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Product Display for Hydrometeorological Discussion


HYDROMETEOROLOGICAL DISCUSSION NORTHWEST RIVER FORECAST CENTER PORTLAND OR 11:30 AM PST MON NOV 23 2009 HYDROMETEOROLOGICAL CONDITIONS...PAST 24 HOURS...4 AM - 4 AM WIDESPREAD WRAP-AROUND MIXED SHOWERS PIVOTED AROUND A LOW SHIFTING OUT OF EASTERN WASHINGTON EASTWARD TOWARD THE MISSOULA FORECAST AREA. HEAVIEST 0.8 TO AROUND 1.5 INCH VALLEY RAIN AND MOUNTAIN SNOW TENDED TO CONCENTRATE MAINLY ALONG THE WASHINGTON CASCADES...WITH MORE WIDELY SCATTERED SIMILAR AMOUNTS HITTING THE NORTH-CENTRAL IDAHO PANHANDLE...AS WELL AS THROUGH THE SOUTHWEST FLANK OF THE SAWTOOTH MOUNTAINS. FREEZING LEVELS THIS MORNING RANGED FROM THE SURFACE AT SPOKANE...3500 FEET AT BOISE...3800 FEET AT QUILLAYUTE... AND 9000 FEET AT MEDFORD. OBSERVED HYDROLOGIC CONDITIONS SOME MINOR WESTERN WASHINGTON AND NORTHWESTERN OREGON STREAM RISES TENDED TO TRANSITION INTO MOSTLY FLAT TO RECEDING FLOWS ELSEWHERE. HYDROMETEOROLOGICAL FORECAST...NOV 23 - NOV 27 MONDAY AFTERNOON STRONG WARM FRONTAL RAIN PREVIOUSLY HAMMERING VANCOUVER ISLAND STARTS SAGGING SOUTHEASTWARD AND TRANSITIONS INTO A COLD FRONT THAT CLIPS WESTERN WASHINGTON WITH SOME OCCASIONAL MODERATE MIXED PRECIPITATION INTO EARLY TUESDAY MORNING. TUESDAY AFTERNOON TO WEDNESDAY MORNING A RIDGE SHIFTING EASTWARD ACROSS OUR FORECAST AREA LARGELY SHUTS OFF PRECIPITATION ACROSS THE REGION. WEDNESDAY AFTERNOON A PACIFIC FRONTAL DISTURBANCE SIMILAR TO MONDAY'S SYSTEM...EVENTUALLY SAGS SOUTH ALONG THE BRITISH COLUMBIA COAST INTO WESTERN WASHINGTON. THIS FRONTAL PUSH INITIALLY WILL INITIALLY HAVE HIGH FREEZING LEVELS...AROUND 7000 PLUS FEET...AND IS FORECAST TO GENERATE OCCASIONAL MODERATE RAIN ACROSS WESTERN WASHINGTON INTO WEDNESDAY EVENING. AS WE HEAD INTO THANKSGIVING DAY ON THURSDAY THIS COLD FRONT TENDS TO DIMINISH AS IT EXTENDS SOUTHWARD AND DRIFTS VERY SLOWLY IN ACROSS WESTERN OREGON WHILE STALLING OUT ACROSS ACROSS WASHINGTON. THIS DIMINISHING PATTERN GRADUALLY SHIFTS IN ACROSS THE EASTSIDE THROUGH FRIDAY...WHILE A FOLLOWING WAVE OF UNSETTLED PACIFIC WEATHER RESUMES SOME OCCASIONAL MIXED PRECIPITATION ACROSS OUR WESTSIDE BASINS. FUTURE HYDROLOGIC CONDITIONS LOOK FOR SOME RECURRING MINOR WESTERN WASHINGTON RISES THROUGH THURSDAY THAT TRAIL OFF ACROSS WESTERN OREGON LATER IN THE WEEK. OTHERWISE...FLOWS TEND TO REMAIN MOSTLY FLAT AND UNRESPONSIVE. 6-10 DAY OUTLOOK...NOV 28 - DEC 02 LATEST LONGRANGE MODEL GUIDANCE CONTINUES TO CONVERGE ON A FAIRLY STRONG BLOCKING DRY RIDGE SOLUTION OVER THE PACIFIC NORTHWEST FOR THE MAJORITY OF THE PERIOD. IF THIS VERIFIES...LOOK FOR A RESULTING DROP OFF IN NATURAL FLOWS ACROSS THE REGION. GREEN RIVER LOOKS LIKE SOME OCCASIONAL MODERATE RAIN THIS MONDAY NIGHT AND AGAIN THURSDAY (THANKSGIVING) NIGHT TO FRIDAY. OTHERWISE...THE GREEN RIVER BASIN GETS LITTLE IN THE WAY OF HYDROLOGIC FORCING OUT TO THE END OF THIS COMBINED FORECAST (OUT THROUGH NEXT WEDNESDAY, DECEMBER 2). ML/BA/RV VISIT US ON THE WEB AT HTTP://WWW.NWRFC.NOAA.GOV FOR DETAILED GRAPHICAL PRECIPITