230
FXUS66 KPDT 300524
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
924 PM PST THU JAN 29 2026
KEY MESSAGES
- LOW WEATHER CONCERNS WITH PERIODIC LIGHT RAIN CHANCES THAT ARE
MAINLY CONFINED TO THE MOUNTAINS, HIGHEST OVER WA CASCADES,
INTO TONIGHT, FRIDAY, AND SUNDAY-MONDAY.
- INCREASED POTENTIAL (60-80%) FOR A STAGNANT WEATHER PATTERN
TUESDAY-THURSDAY THAT PROMOTES AIR QUALITY AND FOG CONCERNS AS
CONFIDENCE GROWS FOR LIGHT WINDS IN TANDEM WITH WEAK MIXING
UNDER A STRONG UPPER-LEVEL RIDGE.
- SLIGHTLY ABOVE AVERAGE TEMPERATURES THROUGH THE WEEKEND WITH
THE GREATEST DEPARTURES ABOVE NORMAL IN CENTRAL OR AND THE
MOUNTAINS.
UPDATED AVIATION...06Z TAFS
ALL SITES EXCEPT RDM/BDN ARE
SEEING MVFR OR LOWER DUE TO VIS OF 5SM OR LOWER, WITH YKM SEEING
CIGS BELOW 2500 FT. LIGHT RAIN AND BR HAS BEEN IMPACTING SITES
DLS/PSC/ALW/YKM AGAIN THIS EVENING AND RAIN WILL SLOWLY TRICKLE
OFF THROUGH THE LATE EVENING BEFORE BECOMING DRY OVERNIGHT AND
THE REMAINDER OF THE TAF PERIOD. YKM/PSC/DLS MAY SEE TIMES OF
LOW CIGS (300 FT OR LESS) AFTER 06Z FOR YKM AND 11Z FOR PSC AND
15Z FOR DLS. THESE 3 SITES HAVE 30% CHANCES OF VIS AS LOW AS
1/4SM AND CIGS AS LOW AS 100 FT. OTHERWISE, SITES RDM/BDN ARE
EXPECTED TO REMAIN DRY. WINDS WILL BE LIGHT, 6KTS OR LESS,
THROUGH THE PERIOD.
DISCUSSION
TONIGHT THROUGH THURSDAY. LATEST WATER VAPOR
IMAGERY SHOWS PLUME OF MOISTURE LIFTING NORTHEASTWARD ACROSS
THE REGION AS A WEAKENING WARM FRONT LIFTS NORTH ACROSS WA. A
LOW-LEVEL JET STREAM IS LIFTING NORTH IN TANDEM WITH THE BEST
MOISTURE WEST OF THE CASCADES, OF WHICH LATEST PRECIPITABLE
WATERS ARE AROUND 1.5 PER MIMIC-TPW V2 ON THE COAST WITH
LIMITED PENETRATION INLAND. LATEST RADAR DISPLAY SHOWS SOME WEAK
RETURNS MOVING EAST ACROSS THE BASIN WITH SCANT AMOUNTS SEEN
OVER THE LAST HOUR OVER NORTH CENTRAL OR. WITH THIS CURRENT
ACTIVITY, LIMITED CONFIDENCE IN PRECIPITATIONS CHANCES OUTSIDE
THE CREST OF THE WA AND NORTHERN OR CASCADES OWING TO LIMITED
SPILL OVER GIVEN THE LARGELY MERIDIONAL TRAJECTORY. LIMITED
IMPACTS EXPECTED OWING TO HIGH SNOW LEVELS, 5-7 KFT, WITH
SNOQUALMIE PASS MOST NOTABLY EXPECTED TO SEE AT LEAST A QUARTER
INCH OF RAIN (>60% CONFIDENCE) MAINLY IN THE WINDOW OF NOW
THROUGH 4 AM PST. MEANTIME, THE NEXT 6-12 HRS WILL SEE MID-LEVEL
RIDGING BUILDING OVERHEAD WITH EXPECTATIONS OF PRECIPITATION
ENDING DURING THE EARLY MORNING HOURS.
