659
FXUS66 KPDT 291200 AAA
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
359 AM PST THU JAN 29 2026
DISCUSSION
KEY MESSAGES:
1. WIDESPREAD PRECIPITATION TODAY, FREEZING RAIN POSSIBLE.
*WINTER WEATHER ADVISORIES ACTIVE*
2. MOUNTAIN PRECIPITATION FRIDAY, RETURNING SUNDAY AND MONDAY.
3. WARMING TREND THROUGH SATURDAY AND STAYING ABOVE NORMAL.
CURRENT RADAR AND INFRARED SATELLITE IMAGERY SHOWS LIGHT RETURNS
EXTENDING ACROSS THE EAST SLOPES OF THE CASCADES AND INTO THE
COLUMBIA BASIN UNDER MOSTLY CLOUDY SKIES. THIS IS IN RESPONSE TO
AN INCOMING SHORTWAVE AND WEAK FRONTAL SYSTEM THAT IS FLATTENING
THE UPPER LEVEL RIDGE THAT DEVELOPED ACROSS THE AREA ON WEDNESDAY.
THE PREVIOUSLY POSITIONED RIDGE HAS ALLOWED TEMPERATURES TO DROP
TO NEAR OR SLIGHTLY BELOW FREEZING ACROSS PORTIONS OF THE LOWER
COLUMBIA BASIN AND THE YAKIMA/KITTITAS VALLEYS, WHICH WILL PROVIDE
THE POTENTIAL FOR FREEZING RAIN TO OCCUR AS THE WEAK WARM FRONT
PASSES THROUGH THE AREA THIS MORNING. THE BEST CHANCE FOR FREEZING
RAIN TO OCCUR AND RESULT IN ICE ACCUMULATIONS OF BETWEEN 0.03-
0.10" WILL BE ACROSS THE KITTITAS VALLEY (60-70% CHANCE), WITH
MUCH LOWER CHANCES EXTENDING INTO THE YAKIMA VALLEY (20-40%
CHANCE), TRI-CITIES (10-20% CHANCE) AND THE HANFORD (15-25%
CHANCE) AREA. THUS, WINTER WEATHER ADVISORIES HAVE BEEN ISSUED
ACROSS THE KITTITAS VALLEY AND THE UPPER/LOWER EAST SLOPES OF THE
WASHINGTON CASCADES UNTIL NOON. SLICK ROADS ARE EXPECTED THROUGH
THE MORNING HOURS, SO USE CAUTION AND PROVIDE ADDITIONAL TIME IF
TRAVELING.
DUE TO THE PASSING WARM FRONT TODAY, SNOW LEVELS WILL BE
INCREASING FROM 4500-5500 FEET THIS MORNING TO 5500-6500 FEET
TONIGHT, LEADING TO SNOWFALL AT HIGHER ELEVATIONS ACROSS THE
CASCADE AND BLUE MOUNTAINS AND PASS-LEVEL RAINFALL. MOISTURE IS
LACKING WITH THIS SYSTEM AS THE UPPER LEVEL RIDGE CONTINUES TO
BUILD DURING THE SHORTWAVE'S RIDE THROUGH THE AREA, WITH EXPECTED
SNOW AMOUNTS OF 1-2 INCHES AT HIGHER TERRAIN AND LOWER ELEVATION
RAINFALL OF AROUND 0.05" THROUGH THE COLUMBIA BASIN, BLUE MOUNTAIN
FOOTHILLS, AND THE GRANDE RONDE VALLEY. SLIGHTLY HIGHER RAIN
AMOUNTS OF 0.10-0.15" ARE LIKELY THROUGH THE COLUMBIA GORGE AND
THE YAKIMA/KITTITAS VALLEY THROUGH THE DAY TODAY.
THE UPPER LEVEL RIDGE REBUILDS BRIEFLY THIS EVENING BEFORE
SHIFTING EAST AS ANOTHER WEAK SHORTWAVE APPROACHES THE AREA AND
PASSES ALONG THE CANADIAN BORDER. THIS WILL BRING ANOTHER ROUND
OF PRECIPITATION TO OUR MOUNTAIN ZONES AS SNOW LEVELS HOVER
BETWEEN 6000-6500 FEET. THESE HIGHER ELEVATIONS ARE FORECAST TO
PICK UP AN INCH OF ADDITIONAL SNOWFALL, AT BEST. LOWER ELEVATIONS
BETWEEN 2500-5500 FEET ALONG THE EAST SLOPES OF THE WASHINGTON
CASCADES WILL LIKELY EXPERIENCE RAIN AMOUNTS OF BETWEEN
0.05-0.25", WITH TRACE AMOUNTS POSSIBLE OVER THE SIMCOE HIGHLANDS
AND LOWER ELEVATIONS OF THE COLUMBIA BASIN, BLUE MOUNTAIN
FOOTHILLS, AND THE YAKIMA/KITTITAS VALLEYS.
