276
FXUS66 KOTX 302332
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
432 PM PDT MON MAR 30 2026
KEY MESSAGES
- SNOW OVER PASSES WILL IMPACT TRAVEL ON WEDNESDAY AND THURSDAY.
- RISES ON SMALLER CREEKS AND STREAMS ON THE PALOUSE WEDNESDAY
AND THURSDAY.
SYNOPSIS
QUIET WEATHER WILL START THE WEEK WITH COOLER AFTERNOON HIGHS
AND BELOW FREEZING OVERNIGHT LOWS. UNSETTLED WEATHER RETURNS TO
THE REGION WEDNESDAY INTO THURSDAY WITH LOWLAND RAIN, MOUNTAIN
SNOW, AND BREEZY CONDITIONS. WEATHER TRENDS WARMER AND DRIER
FRIDAY INTO THE WEEKEND.
DISCUSSION
MONDAY NIGHT THROUGH TUESDAY: MUCH DRIER AIR HAS SETTLED INTO THE
INLAND NORTHWEST MONDAY AFTERNOON BEHIND LAST NIGHT'S COLD FRONT AND
EXITING UPPER-LEVEL TROUGH. THE PRECIPITABLE WATER VALUE FROM 18Z
OTX SOUNDING CAME IN AT A WHOPPING 0.08 INCHES, WHICH IS BELOW THE
1ST PERCENTILE WHEN COMPARED TO CLIMATOLOGY! VERY DRY. THIS DRY
AIRMASS WILL ALLOW FOR STRONG RADIATIONAL COOLING OVERNIGHT TONIGHT
WITH LOWS DROPPING INTO THE TEENS AND LOW 30S ACROSS THE NORTHERN
VALLEYS AND THE MID 20S TO LOW 30S ACROSS THE COLUMBIA BASIN,
PALOUSE, SPOKANE AREA, AND CAMAS PRAIRIE.
ON TUESDAY, THE FLOW ALOFT BEGINS TO BUCKLE TO THE SOUTHWEST AS AN
UPPER-LEVEL TROUGH MOVES INTO OREGON AND NORTHERN CALIFORNIA. THE
DYNAMICS ASSOCIATED WITH THIS SYSTEM WILL REMAIN FAR ENOUGH SOUTH TO
KEEP THE MAJORITY OF EASTERN WASHINGTON AND NORTH IDAHO
PRECIPITATION-FREE THROUGH TUESDAY, WITH HIG-LEVEL CLOUDS AND
MOISTURE INCREASING.
TUESDAY NIGHT THROUGH FRIDAY: ENSEMBLES ARE IN GOOD AGREEMENT
REGARDING A STRONG UPPER-LEVEL LOW DIGGING FROM THE GULF OF ALASKA
INTO THE REGION WEDNESDAY INTO THURSDAY. AS THIS APPROACHES THE
COAST, A SURFACE LOW DEVELOPS AHEAD OF THE PRIMARY LOW EARLY
WEDNESDAY MORNING, EVENTUALLY FOLLOWING THE COAST LINE AND ROTATING
BACK INTO THE PRIMARY LOW. THE FIRST ROUND OF PRECIPITATION ARRIVES
WEDNESDAY MORNING AS WARM ADVECTION AND ISENTROPIC LIFT ASSOCIATED
WITH THIS FIRST LOW SPREADS MOISTURE INTO THE REGION. DEEP SOUTH-
SOUTHWESTERLY FLOW FROM 850 MB TO 500 MB WILL EFFECTIVELY OVERCOME
THE CASCADE RAIN SHADOW, PROMOTING LIGHT WIDESPREAD PRECIPITATION.
GIVEN THE PLACEMENT OF THE FIRST LOW, LOW-LEVEL WINDS INTO CENTRAL
WASHINGTON WOULD TAKE ON MORE OF A SOUTHEASTERLY TO EASTERLY
COMPONENT ON WEDNESDAY, PROMOTING UPSLOPE FLOW INTO THE EAST SLOPES
OF THE CASCADES AND COLD AIR DAMMING IN THE VALLEYS WOULD BECOME
MORE FAVORABLE. ALTHOUGH LATE IN THE SEASON FOR COLD AIR TO REMAIN
TRAPPED IN THE VALLEYS, A VERY DRY ANTECEDENT BOUNDARY LAYER AHEAD
OF THE PRECIPITATION WOULD SUPPORT BELOW FREEZING WET-BULB
TEMPERATURES. EVAPORATIVE COOLING AS PRECIPITAITON BEGINS COULD
ALLOW PRECIPITATION TO BEGIN AS SNOW FOR THE UPPER CASCADE VALLEYS,
SUCH AS MAZAMA, WINTHROP, PLAIN.
