018
FXUS66 KOTX 051138
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
338 AM PST FRI DEC 5 2025
KEY MESSAGES
- WINTRY MIX FRIDAY MAY RESULT IN A SLICK COMMUTE. 20-40% OF 1"
OF SNOW IN THE NORTHEAST VALLEYS.
- STRONG, POTENTIALLY DAMAGING WINDS IN PORTIONS OF CENTRAL
WASHINGTON FRIDAY NIGHT. GUSTY WINDS IN SOUTHEAST WASHINGTON.
- PERIODS OF MODERATE TO HEAVY MOUNTAIN SNOW IN THE MOUNTAIN
PASSES THROUGH SATURDAY.
- INCREASED POTENTIAL FOR ROCK SLIDES NEXT WEEK WITH A MILD AND
WET WEATHER PATTERN.
SYNOPSIS
A UNSETTLED AND COMPLEX WEATHER PATTERN THROUGH THE WEEKEND AND
INTO NEXT WEEK. WINTRY MIX FOR AREAS OF NORTHEASTERN WASHINGTON
AND NORTH IDAHO FRIDAY WITH SNOW IN THE MOUNTAINS. GUSTY WINDS
DEVELOPING FRIDAY NIGHT. TEMPERATURES WILL MODIFY AND WARM
ABOVE NORMAL WITH MID AND WET WEATHER CONTINUING THROUGH THE
WEEKEND AND INTO NEXT WEEK.
DISCUSSION
TODAY THROUGH SATURDAY: THE ACTIVE WEATHER PATTERN CONTINUES WITH
A STRONG 160KT ZONAL JET STREAM TAKING AIM AT THE INLAND NORTHWEST
TODAY AS A LOW PRESSURE SYSTEM TRACKS ACROSS BRITISH COLUMBIA.
ANOTHER ROUND OF WARM, MOIST, ISENTROPIC ASCENT MOVES THROUGH THE
INLAND NW TODAY PRODUCING ANOTHER ROUND OF PRECIPITATION REACHING
THE CASCADES EARLY TO MID MORNING, AND THEN EASTERN WA/NORTH ID
LATE MORNING INTO THE AFTERNOON. SNOW LEVELS START OFF LOW
INITIALLY FOR THE NORTHERN VALLEYS (1500-2500 FEET) BUT THE WARM
ADVECTION WILL RAISE SNOW LEVELS TO 2500-3500 FEET IN THE
AFTERNOON. ELSEWHERE SNOW LEVELS WILL QUICKLY BE RISING TO
5000-6000 FEET ALLOWING SNOW TO CHANGE TO RAIN EARLY AT STEVENS
PASS, AND FOR LOOKOUT PASS BY THIS EVENING. THE NEXT ISSUE WILL BE
THE WINDS TONIGHT WITH A COLD FRONT PASSAGE. THIS WILL BE
ESPECIALLY TRUE ALONG THE EAST SLOPES OF THE CASCADES INTO THE
WENATCHEE AREA AND WATERVILLE PLATEAU AS 850MB WINDS INCREASE TO
AN IMPRESSIVE 60-65 KTS. THE BIG QUESTION IS WILL THESE WINDS MIX
DOWN INTO THE POPULATED AREAS? FORECAST SOUNDINGS DON'T SHOW QUITE
ENOUGH LOW LEVEL INSTABILITY FOR WIDESPREAD DAMAGING WIND GUSTS,
YET WITH VERY STRONG WINDS ABOVE THE SURFACE AND TURBULENT FLOW
OFF THE CASCADES ISOLATED DAMAGING GUSTS ARE POSSIBLE. HERE ARE
THE HREF CHANCES OF VARIOUS WIND GUST THRESHOLDS BEING MET
TONIGHT:
CITY 40+ MPH 50+ MPH 60+ MPH 70+ MPH
WENATCHEE 80% 45% 20% 5%
CHELAN 70% 5% 0% 0%
MATTAWA 75% 60% 30% 0%
EPHRATA 85% 60% 45% 0%
MOSES LAKE 60% 15% 0% 0%
WATERVILLE 90% 35% 5% 0%
MISSION RIDGE 100% 100% 95% 45%
WITH THIS PATTERN HAVING THE POTENTIAL FOR AT LEAST ISOLATED DAMAGING
WIND GUSTS, WILL BE UPGRADING THE WIND ADVISORY TO A HIGH WIND
WARNING AND EXPANDING TO THE EPHRATA AREA. THE HREF ALSO SHOWING
GUSTS AROUND 50 MPH FOR THE ALPOWA SUMMIT AREA SO WILL CONTINUE
THE WIND ADVISORY HERE AS WELL AND EXPAND ONTO THE PALOUSE.
ALSO FOLLOWING THE COLD FRONT SNOW LEVELS FALL TO AROUND 4000 FEET
ALLOWING RAIN TO CHANGE BACK OVER TO WET SNOW AT STEVENS AND LOOKOUT
PASSES. STRONG UPSLOPE FLOW BEHIND THE FRONT WILL ALLOW THE SNOW TO
CONTINUE INTO SATURDAY.
