945
FXUS66 KOTX 131251
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
551 AM PDT THU MAR 13 2025
SYNOPSIS
A LOW PRESSURE SYSTEM WILL BRING MAINLY MOUNTAIN SNOW AND VALLEY
RAIN THIS MORNING. WINTER TRAVEL CONDITIONS EXPECTED OVER THE
MOUNTAIN PASSES. WINDY CONDITIONS TODAY AS WELL WITH THE
POTENTIAL FOR SNOW AND GRAUPEL SHOWERS THIS AFTERNOON AND AGAIN ON
FRIDAY OVER THE MOUNTAINS. THE WEEKEND WILL REMAIN ACTIVE WITH
MORE SNOW IN THE MOUNTAINS AND RAIN AND SNOW IN THE VALLEYS. THE
WEEKEND WILL BE BREEZY TO WINDY WITH A COLD FRONT PASSAGE.
TEMPERATURES REMAIN NEAR TO OR BELOW NORMAL THROUGH THE WEEK.
DISCUSSION
KEY POINTS
* MODERATE TO HEAVY SNOW ACCUMULATIONS OVER MOUNTAIN PASSES IN THE
CASCADES, UP THE METHOW VALLEY AND IN THE MOUNTAINS OF THE
OKANOGAN HIGHLANDS THURSDAY MORNING.
* ACTIVE WEATHER PATTERN WILL CONTINUE INTO THE WEEKEND WITH
ADDITIONAL ROUNDS OF MOUNTAIN SNOW. LOWLAND VALLEY SNOW
ACCUMULATIONS ARE EXPECTED SATURDAY MORNING. THE PRECIPITATION
FORECAST FOR SUNDAY NIGHT THROUGH MONDAY CARRIES A HIGH AMOUNT
OF UNCERTAINTY.
* WINDY TODAY, AND BREEZY TO WINDY OVER THE WEEKEND.
TODAY: A RIGOROUS LOW PRESSURE SYSTEM WILL TRACK ACROSS NORTH-
CENTRAL WASHINGTON THIS MORNING. SURFACE ANALYSIS HAS A 990 MB LOW
APPROXIMATELY LOCATED IN THE AREA BETWEEN YAKIMA, ELLENSBURG, AND
MOSES LAKE AT 3:00 AM THIS MORNING. IT'S PROGGED TO MAKE A DUE NORTH
TRACK UP THROUGH THE OKANOGAN VALLEY/HIGHLANDS THE NEXT 5 HOURS
INTO SOUTHERN BRITISH COLUMBIA BY AROUND 8:00 AM, AND DEEPEN AS IT
DOES SO DOWN TO AROUND 988 MBS. THE TRACK OF THE LOW PLACES THE
EAST SLOPES IN FAVORABLE EASTERLY UPSLOPE FLOW, AND EARLY MORNING
OBSERVATIONS SHOWS SNOW FALLING IN THE METHOW VALLEY AND OVER LOUP
LOUP PASS. SNOW IS ALSO ACCUMULATING OVER BLEWETT PASS AND
SHERMAN PASS. PERIODS OF HEAVY SNOW IS EXPECTED THIS MORNING WITH
SNOWFALL RATES OF UP TO 1 INCH PER HOUR. A WINTER WEATHER ADVISORY
HAS BEE ISSUED FOR WESTERN OKANOGAN COUNTY THAT INCLUDES THE
METHOW VALLEY AND TRAVEL ALONG STATE ROUTE 20 OVER LOUP LOUP PASS.
THIS GOES ALONG WITH THE WINTER WEATHER ADVISORY ALREADY IN
EFFECT FOR U.S. 2 FROM COLES CORNER AND OVER STEVENS PASS, AND THE
WINTER STORM WARNING IN EFFECT ABOVE 4,000 FEET OVER THE OKANOGAN
HIGHLANDS. EXPECT WINTER TRAVEL CONDITIONS THIS MORNING FOR
MOUNTAIN PASSES ACROSS THESE FORECAST ZONES.
