Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 072146
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
245 PM PDT TUE JUL 7 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY...AN UPPER WAVE MOVING
SOUTHEAST OUT OF BRITISH COLUMBIA WILL SWING THROUGH EASTERN
WASHINGTON TO MONTANA TONIGHT. THE MAIN AFFECT OF THIS WAVE WILL BE
TO SHIFT THE FLOW OVER THE PACIFIC NORTHWEST TO NORTHERLY BY
WEDNESDAY. AS SUCH WILL SEE THE LINGERING MOISTURE OVER THE REGION
BECOME SUPPRESSED TO THE SOUTH AND SOUTHWEST OF SOUTHEAST WASHINGTON
AND NORTHEAST OREGON BY WEDNESDAY. THUS THE THREAT OF SHOWERS AND
THUNDERSTORMS WILL BE TO PORTIONS OF WALLOWA, GRANT, CROOK AND
DESCHUTES COUNTIES AFTERNOONS AND EVENINGS TODAY AND WEDNESDAY. A
FEW THUNDERSTORMS MAY DEVELOP ALONG THE OREGON CASCADE CREST
WEDNESDAY NORTH OF DESCHUTES COUNTY, BUT EXPECT THESE STORMS TO
DRIFT WEST FROM THE CREST. AN UPPER LOW CURRENTLY WEST OF
CALIFORNIA, NEAR 36N/128W, IS STILL EXPECTED TO MOVE INTO THE
WESTERN U.S. LATE WEDNESDAY. THIS LOW WILL AFFECT THE PACIFIC
NORTHWEST THURSDAY AND FRIDAY AS IS IT SLOWLY LIFTS NORTHEAST AND
OPENS INTO AN OPEN WAVE. THIS SYSTEM WILL PULL THE MOISTURE
SUPPRESSED SOUTH OF OUR AREA WEDNESDAY BACK NORTH. THUS STILL EXPECT
CHANCES OF SHOWERS AND THUNDERSTORMS TO INCREASE ACROSS THE REGION
THURSDAY INTO FRIDAY. BEST CHANCES WILL RUN FROM CENTRAL OREGON EAST
TO GRANT COUNTY AND NORTHEAST TO THE BLUES, GRANDE RONDE VALLEY AND
WALLOWA COUNTY. WILL KEEP THESE AREAS WITH HIGH CHANCE TO LIKELY
POPS. TEMPS WILL CONTINUE ABOVE SEASONAL WEDNESDAY AND THURSDAY, BUT
HIGH TEMPS WILL BEGIN TO LOWER FRIDAY DUE TO CLOUD COVER AND
INCREASING ONSHORE SURFACE FLOW. 90

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT...THE EXTENDED
PERIOD WILL START OFF RATHER UNSETTLED WITH HIGH CHANCE TO LIKELY
POPS FOR SHOWERS AND THUNDERSTORMS FRIDAY EVENING RIGHT THROUGH
SUNDAY EVENING. A SERIES OF UPPER LEVEL DISTURBANCES WILL MOVE
THROUGH THE REGION IN ASSOCIATION WITH AN APPROACHING LONG WAVE
TROUGH. THIS COULD MAKE FOR A POTENTIALLY WET AND STORMY WEEKEND
ACROSS MUCH OF THE AREA. IT WILL NOT BE A CONSTANT STEADY RAIN...BUT
INSTEAD EXPECT PERIODS OF SHOWERS AND THUNDERSTORMS WITH THE HIGHEST
CHANCE TO SEE THUNDER IN THE AFTERNOON AND EVENING HOURS WITH THE
ADDED INSTABILITY FROM DAYTIME HEATING. PWATS WILL BE QUITE HIGH
NEAR AND JUST ABOVE 1 INCH IN AND AROUND THE COLUMBIA BASIN REGION.
THEREFORE WILL CERTAINLY NEED TO KEEP AN EYE ON THE POTENTIAL FOR
LOCALLY HEAVY RAINS OVER THE WEEKEND. ALSO CANNOT RULE OUT A FEW
STRONGER THUNDERSTORMS BOTH SATURDAY AND SUNDAY AFTERNOON AS SBCAPE
VALUES RISE AT LEAST INTO THE 800-1200 J/KG RANGE AND 0-6KM SHEAR
VALUES RANGE FROM 15-30 KTS SATURDAY AND 20-40 KTS SUNDAY. ALSO
EXPECT POTENTIALLY BREEZY CONDITIONS FOR PARTS OF THE AREA ON FRIDAY
AND SATURDAY EVENING WITH WINDS OF 15-25KTS AND HIGH GUSTS POSSIBLE.
TEMPERATURES WILL BE MUCH COOLER THAN WE HAVE BEEN EXPERIENCING
LATELY...WITH HIGHS MAINLY IN THE MID-80S TO LOWER 90S FOR THE LOWER
ELEVATIONS AND 70S IN THE MOUNTAINS WHICH IS RIGHT NEAR THE SEASONAL
AVERAGE. THE TROUGH AXIS FINALLY MOVES OVER AND EAST OF THE REGION
BY MONDAY NIGHT AND TUESDAY...ALLOWING A MUCH DRIER WESTERLY FLOW TO
TAKE HOLD. TEMPERATURES WILL SLOWLY WARM TOWARD THE MIDDLE OF NEXT
WEEK. 77

