539
FXUS66 KPDT 211135
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
335 AM PST THU NOV 21 2024
UPDATED AVIATION DISCUSSION
SHORT TERM...TODAY THROUGH SATURDAY
BOTTOM LINE UP FRONT
1. PROGRESSIVELY WET PATTERN CONTINUES THROUGH SATURDAY
2. WINDS WILL RETURN TODAY, HOWEVER, WEAKER THAN PREVIOUS DAYS
CURRENT RADAR SHOWS A FEW RETURNS REMAINING OVER THE REGION WITH
CURRENT WEBCAMS ACROSS THE BLUES SHOWING SOME RAIN FALLING. ALONG
THE OR CASCADES, HIGHER ELEVATIONS SUCH AS SANTIAM PASS IS STILL
SEEING SOME LINGERING SNOWFALL. GROUND OBSERVATIONS ARE SHOWING THE
WINDS TO BE SETTLING A BIT THROUGH THE BLUES WITH MISSION FINALLY
SEEING GUSTS DROP TO BELOW ADVISORY AND CURRENTLY ONLY GUSTING TO 14
MPH. THERE HAVE BEEN A FEW INSTANCES OF GUSTS OVER 25 MPH SO
CONTINUE TO USE CAUTION WHILE DRIVING THROUGH THE BLUES.
WITH THE MODELS SHOWING THE UPPER LEVEL LOW REMAINING OFF SHORE AND
SOUTHWEST FLOW TAKING OVER THE REGION. MODELS SHOW A RELATIVELY
STEADY FLOW OF MOISTURE STREAMING INTO THE REGION. THE SOUTHWEST
FLOW WILL CONTINUE TO CAUSE SNOW LEVELS TO RISE KEEPING MUCH OF THE
AREA UNDER RAIN WHILE ONLY THE CRESTS SEEING SNOW. MODELS AND
ENSEMBLES SHOW TODAY TO BE THE DAY WITH HIGHEST RAIN TOTALS WITH 90-
100% OF THE ENSEMBLES IN AGREEMENT THE OR CASCADES, EASTERN
MOUNTAINS AND THE BLUES WILL SEE NEARLY 0.5 INCHES OF RAIN, WHILE 70-
90% SHOW THE REMAINING AREA, MINUS THE BASIN WILL SEE BETWEEN 0.25-
0.50 INCHES OF RAIN. THE BASIN HOWEVER WILL SEE BETWEEN 0.10-0.30
INCHES OF RAIN WITH ONLY 60-70% PROBABILITIES. AMOUNTS WILL DWINDLE
THROUGH THE PERIOD AS AS DRIER AIR WILL MOVE INTO THE REGION WITH
THE EXCEPTION OF THE MOUNTAINS. WITH THE SHIFT TO A MORE WESTERLY
FLOW ALOFT, COOLER AIR WILL RETURN BRINGING SNOW LEVELS DOWN. SNOW
AMOUNTS ALONG THE I-84 CORRIDOR SATURDAY HAVE 30-60% CHANCE OF
REACHING 0.50 INCHES WHILE 60-80% CHANCES OF 1-2 INCHES ALONG
SNOQUALMIE AND WHITE PASS AND 80-90% ALONG SANTIAM PASS.
MODELS ARE IN RELATIVELY FIRM AGREEMENT WITH THE UPPER LEVEL LOW
REMAINING OFF THE COAST AND BRINGING IN SOUTHWEST FLOW ALOFT.
SOUTHWEST AND WEST FLOW AT THE SURFACE HAS RETURNED AND WINDS HAVE
BEGUN TO SETTLE. MODELS DO HOWEVER SHOW A SHORTWAVE WILL MAKE ITS
WAY ACROSS THE REGION TODAY AND WINDS WILL INCREASE AGAIN MOSTLY
THROUGH CENTRAL OR AND ALONG THE EASTERN MOUNTAINS AND THE BLUES.