A MORE ROBUST FRONTAL SYSTEM FOLLOWS CLOSELY BEHIND THE FIRST LOW
WITH A SECOND ROUND OF PRECIPITATION WEDNESDAY AFTERNOON AND
EVENING. STRONGER DYNAMICS WILL BRING HEAVIER PRECIPITATION TOTALS
TO EASTERN WASHINGTON AND THE IDAHO PANHANDLE. PRECIPITATION TYPE
WITH THIS SECOND ROUND OF PRECIPITATION IN THE CASCADE VALLEYS COMES
WITH MORE UNCERTAINTY. BY THIS TIME, THE BOUNDARY LAYER WOULD BE
CLOSER TO SATURATION WITH LESS WIGGLE ROOM FOR COOLING. IF THIS
FIRST ROUND EFFECTIVELY BRINGS WET BULB TEMPERATURES ABOVE FREEZING,
PRECIPITATION WOULD FALL PRIMARILY AS RAIN IN THE LOWLANDS WITH SNOW
CONFINED TO THE MOUNTAINS. IF NOT, THERE WOULD BE BETTER SUPPORT FOR
SNOW IN THE CASCADE VALLEYS. UNCERTAINTY IN THE PLACEMENT OF THE
HEAVIEST PRECIPITATION AXIS IS REFLECTED BY A WIDE SPREAD IN NBM
PERCENTILES WITH THE 10TH TO 90TH PERCENTILE LIQUID PRECIPITATION
AMOUNTS RANGING FROM 0.05 TO OVER AN INCH IN CENTRAL WASHINGTON, AND
0.25 TO OVER AN INCH ACROSS FAR EASTERN WASHINGTON AND THE IDAHO
PANHANDLE. SNOWFALL AMOUNTS REMAIN CHALLENGING DUE TO THE
TEMPERATURE UNCERTAINTY. HOWEVER, THE SYNOPTIC FLOW PATTERN FAVORS
SNOW ACCUMULATIONS ACROSS THE OKANOGAN HIGHLANDS, NORTHEAST
WASHINGTON MOUNTAINS, AND FAR NORTH IDAHO MOUNTAINS, WITH THE 10TH
TO 90TH PERCENTILE SNOWFALL SPREAD AT SHERMAN PASS AND STEVENS PASS
RANGING FROM 2 TO 7 INCHES AND 1 TO 4 INCHES AT LOOKOUT PASS.
DEPENDING ON THE AXIS OF HEAVIEST PRECIPITATION, WE WILL ALSO NEED
TO MONITOR SMALLER STREAMS AND CREEKS ACROSS THE PALOUSE FOR
NUISANCE FLOODING.
ENSEMBLES ARE IN GOOD AGREEMENT FOR THE UPPER-LEVEL LOW TO SHIFT
INLAND ON THURSDAY WITH WRAP AROUND PRECIPITATION CONTINUING OVER
THE INLAND NORTHWEST THROUGH THURSDAY MORNING AND OVER THE MOUNTAINS
THROUGH EARLY FRIDAY.
FRIDAY THROUGH SUNDAY: ENSEMBLES ARE IN GOOD AGREEMENT FOR AN UPPER-
LEVEL RIDGE TO MOVE INTO THE WESTERN US FRIDAY INTO THE WEEKEND,
THOUGH THERE REMAINS DIFFERENCES IN THE EXACT STRENGTH AND
PROGRESSION OF THIS PATTERN. DESPITE THESE DIFFERENCES, THERE IS
HIGH CONFIDENCE FOR A WARMING AND DRYING TREND. /VMT
AVIATION
00Z TAFS: A VERY DRY AIRMASS HAS SETTLED INTO THE INLAND
NORTHWEST WITH WIDESPREAD VFR CONDITIONS. HIGH CLOUDS WILL
BEGIN TO INCREASE IN COVERAGE EARLY TUESDAY MORNING AS MOISTURE
ASSOCIATED WITH A WEATHER SYSTEM IN OREGON ADVECTS NORTHWARD AND
A FRONTAL SYSTEM APPROACHES THE PACIFIC NORTHWEST. WINDS THROUGH
00Z WEDNESDAY ARE EXPECTED TO BE TERRAIN DRIVEN LESS THAN 10
KTS.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
HIGH CONFIDENCE FOR VFR CONDITIONS. PRECIPTATION WILL SPREAD
INTO CENTRAL IDAHO TUESDAY AFTERNOON WITH A 10-20% CHANCE OF
LIGHT RAIN REACHING AS FAR NORTH AS KLWS/KPUW. CONFIDENCE WAS
TOO LOW TO INCLUDE A MENTION FOR THESE TAF SITES. JW
-----------------------
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 26 51 34 48 35 47 / 0 0 0 70 100 60
COEUR D'ALENE 25 51 34 49 36 45 / 0 0 10 70 100 80
PULLMAN 28 48 35 50 35 44 / 0 20 10 90 100 80
LEWISTON 31 51 39 55 40 51 / 0 10 10 70 100 60
COLVILLE 23 53 29 48 35 50 / 0 0 0 70 90 80
SANDPOINT 23 49 32 46 36 43 / 0 0 10 70 100 100
KELLOGG 24 50 36 50 36 41 / 0 10 20 80 100 100
MOSES LAKE 25 55 35 53 35 56 / 0 0 0 70 80 20
WENATCHEE 31 52 37 48 36 52 / 0 0 0 70 60 30
OMAK 28 53 34 49 38 56 / 0 0 0 60 80 50
OTX WATCHES/WARNINGS/ADVISORIES
WA...NONE.
ID...NONE.
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