Flash Flood Warning 3, NWS Pendleton, OR

NORTHEAST OREGON/SOUTHEAST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
230 PM PDT FRI JUL 19 2002

FIRE WEATHER...SOMEWHAT COOLER AND DRIER AIR IS MOVING EAST OF THE
CASCADES AND ACROSS THE EASTERN SECTIONS OF WASHINGTON AND OREGON.
THE DRIER AIR IS ASSOCIATED WITH WESTERLY FLOW ALOFT BRINGING A
STABLE AIR MASS INTO THE REGION. THUS SHOWERS WILL BE WINDING DOWN
THIS AFTERNOON WITH A FEW ISOLATED EVENING SHOWERS IN THE BLUE
MOUNTAINS. HOWEVER...WALLOWA COUNTY WILL BE ON THE FRINGES OF
MOISTURE WRAPPING AROUND AN UPPER LOW PRESSURE SYSTEM CURRENTLY IN
SOUTHEAST OREGON.THUS CANNOT RULE OUT SCATTERED SHOWERS AND
THUNDERSTORMS IN WALLOWA COUNTY THIS EVENING. ANY THUNDERSTORMS THIS
AFTERNOON OR THIS EVENING IN WALLOWA COUNTY ARE LIKELY TO BE WET.
OTHERWISE...SKIES WILL CLEAR OVER EASTERN OREGON TONIGHT AS THE
AFOREMENTIONED LOW MOVES INTO IDAHO.

SHORT TERM...THE LOW PRESSURE SYSTEM OVER SOUTHEAST OREGON WILL EXIT
EASTERN OREGON THIS EVENING. THE MAIN THREAT OF CONVECTION FOR THE
REMAINDER OF THIS AFTERNOON AND EARLY THIS EVENING WILL BE OVER THE
MOUNTAINS IN THE EXTREME EASTERN OREGON. WASHINGTON AND NORTHERN
OREGON WILL INCREASINGLY COME UNDER THE INFLUENCE OF WESTERLY
FLOW ALOFT AS ANOTHER UPPER LEVEL SHORT WAVE MOVES EASTWARD ACROSS
BRITISH COLUMBIA TONIGHT.  THE SHORT WAVE WILL ALLOW MARINE AIR TO
SPILL EAST OF THE CASCADE CRESTS INTO EASTERN OREGON AND SOUTHEAST
WASHINGTON FOR SLIGHTLY COOLER TEMPERATURES CONTINUING THROUGH THE
WEEKEND. DRIER AND MORE STABLE AIR WILL COVER THE PACIFIC NORTHWEST
OVER THE WEEKEND FOR DRY CONDITIONS.  POLAN

DAYS 3-7...THE RUN-TO-RUN CONTINUITY OF THE AVN/MRF HAS BEEN VERY
POOR. OTHER EXTENDED MODELS ARE NOT MUCH BETTER. 12Z AVN DEVELOPS
A STRONG UPPER LOW OVER THE NORTHERN CALIFORNIA COAST ON MONDAY
THEN MOVES IT NORTHWARD ALONG THE OREGON COAST TUESDAY AND EARLY
WEDNESDAY. THIS DIFFERS SIGNIFICANTLY FROM THE PREVIOUS RUN WHICH
ONLY HINTED AT A WEAK UPPER LOW ON MONDAY. DESPITE THE
DIFFERENCES...BELIEVE THE AVN MAY HAVE A CORRECT SOLUTION. WATER
VAPOR LOOPS INDICATE A WAVE DEVELOPING NEAR 30N/133W. THE INITIAL
DEVELOPMENT IS ALREADY FAIRLY STRONG AND SEE NO REASON WHY IT WILL
WEAKEN. BY FOLLOWING THE 12Z AVN...WILL MENTION A CHANCE OF
THUNDERSTORMS OVER CENTRAL OREGON AND THE OCHOCOS MONDAY THEN OVER
THE REMAINDER OF THE OREGON MOUNTAINS TUESDAY AND WEDNESDAY. WILL
KEEP THURSDAY AND FRIDAY DRY BUT WITH SOME UNCERTAINTY.  SMITH

PDT 0000  ALW 0000  PSC 0000  YKM 0000

KPDT...VCP21..OPERATIONAL.

.KPDT...NONE.