832
FXUS66 KPDT 181140
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
340 AM PST SUN JAN 18 2026
KEY MESSAGES
-FREEZING FOG IMPROVING LATE THIS MORNING AND RETURNING TO THE
FOOTHILLS TONIGHT.
-STAGNANT PATTERN CONTINUES THOUGH AT LEAST TUESDAY.
DISCUSSION
FREEZING FOG ACROSS THE CENTRAL OREGON ZONE WAS EVIDENT WITH ONE
HALF TO THREE QUARTER MILE VISIBILITY FROM THREE RIVERS TO BEND.
ADDITIONALLY THE I-84 CORRIDOR ACROSS DEAD AND PASS/CABBAGE HILL
WAS NEAR ZERO VISIBILITY AND UP TO THREE QUARTERS ACROSS THE LOCAL
MESONET OBS. THESE ADVISORIES REMAIN INTACT UNTIL NOON. SPATIALLY
, SKY COVER SHOULD LINGER ALL DAY IN THE LOWER COLUMBIA AND
FOOTHILLS OF THE BLUES WHERE A THINNER NEAR SURFACE SATURATED
LAYER SHOULD SCATTER OUT NEAR THE CASCADES, (BEND/DLS/YAKIMA
VALLEY) AND SOME SUN MAY BE GETTING THROUGH, HOWEVER CONFIDENCE IS
LOW. THE RISK OF FREEZING FOG BECOMES REDUCED TONIGHT AS THE HRRR
IS SHOWING A CONSIDERABLE DECREASE IN LOW VISIBILITY SPATIALLY
AND MORE TIED TO THE FOOTHILLS OF THE NORTHERN BLUE MOUNTAINS, AND
NOT ACROSS CENTRAL AND NORTH CENTRAL OREGON AS OF LATE. THE MORE
LIKELY SCENARIO WOULD BE FOR FREEZING FOG HEADLINE TO STILL BE
NEEDED ACROSS THE NORTHERN BLUES FOOTHILLS, IF ANYWHERE BASED ON
WHERE THE HRRR IS CONTINUING TO PLACE LOW VISIBILITY FIELDS, AND
AFTER 6 PM OR AS BASED ON THE DEVELOPMENT OF THE FOG LAST EVENING.
THE MIXING HEIGHTS ARE LOWER BY MONDAY HOWEVER THE STRATUS SHOULD
BREAK OUT AS THE TOP OF THE MIXED LAYER WARMS UP A FEW DEGREES TO
ABOVE ZERO. THE STAGNANT PATTERN CONTINUES THOUGH AT LEAST
TUESDAY AND THE CURRENT AIR STAGNATION ADVISORY IS VALID THOUGH
THEN. THIS MIGHT NEED CONSIDERATION OF EXTENDING THOUGH WEDNESDAY,
AS NOTABLE UPTICK IN THE NBM’S MEAN TRANSPORT WINDS AND MIXING
HEIGHTS IS NOT REALLY SEEN UNTIL THURSDAY AFTERNOON. THE NEXT
FORECAST POPS RETURN THURSDAY EVENING AS BOTH THE GFS AND ECMWF
IVT FORECAST SHOW WEAK (250-450 KG/MS) OF MOISTURE TRANSPORT INTO
THE COLUMBIA RIVER REGION AS WEAK AR ROUNDS A SURFACE HIGH
PRESSURE NEAR 38N/135W.
AVIATION...12Z TAFS
MVFR OR LOWER CONDITIONS TO PREVAIL THROUGH
THE PERIOD. UPPER LEVEL RIDGING WILL CONTINUE TO SIT OVER THE
PACNW THROUGH THE TAF PERIOD, REINFORCING THE STRATUS LAYER FROM
CENTRAL OR TO THE UPPER COLUMBIA BASIN. NUMERICAL MODEL GUIDANCE
IS HANDLING THIS PERSISTENT STRATUS LAYER VERY POORLY, THOUGH HREF
MEAN SOUNDING FORECASTS HAVE OVERALL MATCHED CLOSEST TO
OBSERVATIONS. OVER THE TAF PERIOD, HAVE LEANED TOWARDS A
PERSISTENCE FORECAST FOR MOST SITES, WITH TRENDS BASED OFF OF HREF
SOUNDING FORECASTS.
CIGS WILL REMAIN PERSISTENT AT SITES DLS/PSC THROUGH THE PERIOD,
WITH LIMITED SINKING/RISING OF THE CIG HEIGHT. SITES PDT/ALW/YKM
WILL SEE PERSISTENT CIG HEIGHTS THROUGH THIS EVENING, WITH IFR
CIGS DEVELOPING AFTER 03Z. IFR VSBY AT SITE RDM AND LIFR OR LOWER
VSBY AT SITE BDN WILL PREVAIL THROUGH THIS MORNING, IMPROVING TO
MVFR OR HIGHER AFTER 18Z, BUT THEN DECREASING TO IFR OR LOWER
AFTER 01Z. CIGS AT BOTH SITES WILL STAY AROUND 200FT THROUGH 18Z,
THEN LIFTING AS HIGH AS 500FT THIS AFTERNOON BEFORE SINKING TO
200FT AGAIN AFTER 01Z. WINDS WILL BE LIGHT AT ALL SITES THROUGH
THE PERIOD. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 34 23 36 23 / 0 0 0 0
ALW 34 25 36 26 / 0 0 0 0
PSC 36 25 38 24 / 0 0 0 0
YKM 38 23 39 23 / 0 0 0 0
HRI 35 25 37 24 / 0 0 0 0
ELN 37 22 36 22 / 0 0 0 0
RDM 42 17 43 20 / 0 0 0 0
LGD 47 25 48 26 / 0 0 0 0
GCD 52 26 53 27 / 0 0 0 0
DLS 40 27 41 26 / 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 ORZ502-507-510-
511.
WA...AIR STAGNATION ADVISORY UNTIL 4 PM PST TUESDAY FOR WAZ024-
026>029-521.
DISCUSSION...71
AVIATION...82
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