811
FXUS66 KOTX 091146
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
446 AM PDT MON MAR 9 2026
KEY MESSAGES
- COLDER WITH MODERATE TO HEAVY MOUNTAIN SNOW THIS WEEK OVER
THE CASCADE AND NORTH IDAHO MOUNTAIN PASSES.
- POTENTIAL FOR STRONG WINDS WEDNESDAY AND WEDNESDAY NIGHT.
SYNOPSIS
PERSISTENT SNOW WILL BRING SEVERAL DAYS OF WINTER TRAVEL
CONDITIONS OVER THE MOUNTAINS THIS WEEK. WE ARE ALSO MONITORING
WEDNESDAY THROUGH FRIDAY FOR HEAVY MOUNTAIN SNOW, STRONG WINDS,
AND THE POTENTIAL FOR LIGHT LOWLAND SNOW ACCUMULATIONS IN THE
NORTHERN MOUNTAIN VALLEYS. ADDITIONAL MODERATE SNOW IN THE
MOUNTAINS WILL BE POSSIBLE INTO THIS WEEKEND AS WELL.
DISCUSSION
...PERIODS OF HEAVY SNOW IN THE MOUNTAINS THIS WEEK AND
POTENTIAL FOR STRONG WINDS WEDNESDAY EVENING THROUGH THURSDAY...
TODAY: THE MAIN FOCUS TODAY WILL BE AREAS OF MODERATE TO HEAVY
SNOW SHOWERS IN THE CASCADES, COOLER CONDITIONS, AND SCATTERED
RAIN/SNOW SHOWERS DEVELOPING IN THE AFTERNOON REGIONWIDE.
A PUGET SOUND CONVERGENCE ZONE WILL CONTINUE TO BRING PERIODS OF
MODERATE TO HEAVY SNOW FOR THE NEXT FEW HOURS, WITH SNOWFALL
RATES AROUND 1-3”/HR. FROM THE UPPER LEVELS TO THE SURFACE, ALL
CYLINDERS ARE FIRING FOR A SIGNIFICANT AMOUNT OF SNOW BEFORE
SUNRISE. THERE IS A 130 KT 300 MB JET STREAK RIGHT OFF THE COAST
OF WESTERN WASHINGTON, PROVIDING UPPER LEVEL DIVERGENCE IN THE
LEFT EXIT REGION OVER THE SEATTLE METRO. AT 500 MB, TEMPERATURES
CONTINUE TO DECREASE INTO THE LOW -30S AND A VORT MAX MOVING
THROUGH THE OLYMPICS, PROVIDING AMPLE POSITIVE DIFFERENTIAL
VORTICITY ADVECTION OVER THE CONVERGENCE ZONE. THE LOW LEVELS
ARE DOING THE REST OF THE WORK WITH FLOW SPLITTING AROUND THE
OLYMPICS AND CONVERGING BETWEEN SEATTLE AND EVERETT, FOCUSING
THE NARROW BAND OF PRECIPITATION PARALLEL WITH US-2 UP TO
STEVENS PASS. SHORTLY BEFORE SUNRISE, SURFACE TO 850 MB
CONVERGENCE WEAKENS OVER THE NORTHERN SEATTLE METRO AND TURNS
SOUTHWESTERLY, FOCUSING THE PRECIPITATION IN THE NORTH CASCADES
IN WHATCOM/SKAGIT COUNTIES. SNOWFALL INTENSITIES DURING THE DAY
AT STEVENS PASS TODAY WILL BE FAIRLY UNNOTEWORTHY AROUND
0.1-0.5”/HR PERHAPS EVEN COMPLETELY STOPPING AT TIMES. HOWEVER,
LOW LEVEL FLOW IN THE STRAIT OF THE JUAN DE FUCA BECOMES
NORTHWESTERLY IN THE LATE AFTERNOON THROUGH LATE TONIGHT,
BRINGING BACK THE POTENTIAL FOR 1-2”/HR SNOWFALL RATES TO
STEVENS PASS. BETWEEN THESE TWO LARGE THUMPS OF SNOW AND LIGHT
SNOW SHOWERS DURING THE DAY, STEVENS PASS CAN EXPECT AROUND
15-27” OF SNOW THROUGH 5 AM TUESDAY. HI-RES MODELS SHOW SOME
SLOPOVER SNOW REACHING LEAVENWORTH AND STEHEKIN, WHERE AROUND
1-4 INCHES OF SNOW IS EXPECTED THROUGH MONDAY NIGHT. THE UTAH
RRFS SNOW ENSEMBLE SHOWS SNOW TO LIQUID RATIOS AROUND 15-20:1
THROUGH TONIGHT THANKS TO THE COLD AND UNSTABLE CONDITIONS.
