825 FXUS66 KSEW 151816 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 1016 AM PST Mon Dec 15 2025 .SYNOPSIS... A period of very active weather will dominate the week ahead as a series of strong frontal systems produce cascading impacts across Western Washington. In addition to ongoing river flood concerns, periods of windy conditions are expected today and again Tuesday night into Wednesday. Snow levels will tumble to the passes Tuesday night and Wednesday with heavy snowfall expected in the mountains. Cool, unsettled conditions will remain in place through the remainder of the week with substantial additional snowfall in the mountains. && .UPDATE... Rain continues this morning, primarily in the mountains and in the south sound. There remains a slight chance of thunder (20-30% chance) with activity through the afternoon and evening. The front is a little ahead of schedule, which models have picked up on with an earlier peak in maximum wind gusts late this morning through mid afternoon. Remainder of the forecast below is on track with an update to the aviation section. HPR && .SHORT TERM /TODAY THROUGH WEDNESDAY/... Rain is increasing again this morning as a warm front lifts northward across Western Washington. Moderate to locally heavy rain and gusty winds will persist through the day before a trailing cold front sweeps through by early this evening with rain turning to showers and isolated thunderstorms. Though QPF is lighter with this system than those of last week, the additional rainfall and high snow levels will push a number of rivers back into flood flow and continue the threat of landslides. After a brief lull between systems Monday night into early Tuesday, a secondary stronger system arrives later Tuesday. And this one has some worrisome wind potential with it. When combined with saturated soils already in place, the threat of fallen trees increases. Models show a sharp surface mesolow forming to the lee of the Olympics by 09Z Wednesday. This creates a very strong pressure gradient Seattle southward. Isallobaric analysis shows impressively strong pressure rises behind it...as much as 7 or 8 millibars in just three hours early Wednesday morning. So, it`s not just wind speeds alone, but the rapid manner in which they could arrive. As such, we have put up a high wind watch for all of the lowlands Tuesday evening into Wednesday morning with gusts of 50 to 55 mph possible for the interior lowlands and 60 to 65 along the coast. Snow levels will tumble to the passes late Tuesday night with significant snowfall expected. Totals could approach a foot at Snoqualmie Pass by midday Wednesday, 1 to 2 feet at Stevens, and perhaps 2 to 3 feet at Mount Baker. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Model consensus keeps the pattern active and unsettled throughout the extended portion of the forecast. However, the air mass will remain considerably cooler with snow levels at or below passes into the weekend. This will allow rivers to recede while snow piles up in the mountains...a long awaited return to some semblance of normalcy for December. 27 && .AVIATION... Strong southwesterly flow aloft will continue through the TAF period, with a cold front traversing across the region early Monday afternoon and again Tuesday afternoon. Winds at the surface have began to increase ahead of the front and are forecast to gust 20kt to 35kt through 02Z/03Z at all terminals. Winds decrease overnight as mixing subsides, however, winds aloft will still remain strong. Winds will increase and become gusty again late or just beyond this TAF period. As the front treks across the region today, expect light rain/light rain showers with associated IFR to MVFR flight conditions. Conditions are forecast to improve to VFR behind the front overnight. Light rain potential increases again Tuesday morning (between 10Z-13Z) ahead of the next front. Expect IFR to MVFR conditions to return shortly before this next round of rain Tuesday morning. KSEA...MVFR ceilings and visibilities are expected through at least 22Z and instances of IFR flight conditions are possible during this time. Gusty 25kt to 35kt southerly winds will help clear out some of the lower ceilings after 22Z with VFR flight conditions. Southerly gusts come to an end around 02Z as mixing largely subsides, however, winds aloft remain relatively strong. Expect VFR flight conditions through early Tuesday morning before the next round of light rain to light rain showers moves in. Expect MVFR ceilings to precede and accompany any rain. Gusts increase with gusts around 30kts midday Tuesday. && .MARINE... A front will move through the waters today. A stronger system will arrive Tuesday night into Wednesday morning with another system Thursday. Gale force winds today over the waters. Winds easing late this afternoon into tonight. Small craft advisory winds over the coastal waters tonight into Tuesday afternoon. Another round of gales for all the waters later Tuesday into Wednesday morning. Winds easing Wednesday afternoon. Seas 14 to 18 feet today subsiding to 10 to 13 feet tonight. Seas continuing to subside slightly Tuesday before building again to 14 to 18 feet later Tuesday night into Wednesday. Seas subsiding to 9 to 12 feet Wednesday night. Felton && .HYDROLOGY... Atmospheric river arriving later morning with rivers rising again by afternoon. Even with the rises most of the rivers staying below flood stage today. Rivers over flood stage will be the ones that will have not dropped below much below flood stage over the weekend like the Skagit, Cedar, White and Cowlitz below Mayfield Dam. Rain easing tonight into Tuesday before another front reaches the area later Tuesday into Wednesday increasing precipitation rates. This second round of precipitation will drive some rivers above flood stage with major flooding possible along the Skagit and moderate flooding for the river flowing out of the Central Cascades like the Skykomish, Snoqualmie and Snohomish. The Skokomish could also reach moderate flood stage. Cooler air moving into the area Tuesday night adds some uncertainty to the river levels. Current forecasts have snow levels dropping to 2000 to 2500 feet by Wednesday morning. The front Tuesday night into Wednesday has more moisture than the todays system but the cooler air will keep some of the moisture in the mountains in the form of snow. This combination makes for tricky river forecasting. A flood watch is in effect through Thursday afternoon across the lowlands. With a couple more rounds of precipitation the landslide threat will remain very elevated through Thursday. Felton/HPR && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Wind Advisory until 10 PM PST this evening for City of Seattle- Downtown Everett / Marysville Area-Eastern Kitsap County- Eastside-Foothills of the Western and Southern Olympic Peninsula-Grays Harbor County Coast-Island County-Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County- Middle Chehalis River Valley-Northern Hood Canal-Northern Washington Coast-Olympia and Southern Puget Sound-Port Townsend Area-San Juan County-Shoreline / Lynnwood / South Everett Area-Southern Hood Canal-Western Strait of Juan de Fuca-Willapa and Black Hills. High Wind Watch from Tuesday evening through Wednesday morning for City of Seattle-Downtown Everett / Marysville Area- Eastern Kitsap County-Eastern Strait of Juan de Fuca- Eastside-Foothills and Valleys of Central King County- Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills and Valleys of the North Cascades- Foothills of the Western and Southern Olympic Peninsula- Grays Harbor County Coast-Island County-Lake Crescent Area Including US 101-Lower Chehalis River Valley- Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-Middle Chehalis River Valley- Northern Hood Canal-Northern Washington Coast-Olympia and Southern Puget Sound-Port Townsend Area-San Juan County- Shoreline / Lynnwood / South Everett Area-Southern Hood Canal-Western Strait of Juan de Fuca-Willapa and Black Hills. Flood Watch through Thursday afternoon for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-Cascades of Whatcom and Skagit Counties-City of Seattle-Downtown Everett / Marysville Area-Eastern Kitsap County-Eastern Strait of Juan de Fuca-Eastside-Foothills and Valleys of Central King County-Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills and Valleys of the North Cascades-Foothills of the Western and Southern Olympic Peninsula-Grays Harbor County Coast-Lake Crescent Area Including US 101-Lower Chehalis River Valley- Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-Middle Chehalis River Valley- Northern Hood Canal-Northern Washington Coast-Olympia and Southern Puget Sound-Olympics-Port Townsend Area- Shoreline / Lynnwood / South Everett Area-Southern Hood Canal-Western Strait of Juan de Fuca-Willapa and Black Hills. Winter Storm Watch from Tuesday evening through Wednesday evening for Cascades of Pierce and Lewis Counties- Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-Cascades of Whatcom and Skagit Counties-Olympics. PZ...Small Craft Advisory until 10 AM PST Tuesday for Grays Harbor Bar. Gale Warning until 6 PM PST this evening for Admiralty Inlet- Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm- Northern Inland Waters Including The San Juan Islands- Puget Sound and Hood Canal-West Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory from 6 PM this evening to noon PST Tuesday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm- West Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from Tuesday afternoon through Wednesday morning for Central U.S. Waters Strait Of Juan De Fuca-Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-West Entrance U.S. Waters Strait Of Juan De Fuca. Gale Warning until 1 AM PST Tuesday for Central U.S. Waters Strait Of Juan De Fuca. Gale Warning until 1 AM PST Tuesday for East Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from Tuesday evening through Wednesday morning for Admiralty Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands-Puget Sound and Hood Canal. && $$

