351
FXUS66 KPDT 272154
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
254 PM PDT SUN APR 27 2025
SHORT TERM...TODAY THROUGH WEDNESDAY
THE SHORTWAVE TROUGH
GRADUALLY BEGINS MOVING OUT OF THE AREA WITH A UPPER RIDGE
APPROACHING FROM THE OR COAST THROUGH TOMORROW. WINDY CONDITIONS
CONTINUE THROUGH THIS EVENING AS THE NORTHWESTERLY FLOW TAKES OVER
FOR THE CASCADE GAPS. AND WITH THE MARINE STRATUS LAYER REMAINING
PRESENT BASED ON THE CURRENT SATELLITE IMAGERY AND THE SOUNDINGS FOR
THE GORGE AND ELLENSBURG PEAKING AT 30-35 KTS THIS AFTERNOON, THESE
FAVORABLE CONDITIONS WILL STRENGTHEN THE WIND GUSTS UP TO 45-50 MPH
WITH SUSTAINED WINDS OF 25-35 MPH, WHICH WARRANTED FOR A WIND
ADVISORY FROM 2PM TO 11PM PDT FOR THE EASTERN CR GORGE OF WA/OR
AND KITTITAS VALLEY. STRONG TEMPERATURE AND PRESSURE GRADIENTS WILL
ALSO ASSIST THE WIND GUSTS TO LAST THROUGH TONIGHT AS WELL, BUT
MAY DECREASE SLIGHTLY TO 25-35 MPH. ISOLATED THUNDERSTORMS MAY
DEVELOP THIS AFTERNOON AT THE WALLOWAS BUT, CHANCES ARE LOW (<20%)
DUE TO WEAK INSTABILITY (CAPE VALUES UNDER 500 J/KG) AND LOW
MOISTURE LEVEL.
TOMORROW, THE RIDGE WILL THEN BUILD OVER ACROSS THE PACNW WITH WARM
DRY CONDITIONS. LOCALLY WINDY CONDITIONS (25-35 MPH) MAY DEVELOP
OVER THE GORGE, SOUTHERN BLUE MOUNTAINS-FOOTHILLS, AND KITTITAS
VALLEY THROUGH THE DAY. HOWEVER, A FRONTAL SYSTEM WILL ARRIVE
TOMORROW EVENING WITH SHOWERS AT THE WA/OR CASCADES (>35% CHANCE)
AND NORTHERN BLUES INCLUDING YAKIMA VALLEY, LOWER BASIN, AND
SOUTHERN BLUE MOUNTAINS-FOOTHILLS (<20% CHANCE). AND AS THE FLOW
CHANGE FROM NORTHWEST TO MORE WESTERLY, GUSTY WINDS WILL RETURN
AGAIN AT THE GORGE, SOUTHERN BLUE MOUNTIANS-FOOTHILLS, AND KITTITAS
VALLEY BEFORE DECREASING LATER ON AT NIGHT.
WIDESPREAD SHOWERS WILL DEVELOP TUESDAY MORNING AS THE FRONTAL
SYSTEM SWEEPS OVER THE FORECAST AREA. WINDS WILL REMAIN GUSTING UP
TO 35 MPH OR MORE THROUGH THE EARLY EVENING. TUESDAY NIGHT INTO
WEDNESDAY MORNING, CONDITIONS SHOULD IMPROVE WITH PRECIP DRYING OUT
AND LIGHT WINDS RETURNING AS THE RIDGE APPROACHES ONSHORE.
TEMPERATURES WILL BE NEAR TO ABOVE NORMAL FOR THIS TERM. FEASTER/97
LONG TERM...WEDNESDAY THROUGH SUNDAY
WARM, DRY CONDITIONS ARE
FORECAST AREA-WIDE WEDNESDAY THROUGH MUCH OF FRIDAY AS AN UPPER-
LEVEL RIDGE OF HIGH PRESSURE MOVES OVER THE PACIFIC NORTHWEST. THIS
WILL LEAD TO WIDESPREAD MINOR (LEVEL 1 OF 4) HEATRISK THURSDAY AND
FRIDAY. NBM PROBABILITIES OF EXCEEDING 80 DEGREES ARE HIGH (60-90%)
FOR MAJOR POPULATION CENTERS THURSDAY (CENTRAL OREGON, SOUTH-CENTRAL
TO SOUTHEAST WASHINGTON, AND NORTHEAST OREGON) AND FRIDAY (SOUTH-
CENTRAL TO SOUTHEAST WASHINGTON AND NORTHEAST OREGON). MOREOVER, THE
ECMWF EFI HIGHLIGHTS PORTIONS OF OUR CWA BOTH DAYS FOR
ANOMALOUS TEMPERATURES (EFI VALUES OF 0.6-0.9) RELATIVE TO NORMAL.
