609 FXUS66 KSEW 190445 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 845 PM PST Sun Jan 18 2026 .UPDATE... No changes made in this evening`s update. The previous discussion remains below along with an updated aviation section. && .SYNOPSIS... Strong upper level ridge offshore weakening Thursday. Low level flow become light beginning Monday allowing more morning fog to form each morning through Wednesday. Weak system moving over the top of the ridge will try and move into Western Washington late in the week into the weekend. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... Satellite imagery shows clear skies over most of Western Washington this afternoon. Small patch of fog hanging tough around Olympia. Temperatures at 3 pm/23z were in the mid 40s to mid 50s except around Olympia where temperatures are still near 40. High amplitude upper level ridge offshore remaining in place through Wednesday. Interior surface gradients have already gone light and cross Cascade gradient trending back towards zero. Inversion still in place ( temperature at Paradise on Mount Rainier and at 5000 feet on Mount Baker 53 degrees at 3 pm ) and will strengthen overnight. The cross Cascade gradient will continue to move towards zero through Wednesday. The lighter surface gradients will lead to more fog coverage each morning Monday and Tuesday. By Wednesday expect the fog and low clouds to be thick enough to last into the afternoon hours. High temperatures will drift lower each day starting out in the mid 40s to lower 50s Monday and ending up in just the 40s on Wednesday. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Low confidence in the extended forecast. Previous models runs have had a weak system moving over the top of the weakening ridge offshore. The operational runs have gone dry with the system dissipating before reaching Western Washington with another, all be it weaker, upper level ridge rebuilding offshore. Ensemble wet solutions for Friday are decreasing and now down to less than a quarter of the members. Wet solutions over the weekend also decreasing in the ensembles with a majority of the wet solutions Saturday night and Sunday. Pushing back the possible precipitation has allowed the lower levels of the air mass to warm up with less than 10 percent of the solutions indicating light snow in the lowlands Saturday night and Sunday with no snow solutions before Saturday. With the continued uncertainty will continue with the broadbrush chance pop solution from most of the period. If the trends continue look for the forecast to dry out at least for Thursday and Friday. High temperatures in the 40s with lows in the mid and upper 30s through the period. && .AVIATION... Mostly VFR across terminals this evening with weak flow under high pressure. Patchy areas of fog near KOLM & vicinity generating LIFR conditions. Decreasing pressure gradients again tonight under a temperature inversion will leave a moderate chance (40-60%) for fog redeveloping later this evening into Monday morning, with increasing coverage in the morning into portions of Puget Sound, with clearing by the late morning/afternoon Monday. Winds tonight/Monday morning are light NE or variable less than 5 kt. KSEA...VFR through tonight, with light N/NE wind 4-8 kt decreasing to less than 5 kt overnight (may become variable at times). Fog likely to be in the vicinity of the terminal as early as ~06Z with a 30-50% of it drifting over the terminal between 06Z-18Z. VFR for the remainder of Monday. HPR/15 && .MARINE... High pressure/riding will remain offshore through a majority of the week with a thermal trough along the coastline. Fog will be possible in the interior waters Monday morning, with a 50% chance of visibilities less than a mile. There remains no wind concern with the pattern this week (even as the ridge breaks down and a system skirts through towards the end of the week). Seas: 4-6 ft through next weekend. HPR && .HYDROLOGY... No river flooding in the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$

212 FXUS66 KPQR 190530 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 930 PM PST Sun Jan 18 2026 Updated aviation discussion. && .SYNOPSIS...Dry weather prevails as high pressure continues through the middle of the week. Breezy easterly winds continue through the Columbia River Gorge and eastern Portland/Vancouver Metro through early this week. For the few nights, clear skies and light winds will result in frost or freezing fog formation across most interior lowland valleys. Near/below freezing temperatures in combination with any fog may lead to locally slick road conditions. Lower confidence for fog/frost for locations that remain windy and or have persistent stratus. Chances for precipitation return Thursday night. && .DISCUSSION...Now through Saturday night...Sunny skies prevail across the majority of northwest Oregon and southwest Washington as strong high pressure remains overhead. An exception is the central Columbia River Gorge and Upper Hood River Valley, where low stratus is being held in place due to the low level subsidence inversion. High confidence that this pattern continues through at least Tuesday, maintaining dry weather and chilly nights. Breezy easterly winds continue through the Columbia River Gorge, surrounding terrain, and eastern Portland Metro through Monday. Observations as of early Sunday afternoon show wind gusts of 25 to 40 mph across the eastern Portland Metro with locally higher gusts of 40-50+ mph for exposed ridgetops like Crown Point. KTTD-KDLS pressure gradients are around -8 to -9 mb, and most guidance suggests that these gradients will hold through Monday afternoon and maintain similar wind gusts. By Monday night into early Tuesday morning, pressure gradients ease to around -4 to -6 mb and winds