634 FXUS66 KPQR 152340 AFDPQR Area Forecast Discussion National Weather Service Portland OR 340 PM PST Mon Dec 15 2025 .SYNOPSIS...A continued active pattern will bring multiple weather hazards through the next week including heavy rain, urban, small stream, and river flooding, gusty winds, Cascade snow, and hazardous seas. && .SHORT TERM...Now through Wednesday Night...The region remains beneath the storm track as repeated shortwave impulses bring rounds of rain and winds through the next two days. An initial wave approaching the coast was responsible for earlier rainfall, however showers continue, particularly over areas of terrain, where sufficient instability exists above the surface layer to support narrow bandlets of rainfall. These features should trend lower in intensity and coverage from north to south through this evening as the shortwave moves onshore. A strong low-level jet reaching 60-70 kt only a few thousand feet above the ground couped with this convective environment has allowed for strong wind gusts to reach the surface, particularly along the coast and in areas of terrain so far today. As the jet both weakens and moves inland, the risk for further strong wind gusts will decrease into this evening, but isolated occurrences may continue in exposed areas of high terrain. As such, the High Wind Warning along the coast has been allowed to expire, but the Wind Advisory in effect for the Oregon Coast Range and Willapa Hills will remain in place through 4 PM this afternoon. The overnight period will offer a brief respite before another wave brings renewed rain and wind to the region Tuesday into Wednesday. This system is expected to be more potent than the first, with a deep surface low tracking inland near the north end of Vancouver Island and a strong trailing cold front extending southward to the Oregon coast. Another shorter- duration period of high vapor transport will be associated with this atmospheric river, resulting in a relatively brief period of rain across the region, but one that could nonetheless bring heavy enough rain rates to continue a risk of flooding in poor drainage areas, especially given continued high saturation levels in soils across the region. An additional risk from this next system will be further strong winds. Again, just ahead of the cold frontal boundary, a low-level jet reaching 60-70 kt at 925 hPa will move onshore through Tuesday night. As today, periods of strong wind gusts reaching down to the ground appear likely, and there is a 30-50% chance of wind gusts of 55 mph or higher along the immediate coast, and similar or slightly higher chances in higher terrain and particularly along the Cascade crest. Chances for gusts reaching 45 mph in valley areas remains around 10-25%, however an isolated gust over 50 mph also cannot be ruled out. Additional wind hazards may need if confidence in occurrence of these winds increases. Wednesday will bring another relative lull in the pattern, with brief drying and a break from strong winds through much of the day. As the front sags southward, a cooler air mass will arrive in its wake with temperatures closer to seasonal norms but still about 5 degrees above normal. Snow levels falling to 3000 ft or even slightly lower will allow for some snow to accumulate as pass level through Wednesday and Wednesday night. This colder period is when precipitation amounts will be reduced between systems, so snow amounts remain unremarkable, with a 40-60% chance of 6" of more of accumulation at Cascade passes. There is a 10% chance of snow levels falling to 2000-2500 ft. -36 .LONG TERM...Thursday through Monday...Another moderate to strong atmospheric river takes aim at the region Thursday into Friday, bringing additional rain on top of elevated rivers and saturated soils. Initially, heavy rain rates raise the risk for urban or small creek and stream flooding on Thursday, while the risk for river flooding increases late Thursday into Friday as the abundant runoff makes its way downstream. As is typical with ARs, the highest precipitation totals are likely to be over the coastal terrain and across the Cascades, and the warm dynamics will also favor increasing snow levels during the heaviest precipitation. Rainfall forecasts have tended to shift slightly between forecast updates, but guidance remains in good agreement that the AR will impinge on the northern OR coast before tracking southward toward the southern OR coast by Thursday night. Unlike recent ARs which have been directed moreso at the Washington coast, the highest rain totals are currently focused across the southern half of the region, generally south of US-26. Chances to exceed 2" of rainfall Thursday and Thursday night increase from 30% to 50% south along the I-5 corridor from Kelso/Longview to Eugene, and from 50% to 75% in the Coast Range and Cascades. Chances to exceed 4" of rainfall are 5-15% across inland valleys and 20-40% in areas of higher terrain. This amount of precipitation over only 24 hours would support river flooding as saturated soils will allow most of the rain to make its way into area rivers as runoff. Chances for Minor to Moderate river flooding continue to increase, with the highest confidence in flooding for rivers draining the central OR Coast Range, both toward the coast and into the Willamette River. Those who live near areas prone to river flooding should keep a close eye on the forecast moving forward, and additional information can be found in the Hydrology discussion below. The veritable parade of weather systems does not look to let up this weekend and into next week. While confidence in forecast details is low at this lead time, the active pattern and persistent chances for rain will most likely continue. -36 && .AVIATION...Radar imagery as of early Monday afternoon depicts lingering showers as a system moved through the area. This is bringing a mix of MVFR and low-end VFR CIGs across all terminals, with some IFR/LIFR CIGs along the coast. Expect this trend to continue through 03z Tue, with CIGs briefly improving to predominately VFR this evening. High confidence (80% chance or greater) CIGs drop back down to IFR or lower along the coast after 12-15z Tue as the next system moves in. During this same time frame, inland terminals also have a 20-40% chance of dropping back down to MVFR. Southwesterly winds are gusting to 25-30 kt along the coast and 20-25 kt across the Willamette Valley as of early Monday afternoon. Winds around 2000 ft are around 40-50 kt, which will create a strong crosswind especially for E-W aligned runways and some low level speed shear resulting in turbulence. Winds across the area weaken overnight, and become breezy again after 12-15z Tue with the next system with gusts to 20-25 kt across the region. KPDX AND APPROACHES...Mix of high-end MVFR and low-end VFR CIGs, with CIGs trending more VFR this evening. South-southwesterly winds gusting up to 25 kt through the afternoon. Low level speed shear is possible due to 40-50 kt winds around 2000 ft. Winds weaken below 10 kt after 00-03z Tue, with breezy southerly winds returning after 12-15z Tue. -10 && .MARINE...Observations at buoy 46029 and 46050 as of early Monday afternoon show southerly winds with gusts to 30-35 kt and seas hovering around 14-16 ft at 9-10 sec. Should be seeing seas peak around 16-18 ft this afternoon with seas unlikely rising above 20 ft (only a 1-2% chance of exceeding 20 ft). High confidence that winds will gradually weaken this afternoon, decreasing to 10-15 kt with gusts up to 20 kt late this evening. Seas may remain steep and choppy during this brief lull; therefore, a Hazardous Seas Warning is in effect across all waters including the Columbia River Bar from 4 PM this afternoon to 4 AM Tuesday. Seas fall to 10-13 ft by late Tuesday morning. The brief lull ends early Tuesday morning when another frontal system approaches the waters. This will return breezy south- southwesterly winds with widespread gusts ramping up to 25-30 kt between 4 AM-10 AM Tue, then 35-40 kt between 10 AM-4 PM Tue, and strong Gales with gusts up to 48 kt arriving after 4-7 PM Tue. For the inner waters out 10 NM including the Columbia River Bar, there is a 20-30% chance for isolated Storm force wind gusts up to 55 kt due to the potential for a coastal jet. It`s a marginal set-up for a coastal jet since guidance isn`t really showing much of an inversion in the low-level atmosphere to squeeze the strong winds toward the surface. Either way, it will still be very windy. Behind the front, winds turn westerly around 1-4 AM Wednesday. Seas will also re-build to 14-16 ft Tuesday evening, and peaking and holding around 18-20 ft at 10-11 sec between 1 AM-1 PM Wednesday. Another Gale Warning will likely be issued for this system this afternoon. Going forward, an active weather pattern continues through the week bringing additional winds and wave hazards to the coastal waters. Seas are very likely to remain elevated above 10 ft (greater than 90% confidence) from Wednesday through Friday as additional weather systems move onshore. At least models are beginning to hint as some larger breaks between weather disturbances next weekend into the following week, but at this 7-8 day time-scale, the confidence in this slowdown materializing is only low to moderate at this time. -10/27 && .HYDROLOGY...Abundant rainfall is a relatively short period from Thursday through Thursday night atop saturated soils while area rivers remain high following well above normal rainfall thus far in December has resulted in an elevated risk for