312
FXUS66 KPDT 050555
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
955 PM PST WED FEB 4 2026
KEY MESSAGES
- HIGH PRESSURE WITH DRY CONDITIONS AND FOG THROUGH SATURDAY.
- AN INCOMING SYSTEM OVER THE WEEKEND INTO MONDAY WILL BRING
LIGHT MOUNTAIN SNOW AND LOW ELEVATION RAIN.
DISCUSSION
CURRENT SATELLITE IMAGERY SHOWS THE LOW STRATUS LAYER
AND HIGH CLOUDS LINGERING OVER THE COLUMBIA BASIN AREA. MOST OF THE
FOG HAS LIFTED FROM THIS MORNING, BUT ROAD CAMS AND SURFACE
OBSERVATIONS STILL SHOW LOCALIZED PATCHY FOG REMAINING ACROSS I-82
NEAR UPPER MANASTASH RIDGE AND I-84 NEAR CABBAGE HILL AND MISSION.
WITH THE LOW STRATUS LAYER AND LIGHT WINDS, THOSE CONDITIONS MAY
HELP THIS FOG STICK AROUND A LITTLE LONGER THROUGH THE REST OF THIS
AFTERNOON AND INTO EARLY EVENING HOURS.
OTHER THAN THAT, THIS HIGH PRESSURE SYSTEM WILL CONTINUE THROUGH
FRIDAY WITH DRY CONDITIONS. FOG WILL BE THE MAJOR CONCERN WITH THIS
RIDGE AS THE LOW STRATUS LAYER CONTINUES. VISIBILITIES WILL ALSO BE
AFFECTED BY DENSE AREAS OF FOG OVER THE VALLEY ZONES
(KITTITAS/YAKIMA), COLUMBIA BASIN, AND THE GORGE DURING EARLY
MORNING AND NIGHTTIME HOURS. HREF RAW ENSEMBLES HAS 40-70%
PROBABILITY OF VISIBILITIES AT 1 MILE OR LESS FOR
KITTITAS/YAKIMA VALLEYS, THE GORGE, AND THE COLUMBIA BASIN
OVERNIGHT THROUGH LATE THURSDAY MORNING AND AGAIN FOR THURSDAY
NIGHT. AIR STAGNATION IS ALSO POSSIBLE WITH MIXING HEIGHTS AT
1-1.5 KFT AND TRANSPORT WINDS LESS THAN 10 MPH TODAY, BUT WILL
GRADUALLY IMPROVE THURSDAY ONWARD. WINDS MAY BE SLIGHTLY BREEZY
AT 10-15 MPH FOR THE GRANDE RONDE VALLEY (BKE- MEH) WITH THE NAM
AND SREF SHOWING PRESSURE GRADIENTS OF 3-5 MB TODAY AND
POSSIBLY THURSDAY (>50% PROB).
FOG DEVELOPMENT WILL REMAIN AS PROBLEMATIC UNTIL EARLY SATURDAY
MORNING WHEN THE RIDGING PATTERN STARTS TO SLOWLY ERODE. THIS COULD
POTENTIALLY BRING WIDESPREAD LIGHT RAIN SHOWERS WITH POP CHANCES AT
15-30% FOR LOW ELEVATIONS AND ABOUT 40-80% FOR THE MOUNTAINS BEFORE
INCREASING SUNDAY FROM THE APPROACHING SHORTWAVE TROUGH. THERE IS A
20-30% PROB FOR THE CASCADES TO RECEIVE 0.15 INCH OR MORE, BUT 40-
60% PROB FOR 0.05 INCH OR LESS BASED ON THE NBM RAW ENSEMBLES. LIGHT
MOUNTAIN SNOW WILL ALSO DEVELOP UP TO 1 INCH OF SNOWFALL OVER THE
WA/OR CASCADES, PORTIONS OF THE EASTERN MOUNTAINS, AND WALLOWA
COUNTY SUNDAY INTO EARLY MONDAY MORNING. SNOW LEVELS WILL BE ABOVE 6
KFT UNTIL SUNDAY WHEN THEY DECREASE TO 5 KFT OR BELOW, MAKING
THOSE DAYS MOSTLY A LIGHT SNOW-DRIVEN EVENT FOR THE MOUNTAIN
AREAS. FEASTER/97
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
DENSE FOG AROUND PDT
WITH LIFR CONDITIONS EXPECTED LATER AROUND 08Z. OTHER SITES WILL
SEE IFR TO LIFR CONDITIONS CONTINUE TO DEVELOP OVERNIGHT AS
STRATUS CONTINUES TO DROP AND AREAS/PATCHY FOG DEVELOPS.
CONDITIONS LOOK TO IMPROVE VISIBILITY WISE, BUT WE'LL CONTINUE
TO SEE LOW STRATUS DOMINANT THE FORECASTING PERIOD. BDN APPEARS
TO BE THE ONLY SITE IN CONTINUOUS VFR CONDITIONS, BUT CHANCES
ARE LOW (5 TO 15 PERCENT) THAT THE STRATUS WILL REACH DOWN INTO
BDN OVERNIGHT, BUT FOR NOW FEEL MORE COMFORTABLE LEAVING IT AS
VFR. WILL CONTINUE TO MONITOR TO SEE IF BDN WILL BE OBSCURED AND
IF THAT STRATUS REACHES THROUGH THE AREA.
PRELIMINARY POINT TEMPS/POPS
PDT 32 46 32 50 / 0 0 0 0
ALW 35 45 35 50 / 0 0 0 0
PSC 32 47 33 49 / 0 0 0 0
YKM 32 50 33 49 / 0 0 0 0
HRI 32 47 32 49 / 0 0 0 0
ELN 31 46 31 47 / 0 0 0 0
RDM 27 58 26 58 / 0 0 0 0
LGD 37 57 35 57 / 0 0 0 0
GCD 35 60 33 58 / 0 0 0 0
DLS 37 50 36 51 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...AIR QUALITY ALERT UNTIL 10 AM PST THURSDAY FOR ORZ506-509.
DENSE FOG ADVISORY UNTIL 10 AM PST THURSDAY FOR ORZ510.
DISCUSSION...97
AVIATION...95
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