622
FXUS66 KOTX 171805
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1005 AM PST TUE DEC 17 2024
SYNOPSIS
ANOTHER WEATHER SYSTEM WILL MOVE IN TODAY WITH A SLOW RISE IN SNOW
LEVELS. SNOW WILL MAINLY ACCUMULATE OVER HIGH MOUNTAINS AND IN
NORTH-CENTRAL WASHINGTON INCLUDING THE EASTERN CASCADE VALLEYS.
FREEZING RAIN IS EXPECTED ACROSS PORTIONS OF THE CASCADES AND
WATERVILLE PLATEAU THIS EVENING AND THEN SHIFT INTO PORTIONS OF
NORTHERN WA OVERNIGHT. WINDS WILL BECOME BREEZY TO LOCALLY WINDY
WEDNESDAY AFTERNOON. THE REST OF THE WEEK WILL FEATURE MILD
TEMPERATURES AND INTERMITTENT LIGHT PRECIPITATION PRIMARILY
CONFINED TO THE NORTHERN MOUNTAINS.
DISCUSSION
THE NEXT WEATHER SYSTEM IS MOVING INTO WESTERN WA NOW. THERE HAVE
BEEN SOME LIGHT SHOWERS OCCURRING OVER STEVENS PASS THROUGH THE
NIGHT. THE MAIN BAND OF PRECIPITATION WILL NOT MOVE INTO UNTIL
AFTER 8 OR 9 AM. BUT GIVEN THE SHOWER ACTIVITY, DECIDED TO KEEP
THE ADVISORY TIME AS IS TO ACCOUNT FOR THE SHOWERS. SNOW WILL MOVE
INTO CENTRAL WA MID MORNING AND CONTINUE THROUGH THE AFTERNOON.
AFTER ABOUT 4PM THE THREAT OF FREEZING RAIN WILL ENTER THE
CASCADES OF CHELAN COUNTY. (IT WILL BE A FEW HOURS EARLIER SOUTH
IN KITTITAS COUNTY AND SNOQUALMIE) THE FREEZING RAIN WILL SPREAD
NORTH AND EAST THROUGH THE EVENING MOVING INTO DOUGLAS AND
OKANOGAN COUNTIES. OVERNIGHT THE THREAT MOVES INTO NORTHERN WA AS
WELL, BUT ACCUMULATIONS OF ICE WILL BE LESS. ACCUMULATIONS IN THE
CASCADES VARY. MOST LOCATIONS WILL SEE LESS THAN A TENTH OF AN
INCH. THIS FALLING ON TOP OF THE SNOW THAT FALLS THROUGH THE
AFTERNOON WILL PROVIDE LESS OF AN IMPACT. AN AREA OF PARTICULAR
CONCERN WILL BE FROM COLES CORNER UP TO STEVENS PASS, WHERE THEY
COULD SEE A QUARTER OF AN INCH, AND SOME LOCALIZED SPOTS IN THAT
AREA COULD SEE MORE. THE METHOW VALLEY AND THE WATERVILLE PLATEAU
COULD SEE 0.05 TO 0.20. MOST OTHER LOCATIONS WILL SEE A LIGHT
GLAZE TO 0.05.
SNOW AMOUNTS IN THE MOUNTAINS WILL RANGE FROM 5 TO 8 INCHES IN THE
CASCADES, ABOUT 5 INCHES OVER SHERMAN, AND 2 TO 4 FOR LOOKOUT.
MEANWHILE OTHER VALLEYS AND LOWLANDS WILL SEE RAIN OR BRIEF SNOW
TRANSITIONING TO RAIN DURING THE AFTERNOON.
WEDNESDAY GIVEN THE WARM SOUTHERLY FLOW ACROSS THE REGION SNOW
WILL BE CONFINED TO MOST AREAS ABOVE 4K FT. TEMPERATURES WILL
WARM INTO THE 40S, WITH MID 50S FOR THE LC VALLEY. WINDS WILL
INCREASE DURING THE MORNING WITH LATE MORNING AND AFTERNOON GUSTS
30 TO 40 MPH ACROSS PORTIONS OF THE EASTERN COLUMBIA BASIN ONTO
THE WEST PLAINS AND PALOUSE. GUSTS AROUND ALPOWA SUMMIT AND THE
BLUE MOUNTAINS WILL BE STRONGER...45 TO 50 MPH. WINDS WILL
DECREASE THROUGH THE EVENING. WEDNESDAY NIGHT WE WILL SEE A BREAK
IN PRECIPITATION. THE VALLEYS WILL SEE SOME LOW CLOUDS AND FOG.