flooding late this week. As is typical in atmospheric rivers, the highest rainfall totals are likely to be over areas of terrain including the Coast Range and Cascades, while lesser totals can be expected across inland valleys. Nonetheless, rainfall is likely to be measured in inches across most of the region. Unlike recent other ARs, this system looks to favor a more southern placement along the central OR coast of these highest rainfall totals, which may allow some river basins to better handle these rainfall amounts without yielding flooding. Other areas to the north within the Coast Range in Lincoln, Tillamook, Benton, Polk, Yamhill, and Washington Counties may see more overlap between recently observed heavy rainfall and additional heavy rainfall with this upcoming system. Similarly, river basins covering the central OR Cascades in Lane and Linn Counties have a slightly more optimistic outlook than north into Marion and Clackamas Counties, but that does not mean flooding cannot happen in all of the aforementioned areas. Luckily, where rainfall has so far been the heaviest across southwestern Washington and far northwestern Oregon may see the lowest totals from this system, although even 1-2 inches of rain over 24 hours may be enough to cause additional flooding in these very saturated areas. At this point, the rivers with the highest confidence of reaching flood stage are those which drain the central Oregon Coast Range, including the Wilson, Trask, Siletz, and Siuslaw draining toward the coast, and the Marys, Luckiamute, Yamhill, and Tualatin draining toward the Willamette. The chances for these rivers to reach at least Minor flood stage are 25-55% at this lead time. Rivers draining the Cascades, including the Mohawk, Santiam, Pudding, Molalla, Clackamas, and Sandy, have slightly lower but still significant chances of 15-45%. These rivers will begin to rise later on Thursday as heavy rain continues, not cresting until Friday in most cases. The Willamette River main stem itself also has a 5-10% chance of reaching flood stage above Willamette Falls, and slightly higher chances in tidally-influenced portions downstream of Oregon City, however runoff will take longer to reach the Willamette and flooding would be delayed later than in its tributaries. A Flood Watch has been issues across all of northwestern Oregon and southwestern Washington from 4 AM Thursday through 4 AM Saturday to highlight these risks. These river forecasts remain very sensitive to rainfall forecasts, and interested parties should expect changes as the event nears. The latest river forecasts across the region can be found at www.water.noaa.gov/wfo/pqr. -36 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Hazardous Seas Warning until 4 AM PST Tuesday for PZZ210-251>253- 271>273. Small Craft Advisory from 4 AM to 4 PM PST Tuesday for PZZ210- 251>253-271>273. Gale Warning from 4 PM Tuesday to 10 AM PST Wednesday for PZZ210- 251>253-271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

776 FXUS66 KMFR 152219 AFDMFR Area Forecast Discussion National Weather Service Medford OR 219 PM PST Mon Dec 15 2025 .DISCUSSION...The first in a series of fronts is moving into the area bringing rain to the coast and coastal mountains and gusty winds. Strongest north of Cape Blanco. Precipitation will spread farther inland, with winds increasing east of the Cascades. The bulk of the precipitation will be along the coast, coastal mountains and Cascades. Satellite image and radar are showing moderate to occasionally heavy precipitation with a few lightning strikes which is partially being aided by an upper level jet moving towards southwest Oregon. Isolated thunderstorms should remain confined to the south Oregon coast and inland in Curry and western Josephine County into early this evening. Most of the Rogue Valley could end up dry during the day Monday with not much more than occasional showers late this afternoon and early evening due to the non-favorable southwest flow. East of the Cascades will likely get little to rainfall, but it will be windy into early this evening. More fronts will follow the rest of the week into next weekend bringing more rain, moderate to strong winds and higher elevation mountains snow. Detail`s on the timing mentioned below could vary with each individual storm, so be on the lookout for updates to the forecast in the days to come. A second and stronger system will arrive Tuesday night into Wednesday brining moderate to heavy rain to the coast, coastal mountains and Cascades. Moderate to occasionally strong winds are possible at the coast. Not all of the ingredients are there for a winds to reach high wind warning criteria at the coast, but they do for east of the Cascades, especially near and at the ridges. guidance shows 700 mb winds between 60-70 kts Tuesday night through Wednesday morning, then decreasing some Wednesday afternoon. Given the above, the High Wind Watch has been upgraded to a High Wind Warning for the higher terrain in Lake, Modoc and potions of Klamth County. At the same time a Wind advisory has been issued to cover the remainder of Lake, Modoc and to include more of Klamath County. Please see NPWMFR for more details. Snow levels will be between 7000-8000 feet Tuesday, then lowering between 4500-5500 feet Wednesday. Therefore we`ll see rain change over to snow late Tuesday night into Wednesday morning with 3-5 inches possible up towards Willamette Pass, and 2-4 inches around Diamond and Crater Lake by late Wednesday morning. Precipitation will gradually diminish later Wednesday morning through the afternoon and we`ll catch a relative break in the action from Wednesday afternoon into most of Wednesday night. A stronger storm will arrive Thursday and last through Thursday night bringing another round of moderate to heavy precipitation and strong winds. Strong winds will be a concern Thursday, especially east of the Cascades where some of the guidance shows 700 mb winds between 70-80 kts over a large chunk of real estate east of the Cascades. It`s also worth noting, strong winds east of the Cascades could be of longer duration (12-18 hours). Although not as high of a concern, moderate to strong winds will be a concern in the Shasta Valley. However the wind direction in the Shasta Valley has a westerly component which could put a cap on the magnitude of the winds. Guidance shows the Medford to Redding gradient between 8-9 mb. So it`s something we`ll have to keep a close watch on. The coast is another story. Current gradients between Arcata and North Bend peak out at almost 10 mb Thursday afternoon and night which is significant enough for high winds, and guidance shows an enhanced area of strong winds close to 70 kts Thursday afternoon from about Cape Blanco north. Thre`s good agreement the storm that arrives Thursday will have an atmospheric river (AR) component, with a long fetch of moisture extending southwest towards 160W, with the source region coming from the tropics. Additionally, there is favorable upslope flow along the coastal mountains and Cascades. The net result could be a prolonged period (24-36 hours) of heavy precipitation for these areas along with moderate to occasionally heavy rainfall elsewhere. Given the lack of rain the last few weeks, rivers are pretty low, but they will come up over time and we could be looking at potential flooding on the Coquille towards the end of the week. Another factor that could put a cap on the flooding concerns is little to no snowpack. Therefore there will be no additional contribution from snowmelt going into the rivers. Another item worth noting is there are some indications the core of heavier precipitation could shift north of the Umpqua Divide for a brief period of time Thursday afternoon into Thursday night before shifting south over southern Oregon and Northern California Friday. Keep in mind the details could change, so keep a eye out for updates in the days to follow. Looking into next week leading up to Christmas Holiday, there`s strong evidence that`s being supported by the ECMWF, GEFS ensemble means and clusters, we`ll be heading into a colder and wet pattern with storms originating from the Gulf of Alaska as we get towards the following weekend through at least Christmas Day. These typically result in colder temperatures, and precipitation with lower snow levels. The pattern shows below normal 500 mb anomalies with a stronger upper troughing in the western U.S. with ridging and above normal 500 mb anomalies in the northeastern part of the U.S. The anomalies being shown are pretty significant this far out which is unusual since they tend to "wash out" and lean more towards climatology. This is a almost the opposite of the pattern we have experienced for almost the last three weeks, with stronger ridging in the western part of the U.S. and deep upper troughing in the northeastern part of the U.S. In other words, the switch basically gets flipped as the overall pattern changes. -Petrucelli && .AVIATION...15/18z TAFs...The main concern ion the short term will be low level wind speed shear along the coast into early this afternoon, including North Bend. Stronger winds should surface at North Bend early this afternoon, and at the same time winds aloft will be diminishing, thus ending the concern for low level wind speed shear. MVFR and occasional IFR ceilings are expected in precipitation through the TAF period, although could not rule out brief periods of VFR ceilings this evening and tonight as the bulk of the precipitation shifts south, but confidence is not high enough to include improving conditions in the TAF. Inland west of the Cascades, VFR ceilings are being observed and should last for most of the afternoon, the exception will be in Roseburg as the front moves south bringing lowering ceilings and partial mountain