800
FXUS66 KPDT 291027 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
326 AM PDT SAT MAR 29 2025
UPDATED AVIATION DISCUSSION
SHORT TERM...TODAY THROUGH MONDAY
A SHORTWAVE TROUGH IS
CURRENTLY MOVING OVER OUR CWA THIS MORNING. LIGHT PRECIPITATION
IS ONGOING ACROSS THE BLUE MOUNTAINS REGION OF EASTERN OREGON,
PREDOMINANTLY RAIN BELOW 3500-4500 FEET BASED ON SURFACE
OBSERVATIONS. THIS BAND OF PRECIPITATION IS FORECAST TO CONTINUE
THROUGH THE DAY ACROSS THE BLUES AS THE SHORTWAVE TROUGH SLOWLY
TRACKS FROM SOUTHWEST TO NORTHEAST ACROSS EASTERN OREGON. HEAVIEST
PRECIPITATION, RELATIVELY SPEAKING, IS FORECAST ACROSS WALLOWA
COUNTY AND THE HIGHER RANGES OF THE BLUES INCLUDING THE ELKHORNS
AND STRAWBERRIES. WHY? SOME MID-LEVEL PVA, AS WELL AS A RATHER
SUBTLE MID-LEVEL CIRCULATION, WILL BE PLACED ACROSS EASTERN
OREGON THIS MORNING THROUGH THE AFTERNOON. THIS MID-LEVEL
CIRCULATION WILL PLACE MOIST UPSLOPE FLOW (NORTHWEST TO
NORTHEAST) BELOW ROUGHLY 650-600 MB ACROSS NORTHEAST OREGON FOR
THE AFOREMENTIONED RANGES. WILL NOTE THAT SNOW IS ALSO FORECAST
FOR WALLOWA VALLEY, BUT FORECAST SNOW LEVELS OF AROUND 3200-3600
FEET THIS MORNING FOLLOWED BY AFTERNOON SNOW LEVELS OF 3900-4300
FEET AND AFTERNOON TEMPERATURES IN THE UPPER 30S TO LOWER 40S
SHOULD LIMIT SNOW ACCUMULATION. STILL, 1-3 INCHES OF SNOW IS
FORECAST FOR THE HIGHER PORTIONS OF THE VALLEY. CONFIDENCE IN
ADVISORY-LEVEL SNOW (4-6 INCHES) IS LOW (<30%).
PRECIPITATION WILL TAPER OFF THIS EVENING INTO EARLY SUNDAY AS THE
SHORTWAVE TROUGH EXITS TO THE NORTHEAST AND BRIEF SHORTWAVE
RIDGING MOVES OVERHEAD. MOSTLY DRY CONDITIONS ARE THEN FORECAST
FOR ALL THROUGH MID-AFTERNOON SUNDAY.
THE NEXT ROUND OF PRECIPITATION IS SLATED TO ARRIVE BY LATE
SUNDAY AS A CLOSED UPPER LOW DEVELOPS OFFSHORE AND A SHORTWAVE
WRAPS AROUND THE PARENT LOW AND SWINGS THROUGH THE FORECAST AREA.
UNSETTLED CONDITIONS, CHARACTERIZED BY LIKELY (>=75% CHANCE)
SHOWERS FOR THE MOUNTAINS AND FOOTHILLS AND A CHANCE (25-50%) OF
SHOWERS FOR THE COLUMBIA BASIN ACCOMPANIED BY TYPICAL SPRINGTIME
BREEZY SOUTHWESTERLY TO WESTERLY WINDS, ARE FORECAST MONDAY AS A
COUPLE WEAK SHORTWAVES ROTATE AROUND THE OFFSHORE UPPER-LEVEL
LOW. PLUNKETT/86
LONG TERM...TUESDAY THROUGH SATURDAY
MODELS CONTINUE TO
STRUGGLE THROUGH MUCH OF THE PERIOD. HOWEVER, THEY HAVE COME
INTO A LITTLE BETTER AGREEMENT. OVERALL, A BROAD TROUGH IS
EXPECTED TO MAKE ITS HOME OVER MUCH OF THE PACNW THROUGH THE
PERIOD. CLUSTER ANALYSIS SHOW PRETTY GOOD AGREEMENT TUESDAY BUT
DIFFERENCE BEGIN TO BUILD THEREAFTER. BY WEDNESDAY, MUCH OF THE
DIFFERENCES REST OFFSHORE WITH A DEVELOPING UPPER LEVEL RIDGE.
