300
FXUS66 KPDT 301050 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
349 AM PDT SUN MAR 30 2025
UPDATED AVIATION DISCUSSION
SHORT TERM...TODAY THROUGH TUESDAY
UNSETTLED CONDITIONS ARE
FORECAST FOR MOST OF THE PERIOD AS A BROAD UPPER-LEVEL LOW IN THE
PACIFIC DOMINATES THE SYNOPTIC PATTERN. CURRENT WATER VAPOR
IMAGERY REVEALS MULTIPLE CIRCULATION CENTERS EMBEDDED WITHIN THE
BROADER UPPER LOW THAT STRETCHES ACROSS THE NORTHEAST PACIFIC AND
GULF OF ALASKA. NWP GUIDANCE SUGGESTS THE LOW CENTER IN THE
VICINITY OF 44N, 144W WILL BECOME THE MAIN FEATURE OF INTEREST AS
IT FIRST DEEPENS THROUGH TODAY BEFORE SLOWLY WEAKENING AS IT
TRACKS ONSHORE LATE MONDAY THROUGH TUESDAY.
MOSTLY DRY CONDITIONS EARLY THIS MORNING WILL GIVE WAY TO
INCREASING CLOUDS AND SHOWERS THIS AFTERNOON AS A WEAK FRONT
ARRIVES FROM THE SOUTHWEST. PRECIPITATION WILL SPREAD FROM
SOUTHWEST TO NORTHEAST THROUGH THE DAY, WITH ALL AREAS HAVING A
GOOD CHANCE OF SHOWERS THROUGH TONIGHT (60-90%, HIGHEST FOR AREA
MOUNTAINS). BREEZY TO LOCALLY WINDY SOUTHEAST WINDS ARE
ANTICIPATED IN PORTIONS OF CENTRAL AND NORTHEAST OREGON. THE 00Z
HREF SUGGESTS A HIGH CHANCE (60 TO LOCALLY 100%) OF 35 MPH GUSTS,
BUT IS LESS EXCITED ABOUT THE CHANCE (20 TO LOCALLY 60% ALONG THE
SLOPES OF THE NORTHERN BLUE MOUNTAINS) OF REACHING 45 MPH GUSTS
(ADVISORY THRESHOLD). HAVE HELD OFF ON ISSUING ANY WIND HIGHLIGHTS
DUE TO INSUFFICIENT CONFIDENCE.
MONDAY THROUGH TUESDAY, SNOW LEVELS ARE FORECAST TO LOWER TO PASS
LEVEL ACROSS THE FORECAST AREA, AND MOUNTAIN SNOW SHOWERS WILL
RETURN. WHILE NO WINTER HIGHLIGHTS HAVE BEEN ISSUED DUE TO LOW
CONFIDENCE IN REACHING ADVISORY CRITERIA, WILL NEED TO MONITOR THE
TRACK OF THE LOW AS IT COMES ONSHORE (IT IS CURRENTLY FAVORED TO
SWING ACROSS SOUTHWEST OREGON). THE AREA THAT IS MOST LIKELY TO
SEE ADVISORY AMOUNTS IS THE OREGON CASCADES (75% CHANCE AT SANTIAM
PASS FOR THE 48-HR PERIOD ENDING 06Z WEDNESDAY). NBM
PROBABILITIES OF ADVISORY-LEVEL SNOWFALL TOTALS ARE LOW (<30%)
ELSEWHERE.
LASTLY, THERE IS SOME POTENTIAL FOR THUNDER ACROSS THE REGION LATE
TODAY INTO TONIGHT AND ESPECIALLY MONDAY. BEST CHANCES WILL BE
MONDAY AFTERNOON ACROSS THE BLUE MOUNTAINS WHERE 4-HR HREF-
CALIBRATED PROBABILITIES OF THUNDER RANGE FROM 20-40%. PLUNKETT/86
LONG TERM...WEDNESDAY THROUGH SUNDAY
MODELS ARE IN BETTER
AGREEMENT IN THE OVERALL PATTERN. A BROAD UPPER LEVEL LOW WILL
GIVE WAY TO AN IMPRESSIVE UPPER LEVEL HIGH BY THE WEEKEND. THERE
ARE SOME DIFFERENCES IN STRENGTH AND SPEED OF THE UPPER HIGH BUT
OVERALL MODELS ARE IN GOOD AGREEMENT. CLUSTER ANALYSIS SHOWS
NORTHWEST FLOW OVER THE AREA WEDNESDAY AS THE CENTER OF THE UPPER
LEVEL TROUGH MOVES EAST. THE UPPER LEVEL FLOW BECOMES MORE
NORTHERLY AS THE AXIS OF THE UPPER RIDGE MOVES CLOSER TO THE COAST
THURSDAY. 86% OF THE MEMBERS KEEP IT OFFSHORE INTO FRIDAY. THE
UPPER RIDGE CONTINUES TO AMPLIFY IN RESPONSE TO A CUTOFF LOW
DEVELOPING OVER THE FOUR CORNERS REGION. BY FRIDAY, CLUSTERS BEGIN
TO DIFFER ON HOW FAST THE RIDGE BUILDS INTO THE AREA. THE
MAJORITY (53%) OF MEMBERS CONTINUE TO KEEP IT OFFSHORE WHILE
CLUSTER 3 (30% OF MEMBERS) MOVES IT INLAND. CLUSTER 4 (7% OF
MEMBER, MOSTLY GFS) SHOWS IT MOVING EAST OF THE AREA BY SATURDAY.