obscuration north of the Umpqua Divide between 21- 22z. The medford terminal should remain VFR through 0z, then ceilings will lower as the front moves in. Once the front moves south, there could be enough clearing along with a more stable atmosphere and ample low level moisture for low clouds and fog to develop late tonight into Tuesday morning for the Valleys, including the Roseburg and Medford terminals. The timing of when the lower conditions develop in the TAF could change, so watch for updates. East of the Cascades, VFR conditions are expected through the TAF period, although the higher terrain could be partly obscured towards 0z, with ceilings possibly hovering towards 3000 feet at Klamath Falls for a few hours this evening. -Petrucelli && .MARINE...Updated 100 PM PST Monday, December 15, 2025...The first round of south gales north of Cape Blanco is winding down this afternoon. Very steep and hazardous seas will remain elevated, but become less steep as they transition to swell dominated this evening and persist through much of Tuesday. The next front is expected late day Tuesday, bringing another round of southerly gales that quickly switch to the northwest, and remain strong, late Tuesday night. This will build seas again, becoming very steep and hazardous Tuesday night across all waters, with gales expected north of Cape Blanco. Winds ease late Wednesday morning, but seas will remain steep through Wednesday night. Another, more persistent front will take aim at the coast late Wednesday night/early Thursday morning, bringing a longer duration of strong winds. Strong gales are likely with this system, with a 20-40% chance of storm force (>55kt) gusts possible north of Cape Blanco on Thursday morning. Winds will gradually ease from north to south late Thursday night into Friday morning, but seas are likely to remain steep to very steep through Friday. Moderate to heavy rain will accompany each front this week. /BR-y && .MFR WATCHES/WARNINGS/ADVISORIES... OR...High Wind Warning from 10 PM Tuesday to 4 PM PST Wednesday for ORZ030-031. Wind Advisory from 10 PM Tuesday to 4 PM PST Wednesday for ORZ029>031. CA...High Wind Warning from 10 PM Tuesday to 4 PM PST Wednesday for CAZ085. Wind Advisory from 10 PM Tuesday to 4 PM PST Wednesday for CAZ085. PACIFIC COASTAL WATERS...Hazardous Seas Warning until 4 PM PST this afternoon for PZZ350-356-370-376. Small Craft Advisory until 4 PM PST Tuesday for PZZ350-356-370- 376. Gale Warning until 4 PM PST this afternoon for PZZ350-370. && $$

605 FXUS66 KEKA 152219 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 212 PM PST Mon Dec 15 2025 .SYNOPSIS...Moderate to locally heavy rain is forecast tonight through Tuesday night for mostly Del Norte, Humboldt, Trinity and northern Mendocino Counties. A break in the rain is forecast on Wednesday, followed another high chance for heavy rain either on Thursday or Friday. Another chance for heavy rain and strong winds will arrive for the latter portion of the weekend. && .DISCUSSION...A strong low pressure over the NERN Pacific, centered in the Gulf of Alaska, will send a series of frontal systems into NW California through Wednesday. Expect moderate to heavy rain and gusty southerly winds. Frontal passage, cooler and drier air will arrive during the day on Wednesday. Satellite and radar data showed a band of moisture extending southwestward from the Pacific NW coast to just offshore the northern California coast this afternoon. Embedded convection, a few lightning strikes and heavy rain rates (0.30 in/hr) with this stream of deep layer moisture (PWATS 250% above normal) has been moving over Del Norte County this afternoon. HREF continues to depict highest chance for heavy rain > 0.25in/hr over Del Norte and northern Humboldt this afternoon and evening. A secondary precip max spikes up later tonight into early Tue across SW Humboldt as the axis of moisture shifts southward. Coverage of heavier rain rates over 0.25in/hr will expand during the afternoon Tue into Tue night. This will need to watched for possible urban and small stream flooding and possible rock/mud slides. Much lighter rain rates are expected for southern Mendocino and Lake Counties with storm total rain around 0.10 inches or less ending 4 AM WED. Southeast winds will also be gusty through the week. Peak wind gusts at lower elevations will most likely be 20 to 35 mph, with a 30% chance of impactful gusts over 45 mph on high coastal ridges. Winds gusts will most likely be strongest with the second round of rain Tuesday into Wednesday. ECMWF ensemble indicates potential for strongest winds Thursday or Thursday night, though there continues to be large spreads. Above average warmth and fairly high snow levels will severely limit all prospects for significant snowfall except over the highest mountain peaks. There remains generally high confidence (80% chance) that a wet pattern will continue through the end of the week and into the weekend. GFS and ECMWF continues to depict another moist plume impacting the northern most portion of the area on Thursday. Eventually this boundary moves across the area by Friday, though it could speed up or slow down. High pressure and generally drier conditions are expected for Saturday, however another storm in the line up will begin to spin up offshore and may begin to impact the area as early as Sat night or Sun. This low pressure system has the potential to generate strong and damaging winds as well as more heavy rain. Timing is still uncertain. Looking at the chance of IVT > 250 kg/m/s the following week Dec 22-26, confidence is moderate to high in wet weather continuing for latter portion of Dec. CPC`s 8-14 day outlook also has NW CA in a high risk for heavy precip and a moderate risk for high winds. Stay tuned. && .AVIATION...18Z TAFs)...A frontal passage this morning has caused MVFR conditions along the North Coast today due to passing rainshowers with sporadic lightning strikes and moderately low cloud bases. Overcast ceilings around 1500-2000ft are to be expected all over NW CA today. The strongest winds are expected in Del Norte and Humboldt Co. and near coastal plains (i.e. KCEC and KACV). Winds aloft forecasted to decrease significantly through the evening decreasing the threat of LLT and mountain wave formation. Ceilings lower to potential LIFR tonight, yet most of the model data shows IFR is more probable. Rain tomorrow to the North Coast beginning around 15/16Z, with a 30% probability of reaching as far south as KUKI. && .MARINE...Southerly winds present in the northern waters as a warm front moves over the areas. Winds will peak in the northern outer waters while other zones can expect moderate southerly wind gusts but will generally remain calmer. Wind waves creating short period seas over 6 feet in the northern outer waters through tonight. Winds will generally weaken for much of tomorrow, but a mid period westerly swell building to over 10 feet will maintain moderately steep seas at least for the the northern waters. Another storm system will cross the area late tomorrow into early Wednesday. Southerly winds will again, only briefly, increase over 20 kts and be mostly confined to the northern waters. Calmer conditions form again Wednesday as a mid period westerly swell up to 10 feet will likely maintain very moderately steep seas in the northern waters. A stronger storm system is expected later in the week around Friday. This will force the southerly winds into the southern waters with stronger gusts in the norther waters, though the potential for proper gales remains moderate to low (20-40 percent). /JHW/DES && .HYDROLOGY...All main stem rivers are forecast to remain below Monitor or Action Stage through mid week. Minor flooding of smaller rivers, creeks and streams with poor drainage will be possible. Soil moisture is expected to continue increase or saturate late in the week into the weekend with additional rain, increasing the risk of rockslides and mudslides, and minor flooding. Chance of main stem river stages exceeding monitor stage will also increase as we head into the following week, Dec 22-28. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 1 AM to 11 AM PST Tuesday for PZZ450. Small Craft Advisory until 11 AM PST Tuesday for PZZ470. && $$ 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

492 FXUS66 KMTR 152330 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 330 PM PST Mon Dec 15 2025 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 343 AM PST Mon Dec 15 2025 - Wet weather returns late today and persists through the week and likely into next week. - Confidence is increasing that impactful weather will arrive for next week`s holiday travel. Check back for updates. && .SHORT TERM... Issued at 104 PM PST Mon Dec 15 2025 (This evening through Tuesday) Interesting setup this afternoon weather wise. No real change for the Central Valley or interior East Bay as they still deal with Tule Fog impacts. North Bay, SF Bay, and the South Bay on the other hand are seeing a welcomed sight, the sun. Some of these locales struggled to see the sun over the weekend keeping them chilly. That being said, even with some sunshine this afternoon it`s late in the day and not much daytime heating left. Therefore undershot the forecast from the NBM today for most of the Bay Area, especially the interior East Bay. Central Coast will be the warmest of the bunch with a few spots aiming for the lower 70s. So why the change? Lingering offshore flow over the North and East Bay combined with a weak system approaching from the north. Latest surface analysis shows a weak cold front off the far NorCal coast moving S and E. In fact, KMUX radar was switched to precip for the first time in a long time. A few scout showers ahead of the front are being picked off the North Bay coast this