636
FXUS66 KPDT 071213
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
413 AM PST SUN DEC 7 2025
DISCUSSION
BROAD OVERVIEW: THE FORECAST THROUGH THE MIDDLE TO LATTER HALF OF
THIS WEEK CAN BE SUCCINCTLY DESCRIBED AS PREDOMINANTLY WARM, WET,
AND WINDY. A SUBTROPICAL HIGH IN THE PACIFIC COUPLED WITH A
PERSISTENT QUASI-ZONAL TO ZONAL JET STREAM AND MULTIPLE FRONTAL
SYSTEMS WILL DIRECT SEVERAL ROUNDS OF SUBTROPICAL AND TROPICAL
MOISTURE INTO THE PACIFIC NORTHWEST. THIS WILL LEAD TO RISES ON
AREA RIVERS.
KEY MESSAGES:
1. BREEZY TO LOCALLY WINDY TODAY, THEN WIDESPREAD WINDY TO LOCALLY
VERY WINDY MONDAY THROUGH MONDAY NIGHT.
2. AMPLE PRECIPITATION THROUGH WEDNESDAY OR THURSDAY WILL LEAD TO
RISES ON AREA RIVERS.
3. LOW (10 PERCENT) POTENTIAL FOR SNOW IN THE KITTITAS AND WALLOWA
VALLEYS TUESDAY THROUGH THURSDAY.
LIGHT PRECIPITATION IS SPREADING EAST-NORTHEASTWARD ACROSS THE
FORECAST AREA EARLY THIS MORNING IN RESPONSE TO LOW- TO MID-LEVEL
WARM AIR ADVECTION (WAA) ASSOCIATED WITH A PACIFIC WARM FRONT.
SNOW LEVELS ARE ROUGHLY 4500-5500 FT, AND WHILE LIGHT SNOW IS
ANTICIPATED FOR MOUNTAIN PASSES ACROSS THE CASCADES AND BLUE
MOUNTAINS, SNOW ACCUMULATIONS WILL LIKELY (80 PERCENT CONFIDENCE)
REMAIN BELOW ADVISORY THRESHOLDS.
LATER THIS MORNING THROUGH AFTERNOON, SOUTHWESTERLY TO WESTERLY
WINDS ARE EXPECTED TO RAMP, WITH WINDS OF 15-25 MPH ACCOMPANIED
BY GUSTS OF 25-45 MPH ACROSS WIND-PRONE PORTIONS OF THE COLUMBIA
PLATEAU. LOCALLY STRONGER WINDS ARE LIKELY (75 PERCENT CONFIDENCE)
ALONG EXPOSED RIDGES. CONSIDERED ISSUING A WIND ADVISORY FOR
NORTH-CENTRAL OREGON, THE FOOTHILLS OF THE SOUTHERN BLUE
MOUNTAINS, AND THE SIMCOE HIGHLANDS FROM 10 AM TO 4 PM PST, BUT
OPTED TO FORGO DUE TO MEDIUM-HIGH CONFIDENCE (60-70 PERCENT) IN
REACHING WIDESPREAD ADVISORY-LEVEL WIND GUSTS. WILL NOTE THAT
FORECAST SOUNDINGS FROM THE 00Z HREF AND 00Z REFS SHOW A WELL-
MIXED BOUNDARY LAYER DURING THE PERIOD WHICH WOULD FACILITATE
MIXING OF THE FORECAST 40-50 KT LOW-LEVEL JET TO THE SURFACE.
