155
FXUS66 KPDT 211725
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1025 AM PDT WED OCT 21 2026
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS TODAY
- RETURN OF SHOWERS AND ISOLATED THUNDERSTORMS TO THE EASTERN
MOUNTAINS THURSDAY, WITH BREEZY CONDITIONS IN THE LOWER
ELEVATIONS THURSDAY AND FRIDAY
- MODERATE TO HIGH CONFIDENCE (60-90%) IN FREEZING MORNING TEMPERATURES
SATURDAY
DISCUSSION
AN UPPER LOW CONTINUES SPINNING OFF OF THE CENTRAL CA COAST,
WITH RIDGING ACROSS THE INTERIOR NORTHWEST. AS A RESULT, CLOUDS
REMAIN HIGH ACROSS THE CENTRAL AND EASTERN OREGON COUNTIES, WITH
MORE SUN ACROSS THE WASHINGTON ZONES. TODAY WILL BE THE WARMEST
AFTERNOON ACROSS THE BROADER AREA, AND FOR ALL ELEVATIONS,
REACHING THE MID/UPPER 60S AGAIN OVER THE COLUMBIA BASIN AND
KITTITAS/YAKIMA VALLEYS, TO THE LOW/MID 70S ACROSS CENTRAL
OREGON/GRANDE RONDE VALLEY/JOHN DAY BASIN. ANOTHER DAY OF LIGHT
AND DIURNALLY AND TERRAIN DRIVEN WINDS FOR ALL ZONES.
THE NEXT WEATHER SYSTEM WILL IMPACT THE WINDS DUE TO PRESSURE
GRADIENTS ACROSS THE CASCADE GAPS/COLUMBIA RIVER GORGE. NBM
ENSEMBLE MEMBERS SHOW A RANGE OF ABOUT 50 TO 75 PERCENT OFFERING
WIND ADVISORY LEVEL , 39 MPH OR HIGHER GUSTS THURSDAY EVENING.
MORE MID AND HIGH CLOUDINESS WILL BE SPREADING FARTHER NORTH
INTO WA TONIGHT AND THOUGH THE MORNING ON THURSDAY. REFS SHOWS
LIGHT PRECIPITATION ASSOCIATED WITH A WEAK OROGRAPHIC /
DEFORMATION BAND SPREADING NORTH (SOUTHWEST TO NORTHEAST
ORIENTATION) OFF THE BLUE MOUNTAINS, AND BRINGING MEASURABLE
(LESS THAN WETTING RAINS) PRECIPITATION ACROSS THE FOOTHILLS OF
THE BLUES AND INTO THE LOWER COLUMBIA BASIN/CENTRAL OREGON
THOUGH NOON. BETTER FORCING/MOISTURE PROFILES DEVELOP LATER
THURSDAY AND THURSDAY NIGHT AND COOL AIR ALOFT ACTS TO INCREASE
INSTABILITY AND BUMP 3-HR QPF MEANS TO THE 0.10 AND LOCALLY
0.25 AMOUNTS STARTING MID EVENING THURSDAY IN THE SOUTHERN
BLUES, AND ENDING ACROSS THE WALLOWAS SOMETIME MID FRIDAY
MORNING.
FOLLOWING THE EXIT OF THE AMPLIFIED TROUGH, COLDER AIR WILL
GIVE ANOTHER OPPORTUNITY FOR FREEZING TEMPERATURES OVER HIGHER
POPULATED AREAS OF THE LOWER COLUMBIA, AND YAKIMA/KITTITAS
VALLEY ZONES THAT HAVE NOT HAD THE SEASON ENDING FREEZE JUST
YET. THIS OPPORTUNITY COMES SATURDAY MORNING. BLUE MT FOOTHILLS
AND KITTITAS VALLEY, INCLUDING WALLA WALLA, PENDLETON/ELLENSBURG
HAVE AROUND A 90% CHANCE OR HIGHER BASED ON NBM PROBABILITIES
OF SUB FREEZING TEMPS. A BIT LESS CERTAINTY EXISTS AS YAKIMA TO
SUNNYSIDE FALLS IN AT ABOUT A 50 TO 60 PERCENT CHANCE FOR 32
DEGREES OR COLDER SATURDAY MORNING.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. AT THE VERY TAIL END OF THE
PERIOD(16-18Z TOMORROW), SITES PDT/ALW/RDM/BDN MAY SEE LIGHT
RAIN SHOWERS APPROACH THE SITES. AT THIS TIME,
CHANCES/CONFIDENCE TOO LOW TO INCLUDE IN TAF. WINDS WILL BE
LIGHT, 12KTS OR LESS, THROUGH THE PERIOD. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 68 38 61 37 / 0 0 60 50
ALW 68 44 61 41 / 0 0 60 70
PSC 68 36 64 38 / 0 0 20 20
YKM 69 40 68 39 / 0 0 10 0
HRI 68 37 62 38 / 0 0 30 20
ELN 67 37 67 34 / 0 0 10 0
RDM 72 32 63 23 / 0 0 30 10
LGD 74 44 65 37 / 0 0 90 80
GCD 76 43 64 35 / 0 20 90 70
DLS 72 43 70 43 / 0 0 10 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...71
AVIATION...82
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