Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 200923
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
220 AM PDT SAT SEP 20 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT...AN UPPER LEVEL RIDGE WILL
BUILD OVER EASTERN WASHINGTON AND OREGON TODAY AND MOVE EAST INTO
IDAHO SUNDAY. TEMPERATURES WILL BE 5-10 DEGREES WARMER TODAY THAN
YESTERDAY DUE TO SUBSIDENCE FROM THE BUILDING RIDGE WITH EVEN WARMER
DAYTIME TEMPERATURES SUNDAY. WINDS WILL BE GENERALLY LIGHT AS WELL.
A CUTOFF LOW IN SOUTHERN CALIFORNIA TODAY WILL MOVE NORTHEAST INTO
NEVADA SUNDAY. SOME MID/HIGH LEVEL MOISTURE FROM THE LOW WILL MOVE
INTO EASTERN OREGON SUNDAY AFTERNOON IN THE SOUTHERLY FLOW BEHIND
THE RIDGE. SOME FAIR WEATHER CUMULUS MAY DEVELOP OVER THE SOUTHERN
BLUES, OCHOCOS, AND WALLOWA MOUNTAINS. MODELS ARE SUGGESTING
PRECIPITATION FROM A WEAK FRONT MONDAY MORNING ALONG THE CASCADES. I
ADDED SOME SHOWERS IN THE AFTERNOON BUT THINK THE MOISTURE ADVECTION
IS TOO FAST A TRANSITION FROM A DRY RIDGE TO PRECIPITATION. SHOWERS
MAY DEVELOP MONDAY EVENING OVER THE NORTHEAST OREGON MOUNTAINS AS
THE WEAK COLD FRONT STALLS OVER EASTERN OREGON AND WASHINGTON. THERE
WILL BE ENOUGH INSTABILITY IN THE WARM AIR AHEAD OF THE FRONT TO
TRIGGER A FEW THUNDERSTORMS AS WELL. VERY LITTLE PRECIPITATION WILL
OCCUR WITH THIS SYSTEM BECAUSE THE LOW LEVELS WILL BE VERY DRY
INITIALLY.  COONFIELD

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY NIGHT...THE LONG TERM
PERIOD CONTINUES TO SHOW A MAJOR PATTERN CHANGE ON WEDNESDAY AS A
RIDGE OF HIGH PRESSURE MOVES OUT OF THE AREA AND IS REPLACED BY A
TROUGH OF LOW PRESSURE.  A WEAK SHORTWAVE TROUGH WILL PASS OVER THE
AREA LATE TUESDAY NIGHT BRINGING INCREASED CLOUDINESS AND A SLIGHT
CHANCE OF THUNDERSTORMS TO THE NORTHEAST OREGON MOUNTAINS.  A MORE
SIGNIFICANT TRANSITION WILL OCCUR STARTING WEDNESDAY NIGHT AS A COLD
FRONT IS EXPECTED TO ARRIVE AND BRING A GOOD CHANCE OF RAIN TO THE
FORECAST AREA.  THE UPPER LEVEL TROUGH WILL TAKE SOME TIME TO MOVE
ACROSS THE AREA WITH SHOWERS AREAWIDE AND AFTERNOON THUNDERSTORMS
OVER THE NORTHEAST OREGON MOUNTAINS CONTINUING THROUGH AT LEAST
SATURDAY NIGHT.  BIEDA

&&

.AVIATION...12Z TAFS...VFR CONDITIONS UNDER HIGH PRESSURE WILL
OCCUR WITH MOSTLY CLEAR SKIES AND WINDS AOB 15 KTS DURING
THE TAF PERIOD.  BIEDA

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  86  55  87  58 /   0   0   0   0
ALW  86  60  89  64 /   0   0   0   0
PSC  88  55  90  58 /   0   0   0   0
YKM  87  55  91  58 /   0   0   0   0
HRI  88  52  91  56 /   0   0   0   0
ELN  88  53  93  59 /   0   0   0   0
RDM  87  47  88  48 /   0   0   0  10
LGD  86  46  88  50 /   0   0   0   0
GCD  88  49  89  51 /   0   0  10  10
DLS  91  56  91  59 /   0   0   0  10

&&

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

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

$$

76/98/98







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