807
FXUS66 KPDT 130556
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
956 PM PST MON JAN 12 2026
UPDATED FOR AVIATION
AVIATION
06Z TAFS...VFR CONDITIONS AND LIGHT WINDS ARE MAINLY EXPECTED
THROUGH THE PERIOD. LOCAL MVFR IS POSSIBLE, MAINLY AT DLS AND YKM
EARLY TUESDAY MORNING. IT IS POSSIBLE, THAT SOME OTHER LOCATIONS
SEE MVFR AS WELL, BUT CONFIDENCE IS LOW (<30 PERCENT).
PREV DISCUSSION
/ISSUED 245 PM PST MON JAN 12 2026/
DISCUSSION...
A RIDGE OF HIGH PRESSURE ALOFT WILL CONTINUE TO DRIVE THE
SENSIBLE AND IMPACTFUL WEATHER OVER THE NEXT WEEK AND BEYOND. A
STAGNANT AIR PATTERN WILL LEAD TO LOW MIXING HEIGHTS AND WEAK
WINDS AS WELL AS POTENTIAL FOR VALLEY AND LOW LAND FOG
DEVELOPMENT EACH NIGHT.
FOG THIS MORNING HAMPERED THE KITTITAS VALLEY WITH AREAS WITH
DENSE FOG REDUCING VISIBILITY TO A QUARTER MILE BUT SAW IMPROVING
VISIBILITY AT ELN BY MID TO LATE MORNING TO ABOUT A MILE AS THE
DENSE FOG ADVISORY WAS ALLOWED TO BE CANCELED EARLY. THE SAME
SENSIBLE WEATHER IS LIKELY TO REDEVELOP TONIGHT. FOG REMAINS
NOTICEABLE AT THE HIGHEST ELEVATIONS OF THE WASHINGTON CASCADES
EARLY THIS AFTERNOON, AND MAY REDEVELOP IN THE KITTITAS VALLEY
AGAIN IN EARNEST BY AROUND MIDNIGHT ONCE AGAIN BASED ON THE LOCAL
GFS MOS GUIDANCE TRENDS. THE PROBABILITY FOR VISIBILITY TO DROP
TO ONE HALF MILE OR LESS SPIKES TO ABOUT 60% IN THE KITTITAS
VALLEY OVERNIGHT, INCLUDING THE ELLENSBURG AREA, WHICH CAN LINGER
ALL DAY TUESDAY BASED ON THE ENSEMBLE'S TRENDS.
A MARKED INCREASE TOWARD THE 90TH PERCENTILE FOR NBM WINDS WAS
USED ACROSS THE GRANDE RONDE VALLEY AS THE SURFACE PRESSURE
GRADIENT BETWEEN BAKER AND MEACHAM IS FAIRLY STEADY AT AROUND 6 TO
7 MB WHICH DOES NOT BEGIN TO WEAKEN UNTIL EARLY AFTERNOON
TUESDAY. THE WIND ADVISORY WAS EXTEND FOR THE LADD AND PYLES
CANYONS THROUGH 2 PM TUESDAY.
ESAT (ENSEMBLE SITUATIONAL AWARENESS TABLE) SHOWS THAT THE HIGH
PRESSURE OVER THE AREA IS AT ABOUT THE 2 STANDARD FOR LEVELS UP
THROUGH 500 FT THROUGH NEXT WEEKEND. THE NBM WAS SHOWING THE
STAGNANT CONDITIONS DEVELOPING ALREADY BY TONIGHT, WITH A WINDOW
OF OPPORTUNITY FOR MIXING HEIGHTS TO EXCEED 1500 FT ACROSS A
BROADER AREA BY FRIDAY, AN AIR STAGNATION ADVISORY WAS POSTED FOR
AREAS FROM CENTRAL OREGON INTO THE LOWER COLUMBIA BASIN, EASTERN
COLUMBIA GORGE AND NORTH INTO THE KITTITAS VALLEY UNTIL FRIDAY
MORNING. ADDITIONALLY, FOG MAY REDEVELOP IN THE VALLEY AREAS OVER
THE NEXT FEW DAYS ESPECIALLY IN THE KITTITAS VALLEY AND SECTION OF
THE LOWER COLUMBIA BASIN OF WA, A REGION OF GENERALLY COOLER
AIR/LOWER DEW POINT DEPRESSIONS.
AVIATION...
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH WILL STAY THE COURSE
THROUGH THE MAJORITY OF THE PERIOD. THERE IS A POTENTIAL FOR
BRIEFLY REDUCED VISIBILITIES OF 4SM MID-MORNING TUESDAY AT
KYKM/KALW. ELSEWHERE, VFR CONDITIONS ARE EXPECTED UNDER 25KFT
CEILINGS. WINDS WILL STAY LIGHT AND BELOW 8KTS FOR ALL TERMINALS
THROUGH THE PERIOD. 75
PRELIMINARY POINT TEMPS/POPS
PDT 35 54 30 46 / 0 0 0 0
ALW 40 54 33 45 / 0 0 0 0
PSC 35 51 30 44 / 0 0 0 0
YKM 35 52 32 48 / 0 0 0 0
HRI 32 50 30 44 / 0 0 0 0
ELN 36 47 30 45 / 0 0 0 0
RDM 28 59 25 57 / 0 0 0 0
LGD 32 49 32 53 / 0 0 0 0
GCD 32 55 34 57 / 0 0 0 0
DLS 37 51 34 48 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY FROM 7 AM TUESDAY TO 7 AM PST FRIDAY FOR
ORZ041-044-507-508-510-511.
WIND ADVISORY UNTIL 2 PM PST TUESDAY FOR ORZ049.
WA...AIR STAGNATION ADVISORY FROM 7 AM TUESDAY TO 7 AM PST FRIDAY FOR
WAZ024-026>029-521.
SHORT TERM...71
LONG TERM....71
AVIATION...77
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