gradually weaken. Clear skies and light winds away from the winds from the Columbia River Gorge will lead to efficient radiational cooling across the area each night through at least Tuesday night, dropping overnight lows to near or below freezing across the Willamette Valley, southwest WA lowlands, and Upper Hood River Valley. High confidence remains that this would favor widespread frost development, especially over grasses and metal surfaces. Freezing fog may also develop in some locations, particularly across the southern Willamette Valley where surface conditions are more moist. Any freezing fog that develops could lead to locally slick road conditions. Meanwhile, higher elevations above 1500-2000 ft but below 5000 ft will remain much warmer than the lowland valleys due to a strong subsidence inversion. Additionally, stagnant air will be a continued concern under this subsidence inversion as the winds decrease, leading to air quality concerns through mid-week. Mixing heights will remain low and transport winds will be weak. Therefore, an Air Stagnation Advisory remains in effect for most of the Willamette Valley due to this concern and has been extended through 4 PM Wednesday. The Portland Metro area from the West Hills eastward were not included in this advisory due to stronger winds from the Gorge maintaining a more mixed atmosphere. Ensemble guidance indicates the strong high pressure will begin to slowly break down Wednesday into Thursday. Conditions are expected to remain dry on Wednesday with the subsidence inversion likely to begin to break down and temperatures will begin a return to near normal for January. There`s around a 20-40% chance of precipitation returning sometime Thursday, mainly over the coast and terrain. Precipitation chances increase late Thursday night into Friday to 30-50% chance for the interior lowlands and 40-60% for the coast and terrain, continuing into Saturday. Onshore flow appears to return Thursday as well, bringing more mild air. However, about 15% of ensemble members suggest that temperatures will remain cold enough to result in wet, non-impactful snow or rain/snow mix falling down to the Valley floor. This would mainly be Friday night and Saturday night when temperatures are forecast the coldest. If this occurs, impacts would be minimal given air temperatures will be marginally freezing due to onshore flow and roads would be too warm to accumulate snow. One location we would keep a closer eye out on would be the central Columbia River Gorge and Upper Hood River Valley - if easterly winds continue, then colder air may linger longer for these areas. This would result in wintery precipitation, especially if the incoming moisture overlaps the same time as the freezing air. These areas can remain much colder than other interior valleys like the Willamette Valley and southwest WA lowlands. Specific details will become more clear as we get closer to precipitation returning. -10/03 && .AVIATION...A persistent upper level ridge over the region will continue to yield widespread VFR conditions for most terminals through the period. Guidance is varied on whether fog/low stratus develops again through portions of the southern Willamette Valley and the lower Cowlitz with lower confidence than the previous few nights. Given similar conditions to last night, KEUG will have the best shot at seeing sub-VFR conditions. Have added a period of MVFR VIS for the terminal tonight but can`t rule out lower VIS reductions completely based on guidance. Offshore pressure gradient remains in place, producing strong gusts of 30-35 kt continue at KTTD, with gusts up to 45-55 kt east of KTTD at the western end of the Columbia River Gorge. KPDX AND APPROACHES...VFR flying conditions expected through the period. East to southeast winds around 10 kts expected. -19 && .MARINE...Strong ridging aloft continues favoring persistent easterly offshore flow through midweek. While winds are largely at 10 kt or less, areas downwind of gaps in the coastal terrain may see stronger flow with gusts up to 15 kt, mainly west of the mouth of the Columbia River. Seas remain below 10 ft at 10-13 seconds through the middle of the week. -03/36 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Air Stagnation Advisory until 4 PM PST Wednesday for ORZ109- 114>118. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

551 FXUS66 KMFR 182237 AFDMFR Area Forecast Discussion National Weather Service Medford OR 237 PM PST Sun Jan 18 2026 .DISCUSSION...An upper ridge remains in control of conditions across northern California and southern Oregon today and looks to stay in place through midweek. This will keep above seasonal daytime highs and cool overnight lows in the forecast for most areas in the short- term. This stability will also prevent mixing in area valleys. An existing Air Stagnation Advisory has been extended through Wednesday afternoon to address the chance for poor air quality to continue. Fog continues to develop in the Umpqua and Illinois Valleys as well as over Grants Pass. For tonight into Monday morning, a Freezing Fog Advisory for Illinois Valley and Grants Pass as well as a Dense Fog Advisory for the Umpqua Valley are in place. Some patchy morning "sunrise surprise" fog has been reaching the Medford airport, but has been quick to clear out. Late Tuesday/early Wednesday, an approaching trough splits and sends a cutoff low towards the southwestern United States. This looks to flatten the trough briefly, which may cool daytime temperatures slightly on Wednesday and Thursday. Whether this will provide any kind of mixing to ease air quality concerns is not clear. Upper ridging tries to rebuild behind the cutoff low, but a variety of signals in guidance for the end of the week is not helping confidence in any one direction. Deterministic