197
FXUS66 KOTX 282011
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
111 PM PDT MON SEP 28 2026
KEY MESSAGES
- BREEZY WEST TO SOUTHWEST WINDS MAY RESULT IN PATCHY BLOWING
DUST NEAR RECENTLY PLOWED FIELDS TUESDAY AFTERNOON.
- MILD AND DRY PATTERN THIS WEEK, EXCEPT FOR RAIN NEAR THE
CASCADE CREST AND CHANCE OF RAIN NORTH IDAHO PANHANDLE ON
TUESDAY.
SYNOPSIS
MOISTURE OFF THE PACIFIC WILL BRING RAIN TO THE CASCADE CREST
AND NORTHEAST WASHINGTON AND NORTH IDAHO MOUNTAINS ON TUESDAY.
BREEZY WEST TO SOUTHWEST WINDS MAY RESULT IN PATCHY BLOWING DUST
NEAR RECENTLY PLOWED FIELDS TUESDAY AFTERNOON. TEMPERATURES
WILL BE NEAR NORMAL THROUGH THE MIDDLE THE MIDDLE OF THE WEEK
AND THEN TREND TO ABOVE NORMAL FOR THE END OF THE WEEK AND INTO
THE WEEKEND.
DISCUSSION
MONDAY NIGHT THROUGH TUESDAY: : WEAK TROUGHING OVER THE INLAND
NORTHWEST WILL DEPART EASTWARD TODAY, TRANSITIONING TO ZONAL FLOW
ALOFT OVER THE PACIFIC NORTHWEST TONIGHT. A FRONTAL SYSTEM MOVING
INTO NORTHERN BRITISH COLUMBIA WILL DIRECT A MOISTURE PLUME INTO THE
WASHINGTON CASCADES, SUPPORTED BY A 120-125 KT UPPER-LEVEL JET
STREAK POSITIONED NORTH OF THE INTERNATIONAL BORDER. THIS SETUP
FAVORS OROGRAPHICALLY DRIVEN PRECIPITATION DEVELOPING ALONG THE
CASCADES EARLY TUESDAY, SPREADING INTO NORTHEAST WASHINGTON AND
NORTH IDAHO MOUNTAINS TUESDAY AFTERNOON. PRECIPITATION AMOUNTS WILL
BE MAXIMIZED ACROSS THE WEST SLOPES OF THE CASCADES AND AT THE
CASCADE CREST WITH HIGH CONFIDENCE (GREATER THAN AN 80% CHANCE) FOR
AMOUNTS EXCEEDING 0.50 INCHES. STRONG WESTERLY FLOW ALOFT INTO THE
CASCADES WILL PRODUCE A PRONOUNCED RAIN SHADOW EAST OF THE CREST,
WITH AMOUNTS QUICKLY DROPPING OFF FARTHER EAST. PRECIPITATION
AMOUNTS WILL BE MUCH LIGHTER ACROSS NORTHEAST WASHINGTON WITH A 50%
CHANCE FOR 0.10 INCHES OF RAIN ACROSS THE NORTHERN SELKIRKS AND A
25% CHANCE AS FAR SOUTH AS MOUNT SPOKANE.
WINDS WILL ALSO BE BREEZY ON TUESDAY AS 850MB WINDS INCREASE TO 20-
30 KNOTS. THE INLAND NORTHWEST WILL BE WITHIN THE WARM SECTOR WITH
THE BOUNDARY LAYER ONLY MIXING UP TO AROUND 800MB TUESDAY AFTERNOON.
THIS WILL LIMIT THE STRONGER WINDS AT 700MB TO MATERIALIZE DOWN TO
THE SURFACE. DESPITE LOWER MIXING HEIGHTS, THE NATIONAL BLEND OF
MODELS SHOWS A 60-80% CHANCE FOR WIND GUSTS GREATER THAN 30 MPH
ACROSS THE COLUMBIA BASIN INTO THE SPOKANE WEST PLAINS TUESDAY
AFTERNOON. THESE GUSTS MAY RESULT IN PATCHY BLOWING DUST NEAR
RECENTLY PLOWED FIELDS.
WEDNESDAY THROUGH SUNDAY: A WARMING TREND IS ANTICIPATED AS ENSEMBLE
GUIDANCE DEPICTS AN UPPER-LEVEL RIDGE AMPLIFYING ACROSS THE WESTERN
US. UNCERTAINTY EXISTS THURSDAY INTO FRIDAY REGARDING THE NORTHWARD
EXTENT OF THE RIDGE AXIS. APPROXIMATELY 45% OF ENSEMBLE MEMBERS
FAVOR PERSISTENT ZONAL FLOW, WHICH WOULD DIRECT ANOTHER MOISTURE
PLUME INTO THE PACIFIC NORTHWEST WITH AN ADDITIONAL PERIOD OF LIGHT
MOUNTAIN PRECIPITATION. THE REMAINING 55% OF MEMBERS BUILD THE RIDGE
MORE AGGRESSIVELY OVER THE REGION, SUPPORTING A DRIER SOLUTION.
ENSEMBLES ARE IN BETTER CONSENSUS FOR THE UPPER-LEVEL RIDGE TO
BECOME ESTABLISHED OVER THE WESTERN US THIS WEEKEND, RESULTING IN
WARM AND DRY CONDITIONS ACROSS THE INLAND NORTHWEST. /VMT
AVIATION
18Z TAFS: CLEAR SKIES WILL GIVE WAY TO INCREASING HIGH CIRRUS
THIS AFTERNOON THEN MID AND HIGH CLOUDS AFTER 04Z WITH THE
ARRIVAL OF MOISTEN LADEN WESTERLY 500MB JET. SURFACE WINDS TODAY
WILL BE LIGHT THROUGH THE MORNING WITH A SUBTLE INCREASE FROM
THE SOUTH/SOUTHWEST, ESPECIALLY ACROSS THE COLUMBIA BASIN AND
OKANOGAN VALLEY. THE STRONG WESTERLY FLOW ACROSS THE CASCADES
TONIGHT INTO TUESDAY WILL PROMOTE LEE WAVES AND FAVORABLE
PATTERN FOR TURBULENCE WITH GUSTY WINDS SURFACING IN THE
LOWLANDS BY TUESDAY AFTERNOON. THE CASCADE CREST WILL LIKELY
EXPERIENCE WIDESPREAD MTN OBSCURATIONS TUESDAY AS WELL WITH
STEADY PRECIPITAITON. /SB
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
FOR VFR CONDITIONS AT ALL TAF SITES TODAY.
-----------------------
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 45 67 47 68 45 69 / 0 10 10 0 0 0
COEUR D'ALENE 43 63 48 65 45 67 / 0 10 10 0 0 10
PULLMAN 42 66 46 65 43 69 / 0 0 10 0 0 0
LEWISTON 46 74 53 71 49 74 / 0 0 0 10 0 0
COLVILLE 41 66 38 67 36 69 / 10 20 10 0 0 10
SANDPOINT 41 61 44 64 41 65 / 0 30 20 10 0 10
KELLOGG 42 61 48 63 45 67 / 0 10 30 20 0 10
MOSES LAKE 46 73 47 71 44 73 / 0 10 0 0 0 0
WENATCHEE 50 69 51 69 52 70 / 10 20 10 0 0 0
OMAK 48 67 43 69 45 70 / 0 10 10 0 0 0
OTX WATCHES/WARNINGS/ADVISORIES
WA...NONE.
ID...NONE.
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