352
FXUS66 KPDT 280557
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
957 PM PST SAT DEC 27 2025
UPDATED AVIATION DISCUSSION
KEY MESSAGES...
- FOG CONCERNS AS A HIGH PRESSURE RIDGE BUILDS THROUGH MID-WEEK.
- PRECIPITATION CHANCES WITH LIGHT MOUNTAIN SNOW RETURN THURSDAY
ONWARD.
DISCUSSION...CURRENT RADAR AND SATELLITE IMAGERY SHOW LIGHT
RETURNS MAINLY OVER PORTIONS OF UMATILLA AND UNION COUNTIES,
WHICH IS DUE TO THE OROGRAPHIC LIFT FROM THE POST-FRONTAL SYSTEM.
THESE RETURNS IS ASSOCIATED LIGHT SNOW ALONG WITH MIST AND BREEZY
WINDS, MAINLY ALONG AND SOUTH OF CABBAGE HILL EARLIER TODAY.
SURFACE OBSERVATIONS ALSO SHOWED PRECIP AMOUNTS OF 0.10 INCH OR
LESS FALLEN AT UNION COUNTY, JOSEPH STATE AIRPORT (KJSY) AND OTHER
MOUNTAIN AREAS. WEBCAMS ARE NOW SHOWING IMPROVED VSBYS ACROSS THE
AFOREMENTIONED AREA. FOR THE REST OF TODAY, SCATTERED TO BROKEN
HIGH CLOUDS WILL BE LEFT BEHIND AS THE UPPER TROUGH EXITS FURTHER
EASTWARD WITH THE UPPER RIDGE MOVING IN. LIGHT SNOW MAY LINGER FOR
THE CREST OF WA/OR CASCADES TONIGHT FROM THE APPROACHING LIGHT
RETURNS, BUT CHANCES ARE LOW (<20%).
A HIGH PRESSURE SYSTEM WILL THEN ENTER THE PACNW SUNDAY THROUGH
WEDNESDAY. HOWEVER, FOG WILL BE THE MAIN HIGHLIGHT FOR THESE DAYS
DURING MORNING AND OVERNIGHT HOURS. WITH NEAR TO BELOW FREEZING
NIGHTTIME TEMPERATURES AND DEWPOINTS, THERE IS A GOOD CHANCE (>50%)
THAT FREEZING FOG COULD ALSO DEVELOP. VISIBILITIES MAY BE AFFECTED,
BUT WITH LOWER CONFIDENCE (<20%) OF 3 STATUE MILES OR LOWER BASED ON
THE NBM. IN ADDITION TO THAT, AIR STAGNATION COULD BE A CONCERN FOR
MONDAY THROUGH WEDNESDAY WITH THE MIXING HEIGHTS BELOW 1.5 KFT
DURING MORNING AND AFTERNOON HOURS AND TRANSPORT WINDS LESS THAN
10KTS. FOR NOW, WE WILL MONITOR FOR THAT AND SEE IF AN ADVISORY WILL
BE NEEDED. WINDS WILL BE LIGHT ACROSS THE FORECAST AREA WITH SOME
BREEZES OVER THE MOUNTAINS.
THURSDAY ONWARD IS WHEN PRECIP WILL RETURNS WITH AN APPROACHING
TROUGH. THE CASCADES WILL SEE SHOWERS BEFORE BECOMING MORE
WIDESPREAD WITH LIGHT RAIN FOR THE LOW ELEVATIONS WITH MOUNTAINS
RAIN/SNOW MIX TO ALL SNOW. QPF AMOUNTS MAY EXCEED TO 0.10 INCH OR
HIGHER ALONG THE CASCADES AND OTHER MOUNTAIN AREAS BUT LESS FOR THE
LOW ELEVATIONS. THERE SEEMED TO BE A TIMING DISAGREEMENT WITH THE
FRONTAL SYSTEM COMING THURSDAY. THE EURO HAS BEEN FAVORING AN EARLY
ONSET OF THE SYSTEM WHEREAS CANADIAN HAS IT COME IN LATER THURSDAY
AND FRIDAY FOR GFS, MAKING IT CHALLENGING ON WHEN THE SYSTEM WILL
ACTUALLY ARRIVE. FEASTER/97
AVIATION...06Z TAFS.
VFR CONDITIONS CURRENTLY AT ALL TAF
SITES. A WEAK DISTURBANCE WILL MOVE OVERHEAD TONIGHT, RESULTING IN
BKN TO OVC SKIES. WHILE CONFIDENCE IN SUB-VFR CIGS/VSBYS HAS
DECREASED THIS EVENING, THEY WILL REMAIN THE PRIMARY AVIATION
CONCERNS OVERNIGHT THROUGH SUNDAY MORNING. LATEST 00Z HREF
GUIDANCE SUGGESTS LOW (35 PERCENT OR LESS) CHANCES OF MVFR CIGS AT
ALL SITES, WHILE THE 18Z REFS ADVERTISES EVEN LOWER CHANCES (10
PERCENT OR LESS). HAVE STILL ADVERTISED SOME LOW STRATUS, BUT
REMOVED MENTION OF CIGS BELOW VFR. AS FAR AS FOG, HREF/REFS
PROBABILITIES ARE QUITE LOW (15 PERCENT OR LESS) AT ALL SITES.
LIGHT WINDS (10 KTS OR LESS) ARE EXPECTED FOR THE NEXT 24 HOURS.
PRELIMINARY POINT TEMPS/POPS
PDT 26 38 24 35 / 10 10 0 0
ALW 26 36 26 35 / 10 10 0 0
PSC 24 36 23 35 / 10 10 0 0
YKM 21 36 22 36 / 10 0 0 0
HRI 25 38 23 35 / 10 10 0 0
ELN 19 31 21 32 / 10 0 0 0
RDM 20 40 21 43 / 10 0 0 0
LGD 24 36 23 38 / 10 10 0 0
GCD 23 38 24 43 / 10 0 0 0
DLS 31 40 29 38 / 20 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...97
AVIATION...86
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page