THE NEXT WEAK DISTURBANCE MOVES EAST INTO SOUTHERN BC/WA BY LATE
FRIDAY ON A NORTHERLY TRACK AS IT ROTATES AROUND THE PERIPHERY
OF THE UPPER RIDGE CENTERED OVER CA-PACNW. THIS ACTS TO DAMPEN
THE RIDGE SLIGHTLY AND PROVIDES ANOTHER WINDOW FOR PRECIPITATION
TIED PRIMARILY TO THE CREST AND UPPER EASTERN SLOPES OF THE WA
CASCADES. ENSEMBLE IVT FORECASTS SHOW WEAK MOISTURE TAP, SHORT
DURATION SURGE OF PACIFIC MOISTURE, AND A NORTHERLY TRAJECTORY
THAT WILL WORK TO LIMIT SENSIBLE WEATHER IMPACTS AND PENETRATION
EAST OF THE CASCADES. SNOW LEVELS REMAINED ELEVATED AGAIN,
GENERALLY 6 KFT AND HIGHER, WHICH COULD BE ATTRIBUTABLE TO THESE
WARM FLAVOR SOUTHERLY SETUPS AND WEAK FRONTAL SYSTEMS THAT
ARE STAYING LARGELY OFFSHORE/COAST. A LARGER UPPER TROUGH IS
THEN EXPECTED TO FLATTEN THE UPPER RIDGE AS IT EVOLVES AND MOVES
INTO THE AREA LATE SUNDAY AND MONDAY THAT IS CHARACTERIZED BY
ANOTHER MOISTURE WITH A SOUTHERLY FETCH AND STRONG MERIDIONAL
COMPONENT LIMITING BEST PRECIPITATION CHANCES TO THE CREST,
EASTERN SLOPES, AND EASTERN MOUNTAINS. WHILE SOME SHOWERS MAY
SPILL OVER INTO THE LOWER ELEVATIONS, LOW CONFIDENCE IN THE
OCCURRENCE OF WETTING RAIN. HIGHEST CHANCES (80% OR HIGHER)
CONFINED TO THE CREST WHERE 24-HR AMOUNTS OVER 0.25 INCHES OR
MORE IS HIGHLY LIKELY.
AFTER THE END OF THIS UNSETTLED PATTERN, CONFIDENCE IN HIGH
PRESSURE DOMINATING THE REGION TUESDAY INTO EARLY FRIDAY IS
GROWING (60-80%). STRONG, PERSISTENT UPPER-LEVEL HIGH PRESSURE
IS FORECAST WITH RAW ENSEMBLE GUIDANCE SHOWING HEIGHTS GREATER
THAN THE 99TH PERCENTILE. CONCERNS TURN TO A POTENTIAL
STAGNANT WEATHER PATTERN OWING TO ANTICIPATED LIMITED DAYTIME
MIXING, LOWER TRANSPORT WINDS AND LIGHT SURFACE WINDS, AND A
STABLE ENVIRONMENT IN LOWER ELEVATIONS/LOWER BASIN AND ADJACENT
VALLEYS. THIS INCREASES CONCERNS FOR CONDITIONS THAT COULD LIMIT
DISPERSION LEADING TO AIR QUALITY IMPACTS. MEANTIME, THIS POSES
A INCREASED POTENTIAL FOR STRATUS/FOG IN THIS WINDOW MID-EARLY
NEXT WEEK AND WILL BE MONITORED.
PRELIMINARY POINT TEMPS/POPS
PDT 38 52 37 51 / 20 10 10 0
ALW 40 52 39 52 / 30 20 20 10
PSC 35 47 34 48 / 30 20 10 0
YKM 35 45 33 47 / 50 30 10 10
HRI 35 48 35 48 / 30 10 10 0
ELN 34 42 33 42 / 70 40 20 10
RDM 35 55 33 57 / 20 10 0 0
LGD 36 48 34 51 / 20 10 10 0
GCD 35 53 35 54 / 20 10 0 0
DLS 38 49 40 51 / 50 40 20 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
UPDATE...82
DISCUSSION...80
AVIATION...90
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