616 FXUS66 KSEW 181603 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 903 AM PDT Fri Sep 18 2026 .SYNOPSIS... The return of onshore flow to the area will bring more seasonable temperatures and morning clouds to western Washington daily through the weekend and into early next week. Upper level troughing developing over the northeastern Pacific next week will open the door for some systems to make their way into the region, with rain chances increasing mid to late week. && .SHORT TERM /TODAY THROUGH SUNDAY/... The latest forecast remains on track this morning with no updates. An upper level ridge will shift eastward today and over the weekend as an upper level low over eastern OR continues to make its way eastward out of the region. Onshore flow will continue in the low levels through the weekend, bringing rather seasonable temperatures and daily morning cloud cover to western Washington. Stratus may linger along the coast at times over the weekend, particularly today and again on Saturday, but expect stratus to scatter each day across the interior for some afternoon sun. Afternoon highs will be in the low to mid 70s across the interior and in the mid 60s along the coast. Morning lows will be in the upper 40s to low 50s. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Ensembles hint at the pattern changing next week as upper level troughing develops across the northeastern Pacific. While mostly dry conditions look to persist across western Washington through the first half of the week, the development of southwest flow aloft over the area will open the door for systems to make it into western Washington mid to late week. At this time, rain chances look to increase midweek as a weak system brushes the region, with more widespread rain chances following late week. High temperatures will generally trend in the upper 60s to low 70s across the interior and in the 60s along the coast. Morning lows will be in the upper 40s to mid 50s. 14 && .AVIATION... Northwest flow aloft will turn westerly tonight as an upper ridge axis just offshore shifts eastward across the area. The low level flow is light onshore. Marine stratus has made its way across the interior this morning but is forecast to burn back toward the coast by 19-20z. VFR conditions will prevail across the interior this afternoon with stratus making a return and likely with greater coverage on Saturday morning. KSEA...IFR/MVFR stratus currently at the terminal this morning and will likely persist through 18Z or so before lifting and scattering out to VFR for the afternoon. Stratus will return again overnight tonight and likely take longer to clear on Saturday. Surface winds south to southwesterly 4 to 8 knots. 27/41 && .MARINE... Onshore flow will persist into next week as a series of systems pass well north of the area. The onshore flow will increase somewhat early next week as weak frontal systems begin to clip the coastal waters. 27 && .FIRE WEATHER... Onshore flow will bring cooler temperatures, cloud cover, and increased moisture to the area today through the weekend, helping to minimize fire weather concerns. Fire weather concerns will remain minimal through the next week with cooler temperatures and chances of precipitation increasing mid to late week. 14 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$

005 FXUS66 KPQR 181751 AFDPQR Area Forecast Discussion National Weather Service Portland OR 1051 AM PDT Fri Sep 18 2026 Updated aviation discussion. .SYNOPSIS...Temperatures will be around ten degrees cooler than yesterday for inland valleys today due to persistent morning cloud cover and stronger onshore flow. Temperatures warm up a few degrees this weekend as an upper level shortwave ridge moves over the area. Trending a bit cooler again next week as an upper level trough slowly drops southward from the Gulf of Alaska. Dry conditions are heavily favored through Thursday with a possible pattern shift toward cooler and wetter conditions by next Friday, September 25th. && .DISCUSSION..Now through next Friday...Satellite observations from early Friday morning showed a low marine stratus deck along the coast and Coast Range expanding into the lower Columbia and southern Willamette Valley. This cloud deck will most likely (60-80% chance) continue to expand towards sunrise, eventually filling in across the central and northern Willamette Valley, Cowlitz Valley, and greater Portland/Vancouver metro area. Morning clouds will eventually give way to afternoon sun as daytime heating progresses, except at the coast where skies will likely remain mostly cloudy through the day (>60% chance). Given the stronger onshore flow in place today and persistent low clouds in the morning, temperatures will be around ten degrees cooler than what was observed yesterday for inland valleys. Expect highs generally in the mid 70s Friday afternoon over the lowlands, except mid 60s at the coast. Temperatures will warm a bit over the weekend. This is when model ensemble guidance depicts good agreement for an upper level shortwave ridge moving from west to east over the Pacific Northwest. It appears this ridge will move rather slowly with a closed upper low on the southwestern periphery of the ridge and another closed low on the eastern periphery of the ridge. Low-level onshore will favor at least some degree of morning cloud cover this weekend, however forecast soundings suggest the marine stratus deck will become more shallow. This means any cloud cover that does develop inland should dissipate quickly during the mid to late morning hours. Combined with warming temperatures aloft, this should allow for