Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 220517
AFDPDT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
1020 PM PDT MON JUL 21 2014

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...FORECAST ON TRACK AND ONLY MINOR UPDATES PLANNED.
FORECASTERS ARE WATCHING A LINE OF THUNDERSTORMS EXTENDING FROM
KLAMATH FALLS TO SENECA. STORMS APPEAR RELATIVELY WEAK WITH LESS
THAN 50 DBZ RETURNS. AS THE STEERING FLOW SHIFTS MORE TO THE
SOUTH...SHOWERS AND THUNDERSTORMS WILL TRACK ACROSS OUR EASTERN
FORECAST AREA...MAINLY AFFECTING EASTERN GRANT COUNTY, UNION, AND
WALLOWA COUNTIES BY MIDNIGHT. WATER VAPOR SHOWS A MID LEVEL WAVE
OFF THE CENTRAL OREGON COAST THAT MAY RESULT IN ISOLATED SHOWERS
AND THUNDERSTORMS NEAR THE OREGON AND SOUTHERN WASHINGTON CASCADES
LATE TONIGHT AS IT PUSHES EASTWARD. CURRENT FORECAST HAS ALL OF
THESE AREAS COVERED IN ISOLATED THUNDERSTORMS. AN UPDATE WILL BE
MADE TO INCREASE A FEW ZONES INTO THE SCATTERED CATEGORY. WISTER

&&

.AVIATION...06Z TAFS.  ALTHOUGH VFR CONDITIONS WILL PREVAIL FOR THE
NEXT 24 HOURS...THERE IS A POSSIBILITY THAT CIGS AND/OR VSBYS WILL
LOWER TO MVFR OR LESS WITH THUNDERSTORMS.  MID AND HIGH LEVEL CLOUDS
WITH VARYING BASES WILL REMAIN AT ALL TAF SITES THROUGH TUESDAY
EVENING.  THE AIR MASS WILL DESTABILIZE OVER TIME...AND THERE IS A
CHANCE OF THUNDERSTORMS.  WILL INTRODUCE VCTS AT KRDM AND KBDN AFTER
18Z AND AT KPDT AND KALW AFTER 02Z/23RD.  CONFIDENCE IS NOT HIGH FOR
OTHER TAF SITES TO OBSERVE THUNDERSTORMS SO HAVE REMOVED THESE FROM
THE FORECAST.  WINDS WILL BE LESS THAN 10 KNOTS THROUGH THE
PERIOD...BUT THERE IS ALWAYS A POTENTIAL FOR GUSTY AND ERRATIC WINDS
WITH NEARBY THUNDERSTORMS.  WISTER


&&

.PREV DISC... /ISSUED 230 PM PDT MON JUL 21 2014/

SHORT TERM...TONIGHT THROUGH THURSDAY. A LARGE UPPER LOW IS MOVING
ALONG THE BRITISH COLUMBIA COAST TOWARD THE PACIFIC NORTHWEST. THIS
LOW IS TURNING THE UPPER FLOW MORE SOUTHERLY AND WILL INCREASE THE
INSTABILITY OVER THE REGION THE NEXT FEW DAYS. IN THE SHORT
TERM...THUNDERSTORMS ARE DEVELOPING OVER SOUTHEAST OREGON AND MAY
MOVE UP INTO CENTRAL OREGON AND THE JOHN DAY HIGHLANDS LATE
AFTERNOON OR EVENING. IN ADDITIONAL TO THIS A BAND OF MID AND HIGH
LEVEL CLOUDS WILL CONTINUE TO MOVE OVER THE FORECAST AREA TODAY INTO
TONIGHT. ON TUESDAY THE UPPER LOW WILL BE NEAR VANCOUVER ISLAND AND
INSTABILITY OVER THE AREA WILL INCREASE. EXPECT SHOWERS AND
THUNDERSTORMS DURING THE DAY. HIGH TEMPERATURES SHOULD BE A LITTLE
WARMER THAN TODAY WITH HIGHER DEW POINTS AS WELL. BY WEDNESDAY THE
LOW IS MOVING INTO WESTERN WASHINGTON LATE IN THE DAY. EXPECT
ADDITIONAL SHOWERS AND THUNDERSTORMS THROUGH THE DAY. PRESSURE
GRADIENTS WILL BE INCREASING WITH BREEZY WEST WINDS BY AFTERNOON.
BASED ON THE POSITION OF THE JET SOME OF THE STORMS THE NEXT FEW
DAYS COULD BE STRONG. THE LOW MOVES EAST INTO IDAHO/MONTANA ON
THURSDAY. PRECIPITATION WILL BE ENDING AND SKIES CLEARING.
TEMPERATURES WILL BE COOLER WITH BREEZY WEST WINDS CONTINUING. 94