imagery keeps a ridge over the area, although placement varies between the ECMWF and GFS. EC meteograms show some agreement for North Bend to see some light rainfall, but those signals are rare from other sources and are not present for inland locations. Interquartile (25th percentile to 75th percentile) temperature ranges for Medford`s temperatures next weekend are ~10 degrees, which also suggests that long-term guidance is seeing a wide range of possibilities. -TAD && .AVIATION...18/18Z TAFs...Onshore flow near the coast led to low ceilings, some fog and drizzle at the beaches and at North Bend this morning. These ceilings should erode in the next few hours becoming VFR this afternoon. Low-level flow will become offshore again tonight, but there could be a period of IFR/LIFR again with temps dropping quickly after sunset. These could then dissipate by early Monday morning. Meanwhile, status quo inland with LIFR fog/low clouds persisting in the Umpqua Basin (Roseburg) and portions of the Rogue/Illinois valleys (especially Grants Pass/Cave Junction). These will erode this afternoon, breaking for a couple of hours in most places before returning this evening and lasting overnight into Monday morning. Around Medford, fog has been developing out around the Table Rocks and briefly impacting the terminal toward morning. So have gone with persistence allowing for a brief period of IFR/LIFR visibility 14-17Z. && .MARINE...Updated 200 PM PST Sunday, January 18, 2026...An extended stretch of relatively calm conditions will persist through midweek. Generally light winds and low seas are expected tonight. North to northeast winds increase a bit Monday, but both winds and seas should remain below advisory levels. A long period swell will move through the waters Monday night into Tuesday with a brief return of light southerly flow over inner waters that shifts back to the north on Wednesday. North winds could increase enough Thursday or Friday to bring conditions hazardous to small craft, especially south of Cape Blanco. && .BEACH HAZARDS...Updated 200 PM PST Sunday, January 18, 2026...A low amplitude (3-6 ft), but long period (18-20 seconds) swell is expected to move into the coastal waters Monday evening and persist through the high tide on Tuesday. This will increase the risk of sneaker waves on area beaches, especially on the incoming tide Tuesday morning. If you plan to visit area beaches, please be aware of the dangers sneaker waves pose to beach goers. Sneaker waves can run up significantly farther on beaches than normal, including over rocks and jetties. These waves can suddenly knock people off of their feet and sweep them into the ocean. The waves can also move logs or other objects which could crush or trap anyone caught underneath. While sneaker waves can occur at any time, the greatest risk is on an incoming tide. Please be aware of the tides if venturing out onto the beaches. NEVER turn your back on the ocean! && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Beach Hazards Statement from Monday evening through Tuesday afternoon for ORZ021-022. Air Stagnation Advisory until 4 PM PST Wednesday for ORZ023-024- 026-029>031. Dense Fog Advisory from 7 PM this evening to noon PST Monday for ORZ023. Freezing Fog Advisory from 8 PM this evening to noon PST Monday for ORZ024. CA...None. PACIFIC COASTAL WATERS...None. && $$

177 FXUS66 KEKA 190912 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 112 AM PST Mon Jan 19 2026 .SYNOPSIS...Dry weather and above average daytime temperatures will continue through much of this week. Overnight and morning temperatures will remain chilly with patchy dense fog along river valleys and around Humboldt Bay. Chances of precipitation return late in the week or weekend. && .DISCUSSION...Quiet weather conditions continue across Northwest California with dry weather and above average temperatures through much of this week as a resilient high pressure ridge remains over the Western CONUS. A shallow marine layer, around 2000 feet, is expected to continue to blanket the coast through late this morning. While daytime warmth continues, expect chilly mornings with patchy dense fog along the river valleys and around Humboldt Bay through much of the upcoming week. The anomalous 500 mb ridge is expected to weaken by midweek. The pattern shifts late in the work week as the ridge breakdown. Ensemble guidances and cluster analysis show a weak system bringing increasing chances of precipitation late in the week or weekend. There is a 15-45% chances of wetting rain (0.01 inch or more) across the forecast area this weekend, with the highest probabilities along the coastal range in Del Norte and Humboldt counties. The latest WPC/CPC 6-10 day outlook (Jan 23-27) indicate a tilt toward above normal precipitation (33-40% chance). High uncertainty remains regarding the specific details at this moment. A cooling trend is expected as well; however, daytime temperatures are forecast to remain generally above average through the end of the month and into early February. /ZVS && .AVIATION...The marine layer remains in place along much of the coast. Around ACV the clouds are firmly in place and it is likely it will remain LIFR early this morning. It may even drop below 1/4 mile at times. KCEC is a bit more patchy with the clouds. It will likely continue to see periods of LIFR conditions, but there may be some breaks in the clouds at times. This morning clouds are expected to lift slightly in the morning and may break out to VFR in the afternoon. However this will likely be shortlived with the HREF showing a quick return of lower cigs and vis in the evening along the coast. Inland areas are expected to see low clouds and fog return to many of the northern valleys, likely in the areas where there was