afternoon. For tonight: do have showers returning to the North Bay overnight. Not expecting a big precip event tonight, but more of a brush by from a passing boundary. Current forecast doesn`t have precip south of the Golden Gate. If we do actually get some bucket tips from rain this will be the first precip of the month for the region. In other words, it`s been dry lately. One impact that won`t go away tonight will be low clouds and fog, especially East Bay and West Delta. Given the approaching front and increased cloud cover not expecting widespread dense fog like this morning, but patchy dense fog is more likely. For Tuesday; Showers finally make it south of the Golden Gate by the afternoon with minor impacts to the evening commute. Once again, not expecting a wash out, but beneficial precip nonetheless. && .LONG TERM... Issued at 202 PM PST Mon Dec 15 2025 (Tuesday night through next Sunday) Showers will linger through Wednesday as the weak boundary traverses the region. Showers will be most prevalent across the North Bay. Rainfall amounts with this first push of precip will generally be a tenth to a half for the North Bay and a few hundredths elsewhere. Interior areas of the Central Coast will likely not see any precip with this system. We`ll get a brief pause/break in widespread precip late Wednesday evening and Thursday before the atmosphere reloads with another system. If there are a few lingering showers they`ll be across the North Bay. The atmospheric "reload" will come in the way of a low spinning up over the Pacific north of HI and another storm system swinging into the PacNW. This set up will allow for a moisture plume to take aim at the PacNW before sliding down the NorCal coast on Friday. Widespread rain returns initially to the North Bay Friday afternoon before pushing south to the Central Coast on Saturday. By Sunday the newly formed low over the Pacific will move toward the NorCal, which will bring a reinforcing shot of higher PWAT air to the region. As a result, expect another uptick in rain shower activity, coverage, and intensity. This push of moisture will keep precip in the picture Monday and even into Tuesday. A great way to describe the overall weather starting Friday through early next week will be episodes or periods of rain. Not a complete washout, but measurable rain. Initial rainfall projections Thursday through Monday: North Bay and Coastal Mts 2-5", Bay Area and Monterey Bay Region 1-2", Interior Central Coast less than 1". Period of heaviest rainfall looks to be Sunday into Monday. Lots of focus for the extended, and rightfully so as holiday travel and holiday plans come into play. Confidence continues to increase that impactful weather will return to the region beginning around Dec 22 and continuing through the holiday. CPC continues to highlight a large portion of NorCal for excessive rainfall. Longer range ensembles show potential as well, but this far out it`s all about the details - amounts, confidence, timing, impacts. Those will be sorted out in the days to come. Please check back for updates and more details. && .AVIATION... (00Z TAFS) Issued at 330 PM PST Mon Dec 15 2025 Fog and stratus have dissipated across most of the Bay Area with the only regions remaining socked in being the far inland locations lying within the Central Valley east of CCR, LVK, and the Diablo Range. Mid- to high-level clouds are filtering into the region in advance of a system that will bring chances for light showers tonight into Tuesday for the North Bay. Have opted to maintain the previous forecast for widespread stratus with some coastal and valley fog developing tonight, but with the incoming system bringing extensive cloud cover, low confidence in the clearing times on Tuesday morning, which generally come from a persistence forecast. Winds will be light and gentle across the region with a slight onshore impulse in the coastal region through the evening hours, otherwise offshore. Light and terrain-driven winds prevail overnight before a light to gentle onshore pulse resumes Tuesday. Vicinity of SFO... VFR with mid- to high level clouds through the evening. Latest model output depicts MVFR stratus flowing in closer to the 06-07Z timeframe, which fits with the previous TAF forecast. Low confidence that dense fog directly impacts the terminal, but some reduction in visibility is expected overnight. Afterwards, moderate confidence that the stratus persists through the rest of the TAF period. Winds will remain light to gentle throughout the forecast period, with offshore flows at present turning light and west-northwest by Tuesday. Low to moderate confidence of showers developing at the terminal by Tuesday evening. SFO Bridge Approach... Localized stratus and potential for dense fog is expected tonight through Tuesday morning across the southern San Francisco Bay. Otherwise, similar to SFO. Monterey Bay Terminals... VFR with light to gentle northwest breezes through the early evening hours. Low to moderate confidence that stratus and fog return tonight, with the latest model output showing the stratus deck approaching the coast, but not reaching it until close to the end of the TAF period. Have opted to leave the current forecast in place and base the clearing times on persistence, but will monitor stratus evolution through the evening in case confidence in the return of stratus increases. Light drainage flows overnight before light to gentle northwest winds resume on Tuesday. && .MARINE... (Tonight through next Saturday) Issued at 330 PM PST Mon Dec 15 2025 Southerly flow will prevail north of Pigeon Point ahead of an approaching frontal system. Moderate to fresh winds continue across the southern waters with periods of moderate winds expected across the northern waters. Patchy dense fog persists within the West Delta, and expands across the Bays and the coastal waters tonight into Tuesday morning. A weak system will bring moderate long period northwest swell Tuesday into the weekend. Moderate seas return with wave heights building up to 9 feet. Rain chances increase late tonight and remain elevated through the end of the forecast period. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 PM PST Tuesday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...MM LONG TERM....MM AVIATION...DialH MARINE...DialH 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

556 FXUS66 KOTX 152337 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 337 PM PST Mon Dec 15 2025 .KEY MESSAGES... - Rain and high mountain snow Monday into Tuesday to bring additional river rises and mud and rock slide concerns to Cascades and Idaho Panhandle. - High confidence for strong winds Tuesday night into Wednesday. Chances for wind gusts greater than 50 mph range from 60% to 90% and 30% to 70% for greater than 60 mph winds across much of the region. - High confidence for heavy mountain snow impacting the Cascades starting overnight Tuesday. There is a 90% chance of 2 feet or more of snow at Stevens Pass through Friday afternoon. && .SYNOPSIS... An extremely active pattern begins today. Rain and high mountain snow Monday into Tuesday night will bring additional river rises with mud and rock slide concerns in steep terrain of the Cascades and Idaho Panhandle. Strong, potentially damaging winds, will then develop Tuesday night into Wednesday, along with a transition from rain to heavy snow at pass levels. Temperatures remain above normal at the end of the week but cooler with additional weather systems to bring mountain snow and rain or snow in the valleys. && .DISCUSSION... ...VERY ACTIVE WEATHER PATTERN THIS WEEK WITH RENEWED FLOODING CONCERNS FOR CASCADES AND NORTH ID PANHANDLE INTO TUESDAY, POSSIBLE HIGH WINDS TUESDAY NIGHT INTO WEDNESDAY, AND HEAVY MOUNTAIN SNOW FOR THE CASCADES WEDNESDAY THROUGH THE END OF THE WEEK... Tonight through Wednesday: Through Tuesday breezy to locally windy conditions will impact the area, with precipitation more heavily focused around the Cascades and Idaho Panhandle mountains. Then Tuesday night into Wednesday the precipitation expands across the region along with much stronger winds with the potential for widespread damage and/or impacts. The westerly flow will carry an impulse across the region this evening into the overnight, then a warm front lift in through Wednesday with atmospheric river enveloping starting to impact the region, while a cold front rapidly pushes across the area late Tuesday night into Wednesday morning. Precipitable water values rise to around 0.50 to 0.80 inches (180-250% of normal), peaking with the cold front and Tuesday overnight into early Wednesday morning will have the highest precipitation potential outside the mountains. The mountains will see a more prolonged high precipitation potential, relative to the lowlands. This moisture tap is not at deep or at prolonged as recent ones. The front will lower snow levels Tuesday night into Wednesday, bringing rain changing to snow in the mountains. So the higher impacts from snow will be developing Tuesday night into Wednesday, especially near the Cascades. The Idaho Panhandle and northern mountain passes could also see some light snow accumulation impacts Tuesday overnight into Wednesday. * Precipitation amounts: the Cascades with see 4 to 5 inches of rain along the crest, 1.5 to 2 inches in the mid slopes, and 0.25 to 0.5 of an inch for the valley floors. The rest of Washington ranges from a quarter to three quarters of inch. The western Basin will be lightest with near a tenth. Idaho Panhandle will generally range from 0.4 to 1 inch. * Snow: snow levels drop to around 3000 feet in the Cascades tonight into early Tuesday, then start to rise to around 5-6kft during the day, before starting to drop to around 2-3kft heading into Wednesday. Tonight into Tuesday AM the Cascades could see 3-6 