258
FXUS66 KOTX 091312
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
512 AM PST FRI DEC 9 2022
SYNOPSIS
ONE WEATHER SYSTEM WILL MOVE OUT OF NORTH IDAHO TODAY AS ANOTHER
ONE MOVES INTO THE CASCADES LATER THIS AFTERNOON. MODERATE TO
HEAVY SNOW IS LIKELY FRIDAY NIGHT INTO SATURDAY FOR CENTRAL
WASHINGTON AND PARTS OF NORTHEAST WASHINGTON AS WELL. NEXT WEEK
WILL FEATURE VERY COLD TEMPERATURES ACROSS THE INLAND NORTHWEST.
DISCUSSION
TODAY THROUGH SATURDAY NIGHT : RADAR SHOWS SNOW CONTINUING ACROSS
THE IDAHO PANHANDLE THIS MORNING. THE MAIN BAND OF SNOW WILL BE
OUT OF IDAHO LATE THIS MORNING, BUT THERE COULD STILL BE SOME
MOUNTAIN SHOWERS THROUGH THE AFTERNOON. THE NEXT WEATHER SYSTEM
WILL MOVE ONTO THE WEST COAST THIS AFTERNOON AND BRING MODERATE TO
HEAVY SNOW AMOUNTS TO PARTS OF CENTRAL AND NORTHEAST WASHINGTON.
SNOW WILL BEGIN IN THE CASCADES BY THE LATE AFTERNOON AND THEN
SPREAD EAST THROUGH THE EVENING HOURS. WITH THE LOW OFFSHORE, THIS
WILL PROVIDE GOOD UPSLOPE FLOW INTO THE CASCADES. HREF MODEL AND
SPC SREF IS POINTING AT AN INCH AN HOUR RATES FOR THE CASCADES
TONIGHT. THE HEAVY SNOW WILL BE FOCUSED IN THE CASCADES TONIGHT,
AND THEN TRANSITION SATURDAY TO PARTS OF CENTRAL AND NE WA. THE
FOCUS OF HIGHEST QPF AND THEREFORE SNOWFALL IS CENTERED AROUND THE
HIGHWAY 2 CORRIDOR FROM SPOKANE WESTWARD ONTO THE WATERVILLE
PLATEAU. THE DIFFICULT PART OF THE FORECAST IS HOW FAR NORTH
POSSIBLE WARM AIR WILL REACH. THIS IS THE BIG QUESTION FOR THE
SPOKANE AREA. THE EC IS THE MOST BULLISH, WHEREAS THE GFS KEEPS
SPOKANE ALL SNOW. NAM CHANGES SPOKANE OVER TO RAIN AROUND NOON
SATURDAY. DO HAVE MENTION IN THE AFTERNOON OF A RAIN/SNOW MIX OR
JUST PLAIN RAIN.
SNOW AMOUNTS WILL VARY BY LOCATION, WITH CENTRAL WA INTO NE WA AND
PARTS OF NORTH ID SEEING THE MOST. HAVE UPGRADED THE WATCHES TO
WARNINGS. THE MOUNTAINS COULD SEE 10 TO 20 INCHES WITH THE VALLEYS
SEEING 4 TO 10 INCHES. THE NUMBERS VARY BY LOCATION, WITH
LOCATIONS ALONG THE RIVERS LIKELY SEEING THE LOWER END. THE
HIGHWAY 2 CORRIDOR FROM SPOKANE WESTWARD WILL VARY AS
WELL...SEEING 3 TO 10 INCHES WITH 3 INCHES FOR SPOKANE WHERE WE
COULD TRANSITION TO RAIN BRIEFLY SATURDAY, AND UPWARDS OF 10
INCHES OR MORE FOR WATERVILLE ON THE WATERVILLE PLATEAU. THE I-90
CORRIDOR SOUTHWEST OF SPOKANE WILL SEE LIGHTER AMOUNTS...GENERALLY
1 TO 3 INCHES. SOMETHING TO WATCH WILL BE SNOW ON THE PALOUSE.
SOME OF THE HIGH RES MODELS AS WELL AS THE NAM BRINGS A LOT OF QPF
TO THAT AREA SATURDAY MORNING. CURRENTLY HAVE 3-4 INCHES FOR
PULLMAN, BUT ACCUMULATIONS COULD BE HIGHER IF THE WARM AIR IS SLOW
TO MAKE IT THERE, AS WELL AS IF PRECIP AMOUNTS ARE HIGHER THAN
WHAT WE CURRENTLY HAVE. /NISBET
SUNDAY THROUGH FRIDAY: THE DEEP UPPER LEVEL LOW CONTINUES TO
SLIDE SOUTHWARD LEAVING THE NORTHWEST IN A DEFORMATION ZONE
BETWEEN A WEAK TROUGH IN NORTHERN BRITISH COLUMBIA AND A
STRENGTHENING RIDGE IN ALASKA. ENSEMBLES WILL PUSH THAT RIDGE INTO
BC AS WE START THE NEW WORK WEEK WITH OUR COLD LOW MOVING SOUTH
AND EAST. WHAT'S INTERESTING IS THE RIDGE BEGINS TO EVOLVE AND
BECOMES CENTERED OVER JUNEAU, AK WHICH WILL TURN THE MEAN FLOW OUT
OF THE NORTH FOR THE PACIFIC AND INLAND NORTHWEST.