ECMWF CLUSTER MEMBERS LIKE A MORE AMPLIFIED RIDGE OVER THE EASTERN
PACIFIC WHILE THE GFS MEMBERS ARE SIGNIFICANTLY MORE SUBDUED. BY
FRIDAY, 74% IF MEMBERS SHOW AN IMPRESSIVELY AMPLIFIED UPPER LEVEL
RIDGE JUST OFF/APPROACHING THE COAST. THE ONLY OUTLIER IS A GFS
SKEWED (57% MEMBERS) SOLUTION SHOWING ALMOST ZONAL FLOW OVER THE
REGION. BY SATURDAY, THE HIGHLY AMPLIFIED RIDGE NEARING THE COAST
REMAINS THE DOMINANT SOLUTION (52% MEMBERS) WHILE THE GFS
CONTINUES TO BE AN OUTLIER SHOWING A TROUGH OVER THE EASTERN
PACIFIC. OVERALL, KEEPING THE UPPER LEVEL RIDGE JUST OFFSHORE WITH
A BROAD UPPER LEVEL TROUGH OVER THE PACNW AND GREAT BASIN. THE
ENSEMBLES POINT A SIMILAR PICTURE BUT THE ECMWF ACTUALLY MOVES THE
UPPER LEVEL RIDGE INLAND BY SATURDAY. THE DETERMINISTIC MODELS
ARE IN "GENERAL" AGREEMENT WITH RESPECT TO A BROAD TROUGH OVER THE
AREA THROUGH THURSDAY. THE GFS IS A LITTLE MORE MOTIVATED IN
BRINGING THE AFOREMENTIONED RIDGE OVER THE AREA FRIDAY WHILE THE
ECMWF DELAYS UNTIL SATURDAY. AT THIS TIME, WILL CONTINUE TO LEAN
WITH THE MORE CONSISTENT ECMWF SOLUTION SO UNSETTLED WEATHER,
MOSTLY OVER THE MOUNTAINS, THROUGH MUCH OF THE PERIOD WITH A
DRYING TREND BY THE WEEKEND.
THE BEST CHANCE OF SEEING A 0.10 OF AN INCH OR MORE OF
PRECIPITATION WILL BE TUESDAY OVER THE MOUNTAINS WITH A MODERATE
TO HIGH CHANCE (60-95%) WHILE CHANCES FALL TO LOW (10-20%) OVER
THE BASIN AND CENTRAL OREGON. CHANCES WILL DECREASE THROUGH THE
PERIOD WITH MOSTLY DRY CONDITIONS EXPECTED BY SATURDAY AS THE
RIDGE NOSES INTO THE AREA.
DAYTIME HIGHS WILL BE NEAR TO SLIGHTLY BELOW NORMAL THROUGH MUCH
OF THE PERIOD WITH TEMPERATURES RISING TO ABOVE NORMAL BY
SATURDAY. EARLE/81
AVIATION...12Z TAFS
VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD. CLOUDS WILL DECREASE THROUGH THE DAY AS A SYSTEM EXITS THE
REGION. WINDS WILL BE 10 KTS OR LESS. EARLE/81
PRELIMINARY POINT TEMPS/POPS
PDT 56 35 63 42 / 20 0 0 70
ALW 55 37 61 43 / 20 0 0 80
PSC 61 34 64 43 / 0 0 0 60
YKM 59 34 59 39 / 0 0 0 60
HRI 60 34 63 41 / 10 0 0 70
ELN 56 34 57 38 / 10 0 0 70
RDM 54 30 58 34 / 0 0 10 70
LGD 49 28 54 37 / 50 0 10 70
GCD 49 28 55 37 / 50 0 30 80
DLS 59 37 61 42 / 0 0 30 80
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...86
LONG TERM....81
AVIATION...81
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