553
FXUS66 KPDT 280956
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
256 AM PDT SAT MAR 28 2026
KEY MESSAGES
- DRY CONDITIONS THROUGH SUNDAY MORNING
- A RETURN OF ACTIVE WEATHER LATE SUNDAY AFTERNOON INTO MONDAY
WITH LIGHT PRECIPITATION IN THE MOUNTAINS
- MORE WIDESPREAD PRECIPITATION CHANCES, BREEZY WINDS, AND
COOLER CONDITIONS WEDNESDAY THROUGH THURSDAY
DISCUSSION
TODAY THROUGH SUNDAY MORNING: A BROAD UPPER LEVEL
RIDGE TO THE SOUTH WILL PLACE THE PACNW UNDER A WEST SOUTHWEST
FLOW ALOFT INTO SUNDAY. WARMING UNDER THE UPPER RIDGE PATTERN
WILL RESULT IN AFTERNOON HIGH TEMPERATURES IN THE 60S ACROSS THE
LOWER ELEVATIONS, WITH A LOCALIZED LOW 70S ACROSS THE JOHN DAY
BASIN AND CENTRAL OR THIS AFTERNOON. HIGH LEVEL CLOUD COVER
CONTINUE TO SPREAD ACROSS THE REGION TODAY, LIMITING LOW
TEMPERATURES TO THE MID TO UPPER 30S IN THE MORNINGS, THOUGH
SOME LOCALIZED CLEARING AND DRY CONDITIONS ACROSS CENTRAL OR MAY
ALLOW TEMPERATURES TO BE NEAR TO JUST BELOW FREEZING.
SUNDAY AFTERNOON THROUGH MONDAY NIGHT: PRECIPITATION CHANCES
ACROSS THE MOUNTAINS WILL INCREASE AHEAD OF AN UPPER TROUGH
DROPPING OUT OF THE GULF OF ALASKA BY SUNDAY AFTERNOON. SNOW
LEVELS WILL DROP SUNDAY NIGHT THROUGH MONDAY AS THE UPPER TROUGH
AND AN ATTENDANT SURFACE COLD FRONT SWING SOUTHEAST ACROSS THE
REGION, RESULTING IN LIGHT SNOW ACCUMULATIONS ACROSS THE
CASCADES AND NORTHERN BLUES THROUGH MONDAY NIGHT. TOTAL
ACCUMULATIONS REMAIN BELOW ADVISORY LEVEL, WITH A 40-70% CHANCE
OF 2 INCHES OF SNOW AT PASS LEVEL IN THE OR CASCADES AND
NORTHERN BLUES; CHANCES OF 2 INCHES OF SNOW ACROSS WHITE PASS
WILL BE 40-60%, WHILE SNOQUALMIE PASS WILL SEE A 60-70% CHANCE
OF 4 INCHES OF SNOW THROUGH MONDAY MORNING. BREEZY WESTERLY
WINDS (GUSTS 25-40 MPH) WILL ALSO DEVELOP ACROSS THE LOWER
ELEVATIONS SUNDAY THROUGH MONDAY MORNING WITH THE APPROACH AND
SUBSEQUENT PASSAGE OF THE TROUGH/FRONT SYSTEM.
TUESDAY THROUGH FRIDAY: POST THE TROUGH EXIT MONDAY NIGHT,
ENSEMBLE CLUSTER GUIDANCE IS IN DECENT AGREEMENT OF A SPLIT FLOW
(RIDGE TO THE NORTH, TROUGH TO THE SOUTH) MOVING ACROSS THE
PACNW TUESDAY. ENSEMBLE MEMBERS (ECMWF, GFS, CANADIAN) HAVE COME
INTO BETTER AGREEMENT OF LITTLE TO NO PRECIPITATION CHANCES
ACROSS THE FORECAST AREA FOR TUESDAY, HOWEVER ABOUT 30% OF THESE
MEMBERS DO SHOW LIGHT RAIN/SNOW DEVELOPING IN SOUTHERN
DESCHUTES COUNTY BY TUESDAY AFTERNOON.