highs back into the upper 70s to lower 80s inland and upper 60s to around 70 degrees at the coast, warmest on Sunday. The pattern trends relatively cooler next week as 500 mb flow becomes nearly zonal ahead of broad troughing approaching from the Gulf of Alaska. As this trough slowly approaches, temperatures will cool gradually Monday through Wednesday. However, cooling does not look overly significant as highs in the 70s are still favored inland with highs staying in the 60s at the coast. Confidence is high dry weather will continue Monday through Thursday afternoon, as 85-95% of the total ensemble space from the ENS/GEFS/GEPS shows no QPF at all. The remaining 5-15% showing very light rain amounts is mainly being driven by a few GEPS members. It appears a frontal system over the northeast Pacific will approach western Washington and western Oregon mid-week, which helps explain the small subset of ensemble guidance showing at least some light rain. However, the vast majority of ensemble guidance suggests this frontal system will decay over the coastal waters before pushing inland, hence the reason dry weather is the most likely outcome. That being said, chances for cooler and wetter weather increase more considerably come next Friday, September 25th. This is when roughly 40% of the total ensemble space from the ENS/GEFS/GEPS combined shows rain moving into the area. The remaining 60% keeps conditions dry. -23 && .AVIATION...Through 18Z Saturday...A thick stratus deck remains situated over the majority of NW OR and SW WA west of the Cascades at 1730z Fri. All terminals west of the Cascades are reporting MVFR cigs. Stratus should gradually dissipate after 19-21z Friday across inland areas as daytime heating progresses, bringing a return to widespread VFR conditions inland. However, the coast will most likely remain socked in with MVFR ceilings through the day, though there`s a 40% chance terminals might clear or fluctuate between VFR and MVFR conditions after 21z Fri. Stratus will fill right back in after 00-04z Sat along the coast and become widespread inland again between 10-15z Sat. Most inland terminals are expected to fall to at least MVFR cigs around 1500-3000 ft by 12z Sat. Additionally, there`s a 40-60% chance that all terminals fall to IFR cigs. Stratus on Saturday likely won`t clear until 18-21z. Winds are generally southerly and light less than 8 kts across the area. Winds shift west to northwest after 20z Fri, then northerly after 00z Sat. KPDX AND APPROACHES...MVFR cigs remain locked in over the terminal with light and variable winds at the surface. Ceilings expected to trend back to VFR after 19-21Z Fri as low clouds gradually scatter out and skies become clear again. Stratus is expected to form again by 10-12z Sat, returning MVFR cigs with a 40-60% chance of IFR cigs. Cigs once again not expected to improve to VFR until 18-21z Sat. -03 && .MARINE...High pressure will strengthen over the waters on Friday and then remain in place through the weekend. Relatively light winds on Friday will strengthen out of the north Saturday afternoon and evening with gusts up to 15-20 kt, strongest over the central and southern waters. Northerly winds peak in strength Sunday afternoon and evening when there is a 70-90% chance for maximum wind gusts of 21 kt or slightly stronger across the waters, with the highest chances across the inner waters out to 10 NM offshore. Given wind gusts of this magnitude are not expected to be frequent or widespread, Small Craft Advisories are not anticipated at this time. Significant wave heights will remain around 4 to 6 ft through the weekend, mainly driven by a persistent northwesterly swell with a dominant wave period near 8 seconds. Northerly winds are expected to linger Monday through Wednesday, with wind gusts generally staying under 20 kt. A long period west-northwesterly swell is set to arrive either Monday afternoon or evening, pushing seas up by one or two feet. However, seas will not be particularly steep as the dominant wave period with this swell will be around 11-13 seconds. -23 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

688 FXUS66 KMFR 181718 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1018 AM PDT Fri Sep 18 2026 ...New Aviation Section... .AVIATION (18Z TAFs)... A stratus layer remains along and near the coast impacting both KOTH and KRBG. Some relief is expected this afternoon for Roseburg, but North Bend may end up in MVFR conditions all day with IFR likely tonight. Otherwise, plenty of sun expected farther inland for both KMFR and KLMT where clear skies are likely. Wind speeds will generally be light through this cycle. -Guerrero && .PREV DISCUSSION... /Issued 434 AM PDT Fri Sep 18 2026/ KEY MESSAGES... * Low impact weather expected this weekend and through much of next week. * Cooler than normal temperatures continue today, returning to seasonable values this weekend and through next week. High temperatures peak around 5-10 degrees above normal on Sunday. * Dry conditions expected through at least Thursday next week. Next chance for precipitation possible next weekend (9/25-9/27). DISCUSSION...Upper level low pressure continues to spin over eastern Oregon this morning, and northerly flow on the back side of this low pressure is maintaining some isolated shower activity east of the Cascades. Skies are clear for areas from the Cascades to the Coast Range, and the marine layer blankets the coast and coastal waters. Marine stratus will continue pushing inland this morning, eventually making it into the Umpqua Basin shortly before sunrise. Otherwise, status quo is expected through the