Severe Thunderstorm Warning 2, NWS Pendleton, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
115 PM PDT WED MAY 6 2009

.SHORT TERM...TONIGHT THROUGH SATURDAY...A TROUGH OF LOW PRESSURE
CONTINUES TO MOVE INTO THE PACIFIC NORTHWEST THIS AFTERNOON. THE LOW
CENTER IS CURRENTLY LOCATED BETWEEN 140 W AND 130 W. RADAR IMAGERY
INDICATES THAT RAIN SHOWERS ARE INCREASING OVER THE REGION AGAIN
AHEAD OF A COLD FRONT CURRENTLY OVER WESTERN OREGON AND WASHINGTON.
THIS FRONT WILL MOVE EAST OF THE CASCADES LATER THIS AFTERNOON AND
EVENING. WINDS WILL BE BREEZY AHEAD AND WITH THE COLD FRONT ACROSS
CENTRAL OREGON AND PORTIONS OF THE COLUMBIA BASIN. SNOW LEVELS WILL
LOWER BEHIND THE FRONT TO AROUND 4500-5000 FEET. NOT EXPECTING
SIGNIFICANT SNOW ACCUMULATIONS AS THE BRUNT OF THE MOISTURE WILL BE
AHEAD OF THE FRONT. THE TROUGH WILL CONTINUE OVER THE PACIFIC
NORTHWEST ON THURSDAY AS THE LOW CENTER MOVES THROUGH NORTHERN
WASHINGTON. WINDS WILL INCREASE AGAIN AND BE BREEZY TO WINDY ACROSS
THE COLUMBIA BASIN AND SURROUNDING VALLEYS TOMORROW AFTERNOON.
SHOWERS WILL BE POSSIBLE WITH THE DISTURBANCE
THURSDAY...PARTICULARLY IN THE MOUNTAINS WITH UPSLOPE FLOW. BELIEVE
THAT MOST OF THE COLD UNSTABLE AIR WILL REMAIN NORTH OF THE
AREA...THEREFORE HAVE REMOVED THE SLIGHT CHANCE OF THUNDERSTORMS
FROM WALLOWA COUNTY...THOUGH WOULD NOT RULE OUT THE POSSIBILITY OF A
STRIKE OR TWO IN THE NORTHEAST PORTION OF THE COUNTY. THE REGION
WILL GRADUALLY BEGIN TO DRY OUT ON FRIDAY AND SATURDAY AS A WEAK
RIDGE OF HIGH PRESSURE BUILDS INTO THE AREA. TEMPERATURES WILL WARM
AT THE END OF THE WEEK WITH THE LOWER ELEVATIONS APPROACHING THE 70S
BY SATURDAY. DMH

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. THERE WILL BE A WEAK
RIDGE OF HIGH PRESSURE BUILD INTO THE REGION SATURDAY NIGHT AND
SUNDAY AS A STRONG LOW PRESSURE SYSTEM APPROACHES THE PACIFIC
NORTHWEST. THE LOW WILL TRACK ACROSS THE AREA MONDAY NIGHT THROUGH
TUESDAY.  THERE IS STILL SOME VARIABILITY IN THE TRACK OF THE
LOW...BUT STILL SHOULD BRING COOLER TEMPERATURES AND A CHANCE OF
PRECIPITATION ACROSS THE REGION.  THE TROUGH REMAINS OVER THE REGION
THROUGH MIDWEEK WITH ADDITIONAL LOBES OF ENERGY TO MOVE THROUGH WITH
TEMPERATURES REMAINING BELOW NORMAL. ML

&&

.AVIATION...00Z TAFS...SCATTERED SHOWERS WILL PERSIST OVER THE
REGION THROUGH THE NEXT 12 HOURS WITH SOME BRIEF PERIODS OF MVFR
CEILING AS THE HEAVIER SHOWERS MOVE THROUGH.  SHOWER ACTIVITY SHOULD
BE ENDING AFTER 03Z WITH WINDS INCREASING FROM THE WEST TO SOUTHWEST
10 TO 20 MPH. ML

&&

.HYDROLOGY...SEVERAL RIVERS ACROSS THE AREA CONTINUE TO RUN AT
BANKFULL LEVELS.  THE LIGHT PRECIPITATION AMOUNTS ARE NOT EXPECTED
TO CAUSE THEM TO RISE ABOVE FLOOD STAGE WITH MOST CRESTING BY LATE
THURSDAY AND THEN RECEDING AS DRIER CONDITIONS PREVAIL OVER THE NEXT
SEVERAL DAYS. ML

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  44  57  38  61 /  30  30  10   0
ALW  46  58  42  63 /  30  30  10   0
PSC  46  64  39  67 /  20  20  10   0
YKM  38  59  34  64 /  20  20  10   0
HRI  44  63  38  65 /  20  20  10   0
ELN  40  58  37  62 /  20  20  10   0
RDM  33  54  26  61 /  30  10  10   0
LGD  40  51  34  57 /  50  30  20  10
GCD  37  52  33  57 /  30  20  20  10
DLS  45  60  40  67 /  30  20  10   0

&&

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

TI:GGG
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
84/93/93/93

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE PENDLETON OR
905 AM PDT WED MAY 6 2009

CORRECTED TODAY AND TONIGHT TO ADD LOW HAZARDS LINE

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-071200-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
905 AM PDT WED MAY 6 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TODAY AND TONIGHT

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

A TROUGH OF LOW PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST TODAY
SPREADING RAIN ACROSS THE REGION. THE ASSOCIATED COLD FRONT WILL
BRING COOLER AIR AND AN INCREASE IN WINDS THIS AFTERNOON AND
EVENING. THIS FRONT WILL HELP LOWER SNOW LEVELS TONIGHT WITH RAIN
AND SNOW SHOWERS POSSIBLE IN THE HIGHER TERRAIN OVERNIGHT.
ACCUMULATIONS ARE EXPECTED TO BE LIGHT AS MOST OF THE HEAVIER
PRECIPITATION WILL BE AHEAD OF THE FRONT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS THURSDAY
     NORTHWEST BLUE MOUNTAINS, GRANDE RONDE VALLEY, WALLOWA COUNTY,
     NORTHERN BLUE MOUNTAINS OF OREGON

SOME ATMOSPHERIC INSTABILITY ON THURSDAY AFTERNOON AND EVENING MAY
RESULT IN ISOLATED THUNDERSTORMS AGAIN OVER THE NORTHEAST MOUNTAINS.
ANY STORMS THAT DO FORM ARE EXPECTED TO BE WEAKER THAN ON WEDNESDAY
WITH LESS COVERAGE AND FREQUENCY. HIGHER PRESSURE ALOFT WILL BUILD
OVER THE REGION BEGINNING FRIDAY WITH A WARMING AND DRYING TREND
THAT WILL CONTINUE THROUGH MOST OF THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.