THE WARM, DRY CONDITIONS WILL LIKELY (90% CONFIDENCE) YIELD TO
COOLER, UNSETTLED WEATHER LATE FRIDAY THROUGH SUNDAY AS AN UPPER-
LEVEL LOW FROM THE PACIFIC MAKES ITS WAY ONSHORE. ANALYSIS OF
ENSEMBLE MEMBERS VIA CLUSTER ANALYSIS DOES SHOW SIGNIFICANT SPREAD
IN THE TRACK/MAGNITUDE OF THE AFOREMENTIONED CLOSED LOW AS IT
TRAVERSES THE REGION, TYPICAL FOR A SPRINGTIME PATTERN. OF NOTE, THE
ECMWF EFI IS CURRENTLY HIGHLIGHTING MOST OF THE BLUE MOUNTAINS
REGION, INCLUDING PORTIONS OF THEIR FOOTHILLS, WITH EFI VALUES OF
0.5-0.7 FOR 00Z SATURDAY TO 00Z SUNDAY. ADDITIONALLY, POTENTIAL
EXISTS FOR SOME MOUNTAIN SNOWFALL; THE NBM IS SUGGESTING LOW (ALBEIT
NOTEWORTHY) PROBABILITIES (10-30%) OF 2" OR MORE OF
SNOWFALL FOR MOUNTAIN PASSES WITH THE SYSTEM.
SOME RISES ON AREA RIVERS ARE FORECAST WITH THE WARM TEMPERATURES
FOLLOWED BY PRECIPITATION. CONFIDENCE IS REASONABLY HIGH IN THE
NACHES RIVER NEAR CLIFFDELL REMAINING NEAR OR ABOVE ACTION STAGE
THROUGH THE PERIOD, BUT THE RESPONSE OF RIVERS IN THE BLUE MOUNTAINS
REGION OVER THE WEEKEND WILL LARGELY DEPEND ON HOW MUCH
PRECIPITATION THE REGION SEES SO CONFIDENCE IN CURRENT FORECASTS
THERE IS LOWER.
LASTLY, A SLIGHT CHANCE (15-24%) OF THUNDERSTORMS IS FORECAST FRIDAY
PM FOR PORTIONS OF CENTRAL AND EASTERN OREGON. PLUNKETT/86
AVIATION...18Z TAFS
VFR CONDITIONS ARE FORECAST FOR ALL
STIES THROUGH THE VALID PERIOD. BREEZY TO WINDY SOUTHWESTERLY TO
NORTHWESTERLY WINDS (DEPENDING ON SITE) ARE FORECAST THROUGH MUCH OF
THE PERIOD, STRONGEST THIS AFTERNOON AND EVENING. OTHERWISE, MOSTLY
CLEAR SKIES ARE FORECAST TODAY, WITH MEDIUM (60%) CONFIDENCE IN FEW-
SCT CLOUDS AT 7-10 KFT LATE AFTERNOON INTO THE OVERNIGHT HOURS AT
PDT/ALW/PSC/YKM. PLUNKETT/86
PRELIMINARY POINT TEMPS/POPS
PDT 43 69 48 68 / 0 0 10 70
ALW 46 69 50 67 / 0 0 20 80
PSC 44 74 49 74 / 0 0 10 50
YKM 44 74 49 73 / 0 10 20 20
HRI 44 72 50 72 / 0 0 10 50
ELN 45 66 48 65 / 0 10 30 20
RDM 32 69 41 65 / 0 0 10 20
LGD 39 67 44 60 / 0 0 10 70
GCD 36 69 42 61 / 0 0 10 60
DLS 44 67 50 68 / 0 10 10 20
PDT WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORZ041.
WA...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ024-026.
SHORT TERM...97
LONG TERM....86
AVIATION...86
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