631
FXUS66 KPDT 131731
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1031 AM PDT THU MAR 13 2025
UPDATED AVIATION DISCUSSION
SHORT TERM...
TODAY THROUGH SATURDAY...AN UPPER TROUGH WILL MOVE INLAND TODAY
AND CONTINUE ITS EASTWARD PROGRESSION THROUGH THE AREA THROUGH THE
EVENING. BY MORNING, A DRIER WESTERLY FLOW WILL BE IN PLACE.
ANOTHER WEAK TROUGH FROM THE SOUTH WILL MOVE THROUGH FRIDAY INTO
SATURDAY AND BRING ANOTHER ROUND OF PRECIPITATION.
QPF WITH TODAY'S SYSTEM WILL RANGE FROM UPWARDS OF AN INCH IN THE
CASCADES AND WALLOWAS TO AROUND 0.50 INCHES IN THE HIGHER TERRAIN
ELSE WHERE, TO GENERALLY 0.10 INCHES OR LESS IN THE LOWER
ELEVATIONS, THOUGH THE YAKIMA AND KITTITAS VALLEYS COULD RECEIVE
BETWEEN 0.25 AND 0.50 INCHES. SNOW LEVELS WILL START OFF QUITE
HIGH, GENERALLY BETWEEN 3500 AND 4000 FEET IN THE WASHINGTON
CASCADES AND 4000-6000 FEET ELSEWHERE. HOWEVER, AS THE TROUGH
MOVES ACROSS THE REGION, SNOW LEVELS WILL DROP TO LESS THAN 1000
FEET BY FRIDAY MORNING. SNOW LEVELS WILL THEN RISE BACK TO
BETWEEN 1500 AND 3500 FEET BY FRIDAY AFTERNOON AND ABOUT 2500 FEET
IN THE WASHINGTON CASCADES TO 43500 FEET ELSEWHERE ON SATURDAY.
SNOW AMOUNTS TODAY WILL BE HIGHEST IN THE OREGON CASCADES (WHERE
SNOW WILL ALSO LINGER THE LONGEST) AND THEN THE WASHINGTON
CASCADES. IN THE OREGON CASCADES, AMOUNTS OF 6 TO 12 INCHES ARE
EXPECTED, AND IN THE WASHINGTON CASCADES AMOUNTS OF 5 TO 10 INCHES
ARE EXPECTED. A WINTER STORM WARNING REMAINS IN EFFECT THE THE
OREGON CASCADES AND A WINTER WEATHER ADVISOR FOR THE UPPER EAST
SLOPES OF THE WASHINGTON CASCADES.
THERE WILL BE A BREAK IN THE PRECIPITATION OVER MOST AREAS LATE
TONIGHT INTO EARLY FRIDAY, EXCEPT POSSIBLY OVER THE CASCADES AND
THEN THE NEXT SYSTEM MOVES IN.
QPF WITH THE NEXT SYSTEM IS A BIT LOWER, EXCEPT FOR THE OREGON
CASCADES, WHERE AMOUNTS AROUND AN INCH ARE POSSIBLE, ONCE AGAIN.
FOR THE WASHINGTON CASCADES, AMOUNT AROUND 0.50 INCHES ARE
POSSIBLE ALONG THE CREST. AND 0.50 INCHES FOR THE BLUE MOUNTAINS.
ELSEWHERE GENERALLY 0.10 INCHES OR LESS, WITH ONLY A FEW HUNDREDTH
IN MOST LOWER ELEVATION AREAS.
SNOW AMOUNTS FRIDAY THROUGH SATURDAY LOOK TO BE OVER 8 INCHES
ABOVE 4000 FEET IN THE OREGON CASCADES, AND A WINTER STORM WATCH
IS IN EFFECT BEGINNING EARLY FRIDAY MORNING, AT LEAST THROUGH
SATURDAY AFTERNOON. OTHER AREAS LOOK TO BE BELOW CRITERIA AT THIS
TIME, BUT IT IS POSSIBLE OTHER HEADLINES MAY BE NEEDED AT A LATER
POINT.
