Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 130527
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1030 PM PDT SAT JUL 12 2014

.SHORT TERM...A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED THIS
AFTERNOON AND EARLY EVENING OVER CENTRAL OREGON. THESE SHOULD
DISSIPATE AFTER SUNSET. OTHERWISE CLEAR TO PARTLY CLOUDY SKIES
OVERNIGHT. AN UPPER LEVEL TROUGH CURRENTLY LOCATED OFF THE NORTHERN
CALIFORNIA COAST WILL MOVE SLOWLY NORTHEAST TONIGHT INTO SUNDAY.
THIS SYSTEM COMBINED WITH INCREASING MOISTURE AND INSTABILITY WILL
RESULT IN THUNDERSTORMS OVER OREGON AND WASHINGTON. EXPECT STORMS TO
DEVELOP OVER CENTRAL OREGON LATE MORNING OR EARLY AFTERNOON THEN
INCREASE IN COVERAGE AND SPREAD NORTHEAST DURING THE LATE AFTERNOON
INTO THE EVENING. INCREASING WINDS ALOFT ASSOCIATED WITH THE JET MAY
RESULT IN SOME STRONG STORMS. MODELS SUGGEST THE ACTIVITY MAY
CONTINUE OVERNIGHT MOVING ACROSS THE COLUMBIA BASIN INTO CENTRAL
WASHINGTON. CURRENT FORECAST HAS THIS COVERED WELL. SHOWERS AND
THUNDERSTORMS WILL BE EXITING THE FORECAST AREA LATER MONDAY AS THE
TROUGH MOVES INTO IDAHO. AS FOR TEMPERATURES THE HOT WEATHER WILL
CONTINUE INTO NEXT WEEK. HEAT ADVISORY EXTENDED THROUGH WEDNESDAY
EVENING.  94

.AVIATION...06Z TAFS. SCT-BKN 250 OVERNIGHT INTO SUNDAY MORNING.
CLOUDS INCREASING DURING THE DAY WITH CEILINGS BECOMING 100-200.
SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND EVENING
WITH CEILINGS LOWERING TO 050-100.

&&

.PREV DISC... /ISSUED 249 PM PDT SAT JUL 12 2014/

SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...STRONG DAYTIME HEATING
THIS AFTERNOON HAS RESULTED IN THE DEVELOPMENT OF CUMULUS CLOUDS
OVER THE INTERIOR NORTHWEST MOUNTAINS. CURRENTLY THESE CLOUDS ARE
LOOKING RATHER FLAT, BUT STILL EXPECT A FEW OF THESE TO GROW INTO
THUNDERSTORMS. THESE ISOLATED STORMS SHOULD DISSIPATE WITH SUNSET. A
PACIFIC SYSTEM, ROUGHLY NEAR 38N AND 130W, WILL MOVE NORTH TO A
POSITION NEAR 43N/130W OVERNIGHT. THIS SYSTEM MAY PRODUCE ENOUGH
ELEVATED INSTABILITY TO CAUSE THE DEVELOPMENT OF A STRAY THUNDERSTORM
OVER THE SOUTHERN END OF THE OREGON CASCADE EAST SLOPES TOWARDS
DAYBREAK SUNDAY. THIS SYSTEM IS STILL ON TRACK TO MOVE NORTHEAST
TOWARDS NORTHWEST OREGON SUNDAY AND SUNDAY EVENING, THEN MOVE ACROSS
WASHINGTON STATE MONDAY. THE COMBINATION OF THIS SYSTEM, SUBTROPICAL
MOISTURE AND CONTINUED STRONG DAYTIME HEATING WILL RESULT IN THE
DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
SUNDAY. THESE STORMS WILL GRADUALLY DEVELOP FIRST NEAR THE OREGON
CASCADES LATE MORNING INTO THE AFTERNOON. THE BEST COVERAGE SHOULD
BE OVER CENTRAL OREGON AND ALONG THE CASCADES LATE AFTERNOON AND IN
THE EVENING. SHEAR OVER CENTRAL OREGON IS FORECAST TO RUN IN THE 50
TO 60 KT RANGE. THUS THERE WILL BE THE POTENTIAL FOR STRONG STORMS,
WITH AN OUTSIDE CHANCE OF A SEVERE STORM. THE MAIN THREAT WOULD BE
STRONG WIND GUSTS. AS THE SYSTEM MAKES IT`S WAY INTO THE PACNW
SUNDAY NIGHT INTO MONDAY MORNING, SHOWERS AND STORMS WILL SPREAD
EAST ACROSS MOST OF REMAINDER OF THE AREA. MAINLY EXPECT ISOLATED
COVERAGE OF THUNDERSTORMS OVER MOST AREAS OVERNIGHT INTO MONDAY
MORNING, THOUGH COULD SEE SCATTERED COVERAGE OVER KITTITAS COUNTY
AND NORTHWEST YAKIMA COUNTY. DRIER AIR WILL MOVE INTO THE REGION
FROM WEST TO EAST MID MONDAY MORNING THROUGH EARLY MONDAY EVENING.
THUS WILL SEE SHOWERS AND STORMS END FROM THE WEST DURING THIS
PERIOD. EXPECT DRY CONDITIONS LATE MONDAY EVENING ONWARD. HIGH
TEMPERATURES WILL REMAIN FAIRLY HOT SUNDAY THROUGH TUESDAY, THOUGH
THERE MAY BE FEW DEGREES LOST AT SOME LOCATIONS DUE TO CLOUD COVER
ON SUNDAY AND ADDITIONAL ONSHORE FLOW MONDAY. OVERALL WILL CONTINUE
THE CURRENT HEAT ADVISORY, WHILE ADDING THE NORTHERN OREGON AND
WASHINGTON BLUE MOUNTAIN FOOTHILLS. 90