PRECIPITATION WILL TURN MORE SHOWERY IN NATURE LATER THIS
AFTERNOON INTO TONIGHT AND REMAIN MOSTLY CONFINED TO MOUNTAIN
AREAS. THE NEXT ROUND OF NOTEWORTHY PRECIPITATION IS EXPECTED (80
PERCENT CONFIDENCE) TO BEGIN LATER MONDAY MORNING, PERSISTING
THROUGH WEDNESDAY NIGHT AS MULTIPLE FRONTAL SYSTEMS FOCUS AMPLE
MOISTURE FROM AN ATMOSPHERIC RIVER. THE BEST CHANCE FOR
PRECIPITATION IN THE LOWER ELEVATIONS WILL BE LATER MONDAY MORNING
AND AFTERNOON THROUGH WEDNESDAY AS A BOUNDARY STALLS OVER THE
REGION. WHILE SNOW LEVELS ARE FORECAST TO REMAIN RELATIVELY HIGH
THROUGH MUCH OF THE WEEK, THERE IS A LOW (10 PERCENT) CHANCE THAT
SNOW LEVELS WILL BE LOW ENOUGH TO ENABLE A WINTRY MIX OR ALL SNOW
FOR THE KITTITAS VALLEY AND OTHER AREAS ALONG THE I-90 CORRIDOR UP
TO SNOQUALMIE PASS TUESDAY THROUGH THURSDAY. MOREOVER, THIS LOW-
CONFIDENCE SCENARIO WOULD ALSO ALLOW NOTEWORTHY SNOW IN WALLOWA
COUNTY AND ACROSS THE MOUNTAIN PASSES OF WASHINGTON AND THE
NORTHERN BLUE MOUNTAINS.
MONDAY LOOKS TO BE WINDY TO VERY WINDY ACROSS THE COLUMBIA
PLATEAU AS A STRONG LOW-LEVEL JET SETS UP OVER THE REGION.
MOREOVER, FORECAST SOUNDINGS FROM THE 00Z HREF AND 00Z REFS SHOW A
WELL-MIXED BOUNDARY LAYER SIMILAR TO TODAY, SO CONFIDENCE IS
MEDIUM-HIGH (50-80 PERCENT) IN NEEDING WIND ADVISORIES FOR THE
MAJORITY OF OUR LOW-ELEVATION ZONES WITHIN THE COLUMBIA BASIN
AREA. THERE IS ALSO POTENTIAL FOR A HIGH WIND WARNING, BUT
CONFIDENCE IS LOW-MEDIUM (20-40 PERCENT) IN REACHING THOSE
THRESHOLDS.
ON THE SUBJECT OF HYDROLOGIC CONCERNS, CURRENT FORECASTS FROM THE
NWRFC IN PORTLAND PLACE MULTIPLE RIVERS AT ACTION STAGE BY
TUESDAY THROUGH THURSDAY OF THIS WEEK.
AVIATION...12Z TAFS
VARIABLE CONDITIONS ARE POSSIBLE THIS
MORNING AS A WEAK WEATHER SYSTEM MOVES THROUGH THE REGION,
PROVIDING FOR A CHANCE OF LIGHT RAIN SHOWERS ACROSS MOST TAF SITES
THROUGH THE EARLY AFTERNOON. ONLY BDN/RDM WILL SEE LOW ENOUGH
CHANCES FOR -RA THAT NO MENTION WAS MADE IN THE TAF. MVFR
CONDITIONS ARE POSSIBLE UNDER SHOWERS, BEFORE GRADUAL CLEARING
TAKES PLACE BY THE LATE AFTERNOON / EARLY EVENING. WINDS ARE
EXPECTED TO PICK UP DURING THE DAY AS WELL, MAINLY OUT OF THE W/SW
WITH GUSTS UP TO 20 KTS AT SOME SITES, BEFORE DECREASING HEADING
INTO THE EVENING. 74
PRELIMINARY POINT TEMPS/POPS
PDT 55 42 59 46 / 90 40 80 70
ALW 53 44 58 47 / 90 60 90 80
PSC 56 43 59 47 / 80 20 70 50
YKM 52 36 54 41 / 80 20 80 80
HRI 57 43 61 47 / 90 30 70 70
ELN 47 34 48 37 / 90 30 80 80
RDM 55 37 57 42 / 40 30 50 50
LGD 45 38 50 43 / 90 70 90 90
GCD 49 38 52 44 / 90 50 70 70
DLS 56 47 58 49 / 100 60 100 90
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...86
AVIATION...74
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