079
FXUS66 KPDT 280507
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1010 PM PDT WED OCT 27 2021
UPDATED AVIATION DISCUSSION
SHORT TERM
A BAND OF PRECIPITATION EXTENDS ACROSS THE SOUTHERN
HALF OF WA AND NORTHEAST OR AT THIS TIME, ASSOCIATED WITH A WARM
FRONT LIFTING ACROSS WASHINGTON STATE. A STRONG WESTERLY FLOW
ALOFT IS PROVIDING RAIN SHADOWING OFF THE CASCADES, LEAVING A
LARGE GAP IN PRECIPITATION ACROSS THE LOWER COLUMBIA BASIN. AS THE
WARM FRONT LIFTS INTO NORTHERN WA, PRECIPITATION WILL BE MAINLY
CONFINED TO THE WA CASCADES AND FAR NORTHERN BLUE MOUNTAINS BY
EARLY THURSDAY MORNING. WINDS HAVE DECREASED ACROSS THE AREA AND
SHOULD REMAIN LIGHT FOR MOST OF THE NIGHT BEFORE INCREASING BEHIND
THE FRONT THURSDAY MORNING. FORECAST ON TRACK AND ONLY MINOR
UPDATES WERE MADE. WISTER
AVIATION...06Z TAFS
A WARM FRONT MOVING ONSHORE WILL LOWER
CIGS OVER THE NEXT SEVERAL HOURS BUT STILL REMAIN VFR AT THE
TERMINAL AIRPORTS. ANY RAINFALL THIS EVENING WILL BE VERY LIGHT WITH
AROUND A TRACE. WINDS HAVE DECREASED THIS EVENING AND MOSTLY 15 KTS
OR LESS BUT WILL INCREASE AFTER THE WARM FRONTAL PASSAGE WITH WSW 10-
15 KTS GUSTING TO 25 KTS THURSDAY MORNING. THURSDAY WILL BE MET WITH
VARIABLE MID AND HIGH LEVEL CLOUDS WITH BASES AROUND 7K-15K FEET,
AND WSW WINDS GUSTING TO 20-25 KTS. WISTER
PREV DISCUSSION
/ISSUED 500 PM PDT WED OCT 27 2021/
SHORT TERM...HEADING INTO THURSDAY, BREEZY TO LOCALLY WINDY S-SW
WINDS WILL DEVELOP, AND AFTERNOON HIGHS WILL BE AROUND 10-15
DEGREES WARMER THAN TODAY. STRONGEST WINDS WILL BE ALONG EXPOSED
RIDGES IN THE SIMCOE HIGHLANDS AND EASTERN SLOPES OF THE CASCADES,
THOUGH AREAS OF NORTH-CENTRAL OR AND THE COLUMBIA BASIN OF WA
COULD SEE GUSTS OF 30-35 MPH. NO WIND HIGHLIGHTS ARE EXPECTED AT
THIS TIME. PRECIPITATION ON THURSDAY WILL LARGELY BE CONFINED TO
THE MOUNTAINS, PRIMARILY THE WA CASCADES, AS THE WARM FRONT PUSHES
NORTH AND A PLUME OF MOISTURE IS DIRECTED INTO THE WA CASCADES.
THE WARMER TEMPERATURES WILL BE SHORT LIVED AS A COLD FRONT WILL
SWEEP ACROSS THE REGION FROM NW TO SE FRIDAY MORNING, BRINGING
HIGHS SIMILAR TO THIS AFTERNOON AND A RENEWED CHANCE OF
PRECIPITATION FOR OUR ENTIRE CWA. THE BEST CHANCES FOR
PRECIPITATION WILL BE FAVORED UPSLOPE AREAS SUCH AS THE BLUES,
THOUGH LOWER ELEVATIONS COULD ALSO PICK UP A FEW HUNDREDTHS OF AN
INCH OF RAIN. PRECIPITATION WILL LINGER ACROSS THE SOUTHERN AND
EASTERN PORTIONS OF OUR CWA FRIDAY AFTERNOON AND EVENING WITH
DRIER CONDITIONS RETURNING OVERNIGHT. PLUNKETT/86
LONG TERM...SATURDAY THROUGH WEDNESDAY...A LOT OF MODEL UNCERTAINTY
THROUGH THE EXTENDED PERIOD. MODEL ISSUES BEGIN SATURDAY WITH THE
WAY MODELS HANDLE THE CLOSED LOW OFF THE SW COAST OF OREGON. GFS IS
MOST AGGRESSIVE IN OPENING THE CLOSED LOW INTO A TROUGH AND MOVE IT
INTO THE GREAT BASIN BY LATE SATURDAY. OTHER MODELS HOLD THE CLOSED
LOW AROUND SW OREGON INCLUDING THE ECMWF AS A RIDGE PATTERN BUILDS
ALONG THE COAST. THE ECMWF ATTEMPTS TO BRING THE DECAYING LOW INTO
THE PACIFIC NORTHWEST LATE SATURDAY AND SUNDAY UNDER THE RIDGE AXIS
WHICH IS ALSO MOVING ONSHORE. NBM BLENDS THE DIFFERENCE TO INDICATE
A SLIGHT CHANCE OF PRECIPITATION IN CENTRAL OREGON SATURDAY BUT WITH
LOW CONFIDENCE.
THE RIDGE AXIS BEGINS TO SHIFT EASTWARD LATE SUNDAY INTO MONDAY AS
THE NEXT SYSTEM APPROACHES FROM THE WEST. ONCE AGAIN MODELS DIFFER
ON THE INTENSITY AND PLACEMENT OF THE FEATURES BY MONDAY WITH THE
ECMWF BEING THE MORE AGGRESSIVE WHILE GFS MAINTAINS MORE OF A FLAT
RIDGE OVER THE REGION. STAYED WITH THE NBM WHICH MITIGATES A
WEAKENING SYSTEM PASSING OVER THE FORECAST AREA ON MONDAY.
MODELS SOMEHOW MANAGE TO AGREE ON A TRANSITORY RIDGE OF HIGH
PRESSURE OVER THE FORECAST AREA ON TUESDAY. HOWEVER, THE GFS RIDGE
AXIS IS OVER THE FORECAST AREA BY TUESDAY AFTERNOON WHILE THE ECMWF
KEEPS IT ALONG THE COAST. THE RESULT IS THE GFS BEING FASTER AT
MOVING THE NEXT WEATHER SYSTEM INTO THE FORECAST AREA ON WEDNESDAY
WHILE THE ECMWF STILL HAS THE RIDGE AXIS PASSING OVER THE FORECAST
AREA. AGAIN THE NBM SPLITS THE DIFFERENCE INDICATING AT LEAST A
SLIGHT CHANCE OF PRECIPITATION. ALL THIS UNCERTAINLY LEAD TO A VERY
LOW CONFIDENCE IN THE EXTENDED FORECAST AT THIS POINT.
PRELIMINARY POINT TEMPS/POPS
PDT 44 73 48 59 / 30 10 10 60
ALW 47 74 51 61 / 40 10 10 70
PSC 49 73 55 63 / 40 10 10 50
YKM 39 66 45 59 / 40 20 10 20
HRI 46 74 52 62 / 30 10 10 60
ELN 39 62 44 55 / 70 50 50 20
RDM 43 69 44 56 / 10 0 10 50
LGD 42 63 47 57 / 40 10 10 50
GCD 43 70 45 61 / 20 0 0 30
DLS 48 69 53 61 / 60 20 20 50
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...85
LONG TERM....91
AVIATION...85
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