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000
FXUS66 KPDT 180321
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON
820 PM PDT FRI MAY 17 2013

.UPDATE...ISOLATED SHOWERS REMAIN ALONG THE FOOTHILLS OF THE BLUE
MOUNTAINS AND PORTIONS OF NORTHEAST OREGON BUT NO THUNDER
ASSOCIATED.  EXPECT THESE SHOWERS TO DIMINISH OVER THE NEXT COUPLE
OF HOURS.  WONT STILL RULE OUT A SLIGHT CHANCE OF A SHOWER OR TWO
OVERNIGHT FOR THE MOUNTAINS AREAS.  SO HAVE KEPT A SLIGHT CHANCE
ACROSS THE HIGHER ELEVATIONS.  MODELS CONTINUE TO BACK OFF ON THE
INSTABILITY TO SUPPORT THUNDER TOMORROW.  RIGHT NOW SOUTH CENTRAL
PORTIONS OF OREGON LOOK TO HAVE THE BEST CHANCE FOR THUNDER...AND
EVEN IN THOSE AREAS IT LOOKS TO BE ISOLATED.  WEBER

&&

.PREV DISCUSSION... /ISSUED 220 PM PDT FRI MAY 17 2013/

SHORT TERM...TONIGHT THROUGH MONDAY...A WEATHER DISTURBANCE
CONTINUES TO MOVE ACROSS THE FORECAST AREA THIS AFTERNOON. THERE
WERE LIGHT RAIN SHOWERS REPORTED ACROSS THE BLUE MOUNTAIN FOOTHILLS
AND THE LOWER COLUMBIA BASIN...BUT PRECIPITATION AMOUNTS WERE MAINLY
JUST TRACE AMOUNTS. THE UPPER TROUGH ASSOCIATED WITH THIS SYSTEM IS
NOW LOCATED OVER THE CWA AND IT WILL SLOWLY LIFT OUT TO THE
NORTHEAST TONIGHT. ON SATURDAY ANOTHER WEATHER DISTURBANCE WILL MOVE
INTO THE REGION BRINGING ANOTHER CHANCE OF LIGHT RAIN SHOWERS...
MAINLY TO THE MOUNTAINS...HOWEVER CANNOT RULE OUT A LIGHT SPRINKLE
ELSEWHERE. AGAIN PRECIPITATION AMOUNTS WILL BE VERY LIGHT. THE UPPER
TROUGH WITH THIS NEXT SYSTEM WILL MOVE ACROSS THE CWA LATE SATURDAY
AFTERNOON AND EVENING. BEHIND IT AN UPPER RIDGE WILL BEGIN TO BUILD
INTO THE REGION WITH A DRIER NORTHWEST FLOW ALOFT BEGINNING BY LATE
SUNDAY. THIS UPPER RIDGE WILL PERSIST THROUGH MONDAY EVENING. EXPECT
WARMER TEMPERATURES ON MONDAY AS A RESULT WITH MAXIMUM TEMPERATURE
READINGS CLIMBING BACK INTO THE MID 70S IN THE LOWER ELEVATIONS AND
MID 50S TO MID 60S IN THE MOUNTAINS. THIS WILL BE SLIGHTLY ABOVE
NORMAL. A LARGE UPPER TROUGH WILL THEN SWING DOWN FROM THE GULF OF
ALASKA GOING INTO THE EXTENDED PERIOD WITH COOLER CONDITIONS AND
MORE CHANCES OF PRECIPITATION. 88

LONG TERM...MONDAY NIGHT THROUGH SATURDAY...A RIDGE OF HIGH
PRESSURE SHOULD BRING A WARMER AND MAINLY DRY DAY FOR MONDAY. A
DISTURBANCE WILL APPROACH THE TWO STATE AREA MONDAY NIGHT THAT COULD
SPREAD SOME SHOWERS ALONG THE WA/OR CASCADES. AS A STRONG LOW
PRESSURE SYSTEM DIPS TOWARD THE PACNW TUESDAY...THE SHOWERS SHOULD
MOVE INTO THE REMAINDER OF THE REGION. THE LOW PRESSURE REMAINS
NEARLY STATIONARY AND KEEPS THE CLOUDS AND SHOWERS ALONG WITH THE
COOL TEMPERATURES ACROSS THE TWO STATE AREA THROUGH THURSDAY. THE
LOW IS FORECAST TO DRIFT NORTH AND SOME DRYING IS POSSIBLE FOR
FRIDAY AND SATURDAY ALONG WITH SLIGHTLY WARMER TEMPERATURES.

AVIATION...LCL MVFR CEILINGS WILL OCCUR ON OCCASION AT ALL TAF
SITES. A DISTURBANCE MOVING ACROSS THE REGION WILL BRING SHOWERS TO
PORTIONS OF THE REGION BEFORE SLOWLY MOVING EAST AND CONDITIONS
SHOULD RETURN TO MAINLY VFR BY 02Z. ANOTHER DISTURBANCE WILL
APPROACH THE TWO STATE AREA TOMORROW MORNING AND LOWER CEILINGS WITH
LCL MVFR CONDITIONS MAINLY NEAR TAF SITE KDLS AND KRDM AND KYKM
AFTER 15Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  42  66  40  67 /  20  20  20  10
ALW  48  68  45  67 /  20  20  20  10
PSC  48  73  45  72 /  10  20  10  10
YKM  44  68  42  70 /  10  20  10  10
HRI  46  70  45  70 /  10  20  10  10
ELN  45  66  43  66 /  10  20  10  10
RDM  37  61  30  60 /  10  30  20  10
LGD  40  62  40  60 /  30  20  20  20
GCD  41  59  36  61 /  20  30  20  10
DLS  48  65  45  65 /  10  20  20  10

&&

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

THREAT INDEX
SATURDAY : GREEN
SUNDAY : GREEN
MONDAY : 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

$$

89/97/89