901
FXUS66 KPDT 292337
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
436 PM PDT SUN MAR 29 2026
.UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- A RETURN OF ACTIVE WEATHER LATE THIS AFTERNOON INTO MONDAY
WITH LIGHT PRECIPITATION IN THE MOUNTAINS
- MORE WIDESPREAD PRECIPITATION CHANCES INCLUDING MOUNTAIN
SNOW, BREEZY WINDS, AND COOLER CONDITIONS WEDNESDAY THROUGH
THURSDAY
DISCUSSION
A NARROW BAND OF MID LEVEL MOISTURE WAS TRACKING INLAND NOTED
BY THE GOES AIRMASS RGB SATELLITE IMAGERY AND NAM MODEL 700 TO
300 MPH MEAN WINDS OF AROUND 60 KNOTS ACROSS THE COLUMBIA BASIN.
EC AND GFS AR MODELS WOULD HAVE THIS WEAK BAND OF 200-300 IVT
MOISTURE EAST OF THE FORECAST AREA BY 12 MONDAY. HIGH CONFIDENCE
(80-90%) FOR ADDITIONAL SNOWS ACROSS THE UPPER EASTERN SLOPES
OF THE WA CASCADE CREST BEGINS THIS EVENING HOWEVER THESE
CHANCES WANE TO NEAR ZERO BY THE OVERNIGHT AS THE JET/SPEED MAX
PASSES. WSSI-P HINTS AT AROUND A 10-40% CHANCE FOR MINOR
IMPACTS OWING TO SNOW (WINTER DRIVING CONDITIONS). THE BETTER
CHANCES (40%) ARE TOWARD HIGHER TERRAIN ABOVE THE SNOW SKI AREA
AT SNOQUALMIE, THROUGH ABOUT 5 PM MONDAY. RAIN (LOWER
ELEVATIONS) AND SNOW (MOUNTAIN ZONES) SHOWERS WILL BE A
POSSIBILITY MONDAY NIGHT THOUGH LATE TUESDAY ACROSS THE EASTERN
SLOPES OF THE OREGON CASCADES AS WELL AS THE OVER THE JOHN
DAY/OCHOCO HIGHLANDS AND SOUTHERN BLUE MOUNTAINS (10% NORTH TO
50% SOUTH). TUESDAY WILL ALSO BE CHARACTERIZED BY LIGHT SURFACE
WINDS AREAWIDE AND MOSTLY CLOUDY ELSEWHERE, WITH ONLY A SLIGHT
BUMP IN AFTERNOON HIGH TO THE MID 50S IN THE HIGHLAND VALLEYS
AND LOWER COLUMBIA BASIN.
AS FAR AS THE CLUSTERS RELEVANCE TO THE MEDIUM RANGE, THE SETUP
LOOKS LIKE A HIGH CONFIDENCE, GENERALLY LOWER IMPACT
PROGRESSION WITH NO NOTICEABLE SHIFT OF TAILS. A COLD FRONT
MOVES THROUGH WEDNESDAY DROPPING THE SNOW LEVELS AND BRINGING
DOMINANT SNOW P-TYPE TO ALL OF THE PASS LEVELS IN THE CASCADES,
AND THE NORTHERN BLUE MOUNTAINS. WSSI-P SHOW NO REASONABLE
CHANCES FOR MODERATE IMPACTS ACROSS THE WA CASCADES WEDNESDAY
THROUGH THURSDAY, BUT ABOUT A 40 TO 50 PERCENT CHANCES FOR LIKE
IMPACTS ACROSS THE EASTERN SLOPES OF THE OREGON CASCADES,
ESPECIALLY DESCHUTES COUNTY. THE 24 HR SNOWFALL SPREAD ENDING 5
AM THURSDAY IS 3 TO 6 INCHES (25 TO 75 PERCENTILES ). GREATER
IMPACTS MIGHT BE FOUND AT THE SANTIAM PASS WHERE THE LIKE RANGE
IS FROM 3 TO 8 INCHES WHERE A SECTION OF HIGHWAY 20 CAN GET 6 ON
THE LOWER END AND 12 ON THE HIGHER END AROUND MT. WASHINGTON.
THE AREAS ALONG THE OREGON CASCADES SHOULD HAVE A BIT OF A
LONGER DURATION SNOW EPISODE AS WELL THAT WINDS DOWN INTO
THURSDAY NIGHT. GIVEN AFOREMENTIONED UNCERTAINTIES FROM THE
WSSI, AM PLANNING TO HOLD OFF ON WINTER WEATHER HEADLINES (ANY
WATCHES) AT THIS TIME. RUSSELL/71
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH WILL STAY THE COURSE
THROUGH THE PERIOD. AN INCOMING SYSTEM HAS DROPPED CEILINGS TO
BETWEEN 6-10KFT, WITH KRDM/KBDN EXPECTED TO DROP FURTHER TO AROUND
3.5KFT THIS EVENING. BREEZY WINDS HAVE ALSO INITIATED ACROSS MOST
SITES AS GUSTS OF 20-30KTS ARE ANTICIPATED TO PERSIST INTO THE EARLY
EVENING. WINDS WILL SUBSIDE TONIGHT AS CEILINGS LIFT AND BREAK
RELATED TO HIGH PRESSURE MOVING IN BEHIND THE DEPARTING SYSTEM. 75
HYDROLOGY
SOME RIVERS BEGIN SHOWING A RESPONSE BY WEDNESDAY EVENING AS
THEY ARE ALREADY SENSITIVE TO ADDITIONAL RAINS ON ELEVATED RIVER
LEVELS. HOWEVER ALL OF THE FORECAST HYDROGRAPHS AT THIS TIME
ARE INDICATING CRESTING BELOW THE ACTIONS STAGES LATE IN THE
WEEK. RUSSELL/71
PRELIMINARY POINT TEMPS/POPS
PDT 32 50 27 53 / 20 0 0 10
ALW 34 50 31 54 / 30 10 0 10
PSC 34 55 28 58 / 10 0 0 0
YKM 29 53 28 55 / 10 0 0 0
HRI 32 54 27 56 / 10 0 0 0
ELN 26 48 26 50 / 10 0 0 0
RDM 27 50 25 54 / 10 20 10 10
LGD 32 48 25 55 / 50 20 0 10
GCD 32 49 30 56 / 20 40 20 40
DLS 33 57 32 57 / 20 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...82
AVIATION...71
HYDROLOGY...71
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page