&&

.AVIATION...PREVIOUS DISCUSSION...18Z TAFS...VFR CONDITIONS WILL
PREVAIL THROUGH THE FORECAST PERIOD. INCLUDED VCSH FROM 07/22Z TO
08/03-04Z AT KRDM WITH VCTS DURING THIS SAME TIME PERIOD AT KBDN AS
THE BEST CONVECTION IS FORECAST TO DEVELOP ACROSS SOUTHERN DESCHUTES
COUNTY. WITH THIS SAID CERTAINLY CANNOT COMPLETELY RULE OUT A
THUNDERSTORM AT OR INVOF KRDM LATER THIS AFTERNOON AND WILL AMEND IF
THE CURRENT THINKING CHANGES. OTHERWISE JUST A FEW MID AND HIGH
CLOUDS WILL BE AROUND TODAY...TONIGHT AND INTO WEDNESDAY. WINDS WILL
BE MOSTLY W-NW AT 5-15 KT THIS AFTERNOON AND EARLY EVENING OTHERWISE
TERRAIN DRIVEN THROUGH THE FORECAST PERIOD. THE ONLY EXCEPTION TO
THIS IS AT KDLS WHERE WINDS WILL BE NW 15-25KT THROUGH 08/06Z THIS
EVENING. 77

&&

.FIRE WEATHER...RED FLAG WARNING IN EFFECT FOR FIRE WEATHER ZONES
OR610...611...640...AND 642 FOR THUNDERSTORMS WITH ABUNDANT
LIGHTNING THROUGH 9 PM THIS EVENING. SCATTERED THUNDERSTORMS ARE
EXPECTED ACROSS OR611 AND FOR THE SOUTHERN PORTIONS OF OR
610...640...AND 642. GONE WITH LAL 4 FOR THE 611 ZONE AS THAT AREA
LOOKS WILL SEE THE MOST ACTIVITY. SOUTHERN 640 AND 642 SHOULD SEE
LAL 3. SOME OF THESE STORMS COULD PRODUCE MODERATE TO HEAVY RAIN.  A
BREAK FROM STORMS TOMORROW...THERE MAY BE SOME ISOLATED STORMS IN
611...640...AND 642...BUT NOT EXPECTING ABUNDANT LIGHTNING AT THIS
TIME. THURSDAY THROUGH THE WEEKEND....THUNDERSTORMS ARE EXPECTED TO
INCREASE IN COVERAGE AND INTENSITY ACROSS CENTRAL AND EASTERN OREGON
AS THE LOW OPENS AND DEVELOPS A BROAD TROUGH WEST OF THE ROCKIES.
THE GOOD NEWS IS THAT STORMS MAY BRING HEAVY RAIN...ESPECIALLY LATE
IN THE WEEK. WEBER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  65  98  63  95 /   0   0   0  20
ALW  71  98  68  95 /  10   0   0  20
PSC  64 101  63 100 /  10   0   0  10
YKM  63 101  64 101 /   0   0   0  10
HRI  63 101  66  99 /   0   0   0  10
ELN  64 101  62 101 /  10   0   0  10
RDM  52  93  56  90 /  10  10  10  30
LGD  50  91  53  87 /  10  10  10  30
GCD  59  97  59  94 /  10  20  20  40
DLS  68 100  68  96 /   0   0   0  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 9 PM PDT THIS EVENING FOR ORZ610-611-640-
     642.

WA...NONE.
&&

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

$$

90/77/77/89


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