Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 290155
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
655 PM PDT THU MAY 28 2015

.SHORT TERM...INSTABILITY OVER THE MOUNTAINS TODAY RESULTED IN
CUMULUS BUILDUPS WITH SCATTERED SHOWERS AND THUNDERSTORMS. MOSTLY
OVER THE CASCADES. SOME OF THESE WERE SLOW MOVING AND PRODUCED
LOCALLY HEAVY RAIN. EXPECT THIS ACTIVITY TO DIMINISH QUICKLY AFTER
SUNSET. SKIES WILL BE CLEAR TO PARTLY CLOUDY OVERNIGHT. FLOW ALOFT
TURNS SOUTHWEST FRIDAY AS A LARGE UPPER LEVEL TROUGH APPROACHES
THE WEST COAST. STILL HAVE INSTABILITY OVER THE HIGHER TERRAIN AND
EXPECT CUMULUS BUILDUPS AGAIN WITH SCATTERED SHOWERS AND
THUNDERSTORMS. MOSTLY IN THE AFTERNOON AND EVENING. AIRMASS
CONTINUES TO WARM ALOFT AND HIGHS WILL BE IN THE 80S TO LOWER 90S.
LITTLE CHANGE TO THE PATTERN SATURDAY WITH SOUTHWEST FLOW ALOFT
AND INSTABILITY OVER THE MOUNTAINS. SCATTERED SHOWERS AND
THUNDERSTORMS AGAIN WITH HIGHS IN THE 80S TO LOWER 90S.  94

&&

.PREV DISCUSSION... /ISSUED 202 PM PDT THU MAY 28 2015/

SHORT TERM...TONIGHT THROUGH SUNDAY...LOW PRESSURE CONTINUE TO MOVE
AWAY FROM THE TWO STATE AREA BUT RESIDUAL MOISTURE REMAINS ACROSS THE
REGION AND COMBINING THIS WITH DAYTIME HEATING WAS PRODUCING ISOLD
TSRA MAINLY OVER THE AREA MOUNTAINS THIS AFTERNOON. THE ISOLD
SHRA/TSRA SHOULD PERSIST INTO THE EVENING.

MEANWHILE A WEAK RIDGE OF HIGH PRESSURE IS FORECAST TO SLIP EAST
ALLOWING FOR ADDITIONAL MOISTURE TO MOVE INTO THE REGION. THE BULK
OF THE INSTABILITY IS FORECAST OVER AND NEAR CENTRAL OREGON AND SOME
SHRA/TSRA ARE EXPECTED TO DEVELOP AROUND THIS REGION ON FRIDAY. PART
OF THE CONVECTION BREAKS OFF AND MOVES NE OVERNIGHT SPREADING INTO
THE BLUE/WALLOWA AREAS AS WELL AS PORTIONS OF THE BASIN TOWARD
SATURDAY MORNING. ANOTHER ROUND OF MOISTURE THAT IS EXPECTED TO
COMBINE WITH DAYTIME HEATING SHOULD PRODUCE TSRA ONCE AGAIN OVER
PORTIONS OF CENTRAL OREGON AND THE JOHN DAY HIGHLANDS/BLUE/WALLOWA
AREAS SAT AFTN/EVE. THE MODELS WERE INDICATING THAT A WARM FRONT
COULD MOVE NORTH AND ACROSS WA/OR SATURDAY NIGHT AND SUNDAY MORNING.
WITH THE ABOVE NORMAL TEMPS AND MOISTURE TSRA CHANCES SHOULD
INCREASE ACROSS THE ENTIRE AREA SUNDAY AFTN/EVE.

LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...LATE SUNDAY THE UPPER
LEVEL RIDGE OVER THE REGION WILL BE BREAKING DOWN AS A TROUGH OF LOW
PRESSURE OFF THE COAST MOVES INLAND. THERE WILL BE SOME INSTABILITY
ACROSS THE FORECAST AREA SUNDAY AFTERNOON LEADING TO SOME
THUNDERSTORM DEVELOPMENT BUT THE MAIN PUSH OF THE UPPER LEVEL LOW
INTO THE REGION WILL OCCUR OVERNIGHT. AS SUCH THIS COULD HELP EXTEND
THE THUNDERSTORM ACTIVITY THROUGH THE NIGHT AND INTO EARLY MONDAY.
COOLER BREEZY AND UNSTABLE CONDITIONS ARE EXPECTED ON MONDAY AS THE
LOW CONTINUES SETTLING OVER THE REGION. THE LOW WILL SLOWLY FILL IN
AND BECOME AN OPEN TROUGH OVER THE REGION ON TUESDAY AND CONTINUE
INTO THURSDAY. EXPECT MAINLY DIURNAL SHOWERS DURING THIS PERIOD WITH
SOME SLIGHT CHANCE OF THUNDERSTORMS OVER VARIOUS PORTIONS OF THE
FORECAST AREA WITH COOLER TEMPERATURES PERSISTING.


AVIATION...00Z TAFS...VFR CONDITIONS ARE EXPECTED WITH JUST A FEW
CU BUILDUPS AT 6-8K FEET MAINLY AROUND MOUNTAINS THROUGH THIS
EVENING. EXPECT SOME MORE CU BUILD UPS AROUND THE AREA FRIDAY
AFTERNOON TOO. WINDS WILL GENERALLY BE LESS THAN 10 KT.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  87  60  86 /  10  10  20  10
ALW  60  90  64  89 /  10  10  20  10
PSC  56  93  61  92 /   0  10  10  10
YKM  56  90  60  87 /  10  10  10  10
HRI  55  91  62  91 /   0  10  10  10
ELN  55  90  57  87 /  20  20  20  10
RDM  46  86  50  84 /  10  30  30  20
LGD  49  84  55  84 /  10  20  20  30
GCD  47  86  54  86 /  10  20  20  30
DLS  58  92  61  88 /   0  20  20  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

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

$$

94/



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