fog on Sunday. UKI is not expected to see much fog, although a few brief periods of it are possible. MKK && .MARINE...Northerly winds remain around 10 to 15 kt south of Cape Mendocino with local areas of 20 kt winds south of Cape Mendocino. This will generally bring wind driven waves of 3 to 5 feet. Local areas of 6 foot waves are possible just downwind of Cape Mendocino. North of Cape Mendocino northerly winds remain around 10 to 15 kt. are expected to increase to around 10 kt tonight. These conditions are expected to persist through Monday evening and diminish Monday night. Monday night and Tuesday the GFS wave model is showing a long period west to northwest wave moving in and building to around 5 to 6 feet at 16 seconds. This is expected to combine with a 3 or 4 foot wave of 12 seconds. Lighter winds are expected Tuesday and Wednesday before strong to near gale force winds are expected to return late in the week. MKK && .BEACH HAZARDS...A moderate risk for sneaker wave will arise during the early Tuesday morning hours. A Beach Hazard Statement, BH.S, has been issued for two separate arrival times of a westerly swell 4- 6ft with a period around 16-17 seconds. The earliest estimated arrival is 12z on Tuesday January 20th for Coastal Del Norte, Northern Humboldt Coast, and Southwestern Humboldt ending around 04- 05z Wednesday. The sneaker wave threat for the Mendocino beach zones will arrive around 15z on Tuesday January 20th, ending around 05-06z. /EYS && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Beach Hazards Statement from late tonight through Tuesday evening for CAZ101-103-104. Beach Hazards Statement from Tuesday morning through Tuesday evening for CAZ109. 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

496 FXUS66 KMTR 190546 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 946 PM PST Sun Jan 18 2026 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 1251 PM PST Sun Jan 18 2026 - Dry weather, cool mornings, and warm afternoons this week - Morning fog across the Delta, North Bay Valleys, and interior East Bay Valleys && .SHORT TERM... Issued at 1251 PM PST Sun Jan 18 2026 (This evening through Monday) Temperatures continue to warm as mostly sunny sky conditions have returned to the region. However, there are still high clouds streaming in from the northwest. As such, temperatures are likely to warm into the low to upper 60s across the North Bay, East Bay, and greater San Francisco Bay Area. Across the Central Coast, temperatures are likely to warm into the low to mid 70s. Tonight, look for tule fog to return to the interior East Bay Valleys and Delta (similar timing as the previous nights) and continue through midmorning on Monday. Fog may also impact the North Bay Valleys in response to fog development in the Russian River Valley and/or tule fog advecting in from the east. Monday`s afternoon temperatures will be similar to those today (Sunday) as the region continues to be under the influence of high pressure. This ridge axis extends all the way up to just off of the British Columbia coast. However, high clouds will persist over the region through at least midweek. && .LONG TERM... Issued at 1251 PM PST Sun Jan 18 2026 (Monday night through next Saturday) By mid to late week, troughing will develop out over the north central Pacific. This feature is forecast to develop a cut-off upper level low that will gradually approach the region late in the week. However, there does not appear to be much of a moisture source associated with it, so rainfall has been pushed back until at least Monday, January 26th. With that said, the low pressure system aloft will at least cool temperatures down to near seasonal averages after a prolonged period of very warm afternoon temperatures. Thus, we will have to wait a bit longer for much needed rainfall to return. && .AVIATION... (06Z TAFS) Issued at 944 PM PST Sun Jan 18 2026 VFR continues for most TAF sites through the TAF period. The exceptions will be STS and APC which will see fog overnight as well as fog and haze possible at LVK. Winds will say light through the TAF period with directions being mostly variable. Some sites along the coast will see northwest winds Monday afternoon, while others stay variable, and LVK goes easterly. These winds will reduce into Monday night and turn more variable. Vicinity of SFO...VFR through the TAF period. Expect mostly light and variable winds through the night and much of the Monday before winds turn northwesterly in the late afternoon, but become variable again into the night. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR through the TAF period. Winds have become light and variable across the area. Southeast winds build at SNS in the late night and last into Monday afternoon before turning northwesterly in the mid afternoon. Winds at MTR look to stay light and variable through the end of the TAF period. && .MARINE... (Tonight through next Saturday) Issued at 944 PM PST Sun Jan 18 2026 Moderate winds continue to affect the San Pablo Bay, the Delta, and through the Golden Gate through Wednesday as light to gentle northeast to north winds continue across the rest of the coastal waters. Expect slight increases in winds into the late week. Low seas up to around 6 feet continue through the middle of the week as a northwest swell builds. Chances for rain could return late next weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...RGass LONG TERM....RGass AVIATION...Murdock MARINE...Murdock 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