LONG TERM...TUESDAY THROUGH SATURDAY NIGHT...HIGH PRESSURE WILL
CONTINUE TO DOMINATE THE AREA FOR THE EXTENDED.  THIS WILL KEEP
TEMPERATURES IN THE MID 90S TO MID 100S ACROSS THE LOWER ELEVATIONS
AND IN THE MID 80S TO MID 90S MOUNTAINS.  GENERALLY THE AREA WILL BE
UNDER A DRY NORTHWEST FLOW...BUT THERE IS THE POSSIBILITY OF AN
UPPER LEVEL DISTURBANCE IMPACTING THE AREA ON THURSDAY AND FRIDAY.
THE MODELS HAVE BEEN BACK AND FORTH WITH KEEPING A STRONG HIGH
PRESSURE SYSTEM IN PLACE WITH HOT TEMPERATURES AND THIS UPPER LEVEL
DISTURBANCE...WHICH COULD BRING TEMPERATURES DOWN QUITE A BIT.  LAST
COUPLE OF GFS MODEL RUNS HAVE SUGGESTED ABOUT A 20 DEGREE COOLDOWN
AS THE TROUGH PUSHES THROUGH THE AREA...WITH SHOWERS AND POSSIBLY
THUNDERSTORMS ASSOCIATED.  BUT ECMWF HAS HELD ONTO THE RIDGE...AND
ISOLATING THIS AS A MUCH WEAKER SYSTEM TO THE NORTH OVER CANADA.
RECENTLY THE TWO MODELS HAVE MET IN THE MIDDLE SUGGESTING THE SYSTEM
CLIPS THE AREA THURSDAY NIGHT...KEEPING CONDITIONS DRY...EXCEPT OVER
NORTHEAST WASHINGTON...BUT PICKING UP WINDS A BIT AND DROPPING THE
HIGHS BY ABOUT 10 DEGREES...WHICH IS STILL IN THE 90S ACROSS THE
LOWER ELEVATIONS.  STILL WILL KEEP SHOWERS OUT OF THE FORECAST...BUT
HAVE BUMPED UP THE WINDS A BIT AND BROUGHT DOWN THE HIGHS ON FRIDAY
AND SATURDAY TO ACCOUNT FOR THE POSSIBLE FRONTAL SYSTEM.  WEBER

FIRE WX...ON SUNDAY...SUBTROPICAL MOISTURE WILL MOVE INTO THE
REGION AND COMBINE WITH A WEATHER DISTURBANCE BRINGING A CHANCE OF
THUNDERSTORMS WITH ABUNDANT LIGHTNING TO CENTRAL OREGON AND THE
CASCADES. WITH HOT AND DRY CONDITIONS OVER THE LAST SEVERAL DAYS AND
THE STORMS INITIALLY STARTING OUT WITH LITTLE RAINFALL...THERE IS AN
ENHANCED THREAT OF NEW WILDFIRES. THEREFORE...RED FLAG WARNINGS ARE
BEING ISSUED FOR CENTRAL OREGON AND CASCADE EAST SLOPES FIRE ZONES
SUNDAY AND SUNDAY NIGHT. OTHER ZONES IN THE LOCAL AREA WILL LIKELY
SEE SOME THUNDERSTORM ACTIVITY AS WELL DURING THIS PERIOD...BUT AT
THIS TIME...AREAL COVERAGE IS ONLY EXPECTED TO BE ISOLATED.  COBB

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64 102  68 100 /   0   0  20  20
ALW  68 104  72 101 /   0   0  20  20
PSC  61 105  68 103 /   0   0  20  20
YKM  64 100  71 100 /   0  10  20  10
HRI  62 105  68 102 /   0   0  20  20
ELN  58 102  65 100 /  10  10  30  20
RDM  56  95  57  96 /  20  40  30  10
LGD  54  97  62  95 /  10   0  20  20
GCD  60  98  62  98 /  20  20  20  20
DLS  67  99  69  99 /  10  20  30  10

&&


.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 2 PM SUNDAY TO 5 AM PDT MONDAY ORZ041.

     FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING
     ORZ041-044-049-050-502-503-505>508-510.

     HEAT ADVISORY UNTIL 10 PM PDT WEDNESDAY ORZ041-044-507.

     RED FLAG WARNING FROM 11 AM TO 11 PM PDT SUNDAY
     ORZ505-506-509-511.

     RED FLAG WARNING FROM 11 AM SUNDAY TO 5 AM PDT MONDAY ORZ510.

WA...RED FLAG WARNING FROM 2 PM SUNDAY TO 5 AM PDT MONDAY
     WAZ024-520-521.

     FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING
     WAZ024-028>030-521.

     HEAT ADVISORY UNTIL 10 PM PDT WEDNESDAY WAZ024-027>029.

     FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING
     WAZ026-027.

     FIRE WEATHER WATCH FROM SUNDAY EVENING THROUGH MONDAY MORNING
     WAZ520.

&&

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

$$

94/





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