morning hours today. After bringing almost 1700 lightning strikes to the region since late Tuesday, low pressure will shift eastward into western Idaho this afternoon. Isolated showers east of the Cascades will diminish by late morning/early afternoon as this happens and clouds will gradually dissipate across the East Side. The marine layer will gradually peel back to the immediate coast later today as well, so expect a mostly sunny to sunny day across the forecast area this afternoon. High temperatures trend warmer today, more noticeably so for areas that were under persistent cloud cover yesterday, but still hover around 3 to 7 degrees below normal (low-mid 80s West Side/low 70s East Side). Low impact weather is expected throughout the forecast period at this time (through early Friday 9/25). Dry conditions are expected through this time with near to slightly above normal temperatures (mid 80s West/upper 70s East). Shortwave ridging passes through the region this weekend, maintaining the warming trend and bringing the warmest temperatures of the forecast period. Highs peak in the upper 80s-low 90s for the West Side/upper 70s-low 80s for the East. Weak low pressure moves into central/southern California Monday, weakening and pushing the ridge eastward and turning the flow zonal by Tuesday. The flow amplifies again toward the latter half of next week as upper level troughing deepens over the eastern Pacific and high pressure strengthens over the interior CONUS. As to be expected at this timeframe in the forecast, there is disagreement on the placement of the ridge/trough set up, but longer range guidance is pointing to at least some precipitation potential (15-20%) along the coast as early as Thursday night or Friday. At this time, chances for precipitation farther inland quickly drop off. Beyond that, ensembles are hinting at a wetter and cooler pattern taking hold for the last week of September, though details like precip amounts and inland extent remain yet to be seen. AVIATION...18/12Z TAFs...A mix of IFR/MVFR conditions under marine stratus will persist through the morning along the coast and over the coastal waters. Expect the marine layer to lift to MVFR later this morning, then eventually peel back to the immediate coast by this afternoon, bringing at least a brief period of VFR conditions for coastal locations. Inland, MVFR conditions are developing in the Umpqua Basin but should clear to VFR by around 18z. Recent moisture is bringing a variety of conditions to the remaining inland areas. Satellite is showing some low clouds developing in the Rogue Valley at this early hour, so a brief period of "sunrise surprise" IFR conditions is possible at the Medford terminal this morning. East of the Cascades, low clouds have developed in portions of the Klamath Basin, and a brief period of LIFR conditions in fog is expected at Klamath Falls terminal through sunrise. Higher level cloud cover associated with a departing low pressure persists east of the Klamath Basin with isolated showers that will diminish later this morning. The general trend today will be for improving conditions for all areas to VFR, with VFR prevailing through the afternoon/early evening. Expect the return of IFR/MVFR ceilings along the coast and into the Umpqua Basin late this evening and overnight. MARINE...Updated 1200 AM PDT Friday, September 17, 2026...Light northerly winds and low seas will persist through tonight. Gusty north winds return Saturday with steep seas likely developing south of Cape Blanco by late Saturday evening into Sunday, possibly reaching as far north as Coos Bay or Reedsport. North winds and wind driven seas are likely to build to a peak Monday, and remain near that level on Tuesday, with gales possible south of Cape Blanco. Conditions look to improve for the latter half of next week. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$

613 FXUS66 KEKA 180713 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1213 AM PDT Fri Sep 18 2026 .KEY MESSAGES... * Warmer and drier interior temperatures into the weekend with highs in the 90s by Sunday. * A shallow but strong marine layer forming close to shore with persistent marine clouds. && .SYNOPSIS...A blanket of stratus will encroach on the coast overnight into Friday signaling cool, moist conditions will prevail. Warmer and drier conditions will rebuild this weekend with shallow but persistent marine air along shore. && .DISCUSSION...A high pressure ridge will gradually rebuild Friday and into the weekend. This pattern will allow for interior temperatures to dry back out and warm back into the 90s. Moderate north winds will return near shore, helping form a shallow but persistent marine layer especially north of Cape Mendocino. High pressure will most likely persist through next week. Most models show weak to moderate high pressure, but about 20% of ensemble members show unusually strong high pressure around next Tuesday that could push interior highs closer to 100. There is near 0% chance of wetting rain for the next 10 days. /JHW && .AVIATION...High pressure reforming along shore has helped reinforce a much more expansive and resilient marine layer. This has lead to mostly IFR ceilings gradually lifting to MVFR for both KACV and KCEC. There is a 50% chance of LIFR ceilings overnight which increases closer to dusk at near 70% probability for the coastal terminals. Mos guidance and GFS are signaling lower visibility during this time frame as well with NBM giving 60-65% probability of less than 1/2mile during the early morning hours overnight. Area profilers are also showing a the marine layer being