164
FXUS66 KOTX 181805
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1005 AM PST TUE FEB 18 2025
SYNOPSIS
LINGERING SNOW SHOWERS OVER SOUTHEAST WASHINGTON INTO THE LOWER
IDAHO PANHANDLE THROUGH THE MORNING. THE REMAINDER OF THE REGION
WILL SEE DRIER CONDITIONS INTO TUESDAY. THE NEXT WEATHER SYSTEM
ARRIVES WEDNESDAY BRINGING WIDESPREAD SNOW AND RAIN. WARMER
TEMPERATURES AND RAIN ARRIVE LATE IN THE WEEK INTO NEXT WEEKEND AS
HIGH TEMPERATURES WARM INTO THE 40S. THIS WILL RESULT IN MELTING
SNOW ACROSS THE LOWER ELEVATIONS.
DISCUSSION
TODAY THROUGH WEDNESDAY: MONDAYS SYSTEM WILL CONTINUE TO BRING
ISOLATED SNOW SHOWERS TO SOUTHEAST WASHINGTON AND THE LOWER IDAHO
PANHANDLE THROUGH THE MORNING. A DEEPENING TROUGH ALONG THE COAST
GENERATE A LOW OFF OF THE OREGON COAST. TRACK OF THE LOW HAS
SHIFTED SLIGHTLY NORTH FROM PREVIOUS RUNS AND WILL SLIDE THROUGH
SOUTHERN WASHINGTON. ENSEMBLES HAVE CONTINUED TO TREND SLIGHTLY
WARMER FROM PREVIOUS RUNS. THE WEAK OMEGA IN THE DENDRITIC LAYER
AND POOR LIFT WITH THE SYSTEM ARE KEEPING SNOW AMOUNTS AND RATES
FAIRLY LOW. AS FOR AMOUNTS, THE HIGHER TERRAINS COULD SEE ANOTHER
4-8 INCHES THROUGH THURSDAY. THE LOW LANDS COULD SEE ANOTHER 1-4
INCHES. THE BEST POTENTIAL THESE AMOUNTS IS OVER THE WATERVILLE
PLATEAU DOWN TO WENATCHEE AND LEAVENWORTH. THE TIMING OF THE SNOW
IS IS EXPECTED TO CAUSE MORNING COMMUTE ISSUES FOR THE CASCADES
VALLEYS WEDNESDAY MORNING. AS THE SYSTEM CONTINUES EAST, WARMING
TEMPERATURES COULD LIMIT THE SNOW AMOUNTS FOR EASTERN WASHINGTON
AND THE IDAHO PANHANDLE FOR WEDNESDAY AFTERNOON. HIGHS FOR THE
PERIOD WILL BE IN THE UPPER 20S TO LOW 40S. A NORTHEASTERN FLOW
PATTERN WILL BRING COLD AIR INTO THE NORTHEAST WASHINGTON AND
NORTH IDAHO. WHILE MOST AREAS WILL SEE LOWS IN THE 20S, THESE
AREAS ARE EXPECTED TO DIP INTO THE TEENS AND UPPER SINGLE DIGITS
FOR WEDNESDAY MORNING. /JDC
THURSDAY THROUGH MONDAY: THE SYSTEM THAT BROUGHT WIDESPREAD
PRECIPITATION TO THE INLAND NORTHWEST ON WEDNESDAY WILL CONTINUE
MOVING SOUTHEAST THROUGH THURSDAY MORNING. WHILE MOST PRECIPITATION
WILL HAVE ENDED, MOIST UPSLOPE FLOW INTO THE IDAHO PANHANDLE WILL
SUPPORT LINGERING SNOW SHOWERS, WITH AN ADDITIONAL 1 TO 2 INCHES OF
ACCUMULATION OVER THE MOUNTAINS THROUGH EARLY FRIDAY.
