594
FXUS66 KOTX 091020
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1254 AM PDT WED SEP 9 2026
KEY MESSAGES
- A WARMING AND DRYING TREND EXPECTED WEDNESDAY THROUGH THURSDAY.
- GUSTY WINDS THURSDAY AFTERNOON WHICH MAY RESULT IN PATCHY
BLOWING DUST OVER THE COLUMBIA BASIN AND ELEVATED FIRE WEATHER
IN DRY GRASSES.
- COOL AND SHOWERY CONDITIONS RETURN FRIDAY THROUGH THE WEEKEND.
SYNOPSIS
A WARMING AND DRYING TREND CONTINUES TODAY (WEDNESDAY) AS HIGHER
PRESSURE RETURNS TO THE REGION. WINDS PICK UP OUT OF THE WEST
THURSDAY AFTERNOON AHEAD OF THE NEXT WEATHER SYSTEM, THEN SHOWERS
AND COOLER TEMPERATURES RETURN FRIDAY THROUGH THE WEEKEND.
DISCUSSION
WEDNESDAY: A RIDGE OFF THE CANADIAN COAST WILL CONTINUE TO PROMOTE A
DRYING AND WARMING TREND FOR THE INLAND NORTHWEST THROUGH THE REST
OF THE DAY. THE EARLY MORNING CONTAINS A CHANCE OF FOG THROUGH THE
NORTHERN VALLEYS IN EASTERN WASHINGTON AND IN THE NORTHERN IDAHO
PANHANDLE. VISIBILITIES COULD DROP TO A HALF MILE OR LESS, IMPACTING
THE MORNING COMMUTE FOR PEOPLE THOSE AREAS. THE RIDGE WILL BE AT ITS
STRONGEST TODAY, WITH THE INCREASE IN HEIGHTS BRINGING A 6-8 DEGREE
INCREASE IN HIGH TEMPERATURES ACROSS THE AREA. WINDS FROM THE SOUTH
WILL INCREASE OVER THE COLUMBIA BASIN, WATERVILLE PLATEAU, AND
OKANOGAN VALLEY, RESULTING IN A BREEZY EVENING FOR THESE AREAS WITH
WIND GUSTS 15-20 MPH.
THURSDAY THROUGH FRIDAY MORNING: A LOW PRESSURE SYSTEM STRENGTHENING
OVER WESTERN CANADA AND THEN MOVING INTO CENTRAL CANADA WILL USHER A
TROUGH ACROSS THE REGION THURSDAY AFTERNOON AND EVENING. THIS WILL
BRING STRONG WINDS, LOCALIZED BLOWING DUST POTENTIAL AND FIRE
WEATHER CONCERNS, AND MOUNTAIN RAIN TO THE REGION.
OF MOST IMPACT WILL BE WINDS INCREASING AHEAD OF THE TROUGH MOVING
THROUGH THE AREA THURSDAY MORNING THROUGH EVENING. FOR MUCH OF THE
WATERVILLE PLATEAU, WENATCHEE, COLUMBIA BASIN, MOSES LAKE,
SPOKANE/CDA, AND PALOUSE AREAS, THERE IS A 60-70 PERCENT CHANCE OF
MAXIMUM WIND GUSTS GREATER THAN 30 MPH. IN THE WATERVILLE PLATEAU
AND COLUMBIA BASIN, WIND GUSTS UP TO 40 MPH ARE POSSIBLE. THIS WILL
RESULT IN BLOWING OBJECTS AND TROUBLE DRIVING, ESPECIALLY FOR HIGH
PROFILE VEHICLES.