ENSEMBLES SHOWCASE ANOTHER TRANSIENT UPPER LEVEL RIDGE MOVING
ACROSS THE PACIFIC NORTHWEST ON SATURDAY AHEAD OF ANOTHER
PROGRESSIVE PATTERN OF SHORTWAVES SUNDAY AND MONDAY BEFORE A
STRONGER UPPER LEVEL RIDGE SETS UP OVER THE AREA TUESDAY ONWARD.
ENSEMBLE MEMBERS ALL HIGHLIGHT ANOTHER ROUND OF WIDESPREAD
PRECIPITATION ON SUNDAY AS LOWER ELEVATIONS OF THE COLUMBIA BASIN
AND BLUE MOUNTAIN FOOTHILLS ARE EXPECTED TO SEE 0.01-0.05" THROUGH
THE DAY. MORE UNCERTAINTY DEVELOPS ON MONDAY AS ONLY 52% OF
ENSEMBLE MEMBERS KEEP PRECIPITATION CONFINED TO OUR MOUNTAIN
ZONES. SNOW LEVELS LOOK TO DECREASE TO BETWEEN 5000-5500 FEET
SUNDAY AND 4000-5000 FEET ON MONDAY, BUT THE LACK OF OVERALL
MOISTURE DUE TO THE SYNOPTIC PATTERN BEING MORE DOMINATED BY
RIDGING WILL LEAD TO SNOW ACCUMULATIONS OF LESS THAN AN INCH BOTH
DAYS. ENSEMBLES THEN ALIGN WITH A SUBSTANTIAL UPPER LEVEL RIDGE
BUILDING OVER THE PACIFIC NORTHWEST ON TUESDAY AND LINGERING
THROUGH THURSDAY.
THE OVERALL MERIDIONAL PATTERN OF REBUILDING UPPER LEVEL RIDGES
AND TRANSIENT SHORTWAVE TROUGHS LEADS TO PERSISTENT WEST-
SOUTHWEST FLOW ALOFT, WHICH KEEPS ABOVE NORMAL TEMPERATURES IN THE
FORECAST THROUGH THE WEEKEND AND INTO NEXT WEEK. THE ONLY
ELONGATED TENURE OF AN UPPER LEVEL RIDGE COUPLED WITH SURFACE HIGH
PRESSURE LOOKS TO OCCUR MIDWEEK NEXT WEEK. THIS SHOULD KEEP ANY
DEVELOPING COLD POOLS OR INVERSIONS TO A MINIMUM UNTIL THEN. 75
AVIATION...12Z TAFS
RAIN WILL CREATE MINOR IMPACTS AT MOST OF THE
TERMINALS THIS MORNING. RDM AND BDN LOOK TO REMAIN LARGELY RAIN
SHADOWED WITH VFR CIGS, WHILE DLS WILL SEE RAIN PERSISTING THROUGH
THE MORNING WITH THE MVFR VISIBILITY. TH3E RAIN AT YKM IS CLOSE TO
FREEZING, AT 33 DEGREES, HOWEVER IT LOOKS LIKE THE TEMPERATURES
SHOULD REMAIN STABLE AND NOT SWITCH OVER TO FREEZING RAIN. A TEMPO
PERIOD FOR RAIN AFTER ABOUT 15Z IS ALSO IN STORE FOR PSC/ALW AND PDT.
PRELIMINARY POINT TEMPS/POPS
PDT 52 38 50 36 / 50 20 0 10
ALW 51 39 50 37 / 60 20 10 20
PSC 49 34 47 33 / 60 30 10 10
YKM 44 34 45 33 / 80 40 10 10
HRI 50 34 48 34 / 50 20 0 10
ELN 41 33 40 32 / 90 50 30 20
RDM 51 34 55 32 / 10 10 0 0
LGD 45 35 47 35 / 60 10 0 10
GCD 48 34 52 35 / 40 10 0 0
DLS 47 38 49 39 / 80 40 20 20
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...75
AVIATION...71
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