574
FXUS66 KOTX 210805
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
105 AM PDT THU AUG 21 2025
KEY MESSAGES
- WARM AND DRY THROUGH THE WEEKEND AND INTO NEXT WEEK WITH MUCH
OF CENTRAL WA AND THE L-C VALLEY IN AREAS OF MAJOR HEATRISK
WITH ISOLATED AREAS OF EXTREME HEATRISK.
- BREEZY NORTH TO NORTHEAST WINDS THURSDAY AND FRIDAY.
SYNOPSIS
TEMPERATURES WILL TREND WARMER THROUGH THE WEEKEND AND REMAIN
WARM INTO EARLY NEXT WEEK. WIDESPREAD HIGHS IN THE MID 90S TO
LOW 100S ARE FORECAST FOR SATURDAY THROUGH TUESDAY WITH MODERATE
AND MAJOR HEATRISK FOR FAR EASTERN WASHINGTON AND NORTH IDAHO
AND MAJOR AND EXTREME HEATRISK FOR CENTRAL WASHINGTON.
DISCUSSION
THURSDAY THROUGH WEDNESDAY: MODELS ARE IN GOOD AGREEMENT ON THE
UPPER- LEVEL LOW WHICH BROUGHT BREEZY AND DRY CONDITIONS ACROSS
THE INLAND NORTHWEST YESTERDAY TO MOVE EASTWARD THROUGH CENTRAL
CANADA ON THURSDAY AS ANOTHER UPPER- LEVEL LOW APPROACHES THE
ALASKAN PANHANDLE. THIS PATTERN WILL ALLOW THE FOUR CORNERS HIGH
TO AMPLIFY NORTHWARD, LEAVING THE PACIFIC NORTHWEST SANDWICHED
BETWEEN THESE TWO LOWS AND UNDER THE INFLUENCE OF A
STRENGTHENING RIDGE FOR SEVERAL DAYS.
AS THE RIDGE BUILDS, WINDS WILL SHIFT TO THE NORTH ACROSS THE
INLAND NORTHWEST AS HIGH PRESSURE BUILDS IN BRITISH COLUMBIA.
THIS WILL PROMOTE BREEZY WINDS DOWN THE OKANOGAN VALLEY AND THE
WESTERN COLUMBIA BASIN THROUGH THIS MORNING. FOR FRIDAY AND
SATURDAY, A THERMALLY INDUCED SURFACE PRESSURE TROUGH BUILDS
INTO WESTERN WASHINGTON ALONG WITH A BUILDING HIGH PRESSURE EAST
OF THE CONTINENTAL DIVIDE. THIS WILL SHIFT THE WINDS TO THE
NORTH AND NORTHEAST ACROSS THE INLAND NORTHWEST WITH BREEZY
CONDITIONS ON FRIDAY AND A LITTLE LESS ON SATURDAY. MUCH DRIER
AIR SETTLING BEHIND YESTERDAY'S FRONT AND UNDER THE BUILDING
RIDGE WILL RESULT IN MINIMUM RELATIVE HUMIDITIES IN THE TEENS
DURING THE AFTERNOONS. MODELS CURRENTLY SHOW THIS THERMAL TROUGH
CROSSING EAST OF THE CASCADES BETWEEN SUNDAY AND MONDAY.
TEMPERATURES WILL TREND WARMER THROUGH SATURDAY, THEN REMAINING
VERY WARM INTO EARLY NEXT WEEK. THE CURRENT FORECAST HAS HIGH
TEMPERATURES IN MID 90S TO LOW 100S AND VERY LITTLE SPREAD
BETWEEN THE 25TH AND 75TH PERCENTILE TEMPERATURE FORECASTS IN
THE NATIONAL BLEND OF MODELS (NBM) THROUGH TUESDAY. MODERATE
(ORANGE) HEATRISK WILL BECOME WIDESPREAD ACROSS THE INLAND
NORTHWEST BY SATURDAY, WITH LOCALLY MAJOR (RED) CONDITIONS IN
THE WENATCHEE AREA AND L-C VALLEY. LITTLE CHANGE IN THE RIDGE
POSITION WILL PROLONG THE HEAT INTO EARLY NEXT WEEK, WITH MAJOR
HEATRISK BECOMING MORE WIDESPREAD IN CENTRAL WASHINGTON AND
POCKETS OF EXTREME (MAGENTA) HEATRISK AROUND WENATCHEE. EXTREME
HEATRISK IS RARE AND TYPICALLY OCCURS WHEN SEVERAL CONSECUTIVE
DAYS OF HOT DAYTIME TEMPERATURES COMBINE WITH VERY WARM
OVERNIGHT LOWS (MID 60S TO LOW 70S). THIS LEVEL AND DURATION OF
HEAT WILL POSE A SIGNIFICANT DANGER TO ANYONE WITHOUT ADEQUATE
COOLING OR HYDRATION.
BY EARLY TO THE MIDDLE OF NEXT WEEK, DETERMINISTIC MODELS BEGIN
TO SUGGEST THE NORTHWARD ADVECTION OF MONSOONAL MOISTURE AND
INSTABILITY INTO THE PACIFIC NORTHWEST. THIS WOULD BRING THE
POTENTIAL FOR ELEVATED THUNDERSTORMS, RAISING THE RISK OF NEW
FIRE STARTS. CONFIDENCE REMAINS LOW, WITH ONLY A 5-10% CHANCE OF
THUNDERSTORMS IN THE NBM AT THIS TIME OVER THE MOUNTAINS. THIS
WILL CONTINUE TO BE MONITORED CLOSELY IN THE COMING DAYS. /VMT
AVIATION
06Z TAFS: AN UPPER LEVEL RIDGE WILL BUILD OVER THE PACIFIC
NORTHWEST PROMOTING CLEAR SKIES WITH VFR CONDITIONS AND
LIGHT TERRAIN DRIVEN WINDS.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
FOR CONDITIONS TO REMAIN VFR.
-----------------------
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:/WEATHER.GOV/OTX/AVNDASHBOARD
PRELIMINARY POINT TEMPS/POPS
SPOKANE 86 55 91 58 94 61 / 0 0 0 0 0 0
COEUR D'ALENE 86 55 91 58 94 60 / 0 0 0 0 0 0
PULLMAN 85 51 91 54 94 58 / 0 0 0 0 0 0
LEWISTON 93 61 98 63 101 67 / 0 0 0 0 0 0
COLVILLE 86 46 91 48 94 52 / 0 0 0 0 0 0
SANDPOINT 84 51 89 53 91 54 / 0 0 0 0 0 0
KELLOGG 84 59 89 60 94 64 / 0 0 0 0 0 0
MOSES LAKE 89 55 94 60 98 64 / 0 0 0 0 0 0
WENATCHEE 89 64 93 68 97 72 / 0 0 0 0 0 0
OMAK 89 57 94 60 98 63 / 0 0 0 0 0 0
OTX WATCHES/WARNINGS/ADVISORIES
WA...EXTREME HEAT WATCH FROM SATURDAY AFTERNOON THROUGH TUESDAY
EVENING FOR CENTRAL CHELAN COUNTY-LOWER GARFIELD AND
ASOTIN COUNTIES-MOSES LAKE AREA-OKANOGAN VALLEY-UPPER
COLUMBIA BASIN-WATERVILLE PLATEAU-WENATCHEE AREA-WESTERN
OKANOGAN COUNTY.
ID...EXTREME HEAT WATCH FROM SATURDAY AFTERNOON THROUGH TUESDAY
EVENING FOR LEWISTON AREA.
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