372
FXUS66 KPDT 242210
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
310 PM PDT FRI OCT 24 2025
DISCUSSION
ACTIVE FALL WEATHER IS FORECAST THROUGH THE WEEKEND
AS A SERIES OF LOW-PRESSURE SYSTEMS FROM THE PACIFIC TRACK
ONSHORE. A SHORTWAVE AND ATTENDANT SURFACE COLD FRONT WILL SWEEP
FROM WEST TO EAST ACROSS THE FORECAST AREA THIS AFTERNOON AND
EVENING, PRODUCING WIDESPREAD BREEZY TO WINDY SOUTHERLY TO
WESTERLY WINDS. SATELLITE IMAGERY REVEALS STATIONARY WAVE CLOUDS
DRAPED OVER CENTRAL AND EASTERN OREGON, AND WIND GUSTS OF 35-45
MPH -- LOCALLY 55 MPH -- HAVE ALREADY BEEN OBSERVED TO THE LEE OF
THE CASCADES IN CENTRAL OREGON. SUSTAINED WINDS OF 20-30 MPH AND
GUSTS OF 35-45 MPH ARE EXPECTED (80 PERCENT CONFIDENCE) TO
ACCOMPANY FRONTAL PASSAGE THROUGH THIS EVENING. CONFIDENCE IS HIGH
(70 PERCENT) IN ISOLATED WIND GUSTS UP TO 55 MPH WITH FRONTAL
PASSAGE, BUT CONFIDENCE WANES THE FARTHER NORTH AND EAST INTO THE
COLUMBIA BASIN GIVEN THE FRONT IS NOT EXPECTED TO ARRIVE UNTIL
DIURNAL STABILIZATION BEGINS.
OVERNIGHT INTO SATURDAY MORNING, CONFIDENCE IS VERY HIGH (95
PERCENT) THAT AN OFFSHORE SURFACE LOW WILL CONTINUE TO DEEPEN AS
IT MOVES FROM THE NORTHEAST PACIFIC TOWARDS VANCOUVER ISLAND.
WHILE ENSEMBLE NWP GUIDANCE HAS PREVIOUSLY DISPLAYED SIGNIFICANT
SPREAD AMONG ENSEMBLE SYSTEMS WITH REGARD TO THE TRACK AND
MAGNITUDE OF THE LOW, 12Z RUNS ARE BEGINNING TO CONVERGE ON A MORE
NORTHWESTERLY LOCATION FOR SATURDAY MORNING. THE AFOREMENTIONED
UNCERTAINTY IN THE TRACK OF THE SURFACE LOW, AND JET OF STRONGER
WINDS, IS ONE DRIVER OF UNCERTAINTY IN THE WIND FORECAST FOR
SATURDAY. REGARDLESS, A LOW-LEVEL JET IN THE RANGE OF 35-55 KTS,
PERHAPS AS STRONG AS 60-70 KTS, SHOULD FACILITATE WIDESPREAD
DIURNAL BREEZY TO WINDY WESTERLY WINDS ACROSS THE REGION.
CONFIDENCE IS HIGH (60-80 PERCENT) IN REACHING ADVISORY LEVELS (45
MPH OR GREATER), AND LOW (10-30, ISOLATED AREAS UP TO 50 PERCENT)
FOR WARNING LEVELS (GUSTS OF 58 MPH OR GREATER). HAVE OPTED NOT
TO ISSUE ANY WATCHES, WARNINGS, OR ADVISORIES FOR THE WIND ON
SATURDAY TO AVOID CONFUSION WITH THE ADVISORIES THAT ARE IN EFFECT
THROUGH THIS EVENING.
REGARDING WINTER WEATHER, SNOW LEVELS ARE EXPECTED TO DROP IN THE
WAKE OF TODAY'S COLD FRONT, REACHING MOUNTAIN PASS LEVELS
SATURDAY AFTERNOON AND EVENING AS COOLER AIR MOVES OVERHEAD.
