149
FXUS66 KPDT 181243
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
443 AM PST THU DEC 18 2025
DISCUSSION
CURRENT SATELLITE AND RADAR IMAGERY SHOW LIGHT SHOWERS
DEVELOPING ACROSS THE FORECAST AREA WITH THIS FRONTAL SYSTEM APPROACHING
OUR FORECAST AREA.
THE SHORTWAVE ALONG WITH THE ATMOSPHERIC RIVER (IVT OF 500-700 KG
M/S) WILL BRING WINDY CONDITIONS STARTING THIS LATE MORNING ACROSS
MOST OF THE FORECAST AREA. THESE WINDS WILL CONTINUE TO BE DRIVEN BY
THE STRONG LOW-LEVEL JET STREAK ABOVE 70 KTS ALONG WITH A SURFACE
PRESSURE DIFFERENCE OF 3-7 MB OVER THE GRANDE RONDE VALLEY (BKE AND
MEH) THROUGH MOST OF TODAY AND 9-11 MB BETWEEN (PDX (PORTLAND) AND
GEG (SPOKANE) OVERNIGHT. WIND ADVISORIES WILL BE IN EFFECT FROM 10
AM TODAY TO 1 AM PST TOMORROW FOR THE FOLLOWING AREAS: FROM CENTRAL
OR TO SIMCOE HIGHLANDS (KLICKITAT COUNTY) AND PORTIONS OF THE
FOOTHILLS-NORTHERN AND SOUTHERN BLUE MOUNTAINS. STRONGEST WIND GUSTS
OF 45-55 MPH ARE EXPECTED ALONG EAST SLOPES OF OR CASCADES, CENTRAL
OR, PORTIONS OR NORTH CENTRAL OR, AND NORTHWEST BLUES. OVERNIGHT
INTO LATE TOMORROW MORNING, WINDS WILL THEN SLOWLY DECREASE WITH
LINGERING WINDS AT 30-40 MPH OVER SIMCOE HIGHLANDS AND PORTIONS OF
THE NORTHWEST BLUES INCLUDING HIGH TERRAINS OF CENTRAL OR. HOWEVER,
CONFIDENCE IS ABOUT 30-40% FOR THE EAST SLOPES OF OR CASCADES TO
GUST UP TO 60 MPH OR HIGHER DURING EVENING HOURS.
MOUNTAIN SNOW FOR WA/OR CASCADES WILL CONTINUE WITH WIDESPREAD
PRECIPITATION TAKING OVER THROUGH TOMORROW. WINTER WEATHER
ADVISORIES WILL REMAIN IN EFFECT THROUGH THIS AFTERNOON FOR THE WA
CASCADES AND NORTHERN BLUES OF OR, GIVEN WITH SNOW LEVELS AT 2.5-3.5
KFT WITH ADDITIONAL SNOWFALL UP TO 1 FOOT. THIS ALSO TO TAKE IN
ACCOUNT OF POTENTIAL BLOWING SNOW IN THOSE AREAS WITH GUSTS OF 20-30
MPH OR HIGHER (>60% CONFIDENCE). THE EAST SLOPES OF OR CASCADES HAS
A WINTER WEATHER ADVISORY AS WELL, BUT THROUGH LATER THIS MORNING
WHEN SNOW LEVELS START TO INCREASE ABOVE 5 KFT WITH SNOW TRANSITIONING
TO MOSTLY RAIN. FREEZING RAIN MAY DEVELOP OVER THE WA CASCADES
AND PORTIONS OF THE NORTHERN BLUES, BUT CONFIDENCE IS LOW (15-30%)
CONSIDERING THAT THOSE MOUNTAIN AREAS HAS A BETTER CHANCE AT
RECEIVING MAINLY SNOW.
RIVER FLOOD WATCHES AND FLOOD WATCHES REMAIN IN EFFECT DUE TO
ANTICIPATED RISING RIVER LEVELS THROUGH THE REST OF THIS WEEK.
FEASTER/97
AVIATION...12Z TAFS
WIDESPREAD RAIN AND GUSTY WINDS WILL BE THE
MAIN IMPACT ACROSS ALL SITES THIS PERIOD. RAIN WILL START MOVING
INTO THE AREA FROM THE SOUTHEAST, IMPACTING BDN/RDM AROUND 12-14Z
BEFORE SPREADING TO PSC AND ALW BY 16-17Z AT THE LATEST. RAIN IS
EXPECTED TO BE PERSISTENT, WITH LOCALIZED IFR CONDITIONS OCCURRING
UNDER HEAVIER SHOWERS, HOWEVER CONFIDENCE WAS TOO LOW TO PINPOINT
THE PRECISE TIMING OF IFR CONDITIONS WITHIN THE TAFS. WINDS WILL
START GUSTING AROUND 18-21Z, MAINLY OUT OF THE W AND NW AND GUSTING
AS HIGH AS 40 KTS AT SOME SITES, NAMELY BDN AND RDM, HOWEVER ALW AND
PDT COULD SEE STRONG GUSTS UP TO 40 KTS AT TIMES THIS AFTERNOON AND
EARLY EVENING AS WELL (40-50% CHANCE). RAIN AND WIND IS EXPECTED TO
PERSIST BEYOND THE TAF PERIOD, BUT IS GENERALLY EXPECTED TO IMPROVE
CONDITION-WISE DURING THE OVERNIGHT HOURS HEADING INTO FRIDAY. CIGS
WILL BE LOW UNDER RAIN (MAINLY 2-5 KFT), BEFORE LIFTING OVERNIGHT
(BKN-OVC 10-15 KFT). 74
PRELIMINARY POINT TEMPS/POPS
PDT 56 37 47 33 / 100 90 60 10
ALW 54 39 47 36 / 100 100 70 30
PSC 54 37 49 35 / 100 80 20 10
YKM 46 29 46 28 / 100 90 10 20
HRI 55 38 49 33 / 100 90 40 10
ELN 41 26 39 23 / 100 90 30 40
RDM 56 34 46 23 / 100 100 90 10
LGD 46 34 44 27 / 100 100 90 30
GCD 50 39 46 24 / 100 90 100 20
DLS 48 38 46 36 / 100 100 70 70
PDT WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY FROM 10 AM THIS MORNING TO 1 AM PST FRIDAY FOR
ORZ041-507-508-510-511.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR ORZ502.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORZ509.
FLOOD WATCH THROUGH LATE FRIDAY NIGHT FOR ORZ509>511.
WA...WIND ADVISORY FROM 10 AM THIS MORNING TO 1 AM PST FRIDAY FOR
WAZ024-521.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR WAZ030-
522-523.
FLOOD WATCH THROUGH FRIDAY AFTERNOON FOR WAZ522-523.
DISCUSSION...97
AVIATION...74
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page