389
FXUS66 KOTX 160522
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
922 PM PST FRI NOV 15 2024
SYNOPSIS
DRIER CONDITIONS RETURN TODAY. 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
06Z TAFS: FOG AND STRATUS LIKELY TO BRING ISSUES TO GEG- SFF-
COE- LWS- PUW THROUGH THE PERIOD. THESES LOCATIONS CAN EXPECT
PERIODS WAVER BETWEEN IFR-MVFR CONDITIONS THROUGH THE PERIOD.
60-80% CHANCE OF REACHING PERIODS OF LIFR CONDITIONS FOR GEG-SFF-
COE-SFF- PUW THROUGH THE OVERNIGHT PERIOD. IN ADDITION ANOTHER
WINTER WEATHER FEATURE WILL SPREAD RAIN AND SNOW FROM WEST TO EAST
STARTING NEAR KEAT NEAR 00Z SUNDAY, KMWH NEAR 01Z SUNDAY, AND KGEG
AND VICINITY NEAR 02Z SUNDAY AND BEYOND. /PELATTI
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
CONFIDENCE IS LOW WITH THE FOG AND LOW STRATUS FORECAST AT TAFS
SITES FOR TONIGHT. MODEL GUIDANCE IS SPORADIC WITH COVERAGE OF LOW
CLOUD COVER AND IF THIS WILL RESULT IN LOW STRATUS OR FOG. THERE
IS BETTER CONSENSUS WITH MODERATE CONFIDENCE FOR MVFR CONDITIONS
WITH LOW STRATUS AT KPUW AND KLWS.
-----------------------
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 44 27 38 32 44 30 / 10 10 10 100 90 70
COEUR D'ALENE 44 30 37 32 42 31 / 10 20 10 100 100 90
PULLMAN 41 27 39 32 42 31 / 20 30 10 90 100 90
LEWISTON 47 33 46 38 51 35 / 10 20 0 70 90 70
COLVILLE 44 21 36 28 41 22 / 10 0 30 100 90 60
SANDPOINT 43 29 35 32 40 30 / 20 20 40 100 100 90
KELLOGG 42 31 36 31 39 32 / 20 30 30 90 100 100
MOSES LAKE 49 24 40 34 49 29 / 0 0 10 70 60 20
WENATCHEE 48 28 39 33 46 31 / 0 0 20 70 60 20
OMAK 47 27 38 31 42 25 / 10 0 30 80 60 30
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH MONDAY
AFTERNOON FOR WESTERN CHELAN COUNTY-WESTERN OKANOGAN COUNTY.
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