254
FXUS66 KOTX 172325
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
325 PM PST SUN NOV 17 2024
SYNOPSIS
A COLD FRONT MOVING THROUGH THE REGION WILL TURN PRECIPITATION
MORE SHOWERY WITH MOUNTAIN SNOW SHOWERS CONTINUING THROUGH EARLY
TUESDAY. WEATHER WILL REMAIN UNSETTLED THROUGH THE WEEK WITH THE
NEXT WINTER STORM TUESDAY NIGHT INTO WEDNESDAY BRINGING ANOTHER
ROUND OF WIDESPREAD SNOW. THIS WILL RESULT IN MODERATE TO MAJOR
IMPACTS ACROSS CENTRAL WASHINGTON AND MINOR IMPACTS FOR EASTERN
WASHINGTON AND NORTH IDAHO. ADDITIONAL SYSTEMS PASSING THROUGH
THURSDAY THROUGH NEXT WEEKEND WILL BRING ADDITIONAL PERIODS OF
LOWLAND RAIN AND MOUNTAIN SNOW.
DISCUSSION
THROUGH TUESDAY:
A COLD FRONTAL PASSAGE IS CURRENTLY BRINGING MOUNTAIN SNOW AND
VALLEY RAIN TO PORTIONS OF THE INLAND NORTHWEST. SNOW WILL
CONTINUE IN THE CASCADES AND IDAHO PANHANDLE MOUNTAINS WHERE
WINTER STORM WARNINGS REMAIN IN EFFECT THROUGH MONDAY. PRIMARY
IMPACTS WILL BE ACROSS STEVENS, BLEWETT, AND LOOKOUT PASSES.
LOCALLY BREEZY SOUTHERLY WINDS WILL PERSIST INTO THIS EVENING AS
WELL. OUTSIDE OF THE MOUNTAINS, A BREAK IN ANY HEAVIER PRECIP IS
LIKELY MONDAY INTO MONDAY NIGHT FOR THE LOWER TERRAIN OF CENTRAL
AND EASTERN WASHINGTON. A DISTURBANCE WILL LIKELY BRING LIGHT SNOW
TO THE FORECAST AREA TUESDAY, AND COULD AFFECT THE MORNING
COMMUTE AS WELL. THOUGH AMOUNTS ARE ANTICIPATED TO BE LIGHT, SNOW
LEVELS WOULD BE LOW ENOUGH TO SUPPORT SNOW FOR MOST COMMUNITIES.
/KD
TUESDAY NIGHT THROUGH WEDNESDAY: MODELS CONTINUE TO REMAIN IN GOOD
AGREEMENT IN A LOW PRESSURE UNDERGOING EXPLOSIVE CYCLOGENESIS AS
IT NEARS THE WASHINGTON COAST ON TUESDAY AND AMPLIFIES AN UPPER
LEVEL RIDGE OVER THE INTERIOR WESTERN US. DEEP SOUTHWEST FLOW
ALOFT WILL ALLOW AN ATMOSPHERIC RIVER TO TAKE AIM AT NORTHERN
CALIFORNIA AND SOUTHWESTERN OREGON TUESDAY NIGHT, WHICH IS A BIT
SHIFT SOUTHWARD COMPARED TO PREVIOUS FORECASTS. AS THIS LOW BEGINS
TO OCCLUDE TUESDAY NIGHT AND GRADUALLY SHIFTS NORTHWESTWARD, ITS
ASSOCIATED WARM FRONT WILL LIFT NORTH AND DRAW WARM, MOIST AIR
INTO EASTERN WASHINGTON AND NORTH IDAHO, RESULTING IN WIDESPREAD
MODERATE TO HEAVY PRECIPITATION.
THE SURFACE LOOKS TO START OFF QUITE DRY AND COLD TUESDAY EVENING
WITH DEW POINTS IN THE LOW TO MID 20S WHICH WILL LEAD TO SOME
COOLING AS THE COLUMN SATURATES FROM THE TOP DOWN. THE FOCUS FOR
AN ANOMALOUS SNOW EVENT WILL FOR THE CASCADES, THE EAST SLOPES,
THE WATERVILLE PLATEAU, OKANOGAN VALLEY AND HIGHLANDS AS A STRONG
EAST TO SOUTHEAST PRESSURE GRADIENT OF -14 TO 18 MB FROM SEA-GEG
WILL PROVIDE FAVORABLE UPSLOPE FLOW INTO THESE AREAS. THIS IS
CONSISTENT WITH THE ECMWF EXTREME FORECAST INDEX WHICH HIGHLIGHTS
THESE AREAS FOR AN ANOMALOUS SNOW EVENT TUESDAY NIGHT INTO
WEDNESDAY MORNING. PRECIPITATION WILL FALL AS SNOW ACROSS THE
UPPER COLUMBIA BASIN, NORTHEAST WASHINGTON, PALOUSE, SPOKANE AREA,
AND THE IDAHO PANHANDLE. WHILE THIS WILL PROVIDE THE MOST SNOW
SOME OF THESE LOWLAND AREAS HAVE SEEN SO FAR THIS YEAR, IT IS NOT
BEING HIGHLIGHTED AS PARTICULARLY ABNORMAL.