squished by the incoming ridge and soundings also show low level inversions after 11am Friday so expect reduced flight categories during the daytime hours. KUKI could get advected stratus if the layer is deep enough during the early morning hours. As of 6z, stratus has halted just east of Comptche but could make its way into the Ukiah valley. /EYS && .MARINE...Moderate southerly winds have persisted close to shore through the day with some north winds in the far outer waters. Short period seas have now generally dropped below 6 feet. Moderate to strong northerly winds will gradually return to the southern waters by Friday and gradually spread north through the weekend, though winds will most likely remain much calmer closer to shore. Short period wind waves will dominate the marine environment with only a very minor southwest mid period swell up to 2 feet to speak of. /JHW && .FIRE WEATHER...The thunderstorm risk has ended. New starts will continue to be slow to spread thanks to otherwise cool and moist conditions. A building ridge will bring much drier and hotter conditions through the weekend, but winds will remain gentle and terrain driven. /JHW && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 PM this evening to 9 PM PDT Saturday for PZZ455. Small Craft Advisory from 5 PM this afternoon to 9 PM PDT Saturday for PZZ475. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png

267 FXUS66 KMTR 181824 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1124 AM PDT Fri Sep 18 2026 ...New SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 1057 PM PDT Thu Sep 17 2026 - Warming trend through Saturday - Brief cooldown Sunday - Notable warming trend next week && .SHORT TERM... Issued at 1120 AM PDT Fri Sep 18 2026 (This afternoon through Saturday) The marine layer compressed to around 1,700 feet this morning. That trend will continue over the next 24 hours as a short wave ridge builds over the area. While the W-E gradients are all still weakly positive (SFO-WMC +1.9mb, SFO-SAC +1.2mb) we did see some NE, offshore winds this morning. The gradients will continue to drop and become negative this afternoon, however the onshore sea breeze will overpower any offshore flow during the day. In response to the building ridge and compressed marine layer, Inland temperatures will be roughly 5 degrees warmer today compared to yesterday, and another 5 degrees warmer Saturday. While less expansive, the marine layer will continue to keep high temps along the coast in the 60s with low clouds and possible fog in the morning. The offshore wind gradient will peak overnight, though the strength still isn`t overly impressive. Still, NE winds with gusts up to 20-30 mph are possible across the interior North Bay Mountains late tonight and early Saturday morning. && .LONG TERM... Issued at 1120 AM PDT Fri Sep 18 2026 (Saturday night through next Thursday) The pattern remains quite active in the long term forecast, although the next few features are pretty weak. Saturday`s ridge is quickly replaced by a weak cut-off low approaching from the west through the day Sunday. This will reverse the warming trend and allow the marine layer to expand a bit. This low will gradually slide overhead by Monday morning, giving us a good chance for drizzle. By Tuesday another ridge will start to build from the west, kicking off a warming trend that will last through the rest of the week. The ECMWF ensemble shows a 90% chance that the 850 mb temperature gets above 20C on Wednesday with a mean around 23C. 23C is above the the 90th percentile for this time of year and would bring inland surface temperatures back into the 90s. && .AVIATION... (18Z TAFS) Issued at 1100 AM PDT Fri Sep 18 2026 Lingering low clouds and fog has dissipated from most of the interior valleys and Central Coast but nw winds still feeding a fresh batch of stratus over SF Bay. Most terminals VFR the rest of today into early evening except for SFO/OAK and HAF. Marine layer compressing with onshore winds so stratus should push inland early this evening. Vicinity of SFO...Stubborn broken deck still occurring over SFO and satellite trends indicate upstream stratus still spreading inland. For now tafs will keep 21z for clearing time. Confidence low overall given atypical synoptic pattern. Once clearing occurs expect low clouds to spread back over the terminal around 08-09z tonight. SFO Bridge Approach...Clear skies reported over bridge approach and that should last through at least 03-05z this evening. Monterey Bay Terminals...Low clouds have cleared for this morning. Expect an early return for KMRY, around 02z forecast at this time with low cigs spreading down the Salinas valley overnight. Shallow marine layer depth on Saturday suggests clearing by around 18z. && .MARINE... (Today through Wednesday) Issued at 429 AM PDT Fri Sep 18 2026 Gentle west to northwest breezes become moderate to fresh by the afternoon into the weekend. Strong gusts up to 30 kt are possible across the northern coastal waters, Big Sur coastal jet region, and the Monterey Bay region this morning through Saturday. Winds gradually diminish across the southern coastal waters by Saturday evening, but remain elevated across the north. Slight to moderate wind driven seas persist through the weekend and steadily build to rough by early next week. && .FIRE WEATHER... Issued at 429 AM PDT Fri Sep 18 2026 The marine layer is expected to begin redeveloping itself through the day as a ridge develops over the state. By the evening hours the marine layer should be around 1000-1500 feet, along with attendant impacts of stratus development below the marine layer inversion and poor overnight humidity recoveries within and above the thermal belts. As the ridge develops, weak offshore flow is possible Saturday morning, particularly across the higher elevations of the North and East Bay. DialH && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Saturday for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 9 PM this evening to 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10- 60 NM. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...RW MARINE...RW 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

