451
FXUS66 KOTX 202309
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
309 PM PST WED NOV 20 2024
SYNOPSIS
THURSDAY WILL BE CLOUDY WITH PERIODS OF RAIN AND MOUNTAIN SNOW.
FRIDAY WILL BE QUITE WET WITH THE ARRIVAL OF A STRONG WARM FRONT
CAUSING SNOW LEVELS TO RISE ABOVE MOST MOUNTAIN PASSES BY FRIDAY
AFTERNOON. THE WEEKEND INTO EARLY NEXT WEEK WILL FEATURE
SEASONABLY COOL TEMPERATURES AND CHANCES FOR RAIN MAINLY IN THE
VALLEYS AND PERIODS OF MOUNTAIN SNOW.
DISCUSSION
TONIGHT: A MOIST FRONTAL BOUNDARY WILL STALL ACROSS NORTH IDAHO
AND THE EASTERN THIRD OF WASHINGTON TONIGHT PRODUCING WIDESPREAD
PRECIPITATION. FORCING ALONG THE FRONT WILL BE RELATIVELY WEAK, SO
RAIN AND MOUNTAIN SNOW AMOUNTS WON'T BE AS IMPRESSIVE AS THEY WERE
LAST NIGHT (TUE NIGHT). AMOUNTS OF A TENTH TO QUARTER OF AN INCH
WILL BE COMMON ACROSS THE WEST PLAINS INTO THE LOWLANDS OF
NORTHEAST WASHINGTON AND FAR NORTH IDAHO. SNOW LEVELS ALONG THE
CANADIAN BORDER WILL DROP AS LOW AS 2000-2500 FEET PROMOTING
ACCUMULATIONS UP TO 2 INCHES AROUND METALINE, PRIEST LAKE, AND THE
TERRAIN BETWEEN KETTLE FALLS AND NORTHPORT. THE WINTER STORM
WARNING FOR THE OKANOGAN HIGHLANDS HAS BEEN EXTENDED THROUGH 11 PM
FOR ADDITIONAL ACCUMULATIONS OF 1 TO 3 INCHES FOR SHERMAN AND
WAUCONDA PASSES. THE MOUNTAINOUS TERRAIN OF NORTHEAST WASHINGTON
AND NORTH IDAHO SHOULD GET EVEN MORE ACCUMULATION OVERNIGHT WITH 2
TO 4 INCHES FOR STEVEN AND PEND ORIELLE COUNTIES, AND 4 TO 6 FOR
THE HIGH TERRAIN AROUND BONNERS FERRY AND SANDPOINT. THE CLOUDS
AND MILD SOUTHERLY FLOW ALOFT WILL KEEP OUR LOWS RELATIVELY MILD
WITH MOST OF THE INLAND NORTHWEST IN THE 30S THROUGH THE NIGHT.
THURSDAY: A GLOOMY AND CLOUDY DAY WITH PERIODS OF LIGHT RAIN IS
IN STORE FOR THE INLAND NORTHWEST ON THURSDAY. THE LARGE TROUGH
OFF-SHORE WILL CONTINUE TO FEED THE REGION WITH SUBTROPICAL
MOISTURE. AT LEAST TEMPERATURES WILL BE MILD WITH HIGHS IN THE
40S FOR THE COLUMBIA BASIN, EASTERN THIRD OF WASHINGTON, AND THE
LOWLANDS OF NORTH IDAHO.
FRIDAY: ANOTHER VIGOROUS LOW PRESSURE SYSTEM WILL FOLLOW A SIMILAR
TRACK TO TUESDAY'S "LOW PRESSURE BOMB" AND DELIVER ANOTHER DOSE OF
WIDESPREAD LIGHT TO MODERATE PRECIPITATION. THIS STORM WON'T BE AS
DYNAMIC AND IT WILL BE A WARMER SYSTEM. WITH THE EXCEPTION OF THE
METHOW VALLEY, THE UPPER END OF LAKE CHELAN, AND POSSIBLY SPOTS
ABOVE LEAVENWORTH OUR LOWLANDS WILL RECEIVE PRIMARILY RAIN.
