431
FXUS66 KPDT 130552
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
952 PM PST WED NOV 12 2025
UPDATED AVIATION...06Z TAFS
WHILE MOST SITES ARE CURRENTLY IN VFR,
KALW WILL BE IN LIFR FROM THE LOW CLOUDS. TONIGHT'S CONCERN WOULD
BE FOG/MIST AND LOW CLOUDS, WHICH MAY BRING VSBYS AND/OR CIGS
DOWN MAINLY FOR KALW. BUT, WILL CONTINUE MONITORING FOR OTHER
SITES IN CASE THE FOG/MIST DEVELOPS. AS THE FRONTAL SYSTEM
ARRIVES THURSDAY, WIDESPREAD RAIN SHOWERS WILL DOMINATE ALL SITES
THROUGH THE DAY ALONG WITH MIST. THIS COULD ALSO POTENTIALLY LOWER
VSBYS AND CIGS FOR KPDT/KYKM/KALW/KPSC AND BRING GUSTY WINDS AT
20-25KTS OVER KRDM/KBDN WITH SUSTAINED WINDS OF 12-15KTS THURSDAY
AFTERNOON STARTING AROUND 20Z. FEASTER/97
PREV DISCUSSION
/ISSUED 309 PM PST WED NOV 12 2025/
DISCUSSION
KEY MESSAGES:
1. MOUNTAIN SHOWERS TODAY, BECOMING WIDESPREAD THURSDAY.
2. BREEZY WINDS THURSDAY.
3. PROGRESSIVE PATTERN EXTENDS THROUGH WEEKEND INTO NEXT WEEK.
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS LIGHT RETURNS
ACROSS THE WASHINGTON CASCADES UNDER PARTLY CLOUDY SKIES. THIS IS
IN RESPONSE AN APPROACHING UPPER LEVEL TROUGH AND SOUTHWEST FLOW
ALOFT THAT WILL KEEP MOUNTAIN SHOWERS THROUGH THE DAY TODAY BEFORE
BECOMING WIDESPREAD THURSDAY AS THE TROUGH AND ASSOCIATED FRONTAL
SYSTEM PASS THROUGH THE PACIFIC NORTHWEST. THE STEEP SOUTHWEST
FLOW ALOFT WILL KEEP SNOW LEVELS QUITE HIGH (8000-9000 FEET)
THROUGH THURSDAY BEFORE BRIEFLY DROPPING TO 4500-5500 FEET FRIDAY.
MINIMAL RAIN AMOUNTS OF LESS THAN 0.05" ARE EXPECTED TODAY ACROSS
HIGHER TERRAIN OF THE CASCADES, WITH BETWEEN 0.25-0.50" OF
RAINFALL ON THURSDAY. RAIN AMOUNTS ON THURSDAY HAVE BEEN ON THE
DOWNWARD TREND OVER THE LAST SEVERAL DAYS, WITH CURRENT TOTALS OF
BETWEEN 0.20-0.40" ACROSS THE NORTHERN BLUE MOUNTAINS, 0.05-0.20"
THROUGH THE BLUE MOUNTAIN FOOTHILLS, AND LESS THAN 0.05" OVER THE
LOWER COLUMBIA BASIN AND CENTRAL OREGON. THE FIRST WAVE OF SHOWERS
IS LIKELY TO PASS THROUGH THE AREA AROUND NOON WITH ADDITIONAL
CHANCES AFTER 4 PM AND EXTENDING UNTIL MIDNIGHT ALONG THE BLUE
MOUNTAIN FOOTHILLS. A WEAK, TRANSIENT RIDGE OF HIGH PRESSURE
SLIDES THROUGH THE AREA FRIDAY, ALLOWING FOR CONTINUED RAIN
CHANCES FOR MOUNTAIN AND FOOTHILLS ZONES WHICH WILL BE MORE
CONFINED TO THE WASHINGTON CASCADES AFTER 4 PM.
THE APPROACHING TROUGH AND COLD FRONT, COUPLED WITH THE SLOWLY
DEPARTING RIDGE, WILL ATTRIBUTE TO BREEZY CONDITIONS ACROSS THE
EASTERN MOUNTAINS, CENTRAL OREGON, AND THE GRANDE RONDE VALLEY AS
A PRESSURE GRADIENT DEVELOPS OVER THE BLUE MOUNTAINS. THE NAM AND
SREF ADVERTISE A 5-5.6 MB DIFFERENCE BETWEEN MEACHAM (KMEH) AND
BAKER CITY, WHICH RELATES TO SUSTAINED SOUTH WINDS OF 15-25 MPH
WITH GUSTS UP TO 35 MPH THROUGH THE GRANDE RONDE VALLEY.