GUSTY WINDS AND HIGHER SNOW RATIO SNOW WILL ALSO BRING THE RISK
FOR BLOWING AND DRIFTING SNOW.
THE REST OF THE INLAND NORTHWEST WILL START OFF CHILLY THIS
MORNING IN THE 20S AND 30S AND HIGHS WILL BE BELOW AVERAGE LOW
40S TO UPPER 40S. THERE IS A SMALL CHANCE FOR 20-40% CHANCE FOR
AREAS OF RAIN/SNOW SHOWERS DEVELOPING IN THE AFTERNOON EAST OF
MOSES LAKE THANKS TO A WEAKLY UNSTABLE AIR MASS IN PLACE.
ACCUMULATIONS ARE NOT EXPECTED IN THE VALLEYS WITH THESE
SHOWERS. LOOKOUT PASS WILL SEE AROUND 1-3” OF SNOW THROUGH
TONIGHT WITH THESE SNOW SHOWERS. WINDS WILL REMAIN BREEZY TODAY
OUT OF THE SOUTHWEST, GUSTING TO AROUND 20-35 MPH.
TUESDAY THROUGH THURSDAY: A SIMILAR COOL AND SHOWERY REGIME IS EXPECTED
TUESDAY WITH TEMPERATURES WARMING A COUPLE DEGREES. WINDS WILL
ONCE AGAIN BE BREEZY OUT OF THE SOUTHWEST, GUSTING AROUND 20-25
MPH IN THE AFTERNOON. SNOW WILL RAMP UP IN THE EVENING HOURS
TUESDAY IN THE CASCADES AS THE LONG WINDED ATMOSPHERIC RIVER
APPROACHES THE REGION. SOME MODELS ARE SHOWING SOME AREAS OF
SNOW DEVELOPING IN THE VALLEYS, PARTICULARLY NORTHEAST
WASHINGTON AND NORTH IDAHO WEDNESDAY MORNING BEFORE SNOW LEVELS
RAPIDLY RISE. THE CHANCE FOR 1+” OF SNOW VARIES WIDELY BY
LOCATION (SPOKANE DOWNTOWN: 1%, PULLMAN: 15%, DEER PARK: 20%,
COLVILLE: 20%, NEWPORT: 80%, KELLOGG: 90%). MINOR SNOW
ACCUMULATIONS MAY BRING IMPACTS TO THE WEDNESDAY MORNING
COMMUTE. SNOWFALL IN THE MOUNTAINS WEDNESDAY WILL BE HEAVY
AROUND 1”/HR IN THE CASCADES. SNOW LEVELS IN THE ID PANHANDLE
MOUNTAINS WILL VARY FROM 4000-6000 FEET WEDNESDAY, BRINGING THE
CHANCE FOR LOOKOUT PASS TO CHANGE TO RAIN IN THE AFTERNOON AND
EVEN WEDNESDAY NIGHT. WINDS WILL BE OF CONCERN WEDNESDAY
AFTERNOON THROUGH THURSDAY AS A COLD FRONT SAGS AND STALLS IN
THE INW AND PRESSURE GRADIENTS INCREASE AS A SURFACE LOW MOVES
THROUGH SOUTHERN BC/AB. THERE IS A 30-60% CHANCE FOR SPOKANE,
WENATCHEE, PULLMAN, AND LEWISTON TO GUST GREATER THAN 50 MPH IN
THIS TIME FRAME.
