239
FXUS66 KPDT 161201
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
401 AM PST FRI JAN 16 2026
UPDATED AVIATION DISCUSSION
KEY MESSAGES
- HIGH PRESSURE ALOFT CONTINUES INTO NEXT WEEK.
*FREEZING AND DENSE FOG ADVISORIES ACTIVE*
- STAGNANT AIR CONDITIONS PREVAIL THROUGH LATE TUESDAY AFTERNOON.
*AIR STAGNATION ADVISORIES ACTIVE*
- UNSETTLED WEATHER RETURNS WEDNESDAY ONWARD.
DISCUSSION
CURRENT NIGHTTIME SATELLITE IMAGERY SHOWS A LOW
STRATUS LAYER ACROSS THE COLUMBIA BASIN AREA, YAKIMA VALLEY AND
NORTH-CENTRAL OR. SURFACE OBSERVATIONS AND WEBCAMS ARE ALSO
CURRENTLY SHOWING FREEZING/DENSE FOG IN THOSE AREAS AS WELL.
AS THE HIGH PRESSURE ALOFT CONTINUES DOMINATING THE REGION, FOG WILL
REMAIN AS THE MAIN FEATURE THROUGH NEXT WEEK. STRONG SURFACE
INVERSIONS WILL REMAIN TRAPPING THE COOL AIR NEAR THE SURFACE,
LIMITING HIGH TEMPERATURES TO THE 30S AND 40S. SUBSIDENCE WILL
KEEP THE BOUNDARY LAYER DRY, LOWERING DEWPOINTS AND TEMPS TO FALL
NEAR OR BELOW FREEZING DURING OVERNIGHT HOURS. THIS HAS RESULTED
INTO ISSUING FREEZING FOG ADVISORIES FOR NORTH-CENTRAL OR,
YAKIMA/KITTITAS VALLEYS AND FOOTHILLS-NORTHERN BLUE MOUNTAINS OF
OR THROUGH 12 PM TODAY, ALONG WITH A DENSE FOG ADVISORY FOR THE
FOOTHILLS-BLUE MOUNTAINS OF WA. THE FOG MAY DISSIPATE AROUND THIS
AFTERNOON, BUT CONFIDENCE IS ABOUT 30-40% BASED ON THE STRENGTH OF
THESE INVERSIONS AND LOW STRATUS LAYER THAT COULD KEEP THE FOG
LONGER, PARTICULARLY FOR THE COLUMBIA BASIN AREA. THAT SAID, WE
WILL CONTINUE MONITORING THESE AREAS AND MAKE ANY ADJUSTMENTS TO
THE ADVISORIES IF NEEDED. HREF RAW ENSEMBLES DO FAVOR A 50-70%
PROBABILITY FOR VISIBILITIES LESS THAN 1/2SM AND 20-40% PROB
DURING MORNING HOURS FOR TODAY AND SATURDAY, WHICH MIGHT IMPACT
DRIVING CONDITIONS.
STAGNANT AIR CONDITIONS WILL LAST INTO TUESDAY. IN ADDITION TO
INVERSIONS, THEY WILL HELP ASSIST IN KEEPING ANY POLLUTANTS, HAZE,
AND/OR SMOKE TRAPPED NEAR SURFACE LEVEL THUS RESULTING POOR
VENTILATION. AIR STAGNATION ADVISORIES WILL CONTINUE TO LAST THROUGH
LATE TUESDAY AFTERNOON FOR THE COLUMBIA BASIN AND YAKIMA/KITTITAS
VALLEYS EXTENDING TO CENTRAL OR WITH THIS ONGOING RIDGE.
WEDNESDAY ONWARD, THE RIDGE WILL THEN WEAKEN AND GRADUALLY BRING
UNSETTLED WEATHER BACK TO OUR AREA WITH MOUNTAIN RAIN/SNOW MIX. WITH
SNOW LEVELS DECREASING TO 2.5-3.5 KFT, THIS COULD TRANSITION TO
MOSTLY SNOW (UP TO AN INCH OR LESS) AS WELL. HOWEVER, CONFIDENCE IS
LOW (<30%) AT THIS TIME. FEASTER/97
AVIATION...12Z TAFS
MVFR OR LOWER CIGS AND VSBY EXPECTED TO
IMPACT ALL SITES THROUGHOUT THE PERIOD. CIGS AND VSBY WILL LOWER
TO IFR OR LOWER AT SITES RDM/BDN THIS MORNING, WITH A BRIEF
IMPROVEMENT TO VFR CONDITIONS BETWEEN 18Z TO 03Z, THEN DROPPING TO
IFR OR LOWER LATE IN THE EVENING. CIGS AT SITES PDT/YKM WILL
REMAIN IFR OR LOWER THROUGHOUT THE PERIOD. CIGS WILL REMAIN IFR OR
LOWER AT SITE ALW THROUGH THE PERIOD, WITH BRIEF DROPS IN VSBY TO
IFR OR LOWER IN THE LATE MORNING AND LATE EVENING TIME PERIODS.
CIGS WILL REMAIN IFR OR LOWER AT SITE PSC, WITH VFR VSBY THROUGH
04Z WHEN FOG IS EXPECTED TO IMPACT THE SITE AND BRING VSBY DOWN TO
AT LEAST MVFR CONDITIONS. SITE DLS WILL REMAIN UNDER MVFR CIGS
INTO THE AFTERNOON WITH A BRIEF IMPROVEMENT, BUT CIGS ARE EXPECTED
TO REDEVELOP DURING THE EVENING. WINDS WILL REMAIN LIGHT, LESS
THAN 12KTS, THROUGH THE PERIOD. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 37 25 38 23 / 0 0 0 0
ALW 38 28 38 27 / 0 0 0 0
PSC 38 28 38 26 / 0 0 0 0
YKM 41 25 39 25 / 0 0 0 0
HRI 38 28 39 25 / 0 0 0 0
ELN 40 25 39 24 / 0 0 0 0
RDM 42 19 48 20 / 0 0 0 0
LGD 45 27 46 27 / 0 0 0 0
GCD 49 29 52 30 / 0 0 0 0
DLS 43 30 42 29 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 4 PM PST TUESDAY FOR ORZ041-044-
507-508-510-511.
FREEZING FOG ADVISORY UNTIL NOON PST TODAY FOR ORZ507-510.
WA...AIR STAGNATION ADVISORY UNTIL 4 PM PST TUESDAY FOR WAZ024-
026>029-521.
FREEZING FOG ADVISORY UNTIL NOON PST TODAY FOR WAZ026-027.
DENSE FOG ADVISORY UNTIL NOON PST TODAY FOR WAZ029.
DISCUSSION...97
AVIATION...82
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