inches of snow and 1-2 near Sherman Pass. Then more moderate snow is forecast for Tuesday night into Wednesday, with 8-16 possible near the Cascade crest and 3-8 around the mid-slopes. Winter storm warnings are being issues for the Cascade crest, around places like Stevens Pass, for Tuesday night through Wednesday. Wind will also be breezy/gusty here and blowing snow may reduce visibility. This will be monitored should the highlight need to be upgraded to a blizzard warning. The other mountain passes could see 1-3 inches. * Winds:this afternoon into tonight breezy/gusty winds are in the forecast. This will be weaker wind impact period. Gusts 25-50 mph will be possible. Wind advisories are in place through the night, but we will watch the timing. Then the more impactful winds are expected heading into Tuesday night into Wednesday. Winds speeds increase through later Tuesday into Tuesday night and are expected to peak with the cold front passage later overnight into early Wednesday. The stronger wind gust potential of 40-60 mph are in the forecast or even up to 70 mph. This has the potential to be a significant event, with damaging winds, significant power outages and difficulties for high profile vehicles. High wind watches remain in place. Thursday to Monday: Another system will spread across the area Thursday, with another around of significant precipitation amounts. This go around snow levels will be lower, starting near 2-3kft rising to around 3-6kft in the afternoon. This will likely bring some moderate to heavy snow in the mountains again, with the Cascades potentially seeing feet of snow and the other passes mountain seeing moderate snow. So stay tuned because impacts are possible if heading into the mountain passes. Lowlands may see a rain/snow mix to start then rain. From Saturday to Monday a zonal flow pattern will start to set up over the region. Precipitation potential will continue, with the higher potential around the mountains but still moderate outside. The Inland Northwest will have seasonal temperatures with highs in the 30s and low 40s. Overnight lows will be in the 20s and low 30s /Solveig. && .AVIATION... 00Z TAFs: A moist frontal system will impact the Inland Northwest through tonight. Rain or rain showers will continue to lower ceilings. Areas across NE Washington and the ID Panhandle could see areas of VFR under moderate intensity rainfall. Wind gusts have picked up across all TAF sites and look to be elevated through at least 15Z for KLWS/KEAT, but will last through the rest of the TAF period for KGEG/KSFF/KCOE/KPUW/KMWH. Around 21Z, another wave of precipitation moves in, leading to many PROB30 groups as PoPs stay near 30%. Winds will steadily increase throughout tomorrow afternoon, and especially into Wednesday morning with 45-50kts expected at KGEG/KSFF/KCOE/KPUW/KLWS. Ceilings are projected to drop to MVFR around 20-21Z. .FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Low to moderate confidence in rain timing as precipitation moves through for KGEG/KSFF/KCOE. Moderate to high confidence in wind gusts near 20-25kts. Moderate confidence in MVFR conditions near the end of the TAF period due to steadier rainfall rates. /AS ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports,please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .Preliminary Point Temps/PoPs... Spokane 55 37 50 37 45 32 / 100 30 50 100 60 10 Coeur d`Alene 52 37 48 38 45 32 / 100 60 80 100 80 20 Pullman 51 39 51 36 45 32 / 90 50 50 100 80 20 Lewiston 56 43 58 44 52 37 / 80 40 20 90 70 10 Colville 50 30 45 34 45 27 / 100 30 60 100 60 20 Sandpoint 49 37 44 37 43 31 / 100 80 90 100 90 30 Kellogg 49 38 45 35 43 32 / 100 80 90 100 100 40 Moses Lake 60 36 52 39 48 35 / 70 10 20 80 30 20 Wenatchee 56 38 49 37 45 34 / 90 20 70 100 50 30 Omak 50 33 45 35 45 30 / 100 20 60 100 40 20 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...High Wind Watch from Tuesday evening through Wednesday afternoon for Central Chelan County-Lower Garfield and Asotin Counties-Moses Lake Area-Northeast Blue Mountains- Northeast Mountains-Okanogan Highlands-Spokane Area-Upper Columbia Basin-Washington Palouse-Waterville Plateau- Wenatchee Area-Western Chelan County. Wind Advisory from 1 PM this afternoon to 6 AM PST Tuesday for Moses Lake Area-Northeast Blue Mountains-Spokane Area- Upper Columbia Basin-Washington Palouse-Waterville Plateau. Flood Watch through Wednesday morning for Central Chelan County-Wenatchee Area-Western Chelan County-Western Okanogan County. Winter Storm Watch from Tuesday evening through Wednesday evening for Western Chelan County. ID...Flood Watch from Tuesday afternoon through Wednesday afternoon for Central Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-Northern Panhandle. High Wind Watch from Tuesday evening through Wednesday afternoon for Central Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis and Southern Nez Perce Counties- Lewiston Area-Northern Panhandle. Wind Advisory from 1 PM this afternoon to 6 AM PST Tuesday for Coeur d`Alene Area-Idaho Palouse-Lewis and Southern Nez Perce Counties-Lewiston Area. && $$

699 FXUS66 KPDT 152237 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 237 PM PST Mon Dec 15 2025 .DISCUSSION... Key Messages... 1. Rain, mainly in the Cascades through Tuesday. 2. Breezy to Windy through tonight. 3. Very Windy Wednesday with significant snow over Cascades and lower snow levels through the end of the week. 4. River flooding returns to some areas of the Yakima and Naches Rivers from Wednesday through the end of the week. Rain will continue mainly across the mountains through Tuesday. The lower elevations should be generally dry. The rain will cause runoff, which will begin around Wednesday at some points on the Yakima and Naches. River Flood Watches have been issued. Rivers are expected to remain high into next week, though they will slowly recede. With less rain and lower snow levels expected, while rivers will rise, they are not expected to reach the levels they reached last week. As this first system moves through, breezy to windy conditions are expected through tonight and wind advisories remain in effect. Then the next system, a trough, potent short wave and strong cold front will move across the region later Tuesday into Wednesday. These features will bring very strong winds, snow to the mountains and lowering snow levels. Behind the cold front, there will be about a 10 degree drop in temperatures, though temperatures will still be above normal. Winds will increase and become quite gusty on Wednesday with gusts in the 40 to 50 mph range area wide and some locations getting as high as 60 mph plus. NBM probabilities of wind gusts >=47 mph are >=90 percent over a large part of our area on Wednesday. Wind gusts >=55 mph are 70 to 90 percent over the Yakima Valley, Simcoe Highlands, Columbia Basin, amd Foothills of the Blue Mountains. High wind Watches remain in effect. Snow levels, which currently range from 8000 to over 9000 feet, will drop sharply on Wednesday and by Wednesday afternoon, will be between 2000 to 2500 feet. Snow amounts look to be in the 6 to 10 inch range at Snoqualmie and White Passes. Precipitation will linger over the weekend in the mountains, but amounts will be lighter, while over the lower elevations it will be mainly dry. && .AVIATION... Aside from temporary sub-VFR conditions within rain showers this afternoon and evening, predominantly VFR conditions are anticipated for the next 24 hours. Breezy winds of 10-20 kts with gusts of 25-35 kts are forecast through much of the period. Did include mention of low-level wind shear at YKM/PSC where winds aloft are strongest (45-55 kts at 2kft AGL). && .PRELIMINARY POINT TEMPS/POPS... PDT 43 61 40 50 / 40 10 90 50 ALW 46 60 42 51 / 60 30 100 70 PSC 43 60 42 54 / 20 20 90 30 YKM 37 58 38 50 / 10 50 100 30 HRI 43 61 42 53 / 30 10 90 40 ELN 34 50 33 44 / 30 70 100 50 RDM 37 58 33 45 / 30 10 100 50 LGD 40 55 36 48 / 60 20 90 80 GCD 43 56 36 49 / 40 10 90 80 DLS 45 59 43 51 / 50 60 100 70 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...High Wind Watch from Tuesday evening through Wednesday afternoon for ORZ041-044-507-508-510-511. Wind Advisory until 10 PM PST this evening for ORZ507-508. WA...High Wind Watch from Tuesday evening through Wednesday afternoon for WAZ024-026>029-521. Wind Advisory until 10 PM PST this evening for WAZ026>028. Flood Watch through Wednesday morning for WAZ522-523. Winter Weather Advisory from 4 PM Tuesday to 10 PM PST Wednesday for WAZ522. && $$ SHORT TERM...77 LONG TERM....77 AVIATION...86