107 FXUS66 KOTX 181730 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1030 AM PDT Fri Sep 18 2026 .KEY MESSAGES... - Isolated showers over southeast Washington and the Central Panhandle Mountains Friday. - Warm temperatures through Tuesday with afternoon highs in the mid 70s to low 80s. && .SYNOPSIS... Isolated showers are forecast on Friday over southeast Washington into the Central Panhandle Mountains. Otherwise dry weather is expected through the middle of next week with high temperatures through Tuesday in the mid 70s to low 80s. && .DISCUSSION... Friday through Tuesday: A closed low over SE Oregon will slowly move east today, tracking into southern Idaho. Southeast flow will continue to draw mid level moisture into SE Washington into the Central Panhandle Mountains. This will keep a chance for showers going for the Blue Mountains, Palouse, Camas Prairie, and Central Panhandle Mountains while the remainder of the region experiences warm and dry conditions. Surface based CAPE of 300-800 J/KG could allow allow a few thunderstorms to develop over the high terrain in the afternoon. Brief downpours, small hail, lightning, and wind gusts up to 30 MPH will be the main hazards with any storms that develop. Over the weekend the low continues its trek eastward, reaching Wyoming on Sunday. Upper ridging on the back side of this low will build across the Inland NW promoting warm and dry conditions with highs mainly in the mid 70s to low 80s. The ridge begins to slowly weaken heading into Monday and Tuesday but mostly clear skies and continued southwest flow will allow Monday to be just as warm before slight cooling Tuesday. Wednesday and Thursday: Model clusters have 65 percent of the members showing an upper ridge holding strong enough for continued above normal temperatures and dry, while 35 percent show more significant flattening which would mean a continued cooling trend and a chance for mainly mountain showers. The forecast is a compromise at this point with highs mainly in the 70s, and a 20 percent chance of mainly mountain showers. JW && .AVIATION... 18Z TAFS: VFR conditions will continue for all TAF sites. Moisture wrapping around an upper level low in eastern Oregon and southwest Idaho will bring passing mid to upper level clouds across eastern Washington and the Idaho Panhandle through the morning into the early afternoon. This will also bring showers across the southern Idaho Panhandle, remaining out of the TAF sites. An upper level ridge begins to shift into the region tonight into Saturday with VFR conditions anticipated to continue beyond the TAF period. Winds will pick up this evening through the Cascade gaps with breezy northwest winds into the teens at KEAT after 03Z. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. Low confidence on rain impacting TAF sites. ----------------------- 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 77 49 78 49 80 52 / 10 0 0 0 0 0 Coeur d`Alene 75 50 77 50 79 52 / 10 0 0 0 0 0 Pullman 72 47 74 48 78 49 / 20 0 0 0 0 0 Lewiston 78 54 78 54 82 56 / 20 0 0 0 0 0 Colville 79 44 80 44 81 45 / 0 0 0 0 0 0 Sandpoint 73 47 75 48 77 49 / 10 0 0 0 0 0 Kellogg 73 49 75 50 77 51 / 10 0 0 0 0 0 Moses Lake 79 49 79 49 82 51 / 10 0 0 0 0 0 Wenatchee 80 57 79 58 80 59 / 0 0 0 0 0 0 Omak 80 53 80 52 80 53 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

194 FXUS66 KPDT 181647 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 947 AM PDT Fri Sep 18 2026 .KEY MESSAGES... - Slight chance (15 to 20%) of thunderstorms through the Wallowas through Friday afternoon. - Drier weather pattern through at least the beginning of the week, with high temperatures climbing into the low to mid 80s by the weekend. - Uncertain weather pattern by late next week, as clusters advertise a third/third/third solution on a dry, wet, or zonal pattern by Friday. && .DISCUSSION... The upper level low pressure system that brought showers and thunderstorms in the area earlier on Thursday will continue to push towards the east. We`ll see some lingering moisture develop thunderstorms (15 to 20% chances) across the eastern Blue Mountains and Wallowas through Friday afternoon. By Saturday, the low will move out of the area with an upper level ridge moving in it`s place. We`ll see mostly dry conditions with a warming trend take place through the weekend with high temperatures climbing into the low to mid 80s in the lower elevated areas. By Tuesday, guidance is in good agreement (80-90% chance) that the ridge will then break down with zonal flow taking place and temperatures will be cooler by 5 to 15 degrees as a result. Our next chance of another weather system will be sometime mid to late next week with some guidance members hinting at a trough digging down in the Pacific and pushing onshore by late next week. Guidance is a bit all over the place by this point, with only 32% advertising a wetter pattern with the trough axis moving onshore by Friday afternoon. Another 38% advertise a ridge overhead, while the remaining 30% wants to keep zonal flow in place. Nothing is for sure with late next week, but there is plenty of time to see how this forecast evolves and what impacts it could bring. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... VFR conditions will persist through the forecast period. Winds will be generally below 12 kts at all sites except DLS which will be gusty to near 20 kts through 02Z. CIGs will begin to tapper off through the period to SKC this afternoon as dry conditions push inland. && .Preliminary Point Temps/PoPs... PDT 77 47 78 48 / 10 0 0 0 ALW 77 53 78 53 / 0 0 0 0 PSC 81 51 82 51 / 10 0 0 0 YKM 81 52 81 52 / 0 0 0 0 HRI 81 51 81 50 / 0 0 0 0 ELN 77 50 77 51 / 0 0 0 0 RDM 75 39 78 41 / 0 0 0 0 LGD 74 47 79 48 / 0 0 0 0 GCD 74 46 79 49 / 0 0 0 0 DLS 82 54 85 56 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...95 AVIATION...90