WINDS ARE NOT EXPECTED TO REACH ADVISORY CRITERIA. 40-60% OF THE RAW
ENSEMBLES SHOW THE SOUTHERN PORTION OF THE AREA ACROSS THE EASTERN
MOUNTAINS TO SEE SUSTAINED WINDS OF 15-20 MPH, CENTRAL OR 60-80% AT
10-15 MPH AND 40-60% SHOWING THE I-84 CORRIDOR THROUGH LA GRANDE
SEEING 20-25 MPH. AFTER THE PASSAGE OF THE SHORTWAVE, NBM SHOWS
WINDS TO BEGIN SLOWLY TAPERING DOWN TONIGHT AND OVERNIGHT INTO
FRIDAY AND RETURNING TO NEAR NORMAL THROUGH THE REMAINDER OF THE
PERIOD. BENNESE/90
LONG TERM...SUNDAY THROUGH THURSDAY
MODELS CONTINUE TO KEEP THE
FORECAST AREA UNDER A SW FLOW SUNDAY AND MONDAY AS THE REMNANTS OF
THE UPPER LEVEL LOW CURRENTLY OFF THE COAST PERSIST JUST OFFSHORE.
THIS WILL CONTINUE TO LEAD TO SOME SHOWERS ACROSS THE FORECAST AREA
SUNDAY AND MONDAY BUT WITH OVERALL LOW PRECIPITATION AMOUNTS. THE
LOW WEAKENS AND FINALLY MOVES INLAND AND ACROSS THE FORECAST AREA ON
TUESDAY AS AN OPEN SHORTWAVE FOLLOWED BY A NORTHWEST FLOW WEDNESDAY
AND THURSDAY. TUESDAY WILL BE THE LAST DAY OF SOME WIDESPREAD SHOWER
ACTIVITY ACROSS THE FORECAST AREA. THE NORTHWEST FLOW WEDNESDAY AND
THURSDAY WILL SEE SOME LOWERING SNOW LEVELS WITH LIGHT PRECIPITATION
MAINLY ALONG THE CASCADE CREST AND OVER THE EASTERN MOUNTAINS.
OVERALL THE MAIN CONCERN OVER THE EXTENDED PERIOD WILL BE THE
ACCUMULATION OF LIGHT SNOW AMOUNTS OVER THE MOUNTAINS. PRECIPITATION
AMOUNTS, RATE AND DURATION WOULD INDICATE SOME ACCUMULATING SNOW BUT
LIKELY NEAR OR BELOW ADVISORY CATEGORY.
AVIATION...12Z TAFS
WITH A MOIST SOUTHWEST FLOW CONTINUING ACROSS
THE FORECAST ARE SKIES WILL REMAIN CLOUDY. SOME SHOWERS WILL OCCUR
MAINLY LATE MORNING THROUGH THE AFTERNOON. COULD ALSO SEE SOME LOWER
VISIBILITIES THIS MORNING AS MIST OR FOG DEVELOPS IN THE COOL MOIST
ATMOSPHERE. OVERALL, EXPECT VFR TO MVFR CONDITIONS TODAY WITH SOME
POSSIBLE LOCAL IFR IF THE PATCHY FOG AND MIST DEVELOPS THIS MORNING.
WINDS WILL GENERALLY BE LIGHT AND LESS THAN 10 KTS TODAY BUT EXPECT
SOME INCREASING SOUTHERLY WINDS SUSTAINED 10-20 KTS GUSTS 30-35KTS
AT RDM AND BDN LATE TONIGHT THROUGH FRIDAY MORNING.
PRELIMINARY POINT TEMPS/POPS
PDT 49 39 55 36 / 70 90 90 90
ALW 49 40 56 38 / 80 90 100 90
PSC 47 41 50 40 / 70 90 90 70
YKM 44 33 47 30 / 60 100 80 30
HRI 49 40 51 38 / 60 90 90 80
ELN 43 34 48 30 / 60 90 80 40
RDM 51 42 54 31 / 70 90 60 60
LGD 45 41 51 35 / 90 100 100 90
GCD 49 42 54 35 / 100 100 100 90
DLS 49 43 51 37 / 60 100 90 60
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR
ORZ509.
WA...NONE.
SHORT TERM...90
LONG TERM....91
AVIATION...97
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