238  
FXUS66 KPDT 101710  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
1010 AM PDT SUN AUG 10 2025  
   
UPDATED FOR AVIATION  
 
   
AVIATION  
 
18Z TAFS...VFR CONDITIONS AND WINDS 10 KTS OR LESS ARE EXPECTED  
THROUGH THE TAF PERIOD.  
 
 
   
PREV DISCUSSION  
/ISSUED 1029 PM PDT SAT AUG 9 2025/  
 
UPDATED AVIATION DISCUSSION.  
 
AVIATION...06Z TAFS...VFR CONDITIONS CURRENTLY ACROSS ALL SITES,  
WHICH WILL STAY THE COURSE THROUGH THE PERIOD. CLEAR SKIES AND  
LIGHT, DIURNALLY-DRIVEN WINDS BELOW 11 KTS IS EXPECTED TO PERSIST.  
75  
 
PREV DISCUSSION... /ISSUED 106 PM PDT SAT AUG 9 2025/  
 
DISCUSSION...  
NORTH TO NORTHWEST FLOW OVER THE PACIFIC NORTHWEST WILL  
MOVE EASTWARD THROUGH TONIGHT. THEN, A LARGE AREA OF HIGH PRESSURE  
WILL MOVE OVER THE REGION AND BE THE DOMINANT FEATURE THROUGH  
EARLY NEXT WEEK.  
 
THIS HIGH WILL BRING INCREASINGLY HOT TEMPERATURES THROUGH THE  
MONDAY/TUESDAY TIMEFRAME. AS A RESULT, EXCESSIVE HEAT WARNINGS ARE  
BEING ISSUED FOR MOST OF THE LOWER ELEVATION LOCATIONS. HIGH  
TEMPERATURES ON SUNDAY WILL BE IN THE MID TO UPPER 90S IN MANY  
AREAS, WITH 100 NOT BEING RULED OUT ACROSS THE COLOMBIA BASIN AND  
GORGE AND YAKIMA VALLEY. ON MONDAY AND TUESDAY, THE COLUMBIA  
BASIN, GORGE, YAKIMA VALLEY, BLUE MOUNTAIN FOOTHILLS AND PORTIONS  
OF CENTRAL OREGON SHOULD BE 100 TO 104.  
 
HEATRISK VALUES WILL BE WIDESPREAD MODERATE SUNDAY, AND WIDESPREAD  
MODERATE SUNDAY, WITH MAJOR ACROSS THE COLUMBIA BASIN, GORGE,  
YAKIMA AND KITTAS VALLEY BLUE MOUNTAIN FOOTHILLS AND PORTIONS OF  
CENTRAL OREGON. TUESDAY WILL ALSO SEE WIDESPREAD MODERATE HEATRISK  
WITH MAJOR ACROSS MANY OF THE SAME AREAS.  
 
HIGH TEMPERATURES WILL BE 10 TO 15 DEGREES ABOVE NORMAL AND LOW  
TEMPERATURES WILL REMAIN IN THE 60S AND MAY NOT GET MUCH BELOW 70  
DEGREES IN PORTIONS OF THE COLUMBIA BASIN, GORGE AND FOOTHILLS OF  
THE BLUE MOUNTAINS.  
 
BY MONDAY AND TUESDAY THE ECMWF EFI HAVE ANOMALIES OF 0.7 TO 0.8  
FOR HIGH AND LOW TEMPERATURES, MAINLY ACROSS THE BASIN, BUT 0.6 TO  
0.7 ELSEWHERE ACROSS THE REGION. NBM PROBABILITIES OF HIGH  
TEMPERATURES >=100 ARE >80 PERCENT IN MANY AREAS COME MONDAY AND  
TUESDAY.  
 
THE RIDGE IS SUPPRESSED SOUTH LATER TUESDAY INTO WEDNESDAY AND  
THE AREA GETS INTO A MORE WESTERLY FLOW. THIS WILL BRING A GRADUAL  
COOL DOWN BEGINNING WEDNESDAY THROUGH THE WEND OF THE WEEK.  
 
MORE IMPORTANTLY, IT WILL BRING BREEZY TO WINDY CONDITIONS  
ESPECIALLY LATER TUESDAY INTO WEDNESDAY, ESPECIALLY FOR THE  
CASCADE GAPS, COLOMBIA BASIN, GORGE AND FOOTHILLS OF THE BLUE  
MOUNTAINS. WITH RH VALUES EXPECTED TO BE <20 PERCENT, ENHANCED AND  
EVEN CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE.  
 
AS TEMPERATURES FURTHER DECREASE THURSDAY AND REMAIN CLOSE TO  
SEASONAL THROUGH THE END OF THE WEEK, RH VALUES WILL RISE AND  
WINDS WILL ALSO DECREASE, THOUGH IT WILL REMAIN LOCALLY BREEZY.  
THIS SHOULD HELP ALLEVIATE FIRE WEATHER CONCERNS.  
 
THE NEXT CHANCE OF ANY PRECIPITATION LOOKS TO BE FRIDAY OR  
SATURDAY, AND THE RAIN WOULD BE CONFINED TO THE WASHINGTON  
CASCADES, AT BEST.  
 
 
   
PRELIMINARY POINT TEMPS/POPS  
 
PDT 95 64 100 65 / 0 0 0 0  
ALW 95 70 100 70 / 0 0 0 0  
PSC 98 65 101 66 / 0 0 0 0  
YKM 97 66 100 69 / 0 0 0 0  
HRI 98 65 102 66 / 0 0 0 0  
ELN 97 65 98 66 / 0 0 0 0  
RDM 95 56 100 57 / 0 0 0 0  
LGD 92 60 97 62 / 0 0 0 0  
GCD 94 60 99 61 / 0 0 0 0  
DLS 100 71 102 71 / 0 0 0 0  
 
 
   
PDT WATCHES/WARNINGS/ADVISORIES  
 
OR...EXTREME HEAT WARNING UNTIL 10 PM PDT TUESDAY FOR ORZ041-044-505-  
507-508-510-511.  
 
WA...EXTREME HEAT WARNING UNTIL 10 PM PDT TUESDAY FOR WAZ024-026>029-  
521.  
 
 
 
 
 
SHORT TERM...77  
LONG TERM....77  
AVIATION...77  
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