WINTER WEATHER ADVISORIES REMAIN IN EFFECT FOR THE CASCADES AND
NORTHERN BLUE MOUNTAINS. THE ONLY CHANGE WAS TO REDUCE FORECAST
SNOW TOTALS FOR THE NORTHERN BLUE MOUNTAINS.
THE MOST NOTEWORTHY UPDATE TO THE FORECAST INCLUDED AN
EXPANSION/INTRODUCTION OF A SLIGHT CHANCE (15-20 PERCENT) OF
THUNDERSTORMS SATURDAY AFTERNOON ACROSS THE EASTERN HALF OF THE
COLUMBIA BASIN INTO THE BLUE MOUNTAINS. THE INJECTION OF COOLER
AIR ALOFT WILL LEAD TO STEEPER LAPSE RATES AND SOME INSTABILITY
(MUCAPE OF 250-500 J/KG) ACROSS THE AFOREMENTIONED REGION. COUPLED
WITH EFFECTIVE SHEAR IN EXCESS OF 35 KTS AND STRONG WINDS ALOFT,
STRONGER SHOWERS AND THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
SEVERE OUTFLOW WINDS (50 KTS OR GREATER). SPC HAS INTRODUCED A DAY
2 MARGINAL RISK FOR MUCH OF OREGON AND SOUTHERN WASHINGTON.
LOOKING AHEAD, PRECIPITATION IS EXPECTED TO TAPER OFF SUNDAY NIGHT
WITH A BREAK BETWEEN SYSTEMS ON MONDAY. CONFIDENCE IN PATTERN
DETAILS IS LOW FOR TUESDAY ONWARD.
AVIATION
DETERIORATING CONDITIONS ARE EXPECTED THIS AFTERNOON
FROM WEST TO EAST WITH RAIN DEVELOPMENT IN EARNEST LATE TONIGHT
INTO SATURDAY. A COLD FRONT WILL BE MOVING ACROSS THE REGION
BRINGING STRONG GUSTY DOWNSLOPE WINDS TO THE TERMINALS CLOSER TO
THE CASCADE RANGE. FARTHER EAST TERMINALS LIKE PDT/ALW/PSC ARE IN
AN AREA OF HIGHER UNCERTAINTY FOR WIND STRENGTH AS THE DIURNAL
COOLING MIGHT STABILIZE THE SURFACE ENOUGH TO TEMPER THE MOMENTUM
TRANSFER LATE THIS EVENING, THUS LIMITING GUST POTENTIAL. STILL AN
UPTICK IN WESTERLY SURFACE GUSTS TO AROUND 25 KNOTS SHOULD BE
EXPECTED IN THE 3-5Z TIME WINDOW FOR THOSE TERMINALS.
PRELIMINARY POINT TEMPS/POPS
PDT 44 63 38 55 / 70 90 30 60
ALW 48 63 41 55 / 80 100 50 60
PSC 41 61 39 57 / 60 90 20 50
YKM 35 55 34 52 / 60 90 50 60
HRI 43 62 40 57 / 50 90 20 60
ELN 31 50 30 48 / 80 90 70 60
RDM 37 55 28 50 / 70 90 60 80
LGD 43 58 33 50 / 80 90 60 70
GCD 45 58 33 50 / 80 90 40 70
DLS 43 60 41 55 / 90 100 80 90
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY FROM 8 AM SUNDAY TO 8 AM PDT MONDAY FOR
ORZ502.
WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORZ508-510-511.
WINTER WEATHER ADVISORY FROM 8 PM SATURDAY TO 2 AM PDT MONDAY
FOR ORZ509.
WA...WINTER WEATHER ADVISORY FROM 8 AM SUNDAY TO 8 AM PDT MONDAY FOR
WAZ030.
WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ027-028-521.
WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ029.
WINTER WEATHER ADVISORY FROM 11 PM SATURDAY TO 11 PM PDT SUNDAY
FOR WAZ522.
SHORT TERM...86
LONG TERM....86
AVIATION...71
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