ANOTHER IMPACTFUL RESULT OF THESE WINDS COULD BE LOCALIZED BLOWING
DUST AND FIRE WEATHER CONCERNS THROUGHOUT AREAS THAT HAVE NOT SEEN
MUCH RECENT RAIN AND THUS HAVE DRIER SOILS. FOR BLOWING DUST,
GREATEST CHANCES WILL BE SEEN THROUGHOUT THE WATERVILLE PLATEAU AND
LEWISTON/PULLMAN AREAS. BLOWING DUST CAN BRING VISIBILITIES DOWN TO
A MILE OR LOWER, IMPACTING DRIVERS. HOT DRY WINDY INDEX VALUES
INCREASE THROUGHOUT THE BROADER BASIN AREA ON THURSDAY DUE TO THE
GUSTY WINDS MOVING THROUGH, BRINGING A CHANCE FOR ELEVATED FIRE
WEATHER CONCERNS. IMPACTS INCLUDE RAPID FIRE SPREAD, ESPECIALLY FOR
ANY EXISTING FIRES.
LOCALIZED RAIN CHANCES WILL BE SEEN IN THE IDAHO PANHANDLE THURSDAY
NIGHT INTO FRIDAY MORNING. THERE IS ONLY A 10 PERCENT CHANCE FOR
ACCUMULATIONS TO REACH 0.1 INCHES. HOWEVER, THE MOISTURE OVER THE
AREA WILL RESULT IN A RETURNING CHANCE FOR FOG IN SHELTERED NORTHERN
VALLEYS ON FRIDAY MORNING.
FRIDAY EVENING THROUGH SUNDAY: LOWER HEIGHTS WILL REMAIN OVER THE
AREA ON FRIDAY AS ANOTHER LOW SPINS OFF THE COAST OF BRITISH
COLUMBIA. TEMPERATURES WILL DECREASE NEARLY TEN DEGREES BETWEEN
THURSDAY AND FRIDAY. ON FRIDAY NIGHT, AS THE LOW NUDGES CLOSER TO
THE STATE OF WASHINGTON, THERE IS A 10 TO 20 PERCENT CHANCE OF
PRECIPITATION IN WESTERN OKANOGAN VALLEY.
AS THE CENTER OF THE LOW TRACKS JUST SOUTH OF WASHINGTON THROUGH
OREGON SATURDAY INTO SUNDAY, CHANCES OF PRECIPITATION WIDELY
INCREASE REGIONWIDE. NEARLY ALL OF THE INLAND NORTHWEST HAS A 20
PERCENT CHANCE AND ABOVE AT SEEING 0.10 INCHES OF RAIN FROM SATURDAY
NIGHT INTO SUNDAY AFTERNOON.
AHEAD OF THE MAIN LOW PASSAGE ON SATURDAY MORNING, WINDS WILL AGAIN
INCREASE THROUGHOUT MUCH OF THE AREA AS A NORTH-SOUTH SURFACE
PRESSURE GRADIENT STRENGTHENS. WIND GUSTS THROUGH THE BASIN,
WATERVILLE PLATEAU, AND OKANOGAN VALLEY COULD REACH 35-40 MPH
SATURDAY MORNING AND AFTERNOON. AS THE LOW TRACKS EASTWARD, WINDS
BEGIN TO INCREASE IN THE IDAHO PANHANDLE ON SATURDAY NIGHT AND
CONTINUE TO BE ELEVATED WITH GUSTS 20-25 MPH THROUGH SUNDAY MORNING.
RIDGETOPS COULD SEE WIND GUSTS UP TO 35 MPH. IMPACTS WITH THESE WIND
GUSTS INCLUDE BLOWING OBJECTS AND TROUBLE DRIVING, ESPECIALLY FOR
HIGH PROFILE VEHICLES.
