Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 281120 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
420 AM PDT TUE APR 28 2015...UPDATED

UPDATED AVIATION DISCUSSION AND CORRECTED LONG TERM DISCUSSION

.SHORT TERM...TODAY THROUGH THURSDAY...AN UPPER LEVEL TROUGH WILL
MOVE INTO WASHINGTON AND OREGON TODAY. THE ASSOCIATED COLD FRONT
WILL MOVE INTO THE CASCADES TUESDAY AFTERNOON AND ACROSS THE REST OF
THE AREA TUESDAY NIGHT. THIS WILL BRING SPOTTY SHOWERS AND BREEZY
WINDS. MODELS INDICATE MARGINAL INSTABILITY TUESDAY EVENING WITH THE
FRONTAL LIFT. SINCE THE INSTABILITY AND FRONTAL LIFT DO NOT COINCIDE
WITH DAYTIME HEATING I DO NOT THINK THUNDERSTORMS WILL OCCUR.
WEDNESDAY A BROAD TROUGH WILL KEEP SOUTHWEST FLOW ALOFT OVER EASTERN
WASHINGTON AND OREGON. HOWEVER MUCH COOLER AIR BEHIND THE FRONT WILL
LIMIT DAYTIME HEATING SO THE ATMOSPHERE WILL NOT BE AS UNSTABLE. THE
TROUGH MAY TRIGGER A FEW MOUNTAIN SHOWERS AND BREEZY WINDS.
WEDNESDAY NIGHT AND THURSDAY DRIER NORTHWEST FLOW WILL MOVE INTO
EASTERN WASHINGTON AND OREGON.  COONFIELD

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY. A DRY WESTERLY FLOW WILL
BRING NEAR SEASONAL TEMPERATURES AND OCCASIONALLY BREEZY WINDS
THROUGH THE PERIOD.  HIGH TEMPERATURES WILL MAINLY BE IN THE MID 60S
TO MID 70S AND OVERNIGHT LOWS IN THE 30S TO MID 40S.  MODELS IN GOOD
AGREEMENT WITH THIS PATTERN...SO CONFIDENCE IS HIGH...AT LEAST
THROUGH MONDAY.  THERE ARE SOME SIGNIFICANT DIFFERENCES ON TUESDAY
WITH THE ECMWF MAINTAINING A WESTERLY FLOW BUT THE GFS AND CANADIAN
BRINGING A DEEP CLOSED LOW ALONG THE WA/OR COAST.  WISTER


&&

.AVIATION...12Z TAFS. VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD.  HOWEVER...MID LEVEL MOISTURE ASSOCIATED WITH AN APPROACHING
COLD FRONT WILL INCREASE...AND CLOUDS WILL BECOME BKN-OVC 6K-10K
FEET AGL LATE THIS AFTERNOON AND EVENING.  FORECAST SOUNDINGS SHOW A
DEEP MOISTURE LAYER AT KALW AFTER MIDNIGHT TONIGHT THAT WOULD
INDICATE SHOWERS AND POSSIBLY MVFR CIGS.  WINDS WILL INCREASE AS THE
DAY PROGRESSES AND BECOME WESTERLY AT 15-25KT WITH SOME HIGHER GUSTS
FROM 21Z-06Z.  WISTER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  75  43  62  40 /   0  30  10  10
ALW  79  48  66  46 /   0  30  10  10
PSC  82  47  70  43 /   0  40  10  10
YKM  76  40  68  38 /  10  10  10  10
HRI  78  44  69  42 /   0  30  10  10
ELN  72  39  62  38 /  10  10  10  10
RDM  70  34  62  28 /  10  20  10  10
LGD  76  43  61  37 /   0  20  20  10
GCD  82  42  64  32 /   0  20  20  10
DLS  73  44  67  44 /  10  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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