CONFIDENCE IN THESE WINDS ARE MODERATE TO HIGH AS THE HREF
SUGGESTS A 60-70% CHANCE OF GUSTS REACHING 35 MPH OR GREATER,
PEAKING THROUGH THE MORNING HOURS BETWEEN 8 AM AND 11 AM. WINDS
WILL PEAK EARLIER ACROSS CENTRAL OREGON, AROUND MIDNIGHT TONIGHT
AND SHORTLY AFTER. DURING THIS TIMEFRAME, THE HREF SUGGESTS A
60-70% CHANCE OF 35 MPH GUSTS OR GREATER FOR BEND. THESE WIND
CHANCES DECREASE TO AROUND 50% THROUGH THE MORNING BEFORE
DECREASING SUBSTANTIALLY AFTER NOON. A WIND ADVISORY IS UNLIKELY
(<10%) AND NOT EXPECTED FOR EITHER OF THESE AREAS.
GUIDANCE IS IN AGREEMENT WITH THE OVERALL PATTERN OF A MORE
MERIDIONAL FLOW OF TRANSIENT RIDGES AND SHORTWAVE TROUGHS
INITIATING OVER THE WEEKEND AND CONTINUING THROUGH THE WEEK.
HOWEVER, ENSEMBLES STRUGGLE WITH DETAILS AND THE TIMING OF THESE
SYNOPTIC FEATURES. THIS BEGINS ON SATURDAY WITH INCONSISTENCIES
REGARDING THE STRENGTH OF THE TRANSIENT RIDGE THAT BUILDS OVER THE
PACIFIC NORTHWEST. 54% OF ENSEMBLES SUGGEST A WEAKER RIDGE WHICH
RELATES TO HIGHER CHANCES FOR MOUNTAIN PRECIPITATION WITH SNOW
LEVELS OF AROUND 7000 FEET. SATURDAY'S DIFFERENCE IN RIDGE
STRENGTH PROVIDES THE SUBSEQUENT FORECAST THROUGH THE REMAINDER OF
THE WEEKEND AND INTO THE WORKWEEK WITH UNCERTAINTY, PRIMARILY IN
REGARDS TO TIMING AS A STRONGER RIDGE SATURDAY SLOWS DOWN SUNDAY'S
SYSTEM. THESE TROUGHS THROUGH THE EARLY HALF OF THE WEEK ARE
RATHER WEAK, ONLY RESULTING IN MOUNTAIN PRECIPITATION. WITH THAT
SAID, SNOW LEVELS ARE EXPECTED TO DROP BETWEEN 3500-4500 FEET
SUNDAY AND MONDAY, WHICH WOULD PROVIDE SOME LIGHT ACCUMULATIONS OF
AROUND ONE INCH OVER THE 48 HOUR TIMEFRAME. AT THIS TIME, THE NBM
ADVERTISES A 26% CHANCE OF 1 INCH OF SNOW OR MORE OVER SANTIAM
PASS. THIS PROGRESSIVE PATTERN IS ALSO EXPECTED TO BRING
TEMPERATURES DOWN TO NEAR NORMAL STARTING MONDAY, WITH HIGHS
PEAKING IN THE UPPER 40S TO LOW 50S OVER THE LOWER COLUMBIA BASIN.
75
PRELIMINARY POINT TEMPS/POPS
PDT 40 62 44 60 / 0 60 70 40
ALW 43 61 47 59 / 10 70 80 50
PSC 39 54 43 60 / 0 60 60 20
YKM 40 54 39 57 / 10 80 60 10
HRI 40 54 44 60 / 10 60 60 20
ELN 38 51 37 52 / 30 90 80 20
RDM 45 66 37 58 / 10 60 40 10
LGD 46 63 43 59 / 0 60 80 50
GCD 46 66 42 58 / 10 50 70 20
DLS 45 56 46 58 / 30 90 80 40
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...75
LONG TERM....75
AVIATION...97
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