FROM FRIDAY INTO THE WEEKEND, MODELS CONSISTENTLY SHOW A GRADUAL
WARMING TREND AS AN UPPER LEVEL RIDGE SHIFTS INTO THE WESTERN US. A
WEAK FRONT ASSOCIATED WITH A PASSING SYSTEM FRIDAY NIGHT WILL LIMIT
RIDGE AMPLIFICATION, BRINGING LIGHT PRECIPITATION TO THE CASCADES,
FAR NORTHEAST WASHINGTON, AND NORTH IDAHO. AN ACTIVE WEATHER PATTERN
OVER THE GULF OF ALASKA PATTERN WILL SUSTAIN UNSETTLED CONDITIONS
INTO THE WEEKEND, WITH STRONG SOUTHWEST FLOW ALOFT ALLOWING AN
ATMOSPHERIC RIVER TO TAKE AIM AT THE PACIFIC NORTHWEST LATE SATURDAY
INTO SUNDAY. WPC CLUSTERS HIGHLIGHT DISCREPANCIES BETWEEN GLOBAL
ENSEMBLES WITH REGARDS TO HOW FAR NORTH THE RIDGE WILL AMPLIFY,
WHICH WILL INFLUENCE THE AXIS OF MOISTURE AND RESULTANT
PRECIPITATION TOTALS. WHILE CONFIDENCE IN EXACT AMOUNTS REMAINS LOW,
THERE IS HIGH CONFIDENCE IN A WARMER, RAINY PATTERN PERSISTING INTO
EARLY NEXT WEEK.
FOLLOWING A PERIOD OF COLD AND SNOW, THESE CONDITIONS RAISE CONCERNS
FOR RAPID SNOWMELT ACROSS THE LOWLANDS, POTENTIALLY LEADING TO RISES
IN SMALLER CREEKS AND STREAMS AND LOCALIZED FIELD FLOODING. OVERALL,
THE SNOWPACK OVER THE MOUNTAINS IS NOT QUITE PRIMED FOR SIGNIFICANT
MELTING YET AS CURRENT SNOW DENSITIES IN THE 20 TO 30 PERCENT RANGE
SUGGESTS THERE IS STILL ROOM FOR THE SNOWPACK TO ABSORB RAINFALL
(ABOVE 50 PERCENT OR GREATER WOULD SUGGEST BETTER CONDITIONS FOR
MELTING), WHICH WILL MITIGATE MAJOR CONCERNS. HOWEVER, AREAS OF
PARTICULAR CONCERN INCLUDE SPOKANE COUNTY AND THE WASHINGTON AND
IDAHO PALOUSE, WHERE THERE IS AMPLE LOWLAND SNOW AND THE GFS AND NBM
ARE INDICATING A 10 TO 30% CHANCE OF RAPID ONSET FLOODING DURING
THIS TIME PERIOD. PARADISE CREEK IN MOSCOW IS CURRENTLY FORECAST TO
EXCEED MINOR FLOOD STAGE SUNDAY NIGHT, AND WE WILL CONTINUE TO
MONITOR THIS CLOSELY.
PREPARATION AHEAD OF THIS EVENT IS ADVISED, SUCH AS CLEARING GUTTERS
AND STORM DRAINS OF COMPACTED SNOW AND DEBRIS TO HELP MINIMIZE
FLOODING IMPACTS. /VMT
AVIATION
18Z TAFS: INCREASING NORTHEAST BOUNDARY LAYER TUE MORNING INTO
THE AFTERNOON OVER NE WA/N IDAHO PANHANDLE SHOULD HELP THE STRATUS
BECOME SCATTERED AROUND KCOE-KGEG. NEXT STORM SYSTEM WILL BRING
TOP DOWN MOISTENING INTO THE CASCADES 00-06Z WITH -SN DEVELOPING
AROUND WINTHROP AND LEAVENWORTH. SNOW WILL EXPAND INTO KEAT AND
KOMK 6-12Z AND THEN INTO E WA AND N ID AFTER 12Z.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: MODERATE
CONFIDENCE IN KGEG-KSFF-KCOE BECOMING SCT AROUND 4-8Z BEFORE
PRECIP ARRIVES AROUND 16-17Z.
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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 36 24 36 31 38 30 / 0 10 90 80 10 10
COEUR D'ALENE 38 22 36 32 39 30 / 0 0 80 90 30 10
PULLMAN 34 28 36 32 36 29 / 30 0 100 90 40 10
LEWISTON 39 30 40 35 42 31 / 30 0 90 80 20 10
COLVILLE 37 22 35 27 41 29 / 0 10 90 60 10 0
SANDPOINT 37 22 34 31 39 31 / 10 0 80 90 40 20
KELLOGG 37 23 37 32 37 31 / 20 0 80 100 70 20
MOSES LAKE 38 30 38 28 42 28 / 0 30 100 10 0 0
WENATCHEE 36 32 37 30 41 30 / 0 50 100 10 0 0
OMAK 37 29 37 29 41 29 / 0 40 100 20 0 0
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
WEDNESDAY FOR CENTRAL CHELAN COUNTY-WATERVILLE PLATEAU-
WENATCHEE AREA.
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