/NISBET
THURSDAY THROUGH TUESDAY: A STRENGTHENING RIDGE OVER CENTRAL
CONUS WILL KEEP THE PACIFIC NORTHWEST UNDER WARM SOUTHWEST FLOW
PATTERN. SEVERAL SYSTEMS WILL PUSH THROUGH THE INLAND NORTHWEST
GENERATING DECENT PRECIP FOR THE PERIOD. THE WARM AIR DOES NOT
LEAD TO A GOOD SNOW SETUP FOR ELEVATIONS BELOW 4000FT. THE PERIOD
WILL MAINLY BE A MOUNTAIN SNOW AND LOWLAND RAIN. ENSEMBLES ARE
EXPECTING LIGHT MOUNTAIN SHOWER ACTIVITY THURSDAY AND FRIDAY
BEFORE A MORE WIDESPREAD PRECIP EVENT ON SATURDAY. IT WILL THEN BE
FOLLOWED BY A COLD FRONT LATE SUNDAY, EARLY MONDAY THAT WILL
WEAKEN THE RIDGE. IT WILL BRING ANOTHER ROUND OF WIDESPREAD
MOUNTAIN SNOW AND LOWLAND RAIN. DEPENDING ON THE PRECIP FALLING
DURING THE DAY OR NIGHT, LOWLAND AREAS NORTH OF HWY 2 COULD
RECEIVE SNOW OVERNIGHT. ISOLATED POCKETS OF FREEZING RAIN ARE
POSSIBLE IN THE CASCADE VALLEYS BUT PROBABILITIES OF MORE THAN A
TRACE ARE LESS THAN 30%. HIGHS FOR THE PERIOD WILL BE IN THE 30S
TO LOW 40S. LOWS WILL BE IN THE 20S TO LOW 30S. /JDC
AVIATION
18Z TAFS: PRECIPITATION WILL SPREAD ACROSS CENTRAL AND EASTERN
WASHINGTON (AND EVENTUALLY N ID) THRU THE MORNING AND PICK UP IN
INTENSITY THROUGH THE AFTERNOON. THOUGH SNOW FOR MANY LOCATIONS
EARLY, SNOW LEVELS WILL RISE LATER TODAY WITH PRIMARILY RAIN
EXPECTED, THOUGH AREAS OF -FZRA WILL BE POSSIBLE DURING THE
TRANSITION. INCREASING SOUTHWEST WINDS AFTER 09Z WEDNESDAY.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: FZRA MENTIONED
FOR KEAT AND HAVE MODERATE CONFIDENCE FOR IT TO OCCUR. THERE IS A
HIGHER CONFIDENCE OF FREEZING RAIN ACROSS THE CASCADES DURING THE
EVENING AND OVERNIGHT.
-----------------------
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 39 34 46 31 38 32 / 60 90 80 0 10 10
COEUR D'ALENE 37 35 45 31 39 32 / 40 90 90 0 10 20
PULLMAN 39 35 46 31 40 33 / 50 80 90 0 0 10
LEWISTON 44 40 54 34 44 36 / 40 70 70 0 0 0
COLVILLE 33 29 43 24 35 30 / 50 100 90 0 20 20
SANDPOINT 34 33 42 29 37 31 / 40 90 100 0 10 30
KELLOGG 37 35 43 32 39 33 / 30 90 100 10 10 20
MOSES LAKE 38 35 47 30 40 33 / 80 80 20 0 10 10
WENATCHEE 33 33 44 29 36 32 / 100 100 40 0 10 10
OMAK 33 32 44 27 35 32 / 80 100 50 0 10 20
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...WINTER WEATHER ADVISORY UNTIL 4 AM PST WEDNESDAY FOR
OKANOGAN HIGHLANDS-OKANOGAN VALLEY-WESTERN OKANOGAN COUNTY.
WINTER WEATHER ADVISORY UNTIL 4 AM PST WEDNESDAY FOR CENTRAL
CHELAN COUNTY-WATERVILLE PLATEAU-WENATCHEE AREA-WESTERN
CHELAN COUNTY.
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