STRATIFORM PRECIPITATION WILL LIFT NORTH AWAY FROM THE REGION WITH
THE LOW THIS AFTERNOON. A COLD FRONT SWEEPING THROUGH WILL RESULT IN
A TIGHT SOUTH TO SOUTHWEST PRESSURE GRADIENT. WINDS ARE EXPECTED TO
INCREASE THIS MORNING AND BECOME GUSTY INTO THE AFTERNOON. WINDS
ACROSS THE EXPOSED AREAS OF THE BASIN, INTO THE SPOKANE AREA, AND
PALOUSE WILL BE BETWEEN 20-30 MPH WITH GUSTS TO BETWEEN 35-45 MPH.
STRONGEST WINDS LOOK TO BE IN THE LATE MORNING INTO THE EARLY
AFTERNOON HOURS AND THEN BECOMING BREEZY THEREAFTER BEFORE WANING
OVERNIGHT. MID LEVEL LAPSE RATES WILL STEEPEN THIS AFTERNOON UNDER
THE COLD UPPER LEVEL TROUGH. THE ATMOSPHERE WILL DESTABILIZE WITH
SCATTERED SNOW AND GRAUPEL SHOWERS FORMING OVER MUCH OF THE REGION,
BUT PARTICULARLY ACROSS THE EASTERN TWO-THIRDS OF THE FORECAST AREA.
WE WILL ALSO SEE SLOP OVER PRECIPITATION ACROSS THE CASCADES
GENERATING SNOW. DIFFICULT TO SAY IF SNOW WILL MAINTAIN ENOUGH
INTENSITY TO STICK OVER STEVENS PASS. WILL NEED TO MONITOR THOSE
CONDITIONS AND SEE IF THE ADVISORY IS NEEDED TO BE EXTENDED. THE
SAME GOES FOR THE OKANOGAN HIGHLANDS AS WRAP AROUND MOISTURE COULD
KEEP SNOW GOING THERE A BIT MORE INTO THE AFTERNOON THAN ANTICIPATED.
TONIGHT THROUGH FRIDAY: CLOUD COVER WILL DISSIPATE TONIGHT WITH
DRIER AIR AND LOWER DEW POINTS FUNNELING IN BEHIND THE EXITING LOW.
WINDS WILL REMAIN BREEZY OVERNIGHT, BUT WILL BE WEAKENING. THERE IS
A CONCERN THAT MOISTURE ON THE ROADS WITH EVAPORATIVE COOLING
WILL FREEZE RESULTING IN SLICK TRAVEL CONDITIONS OVERNIGHT INTO
THE MORNING COMMUTE ON FRIDAY. PLAN ON LEAVING A LITTLE EARLIER IN
THE MORNING FRIDAY TO ANTICIPATE THE SLICK CONDITIONS.
TEMPERATURES WILL BE MUCH COOLER TONIGHT WITH LOWS DROPPING INTO
THE MID TO UPPER 20S ACROSS MUCH OF THE REGION. THE UPPER LEVEL
TROUGH OF LOWER PRESSURE WILL BE EXITING TO THE NORTHEAST ON
FRIDAY, BUT A -30 CELSIUS COLD POOL AT 500 MB WILL REMAIN ACROSS
THE NORTHERN MOUNTAINS IN THE IDAHO PANHANDLE. DIURNAL HEATING ON
FRIDAY IS EXPECTED TO SPARK OFF CONVECTIVE SNOW AND GRAUPEL
SHOWERS OVER THESE AREAS.
