Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 031522
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
822 AM PDT SUN MAY 3 2015

.SHORT TERM...TODAY THROUGH MONDAY...A FLAT RIDGE OF HIGH PRESSURE
WILL BE OVER THE AREA TODAY PROVIDING CLEAR SKIES...WARM
TEMPERATURES AND LIGHT WINDS. AN UPPER LEVEL LOW PRESSURE SYSTEM
WILL APPROACH THE COAST ON MONDAY WHICH WILL BEGIN TO TURN THE
CURRENT WESTERLY FLOW TO A MORE SOUTHWESTERLY DIRECTION. THIS
COMBINED WITH THE WARMER TEMPERATURES WILL LEAD TO SOME INCREASING
INSTABILITY OVER NORTHEAST OREGON LATE MONDAY LEADING TO SOME
SHOWERS AND EVEN POSSIBLE THUNDERSTORMS.


&&

.PREV DISCUSSION... /ISSUED 204 AM PDT SUN MAY 3 2015/

SHORT TERM...TODAY THROUGH TUESDAY...A WEST TO NORTHWEST FLOW ALOFT
WILL KEEP CONDITIONS DRY AND STABLE FOR ANOTHER DAY TODAY WITH WARM
TEMPERATURES. EXPECT MAXIMUM TEMPERATURES TODAY TO BE IN THE MID TO
UPPER 70S IN THE LOWER ELEVATIONS...WITH MOSTLY 60S IN THE
MOUNTAINS. THE FLOW WILL THEN BECOME SOUTHWEST ON MONDAY AS AN UPPER
TROUGH OFF THE COAST BEGINS TO MOVE INTO THE REGION. THE SOUTHWEST
FLOW WILL HELP TO BRING MORE UNSTABLE AIR WITH INCREASING MOISTURE
INTO THE REGION. THERE COULD BE SOME AFTERNOON THUNDERSTORMS OVER
THE EASTERN MOUNTAINS MONDAY AFTERNOON AND EVENING...BUT JUST A
SLIGHT CHANCE. THE UPPER TROUGH WILL MOVE INTO THE REGION AND
FORECAST AREA ON TUESDAY WITH INSTABILITY AND MOISTURE INCREASING
FURTHER...RESULTING IN A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS IN A MORE WIDESPREAD AREA. THE BEST CHANCE FOR
THUNDERSTORMS ON TUESDAY WILL BE OVER THE CASCADE EAST SLOPES AND THE
ADJACENT VALLEYS EAST OF THE CASCADES. TEMPERATURES WILL BE SLIGHTLY
WARMER ON MONDAY AND THEN THEY WILL COOL OFF ON TUESDAY DUE TO MORE
CLOUD COVER AND THE CHANCE OF SHOWERS. WINDS WILL REMAIN LIGHT TODAY
AND MOST OF MONDAY. THEN THEY WILL BEGIN TO INCREASE MONDAY
AFTERNOON AND EVENING AS SURFACE PRESSURE GRADIENTS INCREASE.
LOCALLY BREEZY TO WINDY CONDITIONS WILL DEVELOP ON TUESDAY AS THE
WEATHER SYSTEM MOVES INTO THE REGION...ESPECIALLY IN THE KITTITAS
VALLEY AND THE EASTERN COLUMBIA RIVER GORGE. UNSETTLED WEATHER WILL
PERSIST INTO THE EXTENDED FORECAST PERIOD. 88

LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...UNSETTLED WEATHER TO
MOVE ACROSS THE AREA FOR THE EXTENDED.  MODELS ARE COMING BETTER IN
LINE FOR THE MID RANGE.  THE LOW PRESSURE SYSTEM WILL MOVE INLAND ON
TUESDAY NIGHT CENTERING OVER THE PENDLETON CWA BY WEDNESDAY EVENING.
THUNDERSTORM CHANCES LOOK BEST OVER THE EAST SLOPES OF THE CASCADES
WITH SHOWERS ELSEWHERE...BUT THAT COULD CHANGE AS MODEL INSTABILITY
CONTINUES TO SHIFT EVERY DAY WITH THE REPOSITIONING OF THE LOW.  BY
WEDNESDAY...WITH THE LOW OVERHEAD...THE CHANCES FOR THUNDER WILL BE
JUST ABOUT EVERYWHERE.  STILL HAVE LOW CONFIDENCE THAT THUNDER WILL
OCCUR OVER THE BASIN...SO HAVE LEFT JUST SLIGHT CHANCE SHOWERS FOR
THAT AREA.  AS THE LOW DIVES SOUTH OVER THE NV/CA BOARDER ON
THURSDAY...RETURN FLOW ALONG CENTRAL OREGON AND THE NORTHEAST
MOUNTAINS WILL PROVIDE THE BEST CHANCES FOR THUNDER...WITH SHOWERS
ELSEWHERE.  BY FRIDAY THE LOW WILL BE NEARLY CENTERED OVER THE LAS
VEGAS AREA...WITH A DEFORMATION ZONE OVER THE SOUTHERN PORTION OF
THE CWA. SO HAVE KEPT SLIGHT CHANCE THUNDER OVER THE NORTHEAST
MOUNTAINS.  DUE TO UNCERTAINTY IN THE MODELS FOR SATURDAY ONWARD
HAVE NOT MADE ANY ADJUSTMENTS TO THE PREVIOUS FORECAST.  AS IT
STANDS SLIGHT CHANCE THUNDER REMAINS MAINLY OVER THE EAGLE CAPS AND
THE ELKHORN MOUNTAINS.  WEBER

AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL FOR THE NEXT 24
HOURS. OCCASIONAL HIGH CLOUDS WILL BE POSSIBLE ESPECIALLY EARLY TO
MID MORNING TODAY. WINDS WILL REMAIN AOB 10 KTS FOR THE NEXT 24
HOURS...EXCEPT AT KBDN AND KRDM WHERE GUSTS TO NEAR 15 KTS COULD
OCCUR BETWEEN 03/21Z AND 04/03Z. WEBER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  74  40  77  46 /   0   0   0   0
ALW  78  44  80  47 /   0   0   0  10
PSC  78  39  82  49 /   0   0   0   0
YKM  77  40  79  44 /   0   0   0   0
HRI  79  39  80  49 /   0   0   0   0
ELN  75  39  76  43 /   0   0   0   0
RDM  76  33  75  38 /   0   0   0   0
LGD  73  38  76  41 /   0   0  20  20
GCD  79  38  82  41 /   0   0  20  10
DLS  81  40  79  47 /   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

$$

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