Severe Thunderstorm Warning 29, NWS Pendleton, OR

NORTHEAST OREGON/SOUTHEAST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
230 PM PDT SUN AUG 12 2001

A SHORT WAVE TROUGH ALONG THE CALIFORNIA/OREGON COAST WILL MOVE
NORTH THE REMAINDER OF TODAY AND STEER A MID LEVEL (700MB) SHORT
WAVE INTO SOUTHERN OREGON THIS AFTERNOON...AND THEN MOVE ACROSS THE
FORECAST AREA TONIGHT. THIS SYSTEM WILL BRING MID AND UPPER LEVEL
MOISTURE INTO THE REGION FOR ISOLATED HIGH BASED...MAINLY DRY...
THUNDERSTORMS. SOME STORMS MAY HAVE MEASURABLE PRECIPITATION...BUT
ANY RAINFALL AMOUNTS WILL BE LIGHT. EXPECT THUNDERSTORMS TO SPREAD
NORTH INTO THE LOWER COLUMBIA BASIN EARLY THIS EVENING. INSTABILITY
WILL CONTINUE OVERNIGHT FOR SCATTERED NOCTURNAL SHOWERS AND
THUNDERSTORMS...MAINLY OVER THE MOUNTAINS OF NORTHEAST OREGON AND
ALONG THE EAST SLOPES OF THE SOUTHERN WASHINGTON CASCADES. THE SHORT
WAVE WILL WEAKEN AS IT MOVES NORTHEAST ACROSS FORECAST AREA ON
MONDAY FOR ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WITH THE
CONVECTIVE ACTIVITY EXPECTED FROM CENTRAL OREGON TO THE MOUNTAINS OF
NORTHEAST OREGON. MONDAY AFTERNOON CONVECTION WILL CONTINUE INTO
MONDAY NIGHT OVER THE BLUES AND WALLOWA MOUNTAINS. AN UPPER LEVEL
RIDGE THEN BUILDS OVER THE FORECAST AREA LATE MONDAY NIGHT INTO
TUESDAY FOR SUBSIDENCE.  POLAN

EXTENDED...LONG RANGE MODELS ARE STILL IN AGREEMENT WITH RIDGE OVER
THE PACIFIC NORTHWEST AND UPPER LOW OVER THE PACIFIC. DRY AND WARM
CONDITIONS WILL CONTINUE THROUGH FRIDAY AS THE RIDGE REMAINS IN
CONTROL. FOR THE WEEKEND THE LOW FILLS AND MOVES INLAND AS A TROUGH
OVER NORTHERN WASHINGTON AND SOUTHERN BRITISH COLUMBIA. DRY
CONDITIONS WILL PREVAIL BUT WITH HEIGHTS AND THICKNESSES
DROPPING...TEMPERATURES SHOULD COOL AT LEAST A CATEGORY FOR NEXT
WEEKEND. MEAD

PDT 3220  ALW 3220  PSC 2200  YKM 3200

.KPDT...WSR-88D...VCP21/CSR21...OPERATIONAL.

.KPDT...RED FLAG WARNING FOR DRY LIGHTNING FOR ALL FIRE WEATHER ZONES
        THROUGH 1100 PM TONIGHT.