FRIDAY THROUGH MONDAY: MODERATE TO HEAVY MOUNTAIN SNOW CONTINUES
IN THE MOUNTAINS AS THE ATMOSPHERIC RIVER PLUME SAGS SOUTH. THIS
PERIOD WILL ALSO NEED TO BE MONITORED FOR BREEZY TO WINDY
CONDITIONS. ENSEMBLE CLUSTERS INDICATE THE HEAVY SNOW WILL RAMP
DOWN (BUT NOT COMPLETELY STOP) INTO THE WEEKEND AS THE HIGH
PRESSURE RIDGE CENTERED OFF THE COAST OF CALIFORNIA STRENGTHENS,
DISPLACING THE POLAR JET WELL INTO CANADA. THERE IS GOOD
AGREEMENT OF ANOTHER ATMOSPHERIC RIVER COMING EARLY NEXT WEEK,
PERHAPS BEING WARM ENOUGH TO BRING HIGH ELEVATION RAIN. THIS
WOULD POSE CONCERNS FOR A RAIN ON SNOW EVENT.
OVERALL, THE AMOUNT OF SNOW IN THE CASCADES THROUGH THIS WEEKEND
WILL BE STAGGERING. THE GLOBAL ENSEMBLE 25-75TH PERCENTILE TOTAL
SNOWFALL SHOWS 40-80 INCHES FOR STEVENS PASS, 33-65 INCHES FOR
SNOQUALMIE PASS, AND 23-50 INCHES FOR WASHINGTON PASS. /DB
AVIATION
12Z TAFS: A DRY BOUNDARY LAYER TODAY WILL PROMOTE MAINLY VFR
CONDITIONS THROUGH 12Z TUE. WINDS HOWEVER WILL REMAIN BREEZY OUT
OF THE WEST AND SOUTHWEST. COLD AIR ALOFT WILL PROMOTE AN
UNSTABLE ATMOSPHERE IN THE AFTERNOON ALLOWING SOME SNOW SHOWERS
TO DEVELOP OVER THE EASTERN THIRD OF WASHINGTON INTO THE ID
PANHANDLE. THESE WILL BE ISOLATED TO SCATTERED IN NATURE, WITH A
PROB30 GROUP INCLUDED FOR KGEG/KSFF/KCOE/KPUW/KLWS.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
FOR VFR CONDITIONS THROUGH 12Z TUE, EXCEPT FOR LOCALIZED MVFR
CONDITIONS WITH SNOW SHOWERS. JW
-----------------------
CONFIDENCE DESCRIPTORS:
LOW - LESS THAN A 30 PERCENT CHANCE
MODERATE - 30 TO 70 PERCENT CHANCE
HIGH - GREATER THAN A 70 PERCENT CHANCE
FOR ADDITIONAL PROBABILISTIC INFORMATION FOR NWS SPOKANE
AIRPORTS,PLEASE REFER TO THE AVIATION DASHBOARD ON OUR
WEBPAGE: HTTPS:/WWW.WEATHER.GOV/OTX/AVNDASHBOARD
PRELIMINARY POINT TEMPS/POPS
SPOKANE 41 26 42 30 47 40 / 20 30 10 30 70 70
COEUR D'ALENE 41 26 41 28 45 39 / 40 50 40 50 90 90
PULLMAN 39 26 39 28 45 42 / 40 60 40 30 90 90
LEWISTON 47 30 46 33 51 45 / 20 50 20 20 80 80
COLVILLE 43 23 44 28 46 34 / 20 20 20 40 80 70
SANDPOINT 41 26 39 28 41 36 / 50 60 60 60 100 100
KELLOGG 37 27 36 28 41 38 / 60 70 80 60 100 100
MOSES LAKE 48 26 47 32 54 41 / 10 10 0 10 30 50
WENATCHEE 44 28 45 32 48 39 / 20 20 10 40 80 80
OMAK 46 25 44 30 46 35 / 10 10 10 40 70 80
OTX WATCHES/WARNINGS/ADVISORIES
WA...WINTER STORM WARNING UNTIL 5 AM PDT TUESDAY FOR WESTERN CHELAN
COUNTY.
WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH FRIDAY
MORNING FOR WESTERN CHELAN COUNTY.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page