473
FXUS66 KOTX 152252
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
252 PM PST FRI NOV 15 2024
SYNOPSIS
DRIER CONDITIONS CONTINUE INTO SATURDAY MORNING. SNOW WILL RETURN
TO THE CASCADES DURING THE DAY SATURDAY AND SPREAD EASTWARD
SATURDAY NIGHT AND SUNDAY. HEAVY SNOW ACCUMULATIONS ARE EXPECTED
ON THE MOUNTAIN PASSES. THE WEATHER PATTERN FOR NEXT WEEK IS
TRENDING WETTER WITH POTENTIAL FOR SEVERAL ROUNDS OF
PRECIPITATION.
DISCUSSION
...HEAVY SNOW ON MOUNTAIN PASSES THIS WEEKEND. FIRST LOWLAND SNOW
POSSIBLE FOR SOME AREAS...
TONIGHT: AS THE WEAK SHORTWAVE CONTINUES TO MOVE EAST, LIGHT SHOWERS
WILL CONTINUE IN EASTERN WA AND THE ID PANHANDLE. THESE SHOWERS WILL
BRING LIGHT RAIN AND/OR GRAUPEL THAT WILL BE SHORT LIVED AS THEY
MOVE SOUTHEAST. WEAK RIDGING WILL BUILD IN BEHIND THIS SHORTWAVE
TONIGHT, WITH CLEARING SKIES AND LIGHT WINDS. TEMPERATURES WILL COOL
INTO THE 20S WITH AREAS OF FOG, SOME LOCALLY DENSE HEADING INTO
SATURDAY MORNING.
SATURDAY THROUGH MONDAY NIGHT: WINTER STORM WARNINGS HAVE BEEN
ISSUED FOR THE CASCADE PASSES AND LOOKOUT PASS, WITH ADDITIONAL
WINTER WEATHER ADVISORIES ALONG THE LEE OF THE CASCADES AND THE
NORTHEAST MOUNTAINS IN WA AND ID PANHANDLE.
MOUNTAINS: THIS SYSTEM WILL BRING 1 TO 3 FEET OF SNOW FOR THE
MOUNTAIN PASSES STARTING SATURDAY AFTERNOON. SNOW WILL FALL HEAVIEST
ON SATURDAY NIGHT WITH RATES UPWARDS OF 1 INCH AN HOUR AT TIMES.
OVERNIGHT INTO SUNDAY, WARM AIR ADVECTION WILL BRIEFLY SWITCH SNOW
TO RAIN AT STEVENS PASS, BUT A STRONG FRONTAL PASSAGE WILL
TRANSITION PRECIPITATION BACK TO SNOW BY EARLY SUNDAY AFTERNOON.
SNOW WILL CONTINUE THROUGH THE DAY ON SUNDAY AND WILL BEGIN TO TAPER
OFF IN THE MOUNTAINS MONDAY EVENING. FOLLOWING THE FRONTS PASSAGE ON
SUNDAY, A PUGET SOUND CONVERGENCE ZONE IS LIKELY TO FORM, PERSISTING
INTO MONDAY MORNING. SNOWFALL WILL MAKE TRAVEL CHALLENGING THROUGH
THE CASCADES AND LOOKOUT PASS.
LOWER ELEVATIONS: THE LOWER ELEVATIONS WILL SEE THEIR FIRST CHANCE
OF SNOW SATURDAY NIGHT AHEAD OF WARM AIR ADVECTION THAT ARRIVES
EARLY SUNDAY MORNING. PRECIPITATION WILL MAINLY FALL AS SNOW ABOVE
1500 FEET WHEN IT ARRIVES SATURDAY EVENING, WITH HIGHEST SNOW
ACCUMULATIONS ON GRASSY SURFACES AS ROADS WILL REMAIN WARM.
PROBABILITIES FOR 2 INCHES OR MORE OF SNOW ARE HIGHEST NORTH OF
SPOKANE (SPOKANE: 0%, SANDPOINT: 50%, DEER PARK: 15%, REPUBLIC: 30%,
NEWPORT: 50%, METALINE: 75%). BEFORE THE SUN RISES ON SUNDAY,
ANTICIPATE SNOW TO TRANSITION TO RAIN. RAIN WILL CONTINUE AT
ELEVATIONS BELOW 3000 FEET THROUGH THE DAYTIME HOURS, RETURNING TO
SNOW OVERNIGHT IN THE NORTHERN MOUNTAINS AND ID PANHANDLE. CENTRAL
WA IS FORECASTED TO RECEIVE 0.10 TO 0.50 INCHES OF RAIN, WHILE
EASTERN WA AND ID PANHANDLE WILL SEE 0.75 TO 1.25 INCHES.
