118
FXUS66 KPDT 241803
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1003 AM PST TUE FEB 24 2026
UPDATED AVIATION DISCUSSION
KEY MESSAGES
- WIDESPREAD PRECIPITATION THROUGH EARLY WEDNESDAY.
- DRY AND WARMING CONDITIONS THROUGH REMAINDER OF WEEK.
- WEAK WEEKEND SYSTEM RETURNS RAIN CHANCES TO AREA.
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS WIDESPREAD
LIGHT SHOWERS ACROSS THE CASCADES, BLUE MOUNTAINS, AND THE
COLUMBIA BASIN. THIS IS A RESULT FROM CONTINUED SOUTHWEST FLOW
ALOFT COUPLED WITH A STATIONARY FRONT THAT IS DRAPED ACROSS THE
PACIFIC NORTHWEST. IN ADDITION, AN ELONGATED UPPER LEVEL TROUGH,
LOCATED OFF THE BRITISH COLUMBIA COAST, IS BEGINNING TO BREAK
OFF AND BECOME A CLOSED LOW THAT WILL SEPARATE FROM THE OVERALL
FLOW. THIS TROUGH HAS HELPED TO PULL MOISTURE IN FROM THE
SOUTHWEST, BUT WILL LOSE THIS EFFICIENCY AS IT SEPARATES FROM
THE UPPER LEVEL FLOW AND PUSH FURTHER OUT INTO THE PACIFIC
WEDNESDAY MORNING. UNTIL THEN, THESE FEATURES WILL KEEP LIGHT
SHOWERS IN THE FORECAST TODAY BEFORE SLOWLY TAPERING OFF TONIGHT
INTO WEDNESDAY MORNING.
THE PRESENCE OF THE STATIONARY FRONT WILL HELP TO ENHANCE SHOWER
POTENTIAL BY ADDING LIFT, BUT ALSO WILL PROVIDE A WIDE RANGE OF
SNOW LEVELS ACROSS OUR AREA. SNOW LEVELS ACROSS THE WASHINGTON
CASCADES WILL BE LOWEST AT 3500-4500 FEET, WITH THE OREGON
CASCADES, BLUE MOUNTAINS, AND WALLOWAS AT 6000-7000 FEET. AS A
RESULT, SNOWFALL AMOUNTS OF 2-5 INCHES ARE EXPECTED AT PASS-
LEVEL AND ABOVE ACROSS THE WASHINGTON CASCADES, WITH 1-4 INCHES
LIKELY OVER THE OREGON CASCADES, NORTHERN BLUE MOUNTAINS, AND
THE WALLOWAS ABOVE 4500 FEET. RAIN AMOUNTS AT LOWER ELEVATIONS
WILL RANGE FROM 0.45"-0.55" ACROSS THE BLUE MOUNTAINS,
FOOTHILLS, AND THE SIMCOE HIGHLANDS TO 0.20-0.35" OVER CENTRAL
OREGON, LOWER COLUMBIA BASIN, AND THE YAKIMA/KITTITAS VALLEYS
THROUGH EARLY WEDNESDAY MORNING.
HIGH TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL FOR MUCH OF THE
REGION TODAY, AS TEMPERATURES PEAK IN THE LOW TO MID-40S ACROSS
THE LOWER COLUMBIA BASIN, BLUE MOUNTAIN FOOTHILLS, WALLOWA
COUNTY, AND THE YAKIMA/KITTITAS VALLEYS. HIGHS WILL BE SLIGHTLY
WARMER ACROSS CENTRAL OREGON AND FURTHER SOUTH OF THE
STATIONARY FRONT, WITH AFTERNOON TEMPERATURES IN THE LOW TO
MID-50S. THESE HIGHS WILL SWAP ON WEDNESDAY DUE THE TIMING OF A
WEAK PASSING COLD FRONT AND INCOMING SURFACE HIGH PRESSURE,
WHICH WILL INITIATE A WARMING TREND THAT WILL EXTEND THROUGH THE
REMAINDER OF THE WORKWEEK AS SURFACE HIGH PRESSURE STRENGTHENS.
HIGH TEMPERATURES WILL APPROACH THE LOW 60S ACROSS CENTRAL
OREGON, LOWER COLUMBIA BASIN, AND THE NORTHERN BLUE MOUNTAINS ON
FRIDAY AS THE TREND PEAKS. CONDITIONS WILL ALSO STAY DRY, WITH
THE EXCEPTION OF HIGH, MOUNTAIN TERRAIN ACROSS THE CASCADES AND
BLUE MOUNTAINS THAT MAY ACCUMULATE UP TO AN INCH OF DAILY
SNOWFALL - WEDNESDAY BEING THE BEST CHANCE.