126 FXUS65 KREV 152218 AFDREV Area Forecast Discussion National Weather Service Reno NV 218 PM PST Mon Dec 15 2025 .KEY MESSAGES... * Chances of rain and high elevation snow increase across the Sierra and far NW Nevada Tuesday afternoon into Wednesday. * Gusty winds may impact recreation and travel on Wednesday with elevated fire concerns in southern Mono County. * Periods of gusty winds, rain and mountain snow possible late this week into early next week. && .DISCUSSION... Our much awaited pattern change is expected to unfold this week as dampening high pressure allows the storm track to dip southward towards the region. We`ll still be on the southern periphery of the storm track so a bulk of the rain and snow will stay north and west of the region, but a couple trough passages will bring periods of light rain and mountain snow this week. The first opportunity for rain and snow will be Tuesday afternoon through Wednesday morning as transient low pressure increases shower chances to 60-90% from the Tahoe Basin towards the Oregon border. Showers likely spill into far NW Nevada Wednesday morning, so don`t be surprised to see light rain across the Greater Reno-Carson-Minden area during the AM commute. Snow levels will remain above 9-10k feet, which would confine snowfall (dusting to 4") to highest Sierra peaks. Winds also begin to intensify along Sierra ridges Tuesday night with gusts reaching/exceeding 100 mph by Wednesday morning. Enhanced winds aloft are transported to the surface Wednesday afternoon, resulting in SW/W gusts of 35-45 mph across lower valleys with wind prone locales seeing gusts upwards of 60 mph. Be prepared for choppy lakes, aviation impacts, and crosswind driving hazards along north- to-south oriented roadways such as I-580, US-395, and US-95. Low-end fire weather concerns will also exist across lower elevations of southern Mono County where RH reductions to near 30% are expected. A second trough passage is slated for Friday, bringing renewed wind impacts and nearly identical shower chances as its predecessor. The weather pattern becomes zonal over the weekend, which will keep moisture directed into the region and support periods of rain and snow through the weekend. Ensembles advertise unsettled weather to continue into next week with more organized storms impacting the region, which increases the likelihood of holiday travel disruptions leading up to Christmas. -Salas && .AVIATION... FG/FZFG and reduced VIS/CIGS continue to be the main concern for Tahoe terminals, especially at KTVL where fog has proven to be more persistent. Fog may return to the KTRK/KTVL tonight into Tuesday morning, otherwise VFR conditions persist through Tuesday morning. Increasing winds and shower chances are expected Tuesday afternoon into Wednesday. -Salas && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory from 10 PM Tuesday to 1 PM PST Wednesday NVZ002. CA...Lake Wind Advisory from 10 PM Tuesday to 1 PM PST Wednesday CAZ072. && $$

584 FXUS66 KSTO 152139 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 139 PM PST Mon Dec 15 2025 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Fog, mist, and low clouds for the Central Valley, Delta, and adjacent foothills continues tonight into early Tuesday. - High temperatures in the Central Valley, Delta, and lower foothills will gradually trend to more mild levels by the middle of the week. - Series of disturbances will bring periods of beneficial rain, breezy south winds and isolated thunderstorms at times from Tuesday into the weekend. - Active weather pattern continues into next weekend, including the holiday travel period, though details remain uncertain. && .DISCUSSION... ...Today - Tonight... Latest satellite imagery continues to show the low stratus deck and patchy fog across the Central Valley and adjacent foothills. A few areas in the northern Sacramento Valley have clear out and temperatures to warm, while the low clouds linger elsewhere. Temperatures underneath the stratus have been well below normal for highs, and areas above the stratus continue to be above average. A disturbance over the Pacific Northwest brushes through far Northern California tonight, bringing some scattered showers to the northern Coastal Range and Shasta County. Dense fog may continue overnight into Tuesday morning, with visibility reductions to a quarter mile or less for areas within the Central Valley. ...Tuesday - Thursday... An upper level wave moves in Tuesday increasing precipitation chances and breezy conditions to the region. Look for continued low ceilings, mist, and foggy conditions Tuesday morning. Precipitation spreads southward through Tuesday, but remains along and north of the I-80 area for the day, then over much of the rest of the area Tuesday night. Coverage will be isolated for the showers for much of Tuesday. By the afternoon instability and moisture increase across the forecast area giving way to thunderstorm chances, though these have trended lower, now 10-15 percent across the area. Best chances will be within the Sierra, Motherlode, Sacramento Valley, and Coastal Range. Coverage will be scattered to widespread across the area for precipitation. With snow levels above 8000 feet, no impacts are expected. A brief lull in precipitation is expected Thursday morning and afternoon, before another round of precipitation moves into the region bringing breezier conditions. ...Friday Onward... An active pattern continues for Friday and into the weekend, with another upper level wave moving out of the eastern Pacific. This system has trended cooler over the past couple of runs of the NBM. Snow levels have trended a little higher and are looking to be above 7500 feet by Friday afternoon and evening and remaining so through the weekend, which has reduced forecast snowfall amounts and should limit travel impacts. Moisture content has trended higher with the system, with chances for widespread largely beneficial precipitation. Breezy conditions are expected with the system as it moves through the area. Confidence remains low on the full development, track, and snow levels with the system, especially into next week. Stay tuned for details! && .AVIATION... Low ceilings and visibilities continue for areas within the Central Valley. Clearing has been observed near RDD and RBL this afternoon, which will be short lived. By this evening stratus will move back into the northern Sacramento Valley, with increasing chances for precipitation. Areas around Sacramento and the San Joaquin Valley will continue to see low stratus and foggy conditions throughout today. Some improvements to the ceilings and visibilities this afternoon before conditions deteriorate again later this evening and overnight. Light and variable winds are expected through the TAF period. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

557 FXUS65 KMSO 152115 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 215 PM MST Mon Dec 15 2025 .DISCUSSION... KEY MESSAGES: - Atmospheric River Impacts: An atmospheric river will bring widespread rain and high-elevation snow through Tuesday. Saturated soils will likely cause rises on streams and rockslides in steep terrain, particularly in northwest Montana and north-central Idaho. - Strong Cold Front Wednesday: A sharp cold front will sweep across the region on Wednesday. Expect a rapid transition from rain to snow, and damaging winds with gusts of 50-70 mph in valleys (higher in mountains). - Winter Conditions Return: Following the front, cooler and unsettled weather will prevail for the remainder of the week, with snow levels dropping to valley floors at times and periods of mountain snow affecting travel. The primary weather story for the next 48 hours is a classic "one-two punch" involving a moisture-laden atmospheric river followed immediately by a sharp cold front. A strong southwesterly flow is currently directing a plume of subtropical moisture into the Northern Rockies. With 700mb temperatures rising, snow levels have ascended above 7000 feet, meaning precipitation will fall primarily as rain. The Weather Prediction Center (WPC) highlights a continued influx of moisture, with high-resolution ensembles suggesting 24-hour rainfall totals of 1.5 to 3.0 inches in the higher terrain of the Cabinets and Clearwaters by Tuesday morning. This rainfall on top of existing snowpack and saturated soils has elevated the risk for rockslides, mudslides, and rises on creeks and small streams. Winds tonight: A powerful upper-level jet streak is moving overhead. While an inversion may protect some protected valleys from the strongest winds initially, expect gusty southwesterly winds to mix down in favorable corridors. Wind advisories are in effect for west-central and northwest Montana for tonight into Tuesday morning for gusts 40-50 mph. The Wednesday Front: Model agreement is high regarding a potent cold front passage on Wednesday. This feature will be dynamic and impactful. Temperature Crash: As the front passes (likely during the morning/mid-day hours), temperatures will plummet with a rapid change to snow. Damaging Winds: The pressure gradient along the front is tight. Widespread wind gusts of 50 to 70 mph are probable in valleys, with gusts exceeding 80 mph on ridgetops. This creates a risk of downed trees (made easier by sodden soil), power outages, and damage to infrastructure. Snow Squalls: The transition from rain to snow will be abrupt. Bursts of heavy snow or snow squalls could lead to near-zero visibility and difficult travel conditions immediately following the frontal passage. Higher valleys, mountain passes, and locations along the Divide have the highest risk for these heavy bursts of snow and snow squalls. Thursday through Sunday: The upper-level pattern will remain active but shift to a cooler regime behind Wednesday`s front. The jet stream will remain positioned over the Pacific Northwest, maintaining a feed of moisture into the region, though the airmass will be colder. Troughing over the region will keep temperatures closer to normal for the end of the week. With colder air in place, snow levels will hover near valley floors on Thursday, creeping slightly upward on Friday. This period will be characterized by frequent mountain snow showers and valley rain/snow mix. While the intensity will not match the early-week atmospheric river, the accumulation of snow on mountain passes (Lookout, Lolo, Marias) will likely necessitate winter travel precautions. A continued unsettled weather pattern with light to moderate precipitation accumulation is expected through the weekend. && .AVIATION...Another atmospheric river will impact the Northern Rockies airspace. This instance will be focused on winds as opposed to precipitation. With some valleys inverted and stable, initially there could be strong low-level wind shear as mid level winds increase 40 to 50 kts. All terminals are expected to mix out and gusts 30 to 40 kts at most terminals are expected. Precipitation will remain all rain, with only minor reductions to visibility forecasted. Winds will remain elevated Tuesday with gusts 15 to 25 kts common. && .MSO WATCHES/WARNINGS/ADVISORIES... MT... High Wind Watch from late Tuesday night through Wednesday afternoon for Bitterroot/Sapphire Mountains... Butte/Blackfoot Region...Flathead/Mission Valleys... Kootenai/Cabinet Region...Lower Clark Fork Region... Missoula/Bitterroot Valleys...Potomac/Seeley Lake Region. Wind Advisory from 5 PM this afternoon to 3 AM MST Tuesday for Kootenai/Cabinet Region...Lower Clark Fork Region. Wind Advisory from 7 PM this evening to 5 AM MST Tuesday for Flathead/Mission Valleys...Potomac/Seeley Lake Region... West Glacier Region. Winter Storm Watch from Tuesday evening through Wednesday evening for West Glacier Region. Wind Advisory from 11 PM this evening to 8 AM MST Tuesday for Missoula/Bitterroot Valleys. ID...High Wind Watch from Tuesday evening through Wednesday afternoon for Lower Hells Canyon/Salmon River Region...Northern Clearwater Mountains...Orofino/Grangeville Region... Southern Clearwater Mountains. High Wind Watch from late Tuesday night through Wednesday afternoon for Eastern Lemhi County...Western Lemhi County. && $$