550 FXUS66 KOTX 190846 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1246 AM PST Mon Jan 19 2026 .KEY MESSAGES... - Dry and stagnant pattern under strong ridge of high pressure through Tuesday. - Areas of low clouds and dense fog to continue through early next week. - Unsettled weather to return as we approach the end of next week. && .SYNOPSIS... Strong high pressure will remain in place through at least Tuesday. In the meantime, low clouds and fog are expected to impact the lowlands through Tuesday. Confidence is low on coverage and timing of low cloud and fog coverage. There is an increasing signal for unsettled conditions to return by the middle of next week. && .DISCUSSION... Today through Tuesday: The persistent ridge is still positioned along the coast and continue to create stable and stagnant conditions for the Inland Northwest. Recent model runs have delayed the breaking down of the ridge pattern. It is expected to remain through Tuesday. Stratus and fog continue to be impact locations across the Basin and valleys. The higher terrain across the region is expected to be in the clear and mostly sunny skies. The atmosphere is trending drier. It will lead to less stratus cloud coverage over the Basin and valleys. Highs will continue to be in the 30s for most. A few locations could reach into the low 40s if the stratus breaks. Overnight lows will be in the upper 20s to 30s. Wednesday through Sunday: With the ridge remaining in place longer, it is not allowing the cold air intrusion of previous model runs. The possibility of precip has also declined. With a weaker influence of the Low over Manitoba, the outlook for the period has shifted to slightly warmer and drier. Moisture associated with shortwave could bring light snow showers to the Idaho Panhandle mountains. Little to no accumulation expected. The next wave is expected late Friday and last into Sunday. The ensembles are trending weaker as the ridge flattens across the Pacific Northwest. The shortwave is not expected to dig much past Southern Canada. It has led to a drier and warmer outlook for the Inland Northwest. While the mountain passes are expected to receive 3 to 6 inches of snow, the low land areas will continue to struggle for up to an inch. Highs will be in the 30s. Lows will upper teens and 20s. /JDC && .AVIATION... 06Z TAFs: Widespread low stratus will continue persisting through the forecast period, bringing many places down to MVFR/IFR conditions. Models continue to handle the stratus poorly. KGEG/KSFF can expect IFR/MVFR ceilings through much of the period. KEAT/KMWH/KCOE/KPUW/KLWS is expected to have clearing late Monday morning and VFR conditions. MVFR ceilings will return for KEAT/KMWH/KCOE by late Monday afternoon. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in areas of persistent low stratus to continue. Low confidence on timing of the VFR and MVFR conditions. There is 30-40% chance that MVFR will continue through the period for all 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 34 24 35 22 36 22 / 0 0 0 0 0 0 Coeur d`Alene 34 24 37 22 37 23 / 0 0 0 0 0 0 Pullman 37 27 38 24 39 25 / 0 0 0 0 0 0 Lewiston 39 27 40 27 39 28 / 0 0 0 0 0 0 Colville 35 22 36 19 36 21 / 0 0 0 0 0 0 Sandpoint 34 24 35 23 34 23 / 0 0 0 0 0 0 Kellogg 36 27 38 24 37 25 / 0 0 0 0 0 0 Moses Lake 35 24 38 22 38 23 / 0 0 0 0 0 0 Wenatchee 35 26 38 26 38 27 / 0 0 0 0 0 0 Omak 35 25 39 23 37 24 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...Air Stagnation Advisory until 4 PM PST Tuesday for Central Chelan County-Moses Lake Area-Northeast Mountains- Okanogan Highlands-Okanogan Valley-Spokane Area-Upper Columbia Basin-Waterville Plateau-Wenatchee Area-Western Chelan County-Western Okanogan County. ID...Air Stagnation Advisory until 4 PM PST Tuesday for Central Panhandle Mountains-Coeur d`Alene Area-Lewis and Southern Nez Perce Counties-Lewiston Area-Northern Panhandle. && $$

322 FXUS66 KPDT 190506 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 906 PM PST Sun Jan 18 2026 .UPDATED AVIATION... && .PREV DISCUSSION... /issued 211 PM PST Sun Jan 18 2026/ DISCUSSION...Satellite shows the stratus encompassing the lower elevations of the PDT region continuing through today and more than likely (70-80 percent chance) to persist until Monday. As we continue to be dominated by high pressure in the synoptic scale, we`ll continue to see freezing fog formation across the lower valleys (especially in sheltered regions). Currently, there`s still an area of dense fog around Cabbage Hill, Poverty Flats, and Deadman Pass with less than a quarter of a mile visibility readings. This will persist through the early to mid afternoon hours, but we`ll likely (70-90 percent chance) see another formation of freezing fog develop in areas below 2500-3000 feet overnight. Another (Freezing) Dense Fog Advisory is likely tonight (60-80 percent chance) for the Foothills of the Blues, Kittitas Valley, Central Oregon, and North Central Oregon. Air Stagnation is another highlight that will continue through 4PM Tuesday, with poor air quality conditions and very light winds through the lower elevations. We`ll get better mixing heading into mid-week with the ridge weakening and a shortwave passing through California, the stratus is probably (50-70 percent chance) going to be eaten up with the subsidence fading away. With that, we`ll see our PoP chances go up to 20-40 percent chances heading into Friday and through the weekend as a cold front approaches from Washington and Canada before stalling over the area. Snow levels will be much lower in this period, dropping to around 2000-3000 feet (and as low as 1500 feet in parts of the Washington Columbia Basin). This will be a mainly snow dominated system, with the heaviest areas in the mountain region receiving up to 3 to 5 inches through the weekend (30-50 percent confidence) and parts of the Foothills of the Blue Mountains (and some parts of the Basin close to the Foothills) getting up to a quarter inch of snow (20-40 percent confidence). Of course, this is all through Day 5-7 currently and