LONG TERM...THURSDAY NIGHT THROUGH MONDAY...MODELS IN AGREEMENT ON
A GENERALLY DRY WEST TO SOUTHWEST FLOW THROUGH THE PERIOD WITH A
WARMING TREND.  TEMPERATURES WILL RETURN TO 5 TO 10 DEGREES ABOVE
NORMAL OVER THE WEEKEND.  THE DEPARTING LOW PRESSURE AREA WILL
PRODUCE BREEZY TO LOCALLY WINDY CONDITIONS THURSDAY NIGHT AND
FRIDAY...BUT WINDS WILL BECOME LIGHTER BEGINNING FRIDAY NIGHT.

FIRE WX...A LOW PRESSURE SYSTEM MOVING INTO THE AREA TUESDAY WILL
CAUSE WIDESPREAD SHOWERS AND THUNDERSTORMS. ALTHOUGH SOME STORMS MAY
PRODUCE WETTING RAIN...ABUNDANT LIGHTNING CAN BE EXPECTED WHICH
COULD START NEW FIRES IN VERY DRY FUELS. STORMS WILL BEGIN
DEVELOPING OVER CENTRAL OREGON AND THE NORTHEAST MOUNTAINS AROUND
MID-DAY TUESDAY AND THEN MOVE NORTH INTO THE WASHINGTON CASCADES AND
LOWER COLUMBIA BASIN TUESDAY AFTERNOON. SCATTERED THUNDERSTORMS
COULD POTENTIALLY LAST THROUGH THE NIGHT IN SOME PLACES BUT THERE IS
A LOT OF UNCERTAINTY AMONG THE FORECAST MODELS. AS THE LOW MOVES
INLAND ON WEDNESDAY...OCCASIONAL SCATTERED THUNDERSTORMS WILL REMAIN
POSSIBLE THROUGH THE EVENING. RED FLAG WARNINGS ARE THEREFORE BEING
ISSUED FOR THE ABUNDANT LIGHTNING TUESDAY AND WEDNESDAY.  COBB

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  82  62  86  62 /   0  10  20  40
ALW  82  66  88  66 /   0  10  20  40
PSC  84  64  90  65 /   0  10  20  30
YKM  78  60  83  62 /   0  10  20  30
HRI  84  62  88  64 /   0  10  20  30
ELN  81  54  80  58 /   0  10  20  30
RDM  81  53  84  55 /  10  20  30  40
LGD  81  57  83  58 /  10  20  40  50
GCD  83  56  87  59 /  20  20  30  50
DLS  83  62  82  65 /   0  20  20  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM TUESDAY TO 11 PM PDT WEDNESDAY
     ORZ041-044-049-050-502-503-505>508-510.

     RED FLAG WARNING FROM 11 AM TUESDAY TO 5 PM PDT WEDNESDAY
     ORZ509-511.

WA...RED FLAG WARNING FROM 11 AM TUESDAY TO 11 PM PDT WEDNESDAY
     WAZ024-026>030-520-521.

&&

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

$$

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