Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 230539
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1033 PM PDT MON SEP 22 2014

.SHORT TERM...WATER VAPOR SHOWING UPPER LEVEL SHORT WAVE MOVING INTO
OREGON THIS EVENING. A LARGE AREA OF SHOWERS AND THUNDERSTORMS HAS
DEVELOPED OUT AHEAD OF THE WAVE IMPACTING PARTS OF THE FORECAST
AREA. MODELS ARE CONSISTENT SHOWING ADDITIONAL SHOWERS AND POSSIBLE
THUNDERSTORMS FOR THE REMAINDER OF THE EVENING INTO THE OVERNIGHT
PERIOD. MEANWHILE A LARGE UPPER LOW AND FRONTAL BOUNDARY WILL BE
MOVING CLOSER TO THE PACIFIC NORTHWEST ON TUESDAY. MOST OF THE
PRECIPITATION WILL REMAIN WEST OF THE CASCADES WITH SKIES REMAINING
MOSTLY CLOUDY. THE FRONT WILL MOVE VERY SLOWLY INTO THE REGION
WEDNESDAY AND THURSDAY WITH A GOOD CHANCE OF RAIN. TEMPS WILL BE
SIGNIFICANTLY COOLER THE NEXT SEVERAL DAYS. 94

.AVIATION...06Z TAFS. CEILINGS MOSTLY 070-120 TONIGHT INTO TUESDAY
WITH SCATTERED SHOWERS. WINDS 5-15KT.

&&

.PREV DISC... /ISSUED 246 PM PDT MON SEP 22 2014/

SHORT TERM...TONIGHT THROUGH WEDNESDAY...AN UPPER TROUGH WILL BE
OFF THE WEST COAST WHILE AN UPPER RIDGE WILL BE OVER THE ROCKY
MOUNTAIN STATES THROUGH THIS PERIOD. AS A RESULT THE PACIFIC
NORTHWEST WILL BE UNDER AN SOUTHWEST UPPER LEVEL FLOW. THIS FLOW
WILL BECOME MORE SOUTH-SOUTHWESTERLY BY WEDNESDAY. A COUPLE OF
DISTURBANCES WITHIN THIS FLOW WILL AFFECT WEATHER CONDITIONS ACROSS
THE INTERIOR NORTHWEST LATE THIS AFTERNOON AND THIS EVENING. THE
FIRST OF THESE WAVES IS MOVING INTO EASTERN SECTIONS OF THE REGION
AT THIS MOMENT. THIS SYSTEM WILL KEEP ISOLATED TO SCATTERED SHOWERS
WITH STRAY THUNDERSTORMS GOING INTO THE EARLY EVENING FROM GRANT
COUNTY NORTH INTO THE BLUES AND NORTHEAST INTO WALLOWA COUNTY. A
SECOND WAVE IS NOW MOVING INTO SOUTHWEST OREGON. THIS SECOND WAVE IS
EXPECTED TO CAUSE SHOWERS AND A FEW THUNDERSTORMS TO REDEVELOP OVER
CENTRAL AND NORTH-CENTRAL OREGON THIS EVENING. THESE SHOWERS AND
STORMS WILL MOVE NORTHEAST THROUGH THE LATE EVENING AND OVERNIGHT.
AT THIS TIME BEST CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED TO OCCUR FROM THE LOWER COLUMBIA BASIN EAST INTO THE BLUE
MOUNTAINS AND THE BLUE MOUNTAIN FOOTHILLS AROUND AND AFTER MIDNIGHT.
WILL RAISE POPS INTO THE 40 TO 60 PERCENT RANGE IN THESE AREAS
OVERNIGHT. A FEW SHOWERS WILL PERSIST OVER THE BLUE MOUNTAINS EAST
TO WALLOWA COUNTY TUESDAY MORNING. A FEW SHOWERS ARE ALSO EXPECTED
NEAR THE CASCADE CREST, ESPECIALLY IN WASHINGTON. A COLD FRONT WILL
THEN SLOWLY WORK INTO WESTERN OREGON AND WASHINGTON TUESDAY NIGHT.
THIS FRONT WILL GRADUALLY PUSH PRECIP INTO THE CASCADE EAST SLOPES
LATE TUESDAY NIGHT AND WEDNESDAY. THIS PRECIP IS EXPECTED TO
CONTINUE TO SLOWLY SHIFT EAST WEDNESDAY, REACHING THE WESTERN LOWER
BASIN SOUTHWEST TO CENTRAL OREGON BY WEDNESDAY AFTERNOON. CLOUD
COVER WILL CAUSE HIGH TEMPS TO COOL EACH DAY, EXCEPT OVER THE GRANDE
RONDE VALLEY AND WALLOWA COUNTY WHERE TEMPS WILL REMAIN WELL ABOVE
SEASONAL DUE TO SUNNIER CONDITIONS. CLOUD COVER WILL ALSO KEEP LOW
TEMPS MILD FOR THIS TIME OF YEAR. 90

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...LOW PRESSURE OVER THE
NE PAC WILL PUMP MOISTURE INTO THE TWO STATE AREA INTO THE END OF
THE WEEK. THIS WILL KEEP CLOUDS AND SHOWERS IN THE FORECAST ALONG
WITH COOLER TEMPERATURES. A DISTURBANCE WILL MOVE INTO THE TWO STATE
AREA FRIDAY AND DRIFT INTO IDAHO SATURDAY WITH A RIDGE OF HIGH
PRESSURE BEHIND IT. THE RIDGE SHOULD BRING DRIER CONDITIONS INTO THE
REGION SATURDAY AND SUNDAY WITH NEAR NORMAL TEMPERATURES EXPECTED
INTO MONDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  58  80  57  78 /  60  10  10  10
ALW  63  81  60  79 /  50  20  10  10
PSC  60  82  59  78 /  50  10  10  20
YKM  58  76  58  68 /  20  10  20  40
HRI  58  82  56  78 /  60  10  10  10
ELN  57  75  57  69 /  20  10  20  60
RDM  50  77  50  72 /  20  10  10  40
LGD  58  81  50  82 /  50  20   0  10
GCD  54  81  52  80 /  40  10  10  10
DLS  58  78  58  72 /  30  10  30  50

&&

.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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