TUESDAY NIGHT THROUGH THURSDAY, ENSEMBLE MEMBERS ARE IN GOOD
AGREEMENT OF AN UPPER LOW APPROACHING THE PACNW AND
TRANSITIONING INTO A TROUGH AS THE LOW FEATURE PUSHES INLAND,
BUT THATS WHERE OVERALL AGREEMENT ENDS. CLUSTER ENSEMBLE MEMBERS
ARE IN DISAGREEMENT ON HOW QUICKLY THE LOW PUSHES ACROSS THE
PACNW, HOW STRONG THE LOW/TROUGH WILL BE AS IT IMPACTS THE
REGION, AND ON THE TIMING OF THE TROUGHS EXIT. OVERALL,
ENSEMBLES ARE TRENDING TOWARDS MODERATE SNOW ACCUMULATIONS (5-12
INCHES) ACROSS THE CASCADES AND NORTHERN BLUES THROUGH THIS
PERIOD, WITH LIGHTER PRECIPITATION IN THE LOWER ELEVATIONS
(CONFIDENCE 50-70%). LOOKING AT THE NBM, THERE IS AT LEAST A
55-80% CHANCE OF SNOW ACCUMULATIONS EXCEEDING 6 INCHES IN A
48-HR PERIOD ENDING FRIDAY MORNING ALONG THE CASCADE PASSES AND
IN THE NORTHERN BLUE MOUNTAINS AROUND AND NORTH OF TOLLGATE.
HOWEVER, THE STRENGTH OF THE TROUGH AND THE COLD AIRMASS
ARRIVING WITH IT WILL ALSO IMPACT HOW LOW THE SNOW LINE WILL
REACH IN THE LOWER ELEVATIONS. AT THIS TIME, THERE IS MODERATE
CONFIDENCE (45-60%) AREAS OF CENTRAL OR WILL SEE LIGHT SNOW (<1
INCH) OVERNIGHT WEDNESDAY, WITH MUCH LOWER CONFIDENCE (<15%) OF
LIGHT SNOW OR A RAIN/SNOW MIX DEVELOPING ELSEWHERE IN THE LOWER
ELEVATIONS. LASTLY, OVER TWO-THIRDS OF THE ENSEMBLE CLUSTER
MEMBERS ARE FAVORING DRIER CONDITIONS DEVELOPING BEHIND THE EXIT
OF THE UPPER TROUGH SOMETIME THURSDAY NIGHT OR FRIDAY MORNING,
WHILE THE REMAINING THIRD OF MEMBERS KEEP THE PACNW UNDER A
TROUGHING PATTERN THAT WILL CONTINUE TO BRING LIGHT RAIN AND
MOUNTAIN SNOW THROUGH FRIDAY. LASTLY, THE INCOMING UPPER LOW
WILL ALSO BRING A RETURN OF BREEZY CONDITIONS (GUSTS 25-40MPH)
ACROSS THE FORECAST AREA WEDNESDAY AND THURSDAY (CONFIDENCE
55-70%). LAWHORN/82
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
VFR CONDITIONS WILL
PREVAIL THROUGH SATURDAY. WINDS WILL MAINLY BE 10 KTS OR LESS
THROUGH SATURDAY LATE MORNING/EARLY AFTERNOON WHEN GUSTS TO 20
TO 25 KTS SHOULD DEVELOP AT DLS, PDT, RDM, BDN AND YKM. THESE
WINDS WILL SUBSIDE DURING THE EVENING HOURS TO 10 KTS OR LESS
ONCE AGAIN.
PRELIMINARY POINT TEMPS/POPS
PDT 63 39 56 30 / 10 10 10 40
ALW 63 42 55 33 / 10 10 30 50
PSC 67 40 61 32 / 0 0 0 10
YKM 64 35 58 28 / 0 0 0 10
HRI 66 40 59 31 / 10 0 0 10
ELN 56 34 50 27 / 0 0 10 10
RDM 65 34 55 22 / 10 0 0 0
LGD 65 37 57 30 / 10 0 20 70
GCD 66 37 62 30 / 0 0 10 40
DLS 63 40 57 32 / 0 0 10 20
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...82
AVIATION...77
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