830
FXUS66 KPDT 142353
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
453 PM PDT SUN SEP 14 2025
UPDATED AVIATION DISCUSSION
AVIATION...00Z TAFS
VFR CONDITIONS PREVAIL THROUGH THE TAF
PERIOD. WHILE CONVECTION WEAKENS, SHOWERS WILL CONTINUE MOVING EAST
ACROSS MOST TAF SITES EXCEPT KDLS/KRDM/KBDN. HOWEVER, BREEZY
CONDITIONS WILL IMPACT ALL THE SITES WITH SUSTAINED WINDS OF 12-
20KTS AND GUSTS AT 20-25KTS. AROUND LATE THIS EVENING THROUGH
MONDAY, THE WEATHER SHOULD THEN BE RELATIVELY QUIET WITH TERRAIN-
DRIVEN, DIURNAL WINDS RETURNING. FEASTER/97
PREV DISCUSSION
/ISSUED 119 PM PDT SUN SEP 14 2025/
DISCUSSION
SATELLITE IMAGERY REVEALS A NEGATIVELY TILTED
TROUGH OVER THE PACIFIC NORTHWEST. THE TROUGH'S ATTENDANT COLD
FRONT PASSED ACROSS THE FORECAST AREA OVERNIGHT THROUGH THIS
MORNING, AND IS NOW TRACKING EAST INTO THE NORTHERN ROCKIES.
WIDESPREAD CUMULUS HAS DEVELOPED IN THE WEAKLY UNSTABLE POST-
FRONTAL ENVIRONMENT, THOUGH MOST UPDRAFTS ARE STILL SHALLOW (<20
KFT). EVEN THE STRONGEST UPDRAFTS ARE STRUGGLING TO REACH HIGH
ENOUGH INTO THE MIXED-PHASE REGION TO GENERATE LIGHTNING.
BREEZY WESTERLY WINDS (GENERALLY 10-20 MPH WITH GUSTS OF 20-35
MPH) WILL CONTINUE THROUGH AFTERNOON. CONFIDENCE IN ADVISORY-
LEVEL SUSTAINED WINDS OR GUSTS IS LOW (20-40%) EXCEPT FOR THE MOST
WIND-PRONE AREAS OF THE EASTERN COLUMBIA RIVER GORGE AND KITTITAS
VALLEY WHERE THERE ARE LOCALLY HIGHER CHANCES (50-80%) OF PEAK
WIND GUSTS REACHING ADVISORY LEVELS (45 MPH OR HIGHER).
DRIER CONDITIONS WILL RETURN MONDAY THROUGH MUCH OF WEDNESDAY AS
THE TROUGH EXITS TO THE EAST AND AN UPPER-LEVEL RIDGE OF HIGH
PRESSURE MOVES OVER THE PACIFIC NORTHWEST. NOTABLY, AS A THERMAL
TROUGH SETS UP LATE MONDAY THROUGH TUESDAY WEST OF THE CASCADES,
WINDS WILL REVERSE DIRECTION SUCH THAT THEY WILL HAVE AN EASTERLY
COMPONENT TO THE FLOW. NOT ANTICIPATING ANY WIDESPREAD OVERLAP OF
WIND AND LOW RH TO WARRANT FIRE WEATHER PRODUCTS, BUT AFTERNOON
RHS WILL BE MARKEDLY LOWER (15-35%) AND OVERNIGHT RH RECOVERY
WILL BE MODERATE TO LOCALLY POOR FOR RIDGES AND MID-SLOPES WITHIN
THERMAL BELTS.
LATE WEDNESDAY INTO THURSDAY, ENSEMBLE MEANS AND CLUSTERS SUGGEST
ANOTHER UPPER-LEVEL TROUGH WILL APPROACH FROM THE PACIFIC, PERHAPS
CLIPPING THE PACIFIC NORTHWEST AS IT DECAYS INTO BRITISH COLUMBIA.
CONFIDENCE IS MEDIUM-HIGH (60-80%) IN BREEZY TO WINDY WESTERLY
WINDS THROUGH THE CASCADE GAPS AND WIND-PRONE PORTIONS OF THE
COLUMBIA BASIN AND BLUE MOUNTAIN FOOTHILLS ON WEDNESDAY. NBM
PROBABILITIES OF ADVISORY-LEVEL GUSTS ARE STILL LOW (20-50%),
HIGHEST FOR THE EASTERN COLUMBIA RIVER GORGE AND KITTITAS VALLEY.
UNCERTAINTY GROWS FRIDAY ONWARD, THOUGH ENSEMBLE MEMBERS ARE
BEGINNING TO CLUSTER AROUND SOME FORM OF A CLOSED LOW BEING
PRESENT OFF THE SOUTHERN CALIFORNIA COAST COUPLED WITH SLIGHTLY
ABOVE-NORMAL 500 HPA HEIGHTS OVER THE PACIFIC NORTHWEST. THIS
WOULD FAVOR ABOVE-NORMAL TEMPERATURES, AND DEPENDING ON PATTERN
DETAILS THE REGION COULD SEE SOME SHOWERS OR THUNDERSTORMS.
CONFIDENCE IN SHOWERS AND THUNDERSTORMS IS CURRENTLY LOW (<20%).
PLUNKETT/86
PRELIMINARY POINT TEMPS/POPS
PDT 48 73 49 82 / 40 0 0 0
ALW 54 73 53 83 / 60 0 0 0
PSC 51 76 49 83 / 30 0 0 0
YKM 47 76 51 81 / 10 0 0 0
HRI 50 75 49 83 / 30 0 0 0
ELN 46 76 46 80 / 20 0 0 0
RDM 36 73 38 83 / 0 0 0 0
LGD 43 71 44 80 / 60 0 0 0
GCD 42 73 44 82 / 30 0 0 0
DLS 49 79 53 86 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...86
LONG TERM....86
AVIATION...97
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