FRIDAY NIGHT THROUGH SATURDAY: A FRONTAL BAND WILL PUSH NORTHEAST
ACROSS THE REGION, AND WILL MOVE THROUGH DURING THE COLDEST PART OF
THE DAY: LATE OVERNIGHT INTO SATURDAY MORNING. DEW POINT
TEMPERATURES WILL START OUT IN THE LOWER 20S. THE FRONTAL BAND LOOKS
RATHER DYNAMIC WITH MODELS INDICATING GOOD FRONTOGENESIS AND MOIST
ISENTROPIC ASCENT ACROSS MUCH OF THE INLAND NORTHWEST. THERE IS SOME
WESTERLY FLOW AS IT PUSHES ACROSS AND THIS WILL RESULT IN A LOCAL
MINIMUM IN PRECIPITATION ACCUMULATIONS IN THE LEE OF THE
CASCADES. EXTREME EASTERN WASHINGTON AND THE IDAHO PANHANDLE WILL
BE FAVORED AREAS FOR PRECIPITATION, AS WELL AS OVER THE CASCADE
CREST. MID LEVEL LAPSE RATES WILL ONCE AGAIN STEEPEN TO 7+ C/KM IN
THE 700-500 MB LAYER ADDING AN INSTABILITY COMPONENT TO AID IN
LIFT ALONG THE FRONT. THERMAL PROFILES ALSO WILL BE ON THE COLD
SIDE WITH TEMPERATURES DOWN TO -3 CELSIUS AT 850 MB. THERE IS
POTENTIAL FOR A PERIOD OF MODERATE SNOW DOWN IN THE LOWLANDS FOR A
FEW HOURS FROM THE PALOUSE TO THE SPOKANE AREA AND ALONG THE
NORTHERN PORTIONS OF THE UPPER COLUMBIA BASIN; NOT TO MENTION,
ACROSS THE NORTHERN MOUNTAIN VALLEYS AND IN THE IDAHO PANHANDLE.
SNOW RATIOS COULD BE SURPRISINGLY HIGHER THAN FORECAST OF 7-10/1
RATIOS AND MORE LIKE 10- 13/1 RATIOS CONSIDERING THE POTENTIAL FOR
MODERATE TO STRONG LIFT IN THE DENDRITIC GROWTH ZONE. EXPECT THE
POTENTIAL FOR 1 TO 3 INCHES OF SNOW IN THE LOWLANDS, AND THAT
COULD ALL COME IN A 2-3 HOUR PERIOD. THIS INCLUDES PULLMAN/MOSCOW,
SPOKANE, DAVENPORT, ST. MARIES, SILVER VALLEY, SANDPOINT,
CHEWELAH, COLVILLE AND REPUBLIC.
SATURDAY ALSO LOOKS TO BE A BREEZY TO WINDY DAY WITH A PRESSURE
GRADIENT TIGHTENING UP BEHIND THE FRONT. EXPECT WINDS NOT QUITE
AS WINDY AS TODAY IN THE 20-25 MPH RANGE AND GUSTING UP TO AROUND
35 MPH. WINDS DO LOOK TO BE STRONGER AROUND THE POMEROY AREA WITH
30 MPH WINDS AND GUSTS TO 45+ MPH MORE LIKELY THERE. THERE IS ALSO
A SLIGHT CHANCE FOR THUNDERSTORMS IN THE AFTERNOON ON SATURDAY.