SNOW AMOUNTS: SNOW WILL INCREASE OVER THE CASCADES AND CENTRAL
WASHINGTON TUESDAY EVENING. STRONG UPSLOPE AND ISENTROPIC ASCENT
INTO THE EAST SLOPES SUGGEST PERIODS OF MODERATE TO HEAVY
SNOWFALL RATES FOR THESE AREAS BETWEEN 10 PM AND 4 AM. SNOW FALL
WILL SPREAD NORTHEAST INTO FAR EASTERN WASHINGTON AND THE IDAHO
PANHANDLE LATE TUESDAY NIGHT. AT THIS TIME, OUR FORECAST IS
CALLING FOR 6 TO 10 INCHES OF SNOW FOR THE CENTRAL WASHINGTON
VALLEYS AND 10 TO 15 INCHES FOR STEVENS, WASHINGTON, SHERMAN, AND
BLEWETT PASSES. THERE STILL REMAINS UNCERTAINTY IN THE EXACT
AMOUNTS FOR THE WENATCHEE AREA AS THE WINDS SHIFT TO THE SOUTH
WEDNESDAY MORNING. FURTHER EAST INTO THE SPOKANE AND COEUR D’ALENE
AREAS, AMOUNTS LOOK TO BE MUCH LESS COMPARED TO CENTRAL
WASHINGTON, BUT MODELS ARE SUGGESTING A 3 TO 5 HOUR PERIOD OF
MODERATE SNOW RATES DURING THE WEDNESDAY MORNING COMMUTE. BE
PREPARED FOR A SLICK DRIVE WEDNESDAY MORNING AS COLDER
TEMPERATURES WILL ALLOW FOR SNOW TO ACCUMULATE ON THE ROADS. WARM
AIR NOSING NORTH/NORTHEASTWARD WEDNESDAY LATE WEDNESDAY MORNING
INTO THE AFTERNOON WILL BRING A TRANSITION FROM SNOW TO RAIN
STARTING IN SOUTHEASTERN WASHINGTON AND WORKING ITS WAY EAST AND
NORTH WITH TIME.
WINDS: THE STRONG EAST TO SOUTHEAST PRESSURE GRADIENT DRAPED
ACROSS THE PACIFIC NORTHWEST WILL RESULT IN GUSTY WINDS FOR THE
CASCADES, THE UPPER COLUMBIA BASIN, THE PALOUSE, L-C VALLEY, AND
THE BLUES. RIDGES IN THE CASCADES AND BLUES HAVE A 40 TO 60
PERCENT CHANCE OF WIND GUSTS ABOVE 45 MPH TUESDAY NIGHT AND
WEDNESDAY. PARTICULARLY OVER THE CASCADES, THE HEAVY SNOWFALL
RATES AND STRONG WINDS WILL RESULT IN DIFFICULT TRAVEL OVER THE
PASSES.
THURSDAY THROUGH SATURDAY: FOR THE LATTER PART OF THE WEEK AND
INTO NEXT WEEKEND, MODELS CONTINUE TO SHOW AN EXTENDED PERIOD OF
UNSETTLED WEATHER AS A PERSISTENT PLUME OF MOISTURE TAKES AIM AT
THE WEST COAST. MODELS DEPICT THIS MOISTURE PLUME TO SHIFT
NORTHWARD LATE THURSDAY INTO FRIDAY AS ANOTHER LOW PRESSURE SYSTEM
MOVES NORTH ALONG THE WASHINGTON COAST. SNOW LEVELS LOOK TO
REMAIN ABOVE THE VALLEY FLOOR UNDER THE WARM, SOUTHWEST FLOW ALOFT
WITH SNOW REMAINING IN THE MOUNTAINS AND RAIN FOR THE LOWLANDS.
/VMT
AVIATION
00Z TAFS: PERIODS OF PRECIPITATION WILL CONTINUE THROUGH THE 24HR
TAF PERIOD. PRECIP SHOULD LESSEN IN INTENSITY AND COVERAGE
BETWEEN 03Z AND 18Z MONDAY, ESPECIALLY ACROSS THE LOWER ELEVATIONS
OF EASTERN WASHINGTON AND NORTH IDAHO. BETTER CHANCES RETURN
AGAIN MONDAY AFTERNOON. LOCALLY BREEZY SSW WINDS CONTINUE INTO
MONDAY AS WELL, ESPECIALLY SOUTHEAST OF A KGEG-KMWH LINE. /KD
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
CONFIDENCE IS HIGH FOR AREAS OF IFR/MVFR CONDITIONS.
-----------------------
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 30 40 26 39 29 39 / 80 40 30 30 40 90
COEUR D'ALENE 31 39 25 37 26 38 / 90 60 60 40 30 80
PULLMAN 30 38 25 37 29 41 / 100 60 60 20 40 80
LEWISTON 34 45 29 43 32 48 / 70 40 30 10 40 60
COLVILLE 22 38 17 35 24 37 / 50 40 30 40 40 90
SANDPOINT 30 36 24 34 22 35 / 90 80 80 60 30 90
KELLOGG 30 35 26 36 23 38 / 100 90 80 50 20 90
MOSES LAKE 28 46 24 42 33 44 / 20 10 20 20 80 70
WENATCHEE 30 44 27 35 30 39 / 20 10 20 40 90 60
OMAK 26 42 23 39 29 40 / 30 0 20 30 80 90
OTX WATCHES/WARNINGS/ADVISORIES
ID...WINTER STORM WARNING UNTIL 4 PM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER STORM WARNING UNTIL 4 PM PST MONDAY FOR WESTERN CHELAN
COUNTY-WESTERN OKANOGAN COUNTY.
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