IT WILL BE BREEZY TO WINDY TODAY WITH WIND GUSTS 25 TO 35 MPH
ESPECIALLY ACROSS THE COLUMBIA BASIN, SIMCOE HIGHLANDS AND YAKIMA
AND KITTITAS VALLEYS AND EVEN STRONGER IN SOME MOUNTAIN AREAS. THE
NBM PROBABILITIES OF WIND GUSTS >= 39 MPH IN THESE AREAS ARE
70-90 PERCENT. WIND GUSTS >= 47 MPH ARE 50 TO 60 PERCENT ACROSS
THE BASIN.
IT WILL BE BREEZY TO WINDY AGAIN ON SATURDAY, PERHAPS A BIT MORE
WIDESPREAD. THE NBM PROBABILITIES OF WIND GUSTS OF 39 MPH ARE 70
TO 90 PERCENT ACROSS A LARGE SWATH OF THE REGION. THE NBM
PROBABILITIES OF WIND GUSTS >= 47 MPH ARE MAINLY CONFINED TO THE
COLUMBIA BASIN, AND THE SIMCOE HIGHLANDS WITH PROBABILITIES OF 60
TO 70 PERCENT.
THE ECMWF EFI ALSO KEYS IN ON THE WINDS FOR SATURDAY WITH AN
ANOMALY OF 0.6 TO 0.7 ACROSS MUCH OF THE AREA. IT ALSO HAS A QPF
ANOMALY OF 0.7 TO 0.8 IN THE OREGON CASCADES AND 0.8 TO 0.9 FOR
SNOW IN THE SAME AREA.
LASTLY, FOR THOSE SKY WATCHERS...THERE IS A TOTAL LUNAR ECLIPSE
TONIGHT INTO EARLY FRIDAY MORNING. UNFORTUNATELY, THE BIGGEST
QUESTION REMAINS WILL CLOUDS OBSCURE THE VIEW? IF YOU WANT A
COMPLETELY CLEAR SKY ACROSS WASHINGTON OR OREGON, THE ODDS OF THAT
ARE SLIM. HOWEVER, SINCE WE WILL BE BETWEEN SYSTEMS TONIGHT,
THERE COULD BE ENOUGH CLEARING/BREAKS IN THE CLOUDS TO SEE AT
LEAST SOME/PARTS OF THE ECLIPSE ESPECIALLY ACROSS THE COLUMBIA
BASIN, FOOTHILLS OF THE BLUE MOUNTAINS, YAKIMA VALLEY AND KITTITAS
VALLEY.
LONG TERM...
SATURDAY NIGHT THROUGH THURSDAY...THE ZONAL PATTERN WILL PROGRESS
OVER THE PACNW WITH THE ASSOCIATED FRONTAL SYSTEM THROUGH SUNDAY.
SUNDAY NIGHT INTO MONDAY, THE UPPER TROUGH WILL THEN SWEEP ACROSS
THE FORECAST AREA. THIS WILL BRING QPF AMOUNTS UP TO 1" AT THE WA/OR
CASCADES WITH THE RAW ENSEMBLES SUGGESTING A 50-70% PROBABILITY AND
A 20-30% PROB FOR THE NORTHERN BLUES SUNDAY NIGHT. OTHERWISE, THE
REMAINING FORECAST AREA WILL HAVE RAINFALL UP TO 0.75" OR BELOW
(>50% CHANCE). SNOWFALL MIGHT ACCUMULATE AT 7-15" ALONG THE WA
CASCADES WITH THE OR CASCADES AT LEAST 12 INCHES. THE BLUES,
PARTICULARLY NORTHERN BLUES, WILL REACH UP TO AT LEAST 6 TO 12 OR
LESS. NONETHELESS, PROCEED WITH CAUTION WHEN TRAVELING IN THESE
AREAS. THIS PATTERN WILL ALSO INDUCE GUSTY WINDS UP TO 30 MPH ACROSS
THE FORECAST AREA, GIVEN THE STRENGTHENING SURFACE GRADIENTS.
