090
FXUS66 KPDT 260005
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
505 PM PDT SUN OCT 25 2026
KEY MESSAGES
1. MOUNTAIN SHOWERS AND HIGH ELEVATION SNOW
2. NEW PATTERN WILL BRING SLIGHTLY BELOW SEASONAL TEMPERATURES
3. WIDESPREAD CHANCES OF PRECIPITATION AT THE START OF THE WEEK
DISCUSSION
CURRENT SATELLITE IS SHOWING CLOUDS MOVING ACROSS THE REGION. RADAR
SHOWS A BAND OF MOISTURE IS ALSO MOVING ACROSS THE CASCADES WITH
GROUND OBSERVATIONS AT OR ABOVE 5400 FEET SEEING SNOWFALL.
TEMPERATURES THROUGH THE PASS ARE MARGINAL IN THE LOW TO MID 30S,
BUT EXPECTING SOME ACCUMULATION ALONG THE CHINOOK PASS THROUGH THE
REMAINDER OF THE DAY BEFORE THE SYSTEM MOVES EAST AND DISSIPATED.
OTHERWISE, RAIN WILL BE THE PRIMARY FORM OF PRECIPITATION BELOW 5400
FEET.
THE CHANGE IN THE SYNOPTIC PATTERN WILL LEAD TO BELOW SEASONAL
AVERAGE TEMPERATURES CONTINUING WITH THE COOLEST DAY BEING TOMORROW
(MONDAY). DETERMINISTIC GUIDANCE MODELS SHOW AN UPPER LEVEL LOW OFF
THE COAST OF THE PACNW AND A RAIN BAND ALONG THE LEADING EDGE WHICH
IS CAUSING SOME RAIN/SNOW ALONG THE CASCADES. MODELS ARE IN GOOD
AGREEMENT WITH THE INITIAL LOW MAKING ITS WAY FULLY ONSHORE BY
MONDAY AFTERNOON. THIS WILL BRING WITH IT BELOW SEASONAL AVERAGE
TEMPERATURES WITH IN HOUSE CALCULATIONS SHOWING NEARLY 5-10 DEGREES
BELOW NORMAL ACROSS CENTRAL OR, EASTERN MOUNTAINS AND THE FOOTHILLS
OF THE BLUES WHILE THE GORGE BASIN AND ADJACENT VALLEYS WILL SEE
TEMPERATURES 1-5 DEGREES BELOW SEASONAL NORMAL. MONDAY HREF RAW
ENSEMBLES SHOW 70-80% CHANCES OF THE BASIN SEEING MID TO UPPER 50S
WHILE THE REMAINDER OF THE REGION WILL SEE TEMPERATURES IN THE MID
40S. TEMPERATURES WILL STEADILY TREND DOWNWARD THROUGH THE WEEK
WITH THE COOLEST DAY BEING FRIDAY.
NOT ONLY WILL THIS UPPER LEVEL LOW BRING COOLER TEMPERATURES, BUT
MODELS ARE ALSO SHOWING INCREASED CHANCES OF PRECIPITATION. CURRENT
RADAR SHOWS A PRECIPITATION BAND ALONG THE NORTHERN CASCADES OF WA.
THE RAIN WILL CONTINUE TO SPREAD ACROSS THE REGION THROUGH MONDAY
BECOMING WIDESPREAD BETWEEN 11 AM AND 5 PM. LOOKING AT THE HREF RAW
ENSEMBLES FOR THE 24 HOUR PERIOD, THE ENSEMBLES SHOW A 60-80% CHANCE
THE EASTERN MOUNTAINS, BLUES, FOOTHILLS AND THE EASTERN SLOPES OF
THE CASCADES WILL SEE NEAR 0.05 INCHES OF RAIN WITH HIGHER PEAKS
ABOVE 5400 FEET SEEING NEAR 0.5 INCHES OF SNOW. THE REMAINING
LOCATIONS WILL SEE 0.01-0.04 INCHES OF RAIN. AS THE LOW CONTINUES TO
MOVE TO THE EAST, CLUSTERS AND DETERMINISTIC MODELS BEGIN TO
DIVERGE. NBM SHOWS RAIN SHOWERS CONTINUING ON WEDNESDAY WHILE THE
VARIANCE BETWEEN THE MODELS DIFFER IN TIMING AND PRECIPITATION
AMOUNTS.
AFTER WEDNESDAY THE MODELS BEGIN TO DIVERGE SLIGHTLY WITH THE
TRAJECTORY OF THE NEXT UPPER LEVEL LOW. CLUSTERS SHOW A
POSITION/TIMING VARIANCE. TIMING IS MOSTLY LINKED TO THE INCOMING
QPF WITH THE EURO BRINING IN PRECIPITATION AS EARLY AS WEDNESDAY
MORNING ACROSS THE REGION WHILE THE GFS HAS THE PRECIPITATION LOCKED
IN ALONG THE CASCADES. REGARDLESS OF THE TIMING OF THE QPF,
PRECIPITATION IS EXPECTED TO CONTINUE THROUGH THE WEEK WITH THE
POTENTIAL FOR SNOW LEVELS TO DROP BELOW 4000 FEET BY FRIDAY.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
A TROUGH AND COLD FRONT SYSTEM WILL SPREAD RAINS ACROSS THE
CASCADES AND OCCASIONAL SHOWERS TO RDM/BDN/DLS/ALW. SOUTH AND
SOUTHWEST WINDS WILL TURN MORE WESTERLY AND NORTHWESTERLY LATE
MONDAY MORNING/EARLY MONDAY AFTERNOON. CEILINGS ABOVE ABOUT 5
KFT SHOULD LIMIT THE DROPS IN VISIBILITY DURING ROUNDS OF RAIN
SHOWERS.
PRELIMINARY POINT TEMPS/POPS
PDT 33 53 37 55 / 0 20 40 30
ALW 39 53 42 54 / 0 30 60 50
PSC 33 56 39 59 / 10 20 10 0
YKM 36 56 35 58 / 20 20 10 0
HRI 33 55 40 57 / 10 20 20 0
ELN 30 53 31 54 / 30 40 20 0
RDM 28 47 32 48 / 40 60 20 20
LGD 39 55 36 53 / 0 80 70 80
GCD 35 50 34 49 / 0 70 40 50
DLS 39 58 42 60 / 40 60 30 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...90
AVIATION...71
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page