THE WEAK PASSING COLD FRONT WEDNESDAY AND THE SUBSEQUENT HIGH
PRESSURE SLIDING IN BEHIND WILL ALSO BRING WITH IT BREEZY
CONDITIONS ACROSS THE EAST SLOPES OF THE WASHINGTON CASCADES,
LOWER COLUMBIA BASIN, AND BLUE MOUNTAIN FOOTHILLS. A PASSING
UPPER LEVEL TROUGH WILL FURTHER TIGHTEN THE PRESSURE GRADIENT
ALONG THE CASCADES TO PROMOTE THESE ELEVATED, WEST-SOUTHWEST
AFTERNOON WINDS, AS GUSTS OF UP TO 35 MPH WILL BE POSSIBLE BOTH
DAYS. CONFIDENCE IS HIGH IN THESE GUSTS AS THE NBM ADVERTISES A
60-90% CHANCE OF 35 MPH GUSTS OR GREATER OVER THE
AFOREMENTIONED AREAS. THESE WINDS ARE EXPECTED TO STAY BELOW
ADVISORY CRITERIA (45 MPH GUSTS OR GREATER) BOTH DAYS, WITH ONLY
A 20-40% CHANCE OF GUSTS EXCEEDING 44 MPH - BEST CHANCES ACROSS
THE BLUE MOUNTAIN FOOTHILLS ON WEDNESDAY.
ENSEMBLES ARE IN THE GOOD AGREEMENT THAT THE CUTOFF LOW THAT
WILL SEPARATE FROM THE OVERALL UPPER LEVEL FLOW MIDWEEK WILL
REJOIN THE FLOW AND APPROACH THE WASHINGTON/OREGON COASTS OVER
THE WEEKEND. IN ADDITION, BOTH GFS AND ECMWF AI MODELS
REINTRODUCE SOUTHWEST FLOW ALOFT AND LIGHT SHOWERS ACROSS
THE OREGON CASCADES AND CENTRAL OREGON EARLY SATURDAY MORNING.
56% OF ENSEMBLE MEMBERS SUGGEST SHOWERS AS EARLY AS 4 AM
SATURDAY, WITH 87% ALIGNING WITH MEASURABLE RAINFALL (0.01" OR
GREATER) EXTENDING ACROSS OUR OREGON ZONES AND STAYING SOUTH OF
THE WASHINGTON BORDER ON SATURDAY. HOWEVER, RAIN AMOUNTS ARE
LACKING AS THE NBM SHOWS ONLY A 20-45% CHANCE OF MEASURABLE
RAINFALL OVER OUR OREGON ZONES. SNOW AMOUNTS WILL ALSO BE
MINIMAL WITH UP TO AN INCH AT HIGHER TERRAIN AS SNOW LEVELS
HOVER BETWEEN 3500-4500 FEET.
INCONSISTENCIES WITH ENSEMBLES AND DETERMINISTIC GUIDANCE STEMS
FROM SYSTEM STRENGTH ASSOCIATED WITH THE HIGH PRESSURE MIDWEEK
AND THE REINTRODUCTION OF THE UPPER LEVEL TROUGH/LOW FEATURE
INTO THE WEEKEND. GUIDANCE SEEMS TO ALIGN MORE WITH THE INCOMING
TROUGH FEATURE WEAKENING SUBSTANTIALLY DUE TO THE INCUMBENT
HIGH PRESSURE. THIS SEEMS TO 'EAT AWAY' AT THE LOW AS IT
APPROACHES, WHICH IS ESPECIALLY EVIDENT IN THE ECMWF AI AND
ENSEMBLES. THE GFS AI/ENSEMBLES AND THE CAN ALSO DEPICT THIS,
BUT NOT TO THE EXTENT WHICH IS RELATED TO THE ECWMF ALLOWING THE
EARLIER RIDGE AND HIGH PRESSURE TO BE SLIGHTLY STRONGER.
NEEDLESS TO SAY, NO SUBSTANTIAL IMPACTS ARE EXPECTED FROM THIS
WEEKEND SYSTEM, WHICH IS LIKELY TO BRING ONLY LIGHT
PRECIPITATION BEFORE DRIER CONDITIONS RETURN EARLY NEXT WEEK.
GUIDANCE IS IN GOOD AGREEMENT WITH UPPER LEVEL RIDGING AND HIGH
PRESSURE RETURNING IN THE WAKE OF THE PASSING WEEKEND SYSTEM. 75
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
FOR THE REMAINDER OF
THIS MORNING, A MIX OF FLIGHT CATEGORIES WILL BE PREVAILING BETWEEN
MVFR AND LIFR FOR KDLS, KPDT, KYKM, KALW, AND KPSC. KRDM/KBDN ARE
CURRENTLY VFR, BUT ARE EXPECTED TO DETERIORATE TO MVFR FOR THE REST
OF TODAY. WITH PERIODS OF RAIN, MIST AND LOW TO MID CIGS, MOST SITES
MAY FALL UNDER MVFR CONDITIONS OR LOWER THROUGH THE REMAINDER OF
TODAY. HOWEVER, KYKM COULD RETURN TO VFR AROUND 9Z TONIGHT. FOG WITH
LESS THAN A MILE MAY DEVELOP FOR KPDT AROUND 8Z TONIGHT (30-40%
CONFIDENCE). FEASTER/97
PRELIMINARY POINT TEMPS/POPS
PDT 34 49 31 54 / 80 20 0 0
ALW 36 49 34 53 / 80 30 0 0
PSC 33 54 32 55 / 50 10 0 0
YKM 28 49 27 51 / 30 0 0 0
HRI 34 52 31 55 / 60 10 0 0
ELN 27 44 29 47 / 30 10 10 10
RDM 31 47 21 52 / 50 10 0 0
LGD 36 46 26 51 / 90 50 0 0
GCD 36 45 24 50 / 70 40 0 0
DLS 36 51 32 53 / 60 20 10 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...75
AVIATION...97
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