271 FXUS65 KREV 180719 AFDREV Area Forecast Discussion National Weather Service Reno NV 1219 AM PDT Fri Sep 18 2026 .KEY MESSAGES... * Smoke from local wildfires may lead to periods of degraded air quality across the Reno area, Tahoe Basin, and eastern Sierra today. * Dry and breezy conditions prevail today with a slight cooldown and a shift from west to north winds. * Plan on dry conditions through the weekend with the possibility of rain and thunderstorm chances returning to the Sierra south of Tahoe early next week. && .DISCUSSION... * Drier and breezier conditions follow on the back side of the upper trough venturing eastward today. The main concern with a dry, cool front passing through will be a shift from west/southwest winds to north winds around midday with gusts up to 25 mph for most areas. Ridge winds may reach up to 40 mph, particularly in the afternoon as the north winds with the front pass through the region. Winds will likely "slosh" around any lingering smoke and haze from nearby wildfires. Lighter, more easterly winds overnight may bank up any remaining bits of smoke/haze against the foothills. For air quality concerns and information, refer to fire.airnow.gov * There won`t be a significant dip in the temperatures, but rather a slowdown in the warming trend as we head into the weekend. While temperatures today will remain a bit below normal, a shortwave ridge over the Sierra and western Nevada for the weekend will allow temperatures to climb into the low 80s for the lower valley areas. Temperatures will "hit the brakes" again by Monday and Tuesday as the ridge exits and another low passes across central CA. While there is uncertainty with this cut-off low, we may see a return of precipitation potential across the southern tier of the region (5-15% chances Mono/Mineral counties) as it slowly passes through from Monday into Tuesday. * Ensemble clusters from Wednesday - Saturday show signals for a Pacific Northwest trough setting up off the coast, but there are variations in its progression. Blended guidance for the last weekend in September do show some increased potential for precipitation, but that will all be driven by when/how the large trough moves across the area. Plan on typical late September temperatures for now with a slight lean toward precipitation chances for next weekend. -Edan && .AVIATION... * Smoke and visibility impacts: Smoke from nearby wildfires (Floriston fire west of Reno and Dome fire west of Yosemite) may impact slantwise visibility today at KMMH, KTRK, KTVL, and KRNO. * Winds: Wind direction will gradually shift today with W/SW winds in the morning banking to N and NE winds by the late afternoon and evening. Winds will generally remain light with gusts 20-25kts possible after 20z. * Winds will become light and easterly for late Friday into Saturday with dry and VFR conditions. -Edan && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

189 FXUS66 KSTO 171913 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1213 PM PDT Thu Sep 17 2026 .KEY MESSAGES... - Cooler weather, breezy onshore winds, and increased humidity today - Isolated shower and thunderstorm chances today, mainly across Coast Range, Shasta County, and southern Cascades through 8 PM - Warming and drying conditions Friday and over the weekend with near normal temperatures and general offshore flow && .DISCUSSION... Today: Current GOES-West visible satellite imagery shows the marine stratus intrusion lingering across much of the Sacramento Valley in the form of low clouds, with some additional cumulus development over the mountains. Surface observations are showing temperatures trending approximately 5 to 10 degrees cooler than this time yesterday afternoon. The upper level pattern features an area of low pressure over northern California, bringing cooler temperatures, breezy onshore (S to W) flow, higher humidity, and isolated mountain shower/thunderstorm chances. There is a 15-20% chance of thunderstorms over the Coast Range, Shasta County, and southern Cascades mainly between 1 and 8 PM PDT today. Potential impacts with any storms that develop would be lightning, possible fire starts, gusty winds, brief heavy rain and small hail. Forecast highs are expected to be in the 70s in the Valley and foothills and 50s to 70s in the mountains. Friday-Weekend: Upper low weakens and shifts eastward with upper level ridging then building back in Friday and Saturday bringing temperatures up closer to normal for this time of year. Dry conditions with lower humidity are also anticipated, along with general offshore (N to E) flow. Localized breezes are expected in the Valley during the day Friday and in the mountain/foothill gaps and canyons in the overnight through early morning periods. Afternoon humidity lowers to the 20s on Friday and down into the teens in portions of the