CHANCE OF SNOW : 6” 12” 24” 36” SAT PM-MON PM:
-----------------------------------------------
STEVENS PASS : 100% 95% 45% 15%
WASHINGTON PASS: 100% 100% 50% 5%
SHERMAN PASS : 60% 5% 0% 0%
LOOKOUT PASS : 100% 75% 15% 0%
WINDS WILL ALSO INCREASE ON SUNDAY AFTERNOON IN THE COLUMBIA BASIN
AND PALOUSE AREA, WITH SOUTHERLY GUSTS UP TO 35 MPH, DECREASING
SLIGHTLY SUNDAY NIGHT. WINDS WILL CONTINUE TO BE BREEZY WITH GUSTS
TO 25 MPH MONDAY. /KM
TUESDAY THROUGH FRIDAY: THE ENSEMBLES HAVE THROWN A WRENCH INTO THE
FORECAST. AS STATED IN THE PREVIOUS AFD, THE TRENDS ARE STARTING TO
PUSH THE APEX OF THE RIDGE MORE OVER THE ROCKIES. A GULF OF ALASKA
LOW IS LOOKING TO BRING ANOTHER WARM MOISTURE PLUME ACROSS THE
REGION. PREVIOUS FORECASTS HAD A STABLE DRY PERIOD OVER THE PACIFIC
NORTHWEST. THE CURRENT TREND BRINGS A STEADY STREAM OF MOUNTAIN SNOW
AND LOWLAND RAIN ACROSS THE REGION. THE HEAVIEST SNOW PERIOD IS
LOOKING TO BE TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING. THE
CASCADES COULD SEE ANOTHER 8 TO 12 INCHES, WHILE THE REST OF THE
MOUNTAINS COULD GET 3 TO 6 INCHES. THE EARLY MORNING TIME FRAME DOES
HAVE SOME SNOW REACHING BASIN AND VALLEY FLOORS. AMOUNTS FOR THESE
AREA EXPECTED TO BE UP TO 2 INCHES. RAIN AMOUNTS ARE EXPECTED TO BE
A QUARTER TO HALF AN INCH. ENSEMBLES CONTINUE THE WARM PUSH OF
MOISTURE THROUGH THE END OF THE WEEK. A DECENT PRESSURE GRADIENT
WILL KEEP THINGS BREEZY ACROSS THE THE BASIN WITH SUSTAINED INTO THE
TEENS AND GUSTS INTO THE 20 TO 30 MPH RANGE. HIGHS WILL BE IN THE
30S TO LOW 40S. OVERNIGHT LOWS WILL BE IN THE 20S TO LOW 30S. /JDC
AVIATION
18Z TAFS: MIXING HAS ALLOWED FOG DEVELOP OVER GEG-SFF-COE AND
NORTHERN VALLEYS. MVFR CONDITIONS ARE EXPECTED AT KPUW AND KLWS
INTO THE AFTERNOON AS LIGHT NORTHWESTERLY FLOW IN THE BOUNDARY
LAYER SHOULD POOL MOISTURE INTO THESE TERMINALS. EXPECTING A
SIMILAR SITUATION LEADING UP TO 12Z TOMORROW WHERE NOT MUCH FOG
FORMS BUT THE BOUNDARY LAYER MOISTURE IS MODELED TO DEEPEN AHEAD
OF CIRRUS CLOUD COVER FOR KGEG-KSFF.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
CONFIDENCE IS LOW WITH THE FOG AND LOW STRATUS FORECAST AT TAFS
SITES THIS MORNING AND LATER TONIGHT. MODEL GUIDANCE IS SPORADIC
WITH COVERAGE OF LOW CLOUD COVER AND IF THIS WILL RESULT IN LOW
STRATUS OR FOG.
-----------------------
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 26 39 31 44 29 39 / 20 30 100 100 70 60
COEUR D'ALENE 29 38 31 42 31 37 / 30 30 100 100 90 80
PULLMAN 26 40 31 42 29 38 / 50 10 100 100 90 90
LEWISTON 34 46 38 51 35 44 / 40 10 90 100 90 70
COLVILLE 20 38 25 43 20 37 / 10 40 100 90 70 50
SANDPOINT 28 36 29 41 30 35 / 30 50 100 100 100 90
KELLOGG 32 36 32 40 32 34 / 50 50 100 100 100 100
MOSES LAKE 24 41 32 50 26 44 / 0 20 90 70 30 10
WENATCHEE 29 38 33 48 30 42 / 0 30 90 70 40 10
OMAK 27 40 30 47 26 39 / 10 40 90 70 30 10
OTX WATCHES/WARNINGS/ADVISORIES
ID...WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 10 PM PST MONDAY
FOR NORTHERN PANHANDLE.
WINTER WEATHER ADVISORY FROM 10 PM SATURDAY TO 10 PM PST MONDAY
FOR IDAHO PALOUSE.
WINTER STORM WARNING FROM 10 PM SATURDAY TO 10 PM PST MONDAY FOR
CENTRAL PANHANDLE MOUNTAINS.
WA...WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 10 AM PST MONDAY
FOR NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS.
WINTER WEATHER ADVISORY FROM 10 AM SATURDAY TO 10 PM PST SUNDAY
FOR CENTRAL CHELAN COUNTY.
WINTER STORM WARNING FROM 10 AM SATURDAY TO 10 PM PST MONDAY FOR
WESTERN CHELAN COUNTY-WESTERN OKANOGAN COUNTY.
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