Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 021105 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
404 AM PDT WED SEP 2 2015

UPDATED AVIATION DISCUSSION

.SHORT TERM...TODAY THROUGH FRIDAY...AN UPPER LOW MOVING SOUTH ALONG
THE BRITISH COLUMBIA COAST IS DEEPENING THE TROUGH OVER THE PACIFIC
NORTHWEST. A SHORTWAVE IS MOVING INTO THE AREA AND WILL SEND A FRONT
THROUGH THE AREA TODAY. IT WILL BRING SCATTERED RAIN SHOWERS MAINLY
TO THE MOUNTAINS THOUGH CENTRAL AND NORTH CENTRAL OREGON AND THE
BLUE MOUNTAIN FOOTHILLS MAY SEE ISOLATED SHOWERS THIS MORNING. RAIN
AMOUNTS WILL BE AROUND A TENTH OF AN INCH IN THE MOUNTAINS BUT JUST
A FEW HUNDREDTHS OF AN INCH ELSEWHERE. THE FRONT WILL BRING COOLER
AIR INTO THE AREA AND HIGHS WILL BE IN THE LOWER TO MID 70S IN THE
COLUMBIA BASIN AND IN THE 60S NEARLY EVERYWHERE ELSE. THE FRONT WILL
ALSO BRING BREEZY WINDS IN THE LATE MORNING AND AFTERNOON. WEDNESDAY
NIGHT THE SHOWERS WILL SLOWLY TAPER OFF IN THE MOUNTAINS THOUGH
WALLOWA COUNTY MAY HAVE A CHANCE OF RAIN MOST OF THE NIGHT. LOW
TEMPERATURES WILL BE IN THE 40S WITH UPPER 20S AND 30S IN THE
MOUNTAINS. THURSDAY AND THURSDAY NIGHT THE TROUGH AXIS WILL BE ALONG
THE WASHINGTON/OREGON COAST BUT THERE ISN`T MUCH IN THE WAY OF
DISTURBANCES IN THE FLOW SO A SLIGHT CHANCE OF SHOWERS WILL BE
CONFINED TO THE CASCADE CREST AREA AND EASTERN WALLOWA COUNTY.
TEMPERATURES WILL REMAIN IN THE 60S AND LOWER 70S. ON FRIDAY THE THE
TROUGH MOVES OVERHEAD AND THE SHORTWAVE ENERGY MOVES INTO OUR AREA.
HAVE A CHANCE OF SHOWERS IN CENTRAL OREGON AND THE OCHOCO-JOHN DAY
HIGHLANDS WITH A SLIGHT CHANCE OVER MOST OF THE REST OF THE AREA.
EXPECT THAT THE COLUMBIA BASIN WILL REMAIN DRY. WITH VERY COLD AIR
ALOFT, LAPSE RATES WILL BE STEEP AND HAVE ADDED A SLIGHT CHANCE OF
THUNDERSTORMS IN THE AFTERNOON. TEMPERATURES WILL BE IN THE 60S AND
LOWER 70S. PERRY


.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...DIFFICULT FORECAST IN
THE EARLY LONG TERM AS THE MEDIUM RANGE MODELS DISAGREE ON THE
HANDLING OF AN UPPER LEVEL LOW FOR FRIDAY NIGHT INTO SATURDAY. THE
GFS MOVES THE LOW INTO NRN CALIFORNIA WHILE THE ECMWF MOVES THE LOW
DIRECTLY ACROSS OREGON AND INTO IDAHO WITH MORE SIGNIFICANT IMPACTS.
BOTH MODELS HAVE SHOWN RUN TO RUN CONSISTENCY ALTHOUGH THE SOUTHERN
TRACK IN THE GFS IS A NEWER TREND THAT SHOWED UP FIRST IN THE 06Z
TUESDAY MODEL RUN. WITH ALL THIS IN MIND HAVE NUDGED THIS FORECAST
TOWARD THE ECMWF BUT NOT TO THE MAGNITUDE OF ITS CURRENT POPS/QPF IT
IS FORECASTING FOR PORTIONS OF CENTRAL AND EASTERN OREGON. EXPECT
SHOWERS FRIDAY NIGHT AND SATURDAY MAINLY OVER EASTERN OREGON AND
EXTREME SOUTHEAST WASHINGTON. THERE WILL BE AT LEAST A SLIGHT CHANCE
OF THUNDERSTORMS OVER CENTRAL AND NORTHEAST OREGON FRIDAY EVENING TO
GO ALONG WITH THE SHOWERS. ON SATURDAY KEPT THUNDERSTORMS LIMITED TO
WALLOWA COUNTY FOR NOW. BY SUNDAY THE LOW WILL MOVE EAST OF THE AREA
AND BE REPLACED BY DRY NW FLOW WHICH WILL PERSIST INTO THE MIDDLE OF
NEXT WEEK. GRADUALLY HEIGHTS WILL RISE AND TEMPERATURES WILL
MODERATE FROM BELOW NORMAL TO NORMAL OR SLIGHTLY ABOVE. 78


&&

.AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE
FORECAST PERIOD. EXPECT A BKN-SCT CLOUD LAYER AT 5-7 K FEET AGL WITH
MID CLOUD ABOVE. THERE WILL BE PATCHY LIGHT RAIN/RAIN SHOWERS AROUND
BUT WILL JUST CARRY VCSH IN THE TAFS. SKIES WILL PARTIALLY CLEAR
TONIGHT WITH JUST SCATTERED HIGH CLOUDS AFTER 03-06Z. WINDS WILL BE
WESTERLY AT 10-20 KT WITH HIGHER GUSTS DURING THE AFTERNOON AND
EARLY EVENING...BEFORE SLOWLY DIMINISHING AFTER 04-06Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  70  46  69  44 /  20  10  10  10
ALW  71  52  71  50 /  20  10  10  10
PSC  77  49  73  46 /  10   0  10  10
YKM  69  43  67  44 /  10  10  10  10
HRI  74  48  72  46 /  20  10  10  10
ELN  70  43  69  46 /  20  10  10  10
RDM  67  35  67  35 /  20  10  10  10
LGD  67  40  67  37 /  30  20  10  10
GCD  73  40  70  37 /  20  20  10  10
DLS  73  51  72  51 /  20  10  10  10

&&

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

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

$$

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