Valley on Saturday. Good recoveries still expected in the Valleys with locally poor to moderate recoveries possible in the the thermal belts and ridges. Early Next Week: Ensemble guidance then indicates some form of upper low off the coast Sunday or early next week bringing a period of onshore flow and slightly cooler temperatures before the ridge builds back in. The National Blend of Models (NBM) currently points to a low end chance of a shower or thunderstorm (up to 10%) over the Sierra Nevada along and south of Interstate 80 on Monday, however confidence is low in the details at this time. As always, be sure to check the forecast at weather.gov/sacramento for any updates! && .AVIATION... Improvement to VFR conditions at TAF sites, except 50-80% chance of MVFR ceilings from 11Z-17Z Friday for Sacramento area terminals. Otherwise, breezy south to west winds persist through 06z, gradually falling below 12 kts area wide overnight. Strongest gusts 15 to 20 kts expected through the Delta and Sierra Crest. Winds turn northerly after 18Z Friday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

687 FXUS65 KMSO 181828 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 1228 PM MDT Fri Sep 18 2026 .DISCUSSION... KEY MESSAGES: - Thunderstorms this afternoon/evening with locally heavy rain, minor runoff concerns near burn scars and susceptible terrain. - Steady precipitation tonight into Saturday south of I-90. - Warming and drying trend Sunday into the first part of next week. This afternoon through Saturday afternoon: Broad-scale lift and partial clearing north of an upper low over southwest Idaho will trigger rounds of showers and thunderstorms this afternoon and evening, primarily from I-90 southward. Weak steering flow combined with anomalous moisture (precipitable water 150-200% of normal) will make locally heavy rainfall the primary hazard. Typical rain rates of 0.25-0.50 in/hr are expected, with localized cores exceeding 0.75 in/hr. This poses a localized risk for standing water, rapid runoff, and debris flows over burn scars and susceptible terrain. The upper low will slide across southern Idaho tonight into Saturday, spreading a band of wrap-around stratiform rain with embedded convection from I-90 south into Lemhi County. Precipitation will taper off late Saturday afternoon and evening. Storm-total rainfall will range from 0.50-1.50 inches from northern Lemhi County east to Butte, with isolated totals exceeding 2.0 inches. Sunday through next weekend: Clearing skies Saturday night will favor valley fog and low stratus, particularly in areas that received substantial rainfall. Upper-level ridging builds across the region Sunday and Monday, establishing a warming and drying trend. While deterministic models diverge on the details mid-to-late next week, ensemble clusters favor southwesterly flow, mild temperatures, increased afternoon breezes, and a gradual return of isolated afternoon thunderstorm chances starting as early as Tuesday. By Sunday (Sep 27), ensemble guidance (60-70% confidence) points toward a deeper Pacific Northwest trough pushing inland, bringing cooler temperatures and higher shower chances. && .AVIATION...Multiple rounds of showers and thunderstorms will impact regional terminals south of I-90 this afternoon and evening as partial afternoon clearing allows instability to increase in conjunction with broad scale lift. Primary hazards include erratic convective outflow gusts of 20-30 kt (locally higher with a storm or two) and brief heavy downpours driving localized MVFR visibility reductions. Precipitation turns stratiform tonight through Saturday leading to intermittent MVFR/IFR ceilings/visibility and terrain obscurations. Precipitation diminishes on Saturday afternoon with clearing Saturday night allowing for fog and some low stratus for valley locations. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

553 FXUS65 KBOI 181743 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1143 AM MDT Fri Sep 18 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Showers, scattered thunderstorms, and cooler temperatures today. - Strongest thunderstorms in central Idaho with gusty outflow winds, hail, and brief heavy rain. - Gradual warming and drying trend beginning Saturday and continuing through early next week. && .SHORT TERM /Through Sunday Night/... Issued 258 AM MDT FRI SEP 18 2026 The center of the low pressure system bringing storms and showers to Southern Idaho moves overhead today. This will again support convection this morning through Friday night with showers across the area and scattered thunderstorms this afternoon and evening. Thunderstorms will be capable of producing gusty winds up to 50 mph, small hail, and brief heavy rain. Abundant lightning is also likely, and fast storm motion will keep rainfall amounts low. Inside the center of the low, temperatures cool down 5-10 degrees from Thursday. While thunderstorm activity wanes Friday night, showers continue through Saturday morning as moisture wraps around the eastward low pressure center. A chance of precipitation remains in the higher terrain of Central Idaho through Saturday evening. Behind the low, high pressure returns as a ridge axis moves over the region, leading to warming conditions late Saturday and through Sunday. Temperatures warm up to about 5 degrees above normal by Sunday. && .LONG TERM /Monday through Friday/... Issued 258 AM MDT FRI SEP 18 2026 With models slightly out of phase later in the long term, and the only chance of precipitation associated with a weak low over Southern California, the bulk of the long term forecast is focused on temperature