Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 061744 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PENDLETON OR
1042 AM PDT MON JUL 6 2015

UPDATED AVIATION DISCUSSION

.SHORT TERM...MORNING UPDATE...A SOMEWHAT COMPLICATED UPPER LEVEL
FLOW PATTERN WILL REMAIN OVER THE PACIFIC NORTHWEST TODAY AND
TONIGHT. OUR WASHINGTON AND NORTHERN OREGON ZONES WILL BE UNDER A
RELATIVELY DRY WEST-NORTHWEST UPPER LEVEL FLOW. MEANWHILE THE
REMAINDER OF OUR OREGON ZONES WILL BE UNDER A DEFORMATION TYPE FLOW.
MID AND HIGH LEVEL MOISTURE IS TRAPPED WITHIN THIS DEFORMATION FLOW.
AS A RESULT, THIS MOISTURE AND DAYTIME HEATING WILL COMBINE TO CAUSE
ISOLATED TO SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING OVER
CENTRAL OREGON. ALSO A FEW STRAY STORMS MAY OCCUR ACROSS PORTIONS OF
THE JOHN DAY BASIN AND THE OCHOCO-JOHN DAY HIGHLANDS. OVERALL THE
INHERITED FORECAST PACKAGE WAS IN GOOD SHAPE. THE MAIN UPDATES THIS
MORNING INVOLVED ADJUSTING THE LOCATION AND COVERAGE OF AFTERNOON
AND EVENING THUNDERSTORMS TO FIT CHANGES IN FIRE WEATHER HIGHLIGHTS.
90

.LONG TERM...PREVIOUS DISCUSSION...BROAD SW FLOW ALOFT PATTERN TO
BECOME ESTABLISHED THROUGH THE EXTEND PERIOD WITH AN UPPER TROUGH
GRADUALLY BECOMING ESTABLISHED OFF THE PACIFIC NW COAST. THIS WILL
PROVIDE AN AMPLE SUPPLY OF MID LEVEL MOISTURE TO THE AREA MAINLY TO
THE CENTRAL AND EASTERN MOUNTAINS. AS A RESULT THERE WILL BE A
CHANCE OF THUNDERSTORMS EACH AFTERNOON AND EVENING. THE BEST CHANCES
APPEAR TO BE THURSDAY INTO SATURDAY WHEN SCATTERED COVERAGE APPEARS
POSSIBLE. OBVIOUSLY GIVEN HOW DRY IT HAS BEEN THERE COULD BE FIRE
WEATHER CONCERNS LATER THIS WEEK. IT WILL BE HOT ON THURSDAY WITH
TEMPERATURES NEAR 100 DEGREES LOWER ELEVATIONS BUT IN SUBSEQUENT
DAYS IT WILL BE COOLER WITH LOWER ELEVATION HIGHS MAINLY 88-95.
OVERNIGHT LOWS THROUGH THE PERIOD WILL BE IN THE 60S LOWER
ELEVATIONS WITH 50S IN THE MOUNTAINS. IT WILL BE BREEZY FRIDAY
AFTERNOON AND EVENING CASCADE GAPS AND COLUMBIA BASIN.

&&

.AVIATION...18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE
FORECAST PERIOD. DECIDED TO KEEP JUST VCSH AT KBDN AND KRDM LATE
THIS AFTERNOON AND EVENING AS CONFIDENCE WAS NOT HIGH ENOUGH TO GO
VCTS OR TSRA JUST YET...WILL NEED TO SEE EXACTLY WHERE TSRA DEVELOP
THIS AFTERNOON THEN ISSUE AN UPDATE IF NEEDED. THE BETTER CHANCE TO
SEE ANY TS ACTIVITY WILL BE AT OR INVOF KBDN COMPARED TO LOWER
CHANCES AT KRDM. OVERALL CHANCES ARE LOW AS ANY CONVECTION THAT DOES
DEVELOP SHOULD STAY ISOLATED TO SCATTERED AT BEST. AT KBDN AND KRDM
THERE WILL BE HIGH BASED CU/CB AROUND THIS AFTERNOON AND EVENING AT
8-12 K FEET AGL. OTHERWISE AT THE OTHER TAF SITES JUST EXPECT SOME
VERY HIGH CIRRUS AT AROUND 25-30 KFT AGL. WINDS WILL MAINLY BE AOB
12KTS EXCEPT AT KBDN...KRDM AND KDLS LATER THIS AFTERNOON/EVENING.
WINDS AT KBDN AND KRDM WILL BE NW WITH GUSTS UP TO 15-20KTS AFTER
06/23Z AND AT KDLS EXPECT WNW WINDS WITH GUSTS UP TO 20-25KTS AFTER
06/23Z AS WELL. 77

&&

.FIRE WEATHER...UPDATE...RED FLAG WARNING IN EFFECT FOR FIRE WEATHER
ZONES OR610...611...AND...640 FOR THUNDERSTORMS WITH ABUNDANT
LIGHTNING. THIS WILL START THIS AFTERNOON AND CONTINUE THROUGH
TUESDAY EVENING. DETERMINING HOW FAR NORTH THUNDERSTORMS WILL
MIGRATE THIS AFTERNOON THROUGH WEDNESDAY WILL CONTINUE TO BE A
CHALLENGE. SCATTERED THUNDERSTORMS ARE EXPECTED ACROSS OR611 AND FOR
THE SOUTHERN PORTIONS OF OR 610 AND 640. LIGHTNING FROM PREVIOUS
STORMS HAS BEEN IN THE LAL 4 CATEGORY...SO CWR`S AND LALS HAVE BEEN
BUMPED UP FOR THESE AREAS TODAY. THUNDERSTORMS ARE EXPECTED TO
INCREASE IN COVERAGE AND INTENSITY ACROSS CENTRAL AND EASTERN OREGON
LATE THURSDAY THROUGH NEXT WEEKEND WHEN 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  98  67  98  66 /   0   0   0  10
ALW  98  72  98  72 /   0   0   0  10
PSC 100  69 102  69 /   0   0   0  10
YKM 100  67 102  69 /   0   0   0  10
HRI 101  69 102  68 /   0   0   0   0
ELN  99  66  99  67 /   0   0  10  10
RDM  95  59  95  56 /  20  30  10  10
LGD  93  58  92  57 /   0   0  10  10
GCD  95  60  97  57 /  10  10  10  10
DLS  99  70 100  69 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 3 PM THIS AFTERNOON TO 9 PM PDT TUESDAY
     FOR ORZ610-611-640.

WA...NONE.
&&

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

$$

90/78/77/89


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