CONFIDENCE INCREASES AS THE EFI HIGHLIGHT UNUSUAL EVENTS FOR WIND,
QPF, AND SNOW FOR THIS LONG TERM. GUSTS COULD INCREASE TO 40 MPH BUT
CONFIDENCE IS LOW (<30%). SNOW LEVELS WILL BE GENERALLY ABOVE 2.5
KFT.
DRY CONDITIONS RETURN TUESDAY AS A UPPER RIDGE BUILDS OVER INTO
WEDNESDAY WITH THE TROUGH MOVING OUT OF THE AREA. HOWEVER, LINGERING
SHOWERS MAY CONTINUE OVER THE CASCADES AND BLUES BUT WITH QPF
AMOUNTS LESS THAN 0.25" AND MOUNTAIN SNOW LESS THAN AN INCH.
OVERALL, TUESDAY AND WEDNESDAY WILL BE THE DAYS WITH THE LEAST RAIN
AND SNOW AMOUNTS. SNOW LEVELS FOR TUESDAY WILL BRIEFLY DROP TO 1.8-
2.1 KFT BUT MAY RISE AGAIN TO 2.5 KFT OR HIGHER AROUND THE AFTERNOON
ONWARDS.WINDS WILL DECREASE TO BREEZY CONDITIONS (15-25 MPH) DURING
MORNING AND AFTERNOON HOURS. WEDNESDAY NIGHT INTO THURSDAY, ANOTHER
SYSTEM WILL MAKE ITS WAY TO THE PACNW THUS RETURNING RAIN AND
MOUNTAIN SNOW. THE LOWLANDS WILL BE DRY THROUGH THURSDAY MORNING
BEFORE POPS INCREASE UP TO 40% THURSDAY NIGHT. POPS FOR THE MOUNTAIN
AREAS WILL RANGE AT 30-60%. WINDS WILL REMAIN BREEZY ACROSS THE
FORECAST AREA AS WELL.
HIGH TEMPS WILL BE MAINLY IN THE 40S AND 50S AT THE LOWER ELEVATIONS
AND 30S AND 40S FOR THE MOUNTAINS. HOWEVER, TEMPS COULD REACH UP TO
LOW 60S AT THE LOWER COLUMBIA BASIN FOR TUESDAY AND WEDNESDAY WITH
THE RIDGE IN PLACE. FEASTER/97
AVIATION...18Z TAFS...VFR CONDITIONS PREVAIL FOR ALL SITES FOR THE
WHOLE PERIOD. OUR MAIN CONCERN WILL BE BREEZY WINDS THROUGH THE
BASIN AND HIGHER ELEVATIONS TODAY. TERMINALS WILL EXPERIENCE 15-25
KNOT GUSTS. WINDS WILL CALM DOWN IN THE LATER HALF OF THE PERIOD
TO 10-15 KNOTS. CIGS WILL REMAIN HIGH DUE TO THE STRONGER WINDS
AND VISIBILITY'S ARE NOT EXPECTED TO DROP BELOW P6SM LEVELS.
PRELIMINARY POINT TEMPS/POPS
PDT 51 30 53 37 / 40 10 10 70
ALW 51 31 51 37 / 30 10 10 80
PSC 56 30 55 37 / 50 0 0 50
YKM 50 26 49 32 / 60 10 10 60
HRI 54 28 55 37 / 30 10 10 50
ELN 48 25 46 30 / 60 10 10 60
RDM 45 24 49 30 / 20 10 60 70
LGD 45 24 44 31 / 50 30 30 80
GCD 44 22 42 29 / 70 40 70 90
DLS 51 32 50 37 / 50 20 50 90
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER STORM WARNING UNTIL 11 PM PDT THIS EVENING FOR ORZ509.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON
FOR ORZ509.
WA...WINTER WEATHER ADVISORY UNTIL NOON PDT TODAY FOR WAZ522.
SHORT TERM...77
LONG TERM....97
AVIATION...95
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