TEMPERATURES IN THE METHOW VALLEY AREN'T HANDLED PARTICULARLY WELL
BY THE MODELS THAT LARGELY COMPRISE THE NATIONAL BLEND OF MODELS
(NBM). THE HIGH RESOLUTION ENSEMBLE FORECAST (HREF) CURRENTLY GOES
OUT THROUGH EARLY FRIDAY MORNING AND GENERATES SNOW FOR THE METHOW
WHICH IS SIMILAR TO THE OPERATIONAL NAM AND GFS SOLUTIONS. AT THIS
TIME IT LOOKS LIKE A 2 TO 4 INCH WET SNOW FOR THE METHOW FRIDAY
MORNING WITH A CHANGE TO RAIN BY THE AFTERNOON. /GKOCH
SATURDAY THROUGH TUESDAY: THE INLAND NORTHWEST WILL REMAIN IN AN
UNSETTLED PATTERN THROUGH EARLY NEXT WEEK AS A BROAD UPPER LEVEL LOW
SITS OFFSHORE. MODELS ARE IN GENERAL AGREEMENT FOR ROUNDS OF
SHORTWAVES TO ROTATE AROUND THE BASE OF THE LOW THE PACIFIC
NORTHWEST. SNOW LEVELS WILL GRADUALLY DECREASE UNDER THE INFLUENCE
OF THIS TROUGH WITH PERIODS OF MOUNTAIN SNOW AND LOWLAND RAIN/SNOW.
LOOKING AT BIT CLOSER AT THE SATURDAY TO SUNDAY TIMEFRAME, RECENT
RUNS OF DETERMINISTIC MODELS (ECMWF/NAM) DEPICT A STRONGER SHORTWAVE
MOVING INTO THE INLAND NORTHWEST, WHERE THE GFS AND CANADIAN FOCUS
THE STRONGEST ENERGY TO OUR SOUTH AND EAST. A MORE NORTHWARD TRACK
WOULD BRING ANOTHER ROUND OF HEAVIER PRECIPITATION ACROSS EASTERN
WASHINGTON AND NORTH IDAHO AND A MORE TO THE SOUTH AND EAST SOLUTION
WOULD RESULT IN DRIER CONDITIONS OVER EASTERN WASHINGTON THROUGH
SUNDAY. WITH THAT SAID, THE NBM CURRENTLY IS GIVING FAR EASTERN
WASHINGTON AND NORTH IDAHO A 40 TO 60 PERCENT CHANCE FOR OVER 0.10
INCHES OF RAIN THROUGH SUNDAY.
WITH SIGNIFICANT DIFFERENCES IN THE FINER DETAILS OF THE UPPER LEVEL
FLOW PATTERN, THE MAIN MESSAGE FOR THE LATTER HALF OF THE WEEK WILL
REMAIN BROAD FOR NOW. MODELS ARE DEPICTING THE BROAD LOW OFFSHORE TO
FINALLY MOVE INLAND BY THE LATE TUESDAY TO WEDNESDAY TIMEFRAME, BUT
WHETHER IT SHIFTS INTO THE PACIFIC NORTHWEST OR TAKES A DIVE INTO
NORTHERN CALIFORNIA REMAINS UNCERTAIN. /VMT
AVIATION
18Z TAFS: WITH THE REGION IN A DRY SLOT OF THE SYSTEM, IMPROVING
VISIBILITY AND CEILING ARE OCCURRING. RISING SNOW LEVELS TONIGHT
AND A WARM FRONT PASSAGE WILL LEAD TO ADDITIONAL RAINS AT THE
TERMINALS BRINGING IFR/MVFR CEILINGS AROUND 3-9Z. WITH THE LOW
REMAINING IN THE REGION, SHOWER ACTIVITY WILL CONTINUE ACROSS THE
REGION WITH MVFR/IFR CEILINGS THROUGH THURSDAY MORNING.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
CONFIDENCE IS HIGH FOR SNOW WITH IFR CONDITIONS THIS MORNING
CONFIDENCE IS ALSO HIGH THAT KMWH-KGEG- KSFF-KCOE WILL SEE
CEILINGS LIFT TO BETWEEN 2-4 KFT WITH MVFR CONDITIONS. LOW
CONFIDENCE ON THE MVFR/IFR CONDITIONS ON THURSDAY MORNING.
-----------------------
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 35 44 37 48 37 43 / 90 60 60 100 80 30
COEUR D'ALENE 35 44 37 48 36 42 / 100 60 70 100 90 50
PULLMAN 37 45 39 49 35 42 / 70 70 80 90 90 50
LEWISTON 42 51 44 55 39 48 / 40 40 70 80 80 40
COLVILLE 32 40 32 42 32 41 / 90 60 60 100 80 40
SANDPOINT 33 40 35 42 35 39 / 100 90 80 100 90 70
KELLOGG 33 43 40 46 36 39 / 100 90 80 100 100 80
MOSES LAKE 36 46 38 49 35 44 / 70 50 70 90 40 10
WENATCHEE 34 38 36 42 32 42 / 40 50 70 90 20 10
OMAK 33 38 34 41 33 43 / 60 50 60 90 50 10
OTX WATCHES/WARNINGS/ADVISORIES
ID...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHERN PANHANDLE.
WINTER WEATHER ADVISORY UNTIL 7 AM PST THURSDAY FOR CENTRAL
PANHANDLE MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST MOUNTAINS.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR OKANOGAN
HIGHLANDS.
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