813
FXUS66 KPDT 142211
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
211 PM PST THU NOV 14 2024
SHORT TERM...TODAY THROUGH SATURDAY
A BROAD UPPER-LEVEL TROUGH
CONTINUES TO MOVE INTO THE PACNW THIS AFTERNOON, BRINGING WITH IT
COOLER AIR AND BREEZY WINDS AHEAD OF ITS AXIS. WINDS HAVE BEEN A BIT
MORE ROBUST THAN WHAT GUIDANCE INITIALLY SUGGESTED, ESPECIALLY IN
THE LOWER COLUMBIA BASIN AROUND TRI-CITIES. EXPECTING THAT TO TREND
DOWNWARD HEADING INTO TONIGHT AS PRESSURE GRADIENTS EVEN OUT.
AS THIS SYSTEM MOVES IN, HOWEVER, SW FLOW ALOFT AHEAD OF ITS AXIS
WILL ALLOW FOR SOME OROGRAPHIC PRECIP ACROSS THE EASTERN MOUNTAINS
OF OREGON. HI-RES GUIDANCE OVER THE LAST 24 HOURS HAVE SHIFTED THEIR
TUNE QUITE A BIT, INITIALLY SHOWING A MOSTLY DRY FORECAST, WHILE NOW
SHOWING A BAND OF SNOW ENVELOPING AN AREA EXTENDING FROM GRANT
COUNTY UP THROUGH THE WALLOWAS TONIGHT THROUGH LATE FRIDAY MORNING.
MODELS HINT AT A VORT MAX POTENTIALLY ASSISTING IN SHOWER
DEVELOPMENT OVER THE MOUNTAINS, BUT SHOULD NOTE THAT EACH INDIVIDUAL
MODEL IS HIGHLY VARIABLE IN TERMS OF HOW HEAVY OF SNOWFALL WE GET
WITH THIS SYSTEM. OPTED TO ADJUST AMOUNTS HIGHER THAN THE INITIAL
WPC FORECAST, BUT AMOUNTS OVERALL STILL LOOK TO FALL BELOW ADVISORY
THRESHOLDS. STILL, THOSE IN THE AFOREMENTIONED AREAS, PARTICULARLY
IN THE BEAR VALLEY, SOUTHERN BLUES (NAMELY AROUND UKIAH), AND I-84
THROUGH MEACHAM SHOULD EXPECT A COUPLE OF INCHES OF SNOW OVERNIGHT
TONIGHT HEADING INTO TOMORROW. MAYBE SOME LIGHT SNOW IN THE WALLOWA
VALLEY AS WELL, BUT CONFIDENCE IS ON THE LOWER END. SHOULD NOTE THAT
NBM PROBABILISTIC GUIDANCE IN PARTICULAR ISN'T EXACTLY ENTHUSIASTIC
ABOUT SNOW TONIGHT OUTSIDE OF THE CRESTS OF THE BLUES AND
STRAWBERRIES.
COLDER, DRIER AIR THEN FILTERS IN BEHIND THE TROUGH HEADING INTO
FRIDAY EVENING AS THE FLOW ALOFT SHIFTS MORE NORTHERLY. EXPECTING
RELATIVELY DRY CONDITIONS FRIDAY NIGHT THROUGH LATE SATURDAY
AFTERNOON, HOWEVER HIGH TEMPS WILL STRUGGLE TO REACH THE 50S, EVEN
ACROSS OUR LOWEST ELEVATIONS BOTH DAYS. THE NEXT SYSTEM OF CONCERN
WILL ARRIVE LATE SATURDAY NIGHT INTO SUNDAY, WHERE MORE WIDESPREAD,
HEAVIER PRECIP IS EXPECTED TO OCCUR. EVANS/74
LONG TERM...SUNDAY THROUGH THURSDAY
WEST TO SOUTHWESTERLY FLOW
AHEAD OF THE NEXT TROUGH FOLLOWED BY THE TROUGH MOVING ACROSS THE
REGION ON SUNDAY INTO SUNDAY NIGHT WILL BRING PRECIPITATION TO
THE PACIFIC NORTHWEST INTO MONDAY. SNOW LEVELS WILL INITIALLY BE
FAIRLY HIGH...RANGING FROM OVER 5000 TO 7000 FEET IN MOST
LOCATIONS TO 3000- 4000 FEET OVER FAR EASTERN OREGON. HOWEVER, BY
MONDAY MORNING, SNOW LEVELS WILL DROP TO 2000-2500 FEET
EVERYWHERE. BEYOND MONDAY INTO TUESDAY, PRECIPITATION SHOULD END
AS RIDGING BUILDS IN BEHIND THE DEPARTING TROUGH. THE RIDGE LOOKS
TO GET QUITE STRONG BY MID TO LATE WEEK, BUT BEFORE THEN, THERE IS
SOME UNCERTAINTY.
