Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 290518 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1020 PM PDT FRI AUG 28 2015

.UPDATE...SATELLITE PICTURE SHOW LARGE AREA OF CLOUDS ACROSS THE
FORECAST AREA, BUT PRECIPITATION IS HAVING A HARD TIME MAKING IT
ONSHORE. THIS SHOULD CHANGE OVER THE FEW HOURS AS WATER VAPOR
PICTURES SHOW PIECE OF ENERGY NEAR 140W DROPPING SOUTH AND AS IT
CONTINUES TO MOVE IT WILL KICK LOW NEAR 130W NORTHEASTWARD AND
SOME LIGHT RAIN WILL SPREAD INTO THE CASCADES BY MORNING. WILL
UPDATE FORECAST FOR SLIGHTLY SLOWER ONSET OF PRECIPITATION. 93

&&

.PREV DISCUSSION... /ISSUED 250 PM PDT FRI AUG 28 2015/

SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A LARGE UPPER LEVEL
TROUGH OF LOW PRESSURE CONTINUES TO EXTEND FROM THE GULF OF ALASKA
SOUTH TO THE EASTERN PACIFIC. THE TROUGH AXIS ROUGHLY RUNS ALONG 135
WEST LONGITUDE, BUT WILL SHIFT TO NEAR 130 WEST SATURDAY. SOUTHWEST
FLOW ALOFT ASSOCIATED WITH THE TROUGH WILL KEEP VARYING CHANCES OF
SHOWERS GOING ALONG THE CASCADE EAST SLOPES TONIGHT. PATCHY SMOKE
WILL CONTINUE ACROSS THE REGION AS WELL, WITH THICKER AREAS OF SMOKE
IN SOUTHEAST GRANT COUNTY. AS THE TROUGH SHIFTS EAST SATURDAY, IT
WILL KICK AN UPPER LOW CURRENTLY NEAR 38N/135W NORTHEAST THROUGH THE
REGION. THE MAIN IMPACT FROM THIS SYSTEM ACROSS SOUTHEAST
WASHINGTON, AND NORTHEAST AND CENTRAL OREGON WILL BE WINDS. AT THIS
TIME WINDS OVER A GOOD PORTION OF THE AREA WILL RUN IN THE 25 TO 35
MPH RANGE. THUS WILL CONTINUE MOST OF THE CURRENT WIND ADVISORIES.
HAVE CANCELLED THE ADVISORIES FOR THE KITTITAS VALLEY AND THE
COLUMBIA RIVER GORGE AS WINDS IN THESE AREAS SHOULD STAY IN THE 20
TO 30 MPH RANGE. BRIEF STRONGER WINDS COULD LOCALLY OCCUR DURING
COLD FRONTAL PASSAGE THOUGH. THIS LOW WILL CAUSE CHANCES OF SHOWERS
FROM SOUTH-CENTRAL WASHINGTON SOUTH TO CENTRAL OREGON. ALSO A FEW
SHOWERS MAY OCCUR OVER NORTHEAST OREGON IN THE AFTERNOON. THERE IS
AN OUTSIDE CHANCE OF A STRAY THUNDERSTORM OVER WALLOWA COUNTY
SATURDAY AFTERNOON AND EVENING. THE UPPER TROUGH WILL MOVE INTO AND
THROUGH THE PACIFIC NORTHWEST SUNDAY AND SUNDAY NIGHT. THUS STILL
EXPECT TO SEE SOME CHANCES OF SHOWERS OVER MUCH OF THE REGION
SUNDAY, WITH SHOWERS LINGERING ALONG THE CASCADE EAST SLOPES OF
WASHINGTON INTO SUNDAY NIGHT. BREEZY WINDS WILL AGAIN BE POSSIBLE
OVER THE COLUMBIA BASIN, BUT WILL BE MAINLY IN THE 15 TO 25 MPH
RANGE. HIGH TEMPS BY SUNDAY AFTERNOON WILL RUN IN THE UPPER 60S TO
MID 70S, WITH MID 50S TO MID 60S IN THE MOUNTAINS. 90