TEMPERATURES WILL REMAIN BELOW NORMAL FOR MID MARCH. /SVH
SATURDAY NIGHT THROUGH MONDAY: QUICKLY ON THE HEELS OF THE SYSTEM
FROM SATURDAY, THE NEXT SYSTEM ARRIVES BETWEEN SATURDAY NIGHT AND
SUNDAY MORNING AS A BROADER TROUGH FROM THE GULF OF ALASKA SHIFTS
SOUTHEASTWARD. THIS WOULD REORIENT THE UPPER LEVEL JET INTO A
SOUTHWESTERLY POSITION WITH AN UPPER LEVEL RIDGE AMPLIFYING ACROSS
THE WESTERN US AND AN EMBEDDED ATMOSPHERIC RIVER WITHIN THE
SOUTHWEST FLOW. MODELS HAVE TRENDED MUCH DIFFERENTLY OVER THE LAST
24 HOURS… AS EXAMINING DETERMINISTIC SOLUTIONS AND VARIOUS ENSEMBLE
SOLUTIONS REVEAL MULTIPLE MID LEVEL WAVES TO TRACK THROUGH BETWEEN
SATURDAY NIGHT AND SUNDAY MORNING. MODELS HAVE TRENDED DRIER FOR
SATURDAY NIGHT INTO SUNDAY WITH THE MOISTURE PLUME REMAINING MORE
FOCUSED INTO OREGON INITIALLY. A SIGNIFICANT DIFFERENCE IN THE MORE
RECENT RUNS VS 24 HOURS AGO IS THE IDEA OF A STRONGER SURFACE LOW TO
DEVELOP SUNDAY AFTERNOON/EVENING OFFSHORE AND DEEPEN AS IT NEARS THE
OREGON/WASHINGTON COAST. THE LATEST RUNS OF THE GFS AND GEFS HAVE
REALLY LATCHED ONTO THIS IDEA WITH A STRONGER WARM FRONT BRINGING
THE MOISTURE PLUME INTO THE INLAND NORTHWEST SUNDAY EVENING/NIGHT,
ALTHOUGH THERE ARE STILL DIFFERENCES IN THE OVERALL STRENGTH AND
EXACT POSITION OF THE LOW. THE LATEST DETERMINISTIC ECMWF SHOWS THE
SURFACE LOW, ALBEIT MUCH WEAKER AND FURTHER SOUTH COMPARED TO THE
GFS AND LESS PRECIPITATION AS A RESULT. EXAMINING THE ECMWF ENSEMBLE
SUITE REVEALS A HANDFUL OF MEMBERS ALIGNING CLOSER TO THE GFS/GEFS,
BUT THERE IS SIGNIFICANT VARIABILITY. THAT BEING SAID, MOST MODELS
STILL DO GENERATE WIDESPREAD PRECIPITATION DURING THIS TIME PERIOD
WITH ONLY A COUPLE ENSEMBLE MEMBERS COMPLETELY DRY. THE BIGGEST
QUESTION REMAINS IN HOW MUCH PRECIPITATION WE COULD RECEIVE. FOR
EXAMPLE, THE DIFFERENCE BETWEEN THE NBM 10TH AND 90TH PERCENTILE QPF
FOR SPOKANE BETWEEN 5AM SUNDAY AND 5 AM MONDAY IS A WHOPPING 0.80
INCHES. THE WETTER SCENARIO WOULD BRING RISES ON SMALL CREEKS AND
STREAMS, ESPECIALLY ACROSS THE PALOUSE WHERE THE FORECAST FOR
PARADISE CREEK CONTINUES TO BRING IT ABOVE BANKFULL ON SUNDAY AND
MONDAY, BUT THIS CARRIES A HIGH UNCERTAINTY.
SINCE MODELS HAVE TRENDED FURTHER SOUTH WITH THE INITIAL AXIS OF
MOISTURE AS THE BROAD UPPER LEVEL TROUGH SHIFTS TO THE SOUTHEAST,
THE SNOW MOUNTAIN SNOW FORECAST FOR SATURDAY NIGHT THROUGH SUNDAY
HAS DECREASED. CURRENT PROBABILITIES FOR 12 INCHES OF SNOW FOR
STEVENS PASS BETWEEN 5 PM SATURDAY AND 5 PM SUNDAY IS 30 PERCENT
(VERSUS 70 PERCENT AT THIS TIME LAST NIGHT). ADDITIONALLY, A FURTHER
SHIFT OF THE INITIAL SYSTEM ON SUNDAY HAS RESULTED IN THE WIND
FORECAST FOR SUNDAY TO DECREASE COMPARED TO LAST NIGHT. HOWEVER,
THERE STILL REMAINS A 30 TO 40 PERCENT CHANCE FOR WIND GUSTS OVER
40 MPH ON SUNDAY, SO THIS SCENARIO IS NOT COMPLETELY OFF THE TABLE
JUST YET.