BY SUNDAY, THE CLUSTERS VARY THE MOST WITH 77% OF MEMBERS SHOWING
THE RIDGE GENERALLY OVER THE PACNW WHILE THE REMAINDER PUSH IT
EAST IN RESPONSE TO AN UPPER LEVEL TROUGH OFF THE COAST. THE
CLUSTERS THAT TEND TO PUSH IT EAST QUICKER ARE PRIMARILY GFS
MEMBERS. AT THIS TIME WILL CONTINUE TO PREFER THE ECMWF AS IT HAS
SHOWN THE MOST CONSISTENCY. AS A RESULT, THE BROAD UPPER LEVEL LOW
WILL MOVE EAST WEDNESDAY OR THURSDAY AS AN UPPER LEVEL RIDGE
NOSES INTO THE PACNW FOR A DRYING TREND INTO THE WEEKEND.
ENSEMBLES GENERALLY AGREE WITH THE ABOVE SCENARIO WITH GFS BEING
THE FASTER TO MOVE THE UPPER RIDGE OVER THE AREA. THE
DETERMINISTIC MODELS ARE IN GENERAL AGREEMENT AS WELL. HOWEVER,
THE ECMWF DEVELOPS A CUTOFF LOW OVER SOUTHEAST OREGON AND NORTHERN
NEVADA FRIDAY NIGHT INTO SATURDAY. AT THIS TIME, THIS IS AN
OUTLIER BUT IT WILL NEED TO BE MONITORED. IN SUMMARY, UNSETTLED
WEATHER, MAINLY OVER THE MOUNTAINS, WILL CONTINUE THROUGH
WEDNESDAY OR THURSDAY BEFORE A DRYING TREND SETTLES OVER THE AREA
THROUGH THE WEEKEND.
QPF WILL GENERALLY BE CONFINED TO THE MOUNTAINS WEDNESDAY AND
THURSDAY WITH A MODERATE TO HIGH CHANCE (50-80%) OF 0.10 OR MORE
OF PRECIPITATION ON WEDNESDAY DECREASING TO A MODERATE CHANCE
(40-70%) BY THURSDAY.
DAYTIME HIGHS WILL BE NEAR NORMAL WEDNESDAY AND THURSDAY RISING TO
ABOVE NORMAL THROUGH THE REST OF THE PERIOD. BY SUNDAY,
TEMPERATURES COULD BE 10-15 DEGREES ABOVE NORMAL. EARLE/81
AVIATION...12Z TAFS
VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD. A SYSTEM WILL BRING WIDESPREAD SHOWERS ACROSS THE REGION
THIS AFTERNOON AND EVENING. BRIEF MVFR CIGS MAY OCCUR IN PERIODS OF
HEAVIER RAINFALL. WINDS 5-10 KTS WILL INCREASE TO 10-20 KTS WITH
HIGHER GUSTS, EXCEPT KDLS WILL REMAIN 5-10 KTS. WINDS WILL DECREASE
TO 10 KTS OR LESS OVERNIGHT. EARLE/81
PRELIMINARY POINT TEMPS/POPS
PDT 63 40 56 35 / 20 70 70 20
ALW 61 42 55 38 / 10 80 80 30
PSC 64 41 60 37 / 10 60 40 10
YKM 60 37 57 34 / 20 70 20 10
HRI 64 40 59 35 / 20 70 50 10
ELN 58 36 54 34 / 10 80 40 10
RDM 57 33 52 29 / 40 60 30 30
LGD 53 37 49 30 / 10 80 90 50
GCD 54 35 49 30 / 40 80 90 50
DLS 59 40 57 37 / 60 80 50 30
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...86
LONG TERM....81
AVIATION...90
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