LONG TERM...MONDAY THROUGH FRIDAY...A LARGE UPPER LEVEL TROUGH WILL
BE OVER THE REGION ON MONDAY AND THEN IT WILL DEVELOP INTO A DEEP
TROUGH FOCUSED OVER THE PACIFIC NORTHWEST BY MIDWEEK. TEMPERATURES
WILL BE SLIGHTLY BELOW NORMAL MONDAY AND TUESDAY THEN DROP EVEN
FURTHER WITH HIGHS ONLY IN THE 70S BY MIDWEEK. THERE WILL BE A
CHANCE OF SHOWERS MAINLY ALONG THE CASCADES MONDAY AND TUESDAY THEN
A MORE WIDESPREAD CHANCE OF PRECIPITATION WEDNESDAY AND THURSDAY AS
THE TROUGH DEEPENS OVER THE NORTHWEST. COOL AND DRIER CONDITIONS ARE
EXPECTED BY FRIDAY.

AVIATION...06Z TAFS...VFR CONDITIONS WILL CONTINUE FOR THE NEXT 24
HOURS BUT ARE EXPECTING A FRONTAL PASSAGE EARLY TO MIDDAY SATURDAY.
CEILINGS WILL BE BROKEN TO OVERCAST AT 8K-12K FEET AGL BUT AGAIN
COULD SEE SOME LOWER CEILINGS AROUND FRONTAL PASSAGE TIME. SMOKE
FROM REGIONAL WILDFIRES WILL CONTINUE TO BE PRESENT ACROSS THE AREA
BUT ARE NOT EXPECTED TO LOWER VISIBILITIES TO MVFR AT ANY TAF SITE.
SHOWERS WILL DEVELOP ALONG THE FRONT AND APPROACH THE CASCADES AFTER
10Z BUT THE PROBABILITY OF RAIN SHOWERS AT ANY TAF SITE IS FAIRLY
LOW DUE TO RAIN SHADOWING. A SIGNIFICANT WIND INCREASE IS EXPECTED
WITH THE FRONTAL PASSAGE ON SATURDAY OF 20-30 KTS AND HIGHER GUST
RESULTING IN BLOWING DUST AND REDUCED SURFACE VISIBILITIES. 91/93

FIRE WEATHER...UPPER LOW AND FRONTAL BOUNDARY CURRENTLY OFFSHORE
WILL MOVE ACROSS THE REGION SATURDAY. THIS WILL PRODUCE STRONG WEST
TO SOUTHWEST WINDS. SOME RAIN IS EXPECTED ALONG THE CASCADES AND
EAST SLOPES OTHERWISE MAINLY DRY. ANOTHER SYSTEM WILL MOVE THROUGH
SATURDAY NIGHT AND SUNDAY. THIS WILL BRING A BETTER CHANCE OF
SHOWERS ALONG WITH COOLER TEMPERATURES. AN UPPER LEVEL TROUGH WILL
REMAIN OVER THE WEST THROUGH NEXT WEEK WITH COOLER TEMPERATURES.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  60  82  54  72 /  10  10  10  30
ALW  66  83  60  74 /  10  20  10  40
PSC  60  83  52  77 /  10  10  20  30
YKM  60  73  50  70 /  10  20  40  20
HRI  61  84  53  76 /   0  10  10  30
ELN  58  73  51  71 /  20  30  50  30
RDM  57  77  44  68 /  10  30  20  20
LGD  53  84  47  69 /  10  20  10  30
GCD  56  81  46  73 /  10  20  10  20
DLS  64  79  60  73 /  20  30  40  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 5 AM TO 6 PM PDT SATURDAY FOR ORZ510-511.

     RED FLAG WARNING FROM 7 AM TO 7 PM PDT SATURDAY FOR ORZ640>645.

     BLOWING DUST ADVISORY FROM 9 AM TO 6 PM PDT SATURDAY FOR ORZ044-
     507-508.

     WIND ADVISORY FROM 9 AM TO 6 PM PDT SATURDAY FOR ORZ044-507-508.

WA...RED FLAG WARNING FROM 7 AM TO 7 PM PDT SATURDAY FOR WAZ641-643-
     645-675.

     BLOWING DUST ADVISORY FROM 9 AM TO 6 PM PDT SATURDAY FOR
     WAZ027>029.

     WIND ADVISORY FROM 9 AM TO 6 PM PDT SATURDAY FOR WAZ027>029-521.

&&

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

93/91/91



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