THE QPF WITH THIS SYSTEM IS UPWARDS OF AN INCH IN THE HIGHER
ELEVATIONS OF THE BLUE MOUNTAINS AND COULD APPROACH 2 INCHES OF THE
HIGHER ELEVATIONS OF THE WASHINGTON CASCADES. AT THE LOWER
ELEVATIONS 0.25 TO 0.5 INCHES IS POSSIBLE IN MANY AREAS EXCEPT
CENTRAL OREGON AND THE COLUMBIA BASIN. BASED ON THESE VALUES, SOME
HEADLINES FOR SNOW MAY BE NEEDED FOR NORTHERN BLUE MOUNTAINS OR
WASHINGTON CASCADES, DEPENDING ON HOW THINGS DEVELOP BY SUNDAY
NIGHT. THE ECMWF EFI HAS 0.7 TO 0.8 FOR QPF ACROSS THE CASCADES ON
SUNDAY.
THE ECMWF HAS A MUCH STRONGER TROUGH IN THE GREAT BASIN/FOUR CORNERS
AREA AROUND TUESDAY AND HAS A STRONGER RIDGE BEHIND IT, WHILE THE
GFS IS WEAKER. THE ENSEMBLE CLUSTERS ONLY HAVE ABOUT 25% SUPPORT FOR
THIS SOLUTION.
THE DRIER WEATHER PATTERN THAT WOULD BUILD IN MID TO LATE WEEK WOULD
STILL POSSIBLY ALLOW FOR SOME PRECIPITATION, MAINLY OVER THE
WASHINGTON CASCADES, AND DEPENDING ON THE ULTIMATE POSITION AND
STRENGTH OF THE RIDGE WE COULD BE LOOKING AT OUR FIRST BOUT OF
STRATUS AND/OR FOG, ESPECIALLY OVER THE FAVORED VALLEY LOCATIONS.
WINDS WILL BE BREEZY ON SUNDAY INTO SUNDAY NIGHT AS THE TROUGH MOVES
ACROSS THE AREA, WITH GUSTS GENERALLY IN THE 25 TO 35 MPH RANGE. NBM
PROBABILITIES OF WIND GUSTS TO 39 MPH ARE GENERALLY 50 TO 80
PERCENT, MAINLY ACROSS THE COLUMBIA BASIN, SIMCOE HIGHLANDS AND
FOOTHILLS OF THE BLUE MOUNTAINS.
HIGH TEMPERATURES WILL START OFF THE PERIOD ABOVE NORMAL ON SUNDAY,
BUT END THE PERIOD SEVERAL DEGREES BELOW NORMAL.
AVIATION...00Z TAFS
VFR CONDITIONS ARE EXPECTED THROUGH THE
EVENING AT ALL TAF SITES. AFTER THAT MVFR CIGS ARE EXPECTED AT
PDT, RDM, BDN AND ALW AS AN UPPER LEVEL TROUGH MOVES ACROSS THE
AREA OVERNIGHT AND INTO THE MORNING HOURS. A PASSING SHOWER CAN
NOT BE RULED OUT AND ALMOST ANY SITE AS WELL, BUT PROBABILITIES
ARE TOO LOW TO INCLUDE IN THE INDIVIDUAL TERMINALS AT THIS TIME.
CONFIDENCE AT MVFR AT BDN AND RDM HAS DECREASED BUT WILL KEEP IT
IN THE TAFS FOR NOW AND WILL ANALYZE LATER GUIDANCE. SOME BREEZY
WINDS REMAIN AROUND THE AREA, BUT THESE SHOULD DECREASE WITH
SUNSET OR SHORTLY THEREAFTER. WINDS FOR THE REMAINDER OF THE
PERIOD SHOULD BE LESS THAN 10 KTS.
PRELIMINARY POINT TEMPS/POPS
PDT 34 44 27 46 / 40 30 0 0
ALW 37 46 30 48 / 30 40 10 0
PSC 37 50 30 48 / 0 10 0 10
YKM 27 51 24 43 / 0 0 0 20
HRI 36 50 29 49 / 10 20 0 10
ELN 30 48 25 43 / 10 0 0 20
RDM 28 42 21 43 / 20 10 0 10
LGD 33 40 26 42 / 40 60 20 0
GCD 32 39 23 41 / 80 70 10 0
DLS 37 51 31 48 / 10 0 0 30
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...74
LONG TERM....77
AVIATION...77
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