SUNDAY THROUGH THURSDAY: SEVERAL ATMOSPHERIC RIVERS TAKE AIM AT THE
REGION RESULTING IN A VERY WET PERIOD FOR THE INLAND NORTHWEST. THE
FIRST ONE IS THE WEAKEST ARRIVING SUNDAY WITH PRECIPITABLE WATER
INCREASING TO 150-175% OF NORMAL. SNOW LEVELS ARE AROUND
4000-5000 FEET SUPPORTING VALLEY RAIN AND MOUNTAIN SNOW. THE NEXT
ONE IS MUCH MORE SIGNIFICANT ARRIVING MONDAY NIGHT INTO TUESDAY
WITH PRECIPITABLE WATER 200-300% OF NORMAL. STRONG UPSLOPE FLOW
WILL PROVIDE ADDED LIFT INTO THE CASCADES WITH SIGNIFICANT
SLOP- OVER PRECIPITATION INTO THE METHOW VALLEY, PLAIN,
LEAVENWORTH, AND WENATCHEE. CURRENT INDICATIONS FROM THE
ENSEMBLE MEANS IS FOR THE ATMOSPHERIC RIVER TO BRIEFLY MOVE
SOUTH INTO OREGON TUESDAY AFTERNOON AND EVENING BEFORE LIFTING
BACK OVER THE AREA TUESDAY NIGHT INTO WEDNESDAY AND PERSISTING
INTO THURSDAY FOR MORE MODERATE TO HEAVY PRECIPITATION.
THE QPF AMOUNTS THE MODELS ARE PRODUCING ARE IMPRESSIVE OVER THIS
MULTI DAY PERIOD. THE ECMWF ENSEMBLE MEAN IS PRODUCING 5-7 INCHES
OF PRECIPITATION ALONG THE CASCADE CREST, 4-5 INCHES FOR THE
PLAIN, LEAVENWORTH, AND STEHEKIN AREAS, AND OVER AN INCH FROM
WENATCHEE UP TO OMAK. THE ID PANHANDLE WILL ALSO SEE SIGNIFICANT
RAINS WITH 1-2 INCHES IN THE VALLEYS AND 2-4 INCHES IN THE
MOUNTAINS. THESE RAIN AMOUNTS COMBINED WITH SNOWMELT WILL LEAD TO
SIGNIFICANT RISES ON RIVERS AND STREAMS. CURRENTLY NO RIVERS ARE
FORECAST TO REACH FLOOD STAGE, BUT THIS WILL BE MONITORED CLOSELY
IN THE COMING DAYS. JW
AVIATION
12Z TAFS: IFR STRATUS WITH LOCALLY DENSE FOG DUE TO A SATURATED
BOUNDARY LAYER AND LIGHT WINDS THIS MORNING. THE NEXT SYSTEM
IS MOVING IN WITH A STRONG UPPER LEVEL JET STREAM AROUND
150-160 KTS FROM WEST TO EAST. ANOTHER ROUND OF PRECIPITATION
WILL OCCUR WITH A MIX OF RAIN AND SNOW. LOW LEVEL WIND SHEAR IS
SHOWN IN MODEL SOUNDINGS FOR KEAT/KMWH/KLWS/KPUW BETWEEN 0Z-6Z
SATURDAY AS WINDS AROUND 2K FEET AGL INCREASE TO AROUND 40-50
KTS, LOCALLY STRONGER AT KEAT. STRONGER GUSTS MAY OCCASIONAL
MIX DOWN TO THE SURFACE IN AREAS OF CENTRAL WA AROUND CHELAN,
WENATCHEE, EPHRATA, AND VANTAGE. THESE POTENTIALLY DAMAGING WIND
GUSTS WILL LIKELY NOT BE LONG DURATION AND SPORADIC GIVEN THE
STABLE BOUNDARY LAYER. THE INCREASED WINDS USHER INCREASED
PROBABILITIES TO BRING IMPROVEMENT TO THE PERSISTENT STRATUS
EXCEPT FAR NE WA AND N ID WHERE THE FLOW PATTERN FAVORS
UPSLOPING FLOW.
.FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
HIGH CONFIDENCE OF WIDESPREAD IFR AND MVFR CONDITIONS ACROSS THE
REGION INTO FRIDAY AFTERNOON GIVEN MORE PRECIPITATION FALLING
INTO AN ALREADY SATURATED BOUNDARY LAYER. HIGH CONFIDENCE FOR
INCREASE WINDS AND LOW-LEVEL WIND SHEAR. CONFIDENCE IS LOW WHERE
AND WHEN THE STRONGEST WINDS GUSTS WILL SURFACE, ESPECIALLY IN
CENTRAL WA. STRONG TURBULENCE EXPECTED AS THE JET CROSSES THE
MOUNTAIN BARRIERS. /SB
-----------------------
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 38 35 44 35 43 38 / 100 40 30 20 80 50
COEUR D'ALENE 39 35 43 35 43 38 / 100 80 70 50 90 70
PULLMAN 43 38 44 37 44 40 / 100 70 60 50 90 80
LEWISTON 48 41 52 40 48 43 / 100 80 50 40 70 60
COLVILLE 35 33 41 28 39 33 / 100 40 40 20 90 40
SANDPOINT 36 33 40 34 40 37 / 100 80 90 70 100 90
KELLOGG 40 35 40 37 41 40 / 100 90 100 80 100 90
MOSES LAKE 40 36 50 35 46 38 / 90 10 0 0 60 10
WENATCHEE 45 38 50 37 45 39 / 90 60 30 20 70 20
OMAK 37 34 43 32 40 34 / 90 40 20 10 60 20
OTX WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY FROM 7 PM THIS EVENING TO 7 AM PST SATURDAY FOR
LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE.
HIGH WIND WARNING FROM 7 PM THIS EVENING TO 7 AM PST SATURDAY
FOR MOSES LAKE AREA-WATERVILLE PLATEAU-WENATCHEE AREA.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 PM PST
SATURDAY FOR WESTERN CHELAN COUNTY.
ID...WIND ADVISORY FROM 7 PM THIS EVENING TO 7 AM PST SATURDAY FOR
IDAHO PALOUSE.
WINTER STORM WARNING UNTIL 4 PM PST SATURDAY FOR CENTRAL
PANHANDLE MOUNTAINS.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page