852 FXUS65 KBOI 152145 AFDBOI Area Forecast Discussion National Weather Service Boise ID 245 PM MST Mon Dec 15 2025 .SHORT TERM...Tonight through Wednesday night...At 2 PM MST a weak cold front was in western ID with a band of light rain extending north-south along the OR/ID border. The front was moving steadily east with slightly more pcpn than models predicted but should total less than .15 inch even in the wettest locations. The front will stir up the stagnant air but not enough to end the Air Stagnation Advisory which will continue until 5 AM Tuesday. Clouds and light winds will moderate low temps tonight, and increasing southeast winds will boost max temps to near record highs Tuesday. Tuesday night will be windy and very mild ahead of a very strong Pacific cold front due in the pre-dawn hours Wednesday in OR, and early Wednesday morning in western ID. South/southeast winds will shift abruptly to west/northwest as the front passes and increase to 30 to 40 mph with possible gusts as high as 60 mph in southern zones. A High Wind Watch has been issued in those zones (listed below) for Wednesday morning in OR and through 2 PM MST Wednesday afternoon in western ID. Strongest winds are expected in the western Magic Valley and Camas Prairie. Pcpn will be heavier with the strong cold front with greatest amounts (near 1.00 inch) in eastern Valley County and northern Elmore County in ID late Tuesday night through late Wednesday night. Heaviest pcpn will fall as the cold front passes and may result in rock slides in steep terrain. Travelers would be wise to avoid the Banks-Lowman road in ID and be wary on ID state highway 21 northeast of Idaho City. The rest of ID north of the Snake Basin should have .25 to .50 inch liquid equivalent, while southern areas including the Snake Basin receive .10 to .25 inch, with similar amounts in eastern OR. The snow level will lower rapidly to valley floors later Wednesday in northern zones and to near 5000 feet in southern zones. Snowfall 3 to 6 inches is expected in the higher ID mountains late Wednesday through Wednesday evening. Wednesday night should be calming, drying, and significantly cooling. .LONG TERM...Thursday through Monday...Precipitation chances continue through the extended, with a hefty push during Thursday, Friday, and early Saturday. This comes as another atmospheric river event impacts the Pacific NW from an elongated disturbance, courtesy of the Gulf of Alaska low. A strong, westerly mid-level jet will accompany this disturbance. As a result, this system will pull in a long fetch of considerable subtropical moisture, spreading moderate/heavy precipitation into the area. Snow levels will oscillate quite a bit during this period, associated with the tight temperature gradient, making snowfall accumulations a significant forecast challenge during this period. Overall, snow levels are expected to be lowest across the north, gradually rising from south to north throughout the day Thursday. Snow levels will then gradually lower from north to south as a cold front moves in late Friday/early Saturday. Overall, mountains could see 1 to 2 inches of liquid equivalent throughout this period, along with snowfall totals 1 to 2 feet at the ridgetops (depending heavily on the snow level). The period of rainfall over saturated, steep terrain will also introduce rockslide concerns. In addition to precipitation, strong surface winds are expected to develop across much of the area, particularly Friday, ahead of/along the cold front. Gusts will be strongest across southeast Oregon, the ID/NV border, and the mountains of southwest Idaho. Meanwhile, temperatures are forecast to stay above normal Thursday and Friday, with the coldest air expected across west-central/central Idaho and eastern Oregon. Once the aforementioned system exits, there will be a brief respite from precipitation late Saturday into Sunday morning. This will occur before yet another push of precipitation comes ahead of a upper-level long wave trough slowly moving inland Sunday and Monday. Models currently disagree on how much of the polar air to the north will penetrate E Oregon and SW Idaho, resulting in poor forecast confidence on temperatures and snow levels this far out. Regardless, ample moisture will yield a new round of notable precipitation amounts for the area, with upslope flow favoring the mountains of west-central/central Idaho once again. && .AVIATION...Periods of MVFR in precipitation/low ceilings. Scattered showers will move from NW to SE today, decreasing by Tuesday AM. Snow levels 7-9 kft MSL falling to 6-8 kft MSL by Tuesday AM. Mountains obscured. Periods of LLWS in E Oregon Monday into Tuesday. Surface winds: light/variable, then SW-SE 5-15 kt this PM. Gusts of 20-25 kt in SE Oregon and near NV/ID border. Winds aloft at 10kft MSL: W 25-45 kt. KBOI...VFR. A 15-30% chance of light rain this afternoon and evening. Surface winds: SE 4-9 kt && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Air Stagnation Advisory until 5 AM MST Tuesday IDZ011>014-016-028-033. High Wind Watch from late Tuesday night through Wednesday afternoon IDZ012-014>016-028>030. OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Tuesday ORZ061>064. High Wind Watch from late Tuesday night through Wednesday afternoon ORZ064. High Wind Watch from late Tuesday night through Wednesday morning ORZ061>063. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...LC LONG TERM....CH AVIATION.....CH

646 FXUS65 KLKN 152149 AFDLKN Area Forecast Discussion National Weather Service Elko NV 149 PM PST Mon Dec 15 2025 .KEY MESSAGES... Updated at 1236 PM PST Mon Dec 15 2025 * Unseasonably warm each afternoon through the weekend * Periods of precipitation, focused across Northern Nevada, beginning Tuesday * Strong west-southwest wind gusts in Northern Nevada Wednesday && .DISCUSSION... (This afternoon through next Monday) WEATHER PATTERN OVERVIEW: Skies are partly to mostly sunny this afternoon across northern and central Nevada. Winds are generally light at this time. There are mid and high level clouds that will be traversing the area later this afternoon and evening. Overnight lows will be in the 20s and 30s. A west to east flow will continue tomorrow as a ridge is situated well off the western coast of the United States. A 250mb upper jet will be north of the forecast area and will provide limited dynamics to the northern half of the forecast area. This will allow for the development of light rain showers over locations north of I-80. Precipitation amounts will be limited over the valley locations to roughly a trace to less than a tenth of an inch. Snow levels will be at or above 8500 feet. Highs will be in the 50s and 60s. Look for light, showery precipitation to continue during the overnight with lows in the 30s and 40s. By Wednesday, models continue to depict strong winds developing during the morning and afternoon. Southwest to west winds of 15 to 30 with gusts of 40 to 50 mph are expected. The strongest winds are expected across northern Nevada and a wind advisory may be required as the probability for reaching advisory wind gusts are about forty to seventy percent or higher in the above locations. Snow levels are forecast will again be around 7000 feet or so, though cooler air is expected to filter in by the later afternoon period as winds shift to a west-northwest direction. Highs will again reach the 50s to low 60s. Overnight lows will be in the 30s. Snow levels in the far north are expected to drop to at or above 5000 feet during the overnight. Light snowfall amounts up to a half inch are expected in the north, along SR225 from roughly Wildhorse to the border with Idaho. Thursday through Sunday, periods of showery precipitation are expected through this timeframe as model solutions keep an upper ridge well off the southwest coast. No strong cold pushes are expected through this period with a mostly west to east flow continuing. Highs will be in the 50s to low 60s. Overnight lows will be in the 30s and 40s. Winds will be breezy along the northern sections of the forecast area, north of I-80 with gusts to 30 to 40 mph, each afternoon from Thursday through the weekend. Overnight lows will be in the 30s and 40s. FORECAST CONFIDENCE & DEVIATIONS: Confidence remains high on short term rain fall and high temperatures being above normal. Confidence is also high with respect to strong to very strong winds developing across the northern half of Nevada Wednesday afternoon. Confidence in rainfall and snowfall amounts remain low to moderate at this time. && .AVIATION... VFR conditions expected at all sites through the next 24 hours with light winds. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...86 AVIATION...94