guidance could change, but the overall tone after the current ridge departs, is that we`ll at least see some areas of light to moderate mountain snow (mostly light) and slight chances of a dusting in parts of the Foothills. AVIATION...06Z TAFS...Conditions continue to range from MVFR to LIFR across the region. As the high pressure lingers overhead and winds remain light, there are no chances of mixing which is what is keeping the stratus and fog. Expect all sites to remain MVFR or worse through the forecast period. However, models are suggesting slight clear out tomorrow afternoon, but shows the cloud decks to reform again overnight. && .PRELIMINARY POINT TEMPS/POPS... PDT 24 36 23 36 / 0 0 0 0 ALW 26 36 25 35 / 0 0 0 0 PSC 25 38 24 38 / 0 0 0 0 YKM 23 39 23 40 / 0 0 0 0 HRI 25 37 24 37 / 0 0 0 0 ELN 21 36 22 37 / 0 0 0 0 RDM 18 43 20 49 / 0 0 0 0 LGD 22 48 25 45 / 0 0 0 0 GCD 26 53 27 51 / 0 0 0 0 DLS 27 41 26 40 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Air Stagnation Advisory until 4 PM PST Tuesday for ORZ041-044- 507-508-510-511. WA...Air Stagnation Advisory until 4 PM PST Tuesday for WAZ024- 026>029-521. && $$ SHORT TERM...95 LONG TERM....95 AVIATION...90

643 FXUS65 KREV 190950 AFDREV Area Forecast Discussion National Weather Service Reno NV 150 AM PST Mon Jan 19 2026 .KEY MESSAGES... * Light winds and valley inversions will keep hazy skies and air quality reductions to begin this week with patchy freezing fog in some Sierra valleys. * Dry weather prevails this week with above average daytime temperatures and near average low temperatures. * A pattern change is possible for the latter half of the week allowing gusty mountain ridge winds to return. But, confidence is low. && .DISCUSSION... The latest RAP analysis of the upper air pattern shows generally the same pattern that has been the case for a good number of the previous days: a high pressure ridge residing over the western CONUS and eastern Pacific. Forecast guidance shows this setup continuing through at least midweek, which will allow dry conditions and light winds to persist across the region. The daily widespread freezing fog that has been experienced around the Mono Lake area looks to continue at least today and tomorrow, so please be prepared for lower visibilities if traveling in the area. There may be a few hours in the afternoon today where it dissipates, but the forecast calls for it to return tonight. The Martis Valley and Lake Crowley area also expect to see morning freezing fog continue this morning as well as tomorrow morning. Valley inversions still remain in place allowing hazy skies and localized lower air quality in particularly around urban areas to begin this week. Daytime high temperatures to begin the week are forecast to be in the 40s and 50s with the exception of the Mono Lake area and some other areas where the fog will hinder daytime heating and keep the temperatures from climbing out of the 30s. Overnight low temperatures look to be more or less similar to those experienced over the weekend. By late Wednesday into Thursday, ensemble guidance is picking up on a pattern change with an Pacific upper low making its way across SoCal before opening up into a trough as it reaches AZ on Friday. There is still some model uncertainty in the exact placement and timing of this low`s progression, which does lower forecast confidence. But there is potential for mountain ridge gusts to increase slightly as a result on these two days. The latest NBM run now has a slight chance for light snow in the highest elevations of the Eastern Sierra on Thursday and Friday afternoon. Not the greatest confidence in this occurring due to the run-to-run model differences seen, but little to no accumulating snow is expected should these showers occur. By the weekend, a trailing upper ridge looks to move back over the region allowing for more dry weather. -078 && .AVIATION... VFR conditions and light surface winds continue for area TAF sites to begin the week. The only exception is at KTRK where patchy and mainly shallow FZFG is expected through around 15Z today that may return again tonight. Haze in W.NV may lead to reduced slantwise visibilities. -078 && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

772 FXUS66 KSTO 182041 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1241 PM PST Sun Jan 18 2026 .KEY MESSAGES... - Dry weather expected this week with Valley fog/low clouds - Warm and dry weather at higher elevations with offshore flow - High uncertainty for very light mountain showers next weekend && .DISCUSSION... ...Today Through Friday... Latest GOES-West visible satellite imagery shows the fog and low clouds from this morning gradually lifting and burning off this afternoon, with a few mid to high level clouds passing overhead. The Dense Fog Advisory was allowed to expire at noon as a result of improving visibilities across the Valley and Delta. The region remains under upper level ridging, with dry and mild weather prevailing for much of interior northern California. This inversion pattern is bringing daily chances for fog and low clouds in the Valley and lower foothills, especially from Marysville southward. High resolution guidance shows a 50 to 70 percent chance of visibilities less than 1/2 mile once again tonight into Monday morning. The fog and low clouds will delay some of the daytime heating in those lower elevations. Elsewhere, above normal temperatures are forecast, along with periodically breezy offshore flow. The warmer temperatures and offshore flow will keep humidity fairly dry for higher terrain. Some minor modifications were made to the temperature, fog and humidity to account for the contrasts above and below the fog layer. This pattern will continue through at least the middle of the week before the upper level