Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 021539
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
839 AM PDT TUE JUN 2 2015

.UPDATE...AN IMPULSE IS APPROACHING THE REGION THIS MORNING WITH
CONVECTIVE SHOWERS INITIATING JUST EAST OF THE OREGON/IDAHO
STATELINE. THIS FEATURE COMBINED WITH DAYTIME HEATING WILL
DECREASE INSTABILITY TODAY FAVORING THE CENTRAL TO NORTHEAST
OREGON HIGHLANDS. IT IS EXPECTED THAT THUNDERSTORMS WILL FIRE
ALONG AND TO THE EAST OF THE IMPULSE WHERE CLOUDINESS IS NOT
INHIBITING DAYTIME HEATING. HAVE ADJUSTED POPS AND HIGH
TEMPERATURES SOME DUE TO THE CONTINUED CLOUD COVERAGE OVER
NORTHEAST OREGON. BIEDA

&&

.PREV DISCUSSION... /ISSUED 452 AM PDT TUE JUN 2 2015/

SHORT TERM...TODAY THROUGH THURSDAY...REMNANTS OF AN UPPER LEVEL
LOW PRESSURE SYSTEM WILL REMAIN OVER THE REGION TODAY AND WEDNESDAY
AS AN OPEN TROUGH. A BATCH OF LINGERING SHOWERS WILL BE EXITING
NORTHEAST OREGON AND SOUTHEAST WASHINGTON EARLY THIS MORNING. AS
TEMPERATURES RISE THROUGH THE DAY THE ATMOSPHERE WILL BECOME
INCREASINGLY UNSTABLE RESULTING IN THE POSSIBILITY OF SHOWERS AND
THUNDERSTORMS. EASTERN PORTION OF THE FORECAST AREA SEEING THE MOST
LIKELIHOOD OF SHOWERS AND THUNDERSTORMS INTO THE EVENING. SHOWERS
WILL BEGIN TO TAPPER OFF NEAR SUNSET WITH JUST A FEW LINGERING
SHOWERS THROUGH THE NIGHT. THE PROBABILITY OF SHOWERS WILL AGAIN
INCREASE THROUGHOUT THE DAY WEDNESDAY WITH THE HEATING OF THE DAY.
EASTERN MOUNTAINS WILL STILL BE UNDER THE THREAT OF SOME
THUNDERSTORM ACTIVITY. SHOWERS WILL AGAIN DECREASE NEAR AND AFTER
SUNSET. A PIECE OF ENERGY DROPPING INTO THE TROUGH LATE WEDNESDAY
WILL DEVELOP A CLOSED LOW THAT WILL SAG INTO CALIFORNIA ON THURSDAY.
FOR THE FORECAST AREA THIS MEANS WEAKER INSTABILITY CONFINED MAINLY
TO THE SOUTH AND EASTERN PORTIONS OF THE FORECAST AREA. TEMPERATURES
THURSDAY WILL ALSO BEGIN TO REBOUND FROM THIS COOL SPELL.


LONG TERM...THURSDAY NIGHT THROUGH MONDAY...AN UPPER LOW EXPECTED
TO DEVELOP OVER NORTHERN CALIFORNIA WITHIN A BROADER WESTERN U.S.
TROUGH SHOULD DRIFT TO SOUTHERN CALIFORNIA THURSDAY NIGHT AND
FRIDAY. THIS SCENARIO WOULD RESULT IN AN INCREASING NORTHERLY FLOW
OVER THE REGION. THIS FLOW WOULD CAUSE A DRIER AND MORE STABLE AIR
MASS TO SPREAD OVER THE REGION. AS SUCH, SHOULD SEE A FEW LINGERING
SHOWERS AND THUNDERSTORMS THURSDAY EVENING OVER OUR MOUNTAIN ZONES.
BY FRIDAY, CONDITIONS LOOK TO BE WARMER AND DRIER WITH ONLY A FEW
STRAY SHOWERS OR THUNDERSTORMS OVER OUR EASTERN MOST MOUNTAIN RANGES
IN THE AFTERNOON AND EVENING. UPPER LEVEL RIDGING LOOKS TO THEN
STRENGTHEN OVER THE REGION FRIDAY NIGHT INTO SATURDAY. THIS WOULD
INCREASE STABILIZATION ACROSS THE AREA, AND THEREFORE EXPECT DRY
CONDITIONS FRIDAY NIGHT THROUGH SUNDAY MORNING. HIGH TEMPS SATURDAY
WILL BE QUITE WARM. THERE IS GROWING CONSENSUS THAT THE UPPER LOW
OVER SOUTHERN CALIFORNIA WILL DRIFT TO THE GREAT BASIN SUNDAY
THROUGH MONDAY. THUS EXPECT SOME MOISTURE AND INSTABILITY TO RETURN
TO THE REGION BEGINNING SUNDAY AFTERNOON. THUS WILL CONTINUE TO
INDICATE 20-30 PERCENT CHANCES OF SHOWERS WITH 20 PERCENT CHANCES OF
THUNDERSTORMS OVER OUR EASTERN ZONES SUNDAY AFTERNOON THROUGH
MONDAY. HIGH TEMPS SUNDAY AND MONDAY ARE EXPECTED TO CONTINUE ABOVE
SEASONAL. 90

AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD. CIGS WILL MAINLY RUN 4-10 KFT AGL. THE EXCEPTION IS AT KRDM
AND KBDN WHERE UPSLOPE AFFECTS WILL CAUSE TEMPORARY MVFR CIGS EARLY
THIS MORNING. AN AREA OF RAIN MOVING PAST KALW SHOULD LIFT NORTH
WITHIN THE FIRST TWO HOURS OF THIS PERIOD. OTHERWISE EXPECT
SCATTERED SHOWERS TO DEVELOP WITH DAYTIME HEATING...ESPECIALLY OVER
THE MOUNTAINS. AT THIS TIME WILL INCLUDE VICINITY SHOWERS AT KPDT,
KDLS, KRDM AND KBDN AFTERNOON AND EARLY EVENING. THERE WILL BE A
CHANCE OF THUNDERSTORMS OVER THE EASTERN MOUNTAINS EAST OF THE TAF
SITES. WINDS WILL RUN SOUTHWEST THROUGH NORTHWEST 12-20 KT WITH
HIGHER GUSTS THROUGH EARLY EVENING. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  70  49  71  49 /  20  10  20  10
ALW  73  54  73  54 /  20  10  20  10
PSC  76  54  76  53 /  20  10  20  10
YKM  70  51  71  51 /  20  20  20  10
HRI  74  53  75  51 /  20  10  20  10
ELN  69  50  71  49 /  20  20  20  10
RDM  63  41  64  41 /  40  20  20  10
LGD  65  46  66  46 /  50  30  30  20
GCD  67  45  68  45 /  50  20  20  10
DLS  68  54  72  53 /  20  20  20  10

&&

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

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

$$

98/90/90


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