trends as the synoptic pattern shifts. Monday afternoon through Tuesday evening, the weak Californian low moves across the Southwestern US. During this time, we occupy a slightly moistened northeastern quadrant between the low and zonal flow to our north. Dynamics will favor development of showers in Central and Eastern Idaho Monday and Tuesday afternoons. The chance of precipitation each afternoon is only 10%. Otherwise, that zonal flow to the north moderates temperatures, holding them steady at 5 degrees above normal for most of the long term. Slight warming on Thursday is expected as high pressure builds ahead of a strong Alaskan low pressure system. This low pressure system moves through British Columbia late next week, with model variation on the exact track keeping our forecast low confidence that far out. && .AVIATION /18Z Friday through Saturday/... Issued 1138 AM MDT FRI SEP 18 2026 VFR in eastern Oregon. Mainly VFR in southwest Idaho with occasional MVFR through early Sat/AM amidst scattered to widespread showers and isolated thunderstorms. Storms this afternoon could produce outflows gusts up to 35 kt. Surface winds outside of storms: W-NW 5-15 kt with gusts to 20-25 kt Fri/PM. Winds aloft at 10kft MSL: NW-N 5-15 kt. KBOI...Mainly VFR. Showers developing N and E of KBOI this afternoon. Highest chances for showers over terminal will be late Fri evening, with brief MVFR possible. 10% chance of lightning at the terminal. Clearing early Sat morning with SCT clouds and light winds. Surface winds: NW 5-15 kt. Weekend Outlook...Brief MVFR and mountain obscuration in lingering showers near KTWF-KJER on Saturday, with showers tapering off by midday. Expect VFR conditions otherwise through Sunday with variable winds less than 10 kt overnight and in high terrain and NW 5-15 kt in valleys during the afternoon. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Flash Flood Watch through this evening for IDZ013-028. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....JR SHORT TERM...JM LONG TERM....JM

628 FXUS65 KLKN 180841 AFDLKN Area Forecast Discussion National Weather Service Elko NV 141 AM PDT Fri Sep 18 2026 .KEY MESSAGES... * Rain showers and isolated thunderstorms along the Oregon and Idaho borders, as well as the Utah border, thru this evening * Generally fair weather this weekend * Potential for rain across central Nevada in the Monday/Tuesday time frame && .DISCUSSION... (Today through next Friday) WEATHER PATTERN OVERVIEW: Cut off low ejects east along the northern Nevada border today with the associated weak frontal boundary moving thru northern Nevada from the west. West- northwesterly breezes will be present today, though winds will be more modest than yesterday with gusts remaining less than 30 mph. Light rain showers and isolated thunderstorms can be expected along the Idaho and Oregon borders as well as the Utah border thru this evening. Any rain accumulations will be around 0.10 inches or less and the best opportunity for accumulating rainfall will be across northern Elko County. Will maintain a low chance of light rain showers and isolated thunderstorms into Saturday for the far northeast portion of Elko County, but generally speaking, weather will be fair thru the weekend. Daytime high temperatures today will be several degrees cooler than yesterday. Temperatures will warm thru the weekend with daytime highs returning to the mid 70s to mid 80s by Sunday. A low chance of rain will be present across central Nevada in the Monday and Tuesday time frame as a modest Pacific low moves into central California from the west. That said, latest numerical model solutions are not in agreement on the exact track of the low, which will be the determining factor with regard to rain potential. Fair weather looks to be in place the latter half of the week. FORECAST CONFIDENCE & DEVIATIONS: High confidence exists for showers and thunderstorms along the northern and eastern NV borders today, though confidence is moderate with regard to rain accumulation. Significant grid edits required within PoP grids to better represent rain shower and thunderstorm chances today and this evening. && .AVIATION...VFR conditions will be the primary flight conditions thru Friday night. A weak frontal boundary moving thru northern Nevada from the west today will produce west-northwesterly breezes though gusts will be around 25KT or less at all terminals. There is a low chance of VCTS and SHRA at KENV today and this evening, though confidence remains too low to include this in the TAF. VCTS and SHRA will be more prevalent to the east within Utah and southeast Idaho. && .FIRE WEATHER...A weak frontal boundary associated with a parent cut off low will pass thru northern Nevada from the west today. West- northwesterly breezes will be present though gusts will remain less than 30 mph. Main concern will be for light showers and isolated thunderstorms present thru this evening along the Idaho/Oregon border as well as the Utah border. There is a low chance (10% to 20%) of wetting rains. Low chance of isolated showers and thunderstorms carrying into Saturday for the northern half of zone 470 but generally speaking, weather will be fair this weekend with light winds and mostly sunny to partly cloudy skies. A modest Pacific low looks to move thru southern Nevada early next week. There is a chance of wetting rain within central Nevada though latest numerical model solutions are not in agreement on the exact track of the low, which will be the determining factor with regard to rain. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...92 AVIATION...92 FIRE WEATHER...92