158
FXUS66 KPDT 041806
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1006 AM PST WED FEB 4 2026
UPDATED AVIATION DISCUSSION
KEY MESSAGES
- HIGH PRESSURE THROUGH THE WEEK WILL KEEP THE AREA DRY AND
BRING FOG
- AN INCOMING SYSTEM OVER THE WEEKEND WILL BRING MOUNTAIN AND
LOW ELEVATION PRECIPITATION
DISCUSSION
CURRENT SATELLITE SHOWS MID LEVEL CLOUDS MOVING ACROSS THE
REGION. CURRENT WEBCAMS SHOW MANY AREAS TO BE EXPERIENCING
PATCHY FOG WITH SOME AREAS HAVING VIS TO BELOW 1/4 MILE. THIS
WILL BE THE CASE THROUGH MUCH OF THE WEEK AS THE HIGH PRESSURE
SETTLES OVERHEAD.
MODELS ARE IN FIRM AGREEMENT WITH THE HIGH PRESSURE RIDGE
SETTLING IN OVER THE REGION THROUGH FRIDAY. THIS WILL BRING
INCREASED CHANCES FOR FOG TO DEVELOP OVERNIGHT EACH NIGHT.
LOOKING AT THE HREF RAW ENSEMBLES, THERE IS A 50-70% PROBABILITY
OF THE BASIN, PORTIONS OF KITTITAS/YAKIMA VALLEYS AND ALONG THE
FOOTHILLS OF THE BLUES THAT WILL SEE VIS DROP TO BELOW 3 MILES
THROUGH THE EVENING. THERE ARE GROUND OBSERVATIONS SHOWING
ISOLATED LOCATIONS ALREADY SEEING VIS AS LOW AS 1/4 MILE WITH
THE EXCEPTION OF PORTIONS OF N. CENTRAL OR WHERE THERE IS
WIDESPREAD AREAS OF DENSE FOG. THE FOG IS EXPECTED TO LINGER
THROUGH MUCH OF THE MORNING BEFORE DISSIPATING AFTER NOON. THIS
WILL BE THE NAME OF THE GAME OVER THE NEXT FEW MORNINGS WITH
HREF AND NBM ENSEMBLES SHOWING 60-70% PROBABILITIES OF THE BASIN
AND PORTIONS OF THE BLUES SEEING VIS OF 3 MILES OR LOWER
THURSDAY AND FRIDAY AS WELL. NBM SHOWS MIXING HEIGHTS TO BE
MOSTLY REACHING 1000-2000AGL ACROSS MUCH OF THE REGION, SO THE
CHANCES OF AIR STAGNATION ARE LOW (20-30%) WITH THE EXCEPTION
OF CENTRAL OR WHO HAS AN AIR STAGNATION ADVISORY OUT THROUGH
THURSDAY MORNING. OTHERWISE, DRY CONDITIONS WILL REMAIN THROUGH
FRIDAY NIGHT INTO SATURDAY MORNING.
MODELS ARE IN DECENT AGREEMENT WITH THE NEXT INCOMING SYSTEM DUE
IN OVER THE WEEKEND. CLUSTERS SHOW THE BIGGEST DIFFERENCE WILL
BE WITH TIMING AND OR POSITIONING OF THE NEXT SYSTEM.
REGARDLESS, ALL MODELS AND ENSEMBLES SHOW THE SYSTEM TO BRING IN
PRECIPITATION ACROSS THE REGION WITH HIGHEST AMOUNTS ALONG THE
CASCADES AND THE EASTERN MOUNTAINS. SATURDAY WILL SEE
PERCEPTION MAINLY ALONG THE CASCADES WITH NBM ENSEMBLES SHOWING
40-60% 4 HOUR PROBABILITIES OF 0.05 INCHES OF ACCUMULATIONS. BY
SUNDAY, MODELS SHOW THE PRECIPITATION TO BECOME MORE WIDESPREAD
WITH ACCUMULATIONS OF UP TO 0.05 THROUGH THE LOWER ELEVATIONS
TO BE 40-50% PROBABILITIES AND 50-60% FOR THE BLUES. STORM TOTAL
ACCUMULATIONS OF NEAR 0.5 INCHES ALONG THE CASCADES IS 70-80%
AND 50-60% FOR THE BLUES WITH 40-60% PROBABILITIES OF 0.15 FOR
THE LOWER ELEVATIONS AND 50% FOR BETWEEN 0.05-0.10 INCHES FOR
THE BASIN AND CENTRAL OR. AS THE SYSTEM MOVES IN, SNOW LEVELS
WILL STEADILY DECREASE TO NEAR 5000 FEET BY THE WEEKENDS END
ALLOWING FOR SOME OF THE PRECIPITATION TO FALL AS SNOW ABOVE
5000FT BY SUNDAY NIGHT.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
MVFR OR LOWER
CONDITIONS TO PREVAIL AT MOST SITES THROUGH THE PERIOD. LOW
STRATUS HAS DEVELOPED ACROSS THE COLUMBIA BASIN AND ADJACENT
VALLEYS/FOOTHILLS THIS MORNING, AND IS EXPECTED TO PERSIST
THROUGH THE PERIOD (CONFIDENCE 60-85%). CIG HEIGHTS WILL MAINLY
BE LESS THAN 3KFT AT IMPACTED SITES, WITH HEIGHTS FLUCTUATING
THROUGHOUT THE PERIOD. AS FOR VSBY, SITE PDT WILL CONTINUE TO
SEE IFR VSBY THROUGH THE MORNING, IMPROVING TO VFR THIS
AFTERNOON; SITE PSC WILL SEE IMPROVEMENT TO VFR BY NOON. 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
(<20%) 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 33 47 33 51 / 0 0 0 0
ALW 36 47 36 50 / 0 0 0 0
PSC 34 48 34 50 / 0 0 0 0
YKM 33 50 33 50 / 0 0 0 0
HRI 34 48 33 50 / 0 0 0 0
ELN 31 46 31 47 / 0 0 0 0
RDM 28 57 26 58 / 0 0 0 0
LGD 37 57 36 57 / 0 0 0 0
GCD 34 59 33 59 / 0 0 0 0
DLS 36 50 36 52 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...AIR QUALITY ALERT UNTIL 10 AM PST THURSDAY FOR ORZ506-509.
DISCUSSION...90
AVIATION...82
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