334
FXUS66 KPDT 232151
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
251 PM PDT FRI OCT 23 2026
KEY MESSAGES
- DRY CONDITIONS WILL PERSIST INTO THE WEEKEND AS A RIDGE OF
HIGH PRESSURE MOVES OVERHEAD.
- NEAR- TO SUB-FREEZING LOW TEMPERATURES TONIGHT INTO SATURDAY
MORNING. FREEZE WARNINGS IN EFFECT.
- HIGH CONFIDENCE (70-90%) IN COOLER CONDITIONS AND PERIODS OF
SHOWERY WEATHER EARLY NEXT WEEK, FOLLOWED BY MEDIUM CONFIDENCE
(40-60%) IN PERIODS OF ACTIVE WEATHER MIDDLE TO LATE WEEK.
DISCUSSION
WATER VAPOR IMAGERY SHOWS BROAD TROUGHING OVER THE WESTERN
CONUS, MOVING OUT OF OUR FORECAST AREA. MEANWHILE, PRECIPITATION
HAS TAPERED OFF ACROSS THE BLUE MOUNTAINS AS A VERY DRY
NORTHERLY TO NORTHWESTERLY FLOW ALOFT REPLACES THE PREVIOUS AIR
MASS AND A LOW-AMPLITUDE UPPER-LEVEL RIDGE MOVES OVERHEAD.
MORNING SOUNDINGS (12Z OR 18Z) AT SLE, OTX, MFR, AND UIL ALL
SHOW LOW PWATS OF 0.25-0.35" AND 12Z HREF MODEL GUIDANCE
SUGGESTS VALUES RANGING FROM 0.15" TO 0.45" ACROSS THE FORECAST
AREA TODAY INTO TONIGHT. LINGERING BREEZY CONDITIONS WILL TAPER
OFF THIS EVENING INTO TONIGHT. MOREOVER, THE COMBINATION OF
CLEAR TO MOSTLY CLEAR SKIES AND THE DRY AIR MASS HAS SET THE
STAGE FOR NEAR- TO SUB-FREEZING TEMPERATURES TONIGHT INTO
SATURDAY MORNING. WHILE MOST PUBLIC FORECAST ZONES HAVE OBSERVED
A SEASON-ENDING FREEZE, A WIDESPREAD FREEZE HAS NOT YET
OCCURRED IN THE LOWEST ELEVATIONS OF OUR FORECAST AREA.
CONFIDENCE IS MEDIUM-HIGH (50-95%) THAT A SEASON-ENDING FREEZE
WILL BE OBSERVED IN THE LOWER COLUMBIA BASIN, EASTERN COLUMBIA
RIVER GORGE, YAKIMA VALLEY, AND THE FOOTHILLS OF THE NORTHERN
BLUE MOUNTAINS. LOWEST CONFIDENCE IN A WIDESPREAD FREEZE IS FOR
THE EASTERN COLUMBIA RIVER GORGE; HIGHEST CONFIDENCE IN A
FREEZE IS FOR COLD-PRONE LOCATIONS ALONG THE BLUE MOUNTAIN
FOOTHILLS AND LOWER COLUMBIA BASIN. THAT SAID, OPTED TO UPGRADE
ALL FREEZE WATCHES TO FREEZE WARNINGS.
UNCERTAINTY IN THE 500-HPA HEIGHT FIELD BURGEONS SUNDAY THROUGH
THE REMAINDER OF THE FORECAST PERIOD DUE TO CONTINUED ENSEMBLE
SPREAD IN SOLUTIONS REGARDING THE EVOLUTION OF A CLOSED LOW
THAT IS CURRENTLY DEVELOPING IN THE GULF OF ALASKA. WHILE
ENSEMBLE SOLUTIONS HAVE BEGUN TO CLUSTER AROUND A CLOSED LOW
ENTERING, THEN TRACKING INLAND, ACROSS THE PACIFIC NORTHWEST
REGION LATER SUNDAY THROUGH TUESDAY OF NEXT WEEK, SIGNIFICANT
UNCERTAINTY REMAINS WITH REGARD TO THE TRACK OF THE LOW, THE
DEPTH OF THE LOW, AND HOW QUICKLY IT WILL MOVE INLAND. BASED ON
12Z ENSEMBLE GUIDANCE, THE BEST CHANCES OF PRECIPITATION WILL
BE MONDAY AND TUESDAY. EVEN THEN, CHANCES OF A WETTING RAIN
(0.10" OR GREATER) ARE LOW (40% OR LESS) FOR THE LOWER
ELEVATIONS, WASHINGTON CASCADES, AND OCHOCO-JOHN DAY HIGHLANDS.
HIGHER CHANCES (40-70%) OF A WETTING RAIN ARE FORECAST FOR THE
OREGON CASCADES AND NORTHEAST BLUE MOUNTAINS.
ENSEMBLE SOLUTIONS ARE ROUGHLY SPLIT (50/50) WEDNESDAY THROUGH
THE REMAINDER OF THE WEEK ON WHETHER ANOTHER TROUGH/CLOSED LOW
OR RIDGE WILL BE PRESENT OVER THE PACIFIC NORTHWEST. CONTINUED
COOL, SHOWERY WEATHER WOULD ACCOMPANY THE CLOSED LOW OR
TROUGHING SCENARIO, WHILE DRY CONDITIONS WOULD RESULT FROM THE
RIDGE.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. BREEZY WINDS AROUND 12-17KTS WITH
GUSTS TO AROUND 25KTS WILL IMPACT SITE DLS OVER THE NEXT COUPLE
OF HOURS. OTHERWISE, WINDS WILL BE LIGHT AT ALL SITES THROUGH
THE PERIOD. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 26 57 29 57 / 0 0 0 0
ALW 32 59 37 58 / 0 0 0 0
PSC 28 58 28 57 / 0 0 0 0
YKM 30 58 32 58 / 0 0 0 20
HRI 29 57 30 56 / 0 0 0 0
ELN 24 55 26 54 / 0 0 0 20
RDM 18 59 25 61 / 0 0 0 10
LGD 25 58 32 61 / 0 0 0 0
GCD 25 60 29 63 / 0 0 0 0
DLS 34 62 36 60 / 0 0 0 20
PDT WATCHES/WARNINGS/ADVISORIES
WA...FREEZE WARNING FROM 11 PM THIS EVENING TO 10 AM PDT SATURDAY
FOR WAZ024-027>029.
OR...FREEZE WARNING FROM 11 PM THIS EVENING TO 10 AM PDT SATURDAY
FOR ORZ041-044-507.
DISCUSSION...86
AVIATION...82
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