256
FXUS66 KPDT 042308
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
308 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 /00Z TAFS THROUGH 00Z FRIDAY/
MVFR OR LOWER CONDITIONS
TO PREVAIL AT MOST SITES THROUGH THE PERIOD. LOW STRATUS IS EXPECTED
TO PERSIST THROUGH THE PERIOD (CONFIDENCE 65-85%). CIG HEIGHTS WILL
MAINLY BE LESS THAN 3KFT AT IMPACTED SITES, WITH HEIGHTS FLUCTUATING
THROUGHOUT THE PERIOD. AS FOR VSBY, SITE PDT IS EXPECTED TO SEE
REDUCTIONS DOWN TO IFR OR LOWER THIS EVENING, WHILE SITES ALW/PSC
ARE EXPECTED TO GET DOWN TO MVFR/IFR OVERNIGHT. SITES RDM/BDN WILL
SEE VFR CONDITIONS THROUGH THIS EVENING, HOWEVER THERE IS GROWING
CONFIDENCE (40-65%) THAT SITE RDM WILL SEE STRATUS AND FOG DEVELOP
BY AROUND 12Z, WITH LOW CONFIDENCE (20-25%) IN EARLIER/LATER
DEVELOPMENT. CONFIDENCE WAS TOO LOW (<15%) TO INCLUDE MENTION OF
STRATUS/FOG AT SITE BDN. WINDS WILL BE LIGHT, 12KTS OR LESS, THROUGH
THE PERIOD. LAWHORN/82
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.
DISCUSSION...97
AVIATION...82
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page