MONDAY NIGHT THROUGH WEDNESDAY: SNOW, GRAUPEL, OR RAIN SHOWERS FOR
MONDAY AND TUESDAY STILL LOOK PLAUSIBLE AS THE COLD AND UNSTABLE
UPPER LEVEL TROUGH SHIFTS INTO THE NORTHWEST. A TRANSIENT RIDGE
THEN SHIFTS INTO THE NORTHWEST TUESDAY AFTERNOON AND EVENING.
ENSEMBLES HAVE COME INTO BETTER GENERAL AGREEMENT THAT THIS WILL
MOVE THROUGH PRETTY QUICKLY WITH THE NEXT SYSTEM MOVING THROUGH THE
REGION BETWEEN WEDNESDAY AND THURSDAY. /VMT
AVIATION
12Z TAFS: A TIGHTENING SOUTH TO SOUTHWESTERLY PRESSURE GRADIENT
WILL RESULT IN GUSTY WINDS THIS MORNING INTO THIS MORNING AS A 988
MB LOW PRESSURE SYSTEM SHIFTS INTO SOUTHERN BRITISH COLUMBIA.
EXPECT SUSTAINED WINDS OF 15-25 KTS WITH GUSTS UP TO 30-35 KTS
FROM THE WEST TO SOUTHWEST ACROSS THE REGION. SHOWERS WILL ALSO
CONTINUE THROUGH THE DAY WITH COOLER TEMPERATURES MOVING IN
RESULTING IN LOWERING SNOW LEVELS. SHOWERS WILL BE CONVECTIVE IN
NATURE THIS AFTERNOON WITH A 20-40% CHANCE FOR GRAUPEL OR SNOW
PELLETS ACROSS THE EASTERN TWO-THIRDS OF THE FORECAST AREA THAT
WILL INCLUDE KCQV-KDEW-KSZT-KGEG-KSFF-KCOE-KPUW AIRPORTS. LOW
CEILINGS TODAY, ESPECIALLY THIS MORNING WITH WIDESPREAD MVFR
CONDITIONS. CEILINGS WILL LIFT TO BETWEEN 4-6 KFT THIS AFTERNOON
WITH MOUNTAIN OBSCURATIONS.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
HIGH CONFIDENCE FOR MVFR CONDITIONS ACROSS THE MAJORITY OF THE
REGION THROUGH THIS MORNING. ALSO HIGH CONFIDENCE IN A SUDDEN
INCREASE IN WINDS WITH A COLD FRONT PASSAGE WEDNESDAY MORNING
ACROSS THE REGION BETWEEN 13Z-18Z. THE HREF IS SHOWING A 80%
CHANCE OF WIND GUSTS REACHING 30-35 KTS AT KGEG STARTING BETWEEN
13-15Z.
-----------------------
CONFIDENCE DESCRIPTORS:
LOW - LESS THAN A 30 PERCENT CHANCE
MODERATE - 30 TO 70 PERCENT CHANCE
HIGH - GREATER THAN A 70 PERCENT CHANCE
PRELIMINARY POINT TEMPS/POPS
SPOKANE 47 28 45 32 47 35 / 60 20 10 40 90 80
COEUR D'ALENE 45 27 44 29 44 32 / 70 30 10 40 100 90
PULLMAN 44 27 45 33 45 35 / 50 10 0 50 90 90
LEWISTON 52 33 51 37 53 40 / 40 10 0 50 90 80
COLVILLE 45 23 44 25 44 31 / 100 20 20 30 90 80
SANDPOINT 44 27 42 27 41 33 / 80 50 60 40 100 90
KELLOGG 42 29 41 30 41 35 / 80 40 30 50 100 100
MOSES LAKE 51 28 50 33 53 36 / 60 10 0 50 50 70
WENATCHEE 47 28 46 33 51 35 / 60 10 0 50 40 70
OMAK 49 25 45 31 48 33 / 80 20 0 30 80 70
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...WINTER STORM WARNING UNTIL NOON PDT TODAY FOR OKANOGAN HIGHLANDS.
WINTER WEATHER ADVISORY UNTIL NOON PDT TODAY FOR WESTERN CHELAN
COUNTY-WESTERN OKANOGAN COUNTY.
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