910
FXUS66 KPDT 201123
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
423 AM PDT THU AUG 20 2026
KEY MESSAGES
- LOW PRESSURE WILL APPROACH THE REGION ON FRIDAY AND WILL MOVE
INLAND LATE FRIDAY NIGHT OR EARLY SATURDAY, BRING SHOWER AND
THUNDERSTORM CHANCES, MAINLY TO THE MOUNTAINS AND GUSTY WINDS.
- FIRE WEATHER CONDITIONS LOOK TO BECOME ELEVATED, IF NOT
CRITICAL AS WE APPROACH THE WEEKEND.
DISCUSSION
A RAMP UP OF HOTTER TEMPERATURES IS EXPECTED OVER THE NEXT
COUPLE OF DAYS ASSOCIATED WITH THE STRENGTHENING OF AN UPPER
RIDGE OVER THE INTERIOR NW WHICH IS ANCHORED UNTIL FRIDAY NIGHT
WHEN AN EAST PACIFIC UPPER LOW MOVES ONSHORE NEAR THE WA/OR
COAST. TEMPERATURES ARE FORECAST TO REACH AROUND 100 DEGREES
OVER SOUTHEAST WASHINGTON AND THE GRANDE RONDE VALLEY. HEAT RISK
IS HIGHEST FRIDAY AFTERNOON IN THE THE MODERATE TO MAJOR RISK
CATEGORY ACROSS SECTIONS OF THE LOWER COLUMBIA BASIN/FOOTHILLS
OF THE NORTHERN BLUE MOUNTAINS-OF WA. RELIEF COMES IN THE THE
EVENING AS THE HEAT RISK FALLS TO MODERATE/MINOR OVERNIGHT INTO
SATURDAY MORNING ACROSS THESE FORECAST ZONES. HREF LIGHTNING
REMAINS LARGELY TO TO THE WEST OF THE CASCADE CREST FRIDAY, IN
A ZONE OF UPSLOPE AND MEANINGFUL PROBABILITIES FOR THUNDER (10
TO 20%) FROM NBM MEMBERS SPREAD OVER THE CREST OF THE OREGON AND
WA CASCADES OVERNIGHT FRIDAY AND INTO SATURDAY. THE
PROBABILITIES FOR THUNDERSTORMS ARE MOST ROBUST AT AROUND 20%
CHANCES ACROSS THE WA EASTERN SLOPES AND BLUE MOUNTAINS OF
OREGON ON SATURDAY AFTERNOON WHERE HIGHER CAPES ARE FORECAST
UPWARDS OF 300J/KG. BREEZY TO WINDY GAP WINDS WILL BE
DEVELOPING FRIDAY NIGHT AND PEAKING ON SATURDAY AFTERNOON.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
VFR CONDITIONS WITH SOME LOCALIZED REDUCED VISIBILITY WHERE
LOCALIZED SMOKE LAYER IS CAUSING HAZE IN OBSERVATIONS. WIND
CONTINUES TO BE LIGHT AND VARIABLE FOR ANOTHER 24 HOURS AT ALL
AREA TERMINALS.
FIRE WEATHER
ELEVATED FIRE WEATHER RISK IS PRIMARILY DRIVEN BY THE DRY FUELS
AND LOW RELATIVE HUMIDITY EACH DAY THROUGH FRIDAY. BY FRIDAY
NIGHT AN UPPER LOW WILL MOVE INTO HE PACNW, SPREADING ACROSS THE
REGION FOR THE WEEKEND WHICH WILL INCREASE THE WINDS THOUGH THE
GAPS ON SATURDAY...LEADING TO ELEVATED FIRE RISK FOR WINDY
CONDITIONS, BUT NO WIDESPREAD OVERLAPPING LOW RH AND WINDS ARE
EXPECTED (NO RED FLAG CONDITIONS). THE NBM MEMBERS SUGGEST ABOUT
A 5 TO 10% CHANCE FOR DRY THUNDERSTORMS ACROSS THE BLUE
MOUNTAINS OF OREGON ON SATURDAY AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
PDT 95 62 95 66 / 0 0 0 10
ALW 97 67 99 72 / 0 0 0 10
PSC 97 61 99 64 / 0 0 0 10
YKM 98 65 98 69 / 0 0 0 10
HRI 97 64 97 67 / 0 0 0 10
ELN 94 64 95 66 / 0 0 0 20
RDM 96 56 94 54 / 0 0 0 10
LGD 98 61 100 64 / 0 0 0 10
GCD 98 61 100 63 / 0 0 0 10
DLS 99 67 96 66 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...AIR QUALITY ALERT UNTIL 11 AM PDT THIS MORNING FOR ORZ050-502-
505-506-509>511.
DISCUSSION...71
AVIATION...71
FIRE WEATHER...71
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