mph. && .LKN Watches/Warnings/Advisories... Heat Advisory until 1 AM PDT Thursday NVZ030-031-033-036-038>041. && $$ DISCUSSION...97 AVIATION...97 FIRE WEATHER...97