SATURDAY NIGHT INTO SUNDAY, CHANCES FOR ISOLATED THUNDERSTORMS
INCREASES AS THE LOW MOVES THROUGH. AREAS FROM SPOKANE TO WENATCHEE
AND SOUTHWARD HAVE A 10 TO 20 PERCENT CHANCE OF THUNDERSTORMS. MID
TO LONG RANGE MODELS SHOW CAPE VALUES INCREASING TO 200-300 J/KG,
AND STEEP 3-6KM LAPSE RATES. A HEAVY CAVEAT TO THESE THUNDERSTORM
CHANCES IS THAT THEY COULD CHANGE SHOULD THE TRACK OF THE LOW
PRESSURE CHANGE. EVEN NOW, MANY MODELS SHOW THE HIGHEST CHANCES FOR
THUNDERSTORMS OUTSIDE OF OUR FORECAST AREA TO THE SOUTH AND EAST,
BUT IT IS WORTH A MENTION AND SOMETHING WE'LL KEEP AN EYE ON THROUGH
THE WEEK SINCE IT COULD CREATE LOCALIZED IMPACTS.
MONDAY THROUGH TUESDAY: BY MONDAY, CLUSTERS ARE DIVIDED ON WHERE THE
LOW WILL BE. ABOUT 60 PERCENT OF CLUSTERS HAVE THE LOW FAR ENOUGH
EASTWARD THAT HIGHER HEIGHTS WILL START MOVING OVER THE AREA. THIS
WILL FAVOR A WARMING AND DRYING TREND. 40 PERCENT OF CLUSTERS HAVE
THE LOW CLOSER TO THE REGION, WHICH WOULD INDICATE CONTINUING
CHANCES FOR COOLER AND SHOWERY CONDITIONS. /AS
AVIATION
06Z TAFS: EXPECT VFR CONDITIONS THROUGH THE NEXT FORECAST
PERIOD, ALONGSIDE WINDS LIGHT AND LESS THAN 10KTS. AROUND
07-09Z AND LASTING THROUGH 16Z, PATCHY AND LOCALIZED FOG WILL
DEVELOP IN NORTHERN SHELTERED VALLEYS IN E WA AND THE ID
PANHANDLE. POTENTIAL AIRPORTS IN THESE AREAS THAT COULD SEE
CEILINGS AND VISIBILITIES DROP DOWN TO IFR AND BELOW ARE 63S,
DEW, AND SZT. AT THE MAIN TERMINALS, THERE IS POTENTIAL FOR FOG
AT GEG AND SFF FROM 08Z THROUGH 16Z. HIGH- RES MODELS SHOW SOME
PATCHY FOG ALONG THE I-90, BUT THERE IS LITTLE CONFIDENCE FOR
EITHER TERMINAL TO SEE CONDITIONS DROP BELOW VFR, SO NO
DEGRADATIONS INCLUDED IN TAFS AT THIS TIME.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
FOR VFR CONDITIONS FOR ALL TERMINALS BUT GEG AND SFF. LOW
CONFIDENCE IN PATCHY FOG AT GEG AND SFF FROM 08-16Z. THIS WILL
BE THE MOST IMPACTFUL ALTERNATE SCENARIO AND TERMINALS WILL BE
CLOSELY MONITORED FOR ANY NECESSARY AMENDMENTS. /AS
-----------------------
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 77 51 77 47 69 47 / 0 0 10 0 0 0
COEUR D'ALENE 76 49 76 46 69 47 / 0 0 10 10 0 0
PULLMAN 77 47 76 44 68 43 / 0 0 0 10 0 0
LEWISTON 83 53 84 54 75 52 / 0 0 0 20 0 0
COLVILLE 78 44 78 40 72 41 / 0 10 0 10 0 0
SANDPOINT 74 45 74 42 67 43 / 0 0 20 10 0 0
KELLOGG 74 48 73 47 67 47 / 0 0 10 20 0 0
MOSES LAKE 82 52 81 47 73 48 / 0 0 0 0 0 0
WENATCHEE 83 62 79 52 73 55 / 0 0 0 0 0 10
OMAK 82 55 80 47 74 50 / 0 0 0 0 0 10
OTX WATCHES/WARNINGS/ADVISORIES
WA...NONE.
ID...NONE.
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