Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 312113
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
212 PM PDT MON AUG 31 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY...A BROAD UPPER LEVEL
TROUGH OVER THE PACIFIC NORTHWEST WITH A WESTERLY FLOW WILL KEEP
MOST OF THE FORECAST AREA DRY EXCEPT FOR SOME SHOWERS ALONG THE
CASCADE CREST THROUGH TUESDAY. THEN SOME ENERGY DROPPING INTO THE
TROUGH WILL LEAD TO THE TROUGH DIGGING SOUTHWARD TUESDAY NIGHT AND
WEDNESDAY. THIS WILL PUSH A COLD FRONT TROUGH THE FORECAST AREA WITH
A BAND OF PRECIPITATION ASSOCIATED WITH IT TUESDAY NIGHT AND
WEDNESDAY. THE PRECIPITATION IS LIKELY TO SKIP OVER THE LOWER
ELEVATIONS BUT THE MOUNTAINS COULD END UP SEEING SOME LIGHT
ACCUMULATIONS. BY THURSDAY THE UPPER LEVEL TROUGH IS SETTLING OVER
THE REGION BUT THERE IS SOME MODEL UNCERTAINTY. HAVE INDICATED A
TREND TOWARDS MORE SHOWER ACTIVITY THURSDAY BELIEVING THE INCREASED
INSTABILITY ASSOCIATED WITH THE TROUGH WILL LEAD TO A BETTER CHANCE
OF PRECIPITATION ACROSS MOST OF THE FORECAST AREA. HIGH TEMPERATURES
WILL BEGIN TO COOL ON WEDNESDAY AND BY THURSDAY WILL BE 10 TO 15
DEGREES BELOW NORMAL.


.LONG TERM...THURSDAY NIGHT THROUGH MONDAY...ACTIVE WEATHER
PATTERN THROUGH PERIOD AND MODELS NOT IN AGREEMENT BEGINNING
SUNDAY. UPPER LEVEL LOW PRESSURE AREA TO DROP SOUTH FROM BC INTO PAC
NW ON FRIDAY. THAT MUCH MODELS AGREE UPON.  THIS WILL BRING
UNSETTLED...COOLER...AND SHOWERY CONDITIONS INTO ALL AREAS FOR
FRIDAY AND SATURDAY. ENOUGH INSTABILITY FOR THUNDERSTORMS FRIDAY.
BY SUNDAY...GFS OPENS UPPER LOW INTO A WAVE AND EJECTS INTO IDAHO AND
MONTANA...WHILE GFS/CANADIAN HAVE STRONG JET LEVEL WINDS DIVING
SOUTH ON WEST SIDE OF LOW AND KEEPING IT ANCHORED OVER SOUTHERN
OREGON FOR ABOUT 12-18 HOURS LONGER BEFORE MOVING EAST.
SO WITH THIS IN MIND I HAVE KEPT CHC POPS GOING LONGER ACROSS
EASTERN ZONES...ESPECIALLY WALLOWA COUNTY TO ACCOUNT FOR POSSIBLE
WRAPAROUND MOISTURE AFTER LOW MOVES INTO ID/MT. IF EC/CANADIAN
MODELS PROVE CORRECT...SIGNIFICANT PRECIPITATION COULD OCCUR.  FOR
NOW WILL JUST INCREASE POPS UNTIL MODELS COME INTO AGREEMENT.


&&

.AVIATION...00Z TAFS...VFR CONDITIONS TO PREVAIL WITH GENERALLY DRY
WESTERLY FLOW ALOFT AND ONLY SCT200 AND LGT SFC WINDS EXCEPT G20 AT
KDLS TIL 05Z.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  52  79  55  72 /   0   0  20  20
ALW  59  80  60  75 /   0   0  20  20
PSC  58  83  58  76 /   0   0  10  10
YKM  51  75  51  71 /  10  10  10  10
HRI  55  81  57  75 /   0   0  10  10
ELN  53  77  52  71 /  10  10  20  20
RDM  42  78  46  70 /   0   0  10  10
LGD  48  82  48  71 /   0   0  10  20
GCD  46  85  48  72 /   0   0  10  20
DLS  59  80  58  75 /   0  10  20  20

&&

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

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

$$

91/79/79


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