THIS OPEN DOOR FOR NORTHERLY FLOW WILL BEGIN MONDAY AND CONTINUE
THROUGH THE WEEK. WHILE THE FORECAST LOOKS RATHER DRY AFTER SUNDAY
EVENING, WITH PRECIPITABLE WATER 40-60% OF NORMAL TUE-THU, CLOUD
COVER SHOULD BE MUCH LESS BY MID WEEK. GIVEN THE CURRENT SNOWCOVER
ON THE GROUND AND MORE ANTICIPATED FOR THE COMING SATURDAY STORM,
OUR TEMPERATURES WILL LIKELY TAKE A NOSE DIVE NEXT WEEK. RIGHT
NOW THE NBM GIVES SPOKANE A 60% PROBABILITY OF SEEING MIN
TEMPERATURES TUESDAY BELOW 20F. THE LOW END FORECAST OF 14F FOR A
LOW IS THE 10TH PERCENTILE FOR BOTH THE 4.0 AND 4.1 VERSION OF
NBM. CPC PROBABILISTIC OUTLOOK IS ON BOARD AS WELL WITH A HIGH
RISK OF MUCH BELOW NORMAL TEMPERATURES. FOR A REFERENCE, OMAK'S
NORMAL LOW TEMPERATURE IS 24F, SPOKANE IS 25F. SPEAKING OF OMAK,
THE NBM GIVES A 15% PROBABILITY OF SEEING A LOW TEMPERATURE
TUESDAY OF 10F OR COLDER.
SUFFICE TO SAY, NEXT WEEK LOOKS DRY AND SNOW-FREE, HOWEVER IT WILL
BE VERY COLD WITH OUR SNOW ON THE GROUND AND SOME CLEAR, CLOUD-FREE
DAYS FROM MID-WEEK INTO LATE WEEK. /DEWEY
AVIATION
12Z TAFS: KMWH/KEPH/KEAT WILL SEE VLIFR VIS AND CIGS WITH
IMPROVEMENTS AFT 18Z FOR KEAT. NOT AS CONFIDENT IN IMPROVEMENTS
FOR KEPH & KMWH. THEY MAY REMAIN IN VLIFR UNTIL THE SNOW BEGINS
AFT 03Z. SNOW MOVES INTO THE CASCADES AFT 00Z AND WILL SPREAD
EASTWARD THROUGH THE NIGHT...REACHING KGEG/KSFF/KCOE/KPUW BTWN
08-10Z. SNOWFALL INTENSITY WILL BE HEAVY AT TIMES OVERNIGHT IN
THE CASCADES.
PRELIMINARY POINT TEMPS/POPS
SPOKANE 31 25 35 27 35 21 / 10 80 100 40 30 10
COEUR D'ALENE 32 24 34 28 36 22 / 20 50 90 60 20 10
PULLMAN 32 24 35 27 35 25 / 20 60 100 20 30 20
LEWISTON 37 30 42 32 39 31 / 10 50 70 20 40 30
COLVILLE 29 20 33 24 38 14 / 0 80 90 60 20 10
SANDPOINT 31 25 31 28 35 23 / 20 60 100 70 30 10
KELLOGG 32 24 36 30 37 26 / 60 30 80 60 40 20
MOSES LAKE 31 24 36 26 35 17 / 10 100 90 30 30 10
WENATCHEE 27 23 32 27 35 24 / 10 100 100 30 30 10
OMAK 27 22 32 28 35 20 / 10 100 90 40 20 0
OTX WATCHES/WARNINGS/ADVISORIES
ID...WINTER STORM WARNING FROM 10 PM THIS EVENING TO 5 AM PST SUNDAY
FOR NORTHERN PANHANDLE.
WA...WINTER STORM WARNING FROM 10 PM THIS EVENING TO 5 AM PST SUNDAY
FOR NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS.
WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 7 PM PST
SATURDAY FOR OKANOGAN VALLEY-WATERVILLE PLATEAU-WENATCHEE
AREA.
WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM PST
SATURDAY FOR CENTRAL CHELAN COUNTY-WESTERN CHELAN COUNTY-
WESTERN OKANOGAN COUNTY.
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