ridge starts to flatten and temperatures gradually start to cool later in the week. ...Next Weekend... Ensemble guidance and cluster analysis continue to indicate the potential for a weak system to bring very light precipitation over the weekend, with a 15 to 45 percent chance of 0.01" of rain showers across interior NorCal, with the best chances over the northern mountains and southern Cascades. A cooling trend in temperatures is expected as well, with forecast highs in the 50s to around 60 for the Valley. The Climate Prediction Center is then indicating that above normal temperatures and above normal precipitation chances are favored for much of northern California in the 8 to 14 Day Outlook. This suggests the potential for a somewhat unsettled weather pattern by the end of the month into early February. There is quite a bit of uncertaity with details on this so be sure to check back more for details as we get closer. && .AVIATION... Lingering IFR/LIFR conditions in central/southern Sacramento Valley, Delta, and northern San Joaquin Valley through 22z Sunday, potentially lingering until 00z Monday for some areas. FG/BR expected to develop around 03z-06z Monday with similar aerial extent. Surface winds below 12 kts in the lower elevations, with local E-NE wind gusts of 15-25 kts in the Sierra and Southern Cascades after 06z Monday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

175 FXUS65 KMSO 181937 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 1237 PM MST Sun Jan 18 2026 .DISCUSSION... KEY MESSAGES: - Forecast challenges with valley fog will continue. - Ensembles continue to be challenged with the change to colder weather and snow next weekend. Valley fog continues to be a forecast challenge for the region. The overall surface pressure pattern will change little in the next 24-hours, suggesting a status quo and continued fog and stratus in the valleys. However, tonight a shortwave moves across the region from north to south, which will generate some weak lift, which may help lift some of the fog into a low stratus. The shortwave is also bringing quite a dry air mass aloft with it, which will allow more efficient terrain cooling overnight, which will enhance the valley fog potential. Overall, we expect the fog will continue through Wednesday morning. Subtle changes in the flow aloft will cause it to pile up in different places in the valley for valleys that don`t get totally filled, but overall, the fog will remain. Ensembles continue to be challenged by the potential for a cool down and some heavy snow next weekend. The challenge lies with the positions of the upper level ridge and the core of the cold air at the surface. Thus far, most ensembles have kept the core of the cold air far to the east along the Montana-North Dakota border. A colder model solution would have the core further west which would push more of the cold air over the Continental Divide. If the upper level ridge were to move further westward, that would support pulling more of that cold air to the west. But recent runs have trended further east with the ridge and core of cold air. So it will get much colder next weekend, but won`t be an Arctic intrusion of really, really cold air; that`s all going to the east. Ensembles have also trended towards much less snow next weekend. Compared to 24 hours ago, most ensemble systems have really reduced the high end (90th percentile) snow forecasts for the northern Rockies region. The high end forecast for the weekend in places like Missoula and Kalispell has dropped from 4 to 6 inches down to 2 to 4 inches. The forecast is still calling for plenty of snow in the mountains, so that hasn`t changed, it`s just that the more extreme forecasts are becoming less likely. Ensemble clusters based on QPF (the liquid equivalent of an precipitation) are split into two main scenarios. The most likely scenario with 61% of ensembles supporting it has less than 0.5 inches of liquid precipitation across the northern Rockies, and that would mainly be in the mountains. About 35% of ensembles are still supporting the wetter forecasts with 0.75 to 1.5 inches of liquid precipitation in the mountains. So, in the last 24 hours the ensembles have veered to the drier solutions. In any case, we`re still expected a cool down and snow this weekend. Don`t let the trends fool you, there will still be winter weather impacts, especially in the mountains. So if you plan on being out and about next weekend, be prepared for winter driving. It`s just that right now forecasts are trending more towards a winter weather advisory level of impact instead of a winter storm warning level of impacts. && .AVIATION... Valley fog and stratus are expected to continue through Wednesday morning across the region. A shortwave moving over the region tonight may help the stratus lift some, but it is also bringing a lot of dry air aloft with it. The dry air will enhance the radiational cooling, strengthening the cold pools and ultimately making the fog and stratus worse. Terminals KGPI and KSMN are the most affected by the fog and stratus. Terminal KBTM is too elevated to be affected by the cold pools, and light down valley flow and drier air has kept the fog out of KHRF so far. Terminal KMSO remains on the boundary of the fog daily, but with the cold pools getting stronger, expect the fog to become more frequent and persistent at KMSO over the next couple of days. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...ID...Air Stagnation Advisory until 4 PM PST Tuesday for Northern Clearwater Mountains...Orofino/Grangeville Region... Southern Clearwater Mountains. && $$

