000
FXUS66 KPDT 150948
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
248 AM PDT WED MAY 15 2013

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT...A WEAK DISTURBANCE WILL
BRING A SHALLOW TROUGH TO THE PACIFIC NORTHWEST COAST TODAY. THE
DISTURBANCE WILL BE WEAKENING AS IT REACHES OUR AREA BUT WILL STILL
BRING A CHANCE OF LIGHT RAIN SHOWERS TO THE CASCADE CREST REGION
TODAY AND TONIGHT. A FEW SHOWERS MAY MAKE IT INTO ELLENSBURG, YAKIMA
AND SUNRIVER THIS AFTERNOON BUT THE REST OF THE LOWER ELEVATIONS
WILL REMAIN DRY. THE EASTERN MOUNTAINS WILL ALSO HAVE A SLIGHT
CHANCE OF SHOWERS IN THE LATER AFTERNOON AND TONIGHT. PRESSURE
GRADIENTS WILL TIGHTEN UP AND BREEZY WINDS WILL DEVELOP IN THE
COLUMBIA GORGE IN THE AFTERNOON AND EARLY EVENING. A SECOND STRONGER
DISTURBANCE WILL DEEPEN THE TROUGH AND MOVE INTO NORTHERN CALIFORNIA
AND SOUTHERN OREGON THURSDAY MORNING. MOST OF THE ENERGY WILL BE TO
OUR SOUTH, BUT THERE SHOULD BE A CHANCE OF SHOWERS ALONG THE
CASCADES AND CENTRAL OREGON AND IN THE HIGHER TERRAIN FROM THE
OCHOCO-JOHN DAY HIGHLANDS INTO WALLOWA COUNTY THROUGH THE DAY AND
INTO THE EVENING. FURTHER NORTH, THE REST OF THE EASTERN MOUNTAINS
WILL HAVE A SLIGHT CHANCE OF SHOWERS. THE SHOWERS WILL TAPER OFF
OVERNIGHT BUT THERE WILL STILL BE A SLIGHT CHANCE OF SHOWERS IN THE
OREGON CASCADES AND THE SOUTHERN FRINGES OF THE FORECAST AREA. WITH
A TROUGH TO OUR EAST AND A MOIST SOUTHWEST FLOW INTO OUR AREA WOULD
NORMALLY EXPECT A FEW THUNDERSTORMS THURSDAY AFTERNOON AND EVENING
BUT MODELS ARE NOT SHOWING MUCH IF ANY INSTABILITY, SO HAVE LEFT
THUNDERSTORMS OUT OF THE FORECAST. TEMPERATURES WILL CONTINUE NEAR
NORMAL AND SIMILAR TO THE LAST COUPLE OF DAYS TODAY. ON THURSDAY THE
COOLER AIR WITH THE TROUGH ALONG WITH CLOUDS AND RAIN WILL COOL
TEMPERATURES IN THE SOUTHERN PORTIONS OF THE AREA 4 TO 7 DEGREES
WHILE THE NORTH WILL ONLY BE DOWN A DEGREE OR TWO. PERRY

.LONG TERM...FRIDAY THROUGH TUESDAY...MODELS AGREE ON A SPLIT FLOW
AND BROAD SCALE TROUGHING OVER THE PACIFIC NORTHWEST FRIDAY. THE
SPLIT FLOW WILL SHIFT EAST TO THE ROCKIES SATURDAY...BUT BROAD SCALE
TROUGHING WILL CONTINUE OVER EASTERN WASHINGTON AND OREGON THROUGH
SATURDAY (GFS) OR SUNDAY (ECMWF). THIS PATTERN WILL PRODUCE DIURNAL
SHOWERS...PARTICULARLY IN UPSLOPE AREAS AND THE MOUNTAINS. MONDAY A
TRANSITORY FLAT RIDGE WILL DEVELOP OVER THE PACIFIC NORTHWEST
FOLLOWED BY AN UPPER LEVEL LOW AND TROUGH MONDAY NIGHT AND TUESDAY.
THE BROAD PATTERN IS REFLECTED IN THE ENSEMBLES AS WELL...BUT THE
DETAILS OF THE LOW AND TROUGH POSITION ARE INCONSISTENT. DUE TO
MODEL INCONSISTENCIES DID NOT CHANGE CURRENT LOW POP FORECAST FOR
MONDAY AND TUESDAY...BUT EXPECT THAT POPS FOR TUESDAY ARE TOO LOW.
COONFIELD

&&

.AVIATION...PREVIOUS DISCUSSION...06Z TAFS...VFR CONDITIONS ARE
EXPECTED OVER THE NEXT 24 HOURS. SKY COVER WILL BE GENERALLY SCT-BKN
ABOVE 15000 FEET AGL OVERNIGHT BUT LOWER TO AROUND 6000-8000 FEET
AGL AND BECOME BKN-OVC ON WEDNESDAY AS A SYSTEM PASSES OVER THE
REGION. WINDS WILL BE LESS THAN 10 KTS TONIGHT INCREASING TO 10-20
KTS AFTER 15/18Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  70  45  69  46 /  10  10  10  10
ALW  71  49  71  51 /  10  10  10  10
PSC  75  47  75  48 /  10  10  10  10
YKM  71  46  73  48 /  20  20  10  10
HRI  73  47  74  49 /  10  10  10  10
ELN  68  45  70  46 /  20  20  10  10
RDM  68  38  64  41 /  10  10  20  20
LGD  69  43  66  42 /  10  20  20  20
GCD  68  43  64  43 /  10  20  20  20
DLS  68  49  73  51 /  20  20  10  10

&&

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

THREAT INDEX
TODAY : GREEN
THURSDAY : GREEN
FRIDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

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

$$

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