310 FXUS65 KBOI 190347 AFDBOI Area Forecast Discussion National Weather Service Boise ID 847 PM MST Sun Jan 18 2026 .DISCUSSION...The broad area of low stratus and fog remains well-established across the lower valleys tonight, while also expanding across south-central ID and up the valleys in the Boise Mountains. Webcams and observations depict areas of dense fog across the Magic Valley and impacting I-84 and US-93, which has warranted a Dense Fog Advisory to remain in effect through at least Monday morning. Fog is expected to lift above the surface through Monday afternoon for most areas as gentle vertical mixing occurs. Hi-res models suggest the stratus will temporarily retreat from E to W for the Magic Valley and portions of the Upper Treasure Valley throughout the afternoon and evening, as a weak upper disturbance passes through eastern Idaho. && .AVIATION...Widespread IFR/LIFR below 5000ft MSL from the Magic Valley of Idaho to the Lower Treasure Valley of Oregon. Mountain obscuration below approx 5000ft MSL, while higher elevations remain clear. Surface winds: variable less than 6 kt. Winds aloft at 10kft MSL: N-NW 10-25 kt. KBOI...Generally IFR/LIFR in persistent low stratus along with visibility restrictions at times due to mist. Best chance for LIFR ceilings with reduced visibility 08Z-17Z Monday. Surface winds: variable up to 5 kt. && .AIR STAGNATION...Dominating high pressure will continue to promote stagnant conditions across the region through Thursday. Expect light winds and little vertical mixing as mixing heights remain at/below 2000 feet AGL. The temperature inversion will continue to trap pollutants near the surface while low clouds and freezing fog remain entrenched across lower valleys and basins. && .PREV DISCUSSION... SHORT TERM...Tonight through Tuesday night...Stratus held on really strong today, in line with thinking from yesterday, but showing almost no signs of dissipation. It`ll likely stick around through tonight, with slight lowering to bring fog back to some relative high points around the Snake Plain and surrounding basins, especially near the edge of the stratus such as in the Magic Valley. This morning`s Dense Fog Advisory was expired after an extension, and we anticipate more dense fog to form tonight. The overall pattern remains the same, a ridge sits over us, keeping conditions dry and inverted. Stagnant air is present in many of our valleys. We expect the valley fog/stratus to continue through the short term with daily high temperatures 5-10 degrees colder than normal under the stratus. LONG TERM...Wednesday through Sunday...The upper level ridge will remain overhead through Thursday morning. The pattern gets a little tricky as the upstream wave breaks into a cut off low off the Californian coast. Amongst most guidance this increases cloud cover for our area bringing a weak trough axis through from a deep Hudson Bay low. However, compared to previous runs this is a less significant set up for our area. The cut off low would carry most of its energy away from our area, preventing precipitation Thursday-Friday morning. By Friday evening the cut off low begins making landfall in SoCal as it rejoins the primary low, too far east to carry precip through the area again. Deterministic guidance for Saturday-Sunday has trended towards a slight ridge. While this seems to be the mean outcome, there is still a strong contingent of guidance showing a more unsettled pattern with zonal flow aloft. If we don`t get a precipitation event or a decent wave through the area, we could see the inversion hang on for a few more days. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Air Stagnation Advisory until 11 AM MST Thursday IDZ011>014-016-028-033. Dense Fog Advisory until 11 AM MST Monday IDZ016. OR...Air Stagnation Advisory until 11 AM MST /10 AM PST/ Thursday ORZ061>064. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise DISCUSSION...SH AVIATION.....MC AIR STAGNATION...SH SHORT TERM...JM LONG TERM....JM

156 FXUS65 KLKN 190913 AFDLKN Area Forecast Discussion National Weather Service Elko NV 113 AM PST Mon Jan 19 2026 .KEY MESSAGES... Updated at 1253 AM PST Mon Jan 19 2026 * Dry weather persists thru the next several days * High temperatures will be warmer than seasonal values each afternoon thru Thursday * A change in the weather pattern is possible Friday and Saturday && .UPDATE... Issued at 1253 AM PST Mon Jan 19 2026 Current forecast remains on track at this time and no changes have been required. && .DISCUSSION... (This afternoon through Saturday) WEATHER PATTERN OVERVIEW: Daytime high temperatures this afternoon will be a couple of degrees cooler than the previous few days and will reside mostly in the 40s. Low temperatures tonight will be in the teens,with the typical colder valleys observing single digits. A ridge of high pressure will amplify over California Tuesday. This ridge of high pressure will move eastward Wednesday and Thursday. A warming trend is expected Tuesday and Wednesday. By Wednesday afternoon, maximum temperatures across Northern and Central Nevada will be around ten degrees warmer than normal for this time of year. High temperatures Thursday afternoon will remain well above seasonal values. A series of trofs of low pressure will move southeastward across Northern and Central Nevada Friday night thru Saturday evening, resulting in a slight chance of rain and snow showers. FORECAST CONFIDENCE & DEVIATIONS: High forecast confidence regarding dry weather persisting thru the next several days. High forecast confidence in high temperatures well above seasonal values each afternoon thru Thursday. Low forecast confidence regarding a change in the weather pattern Friday and Saturday with dry conditions becoming more favorable. No deviations from the NBM model output. && .AVIATION... VFR conditions, with light winds, will persist at all terminals for at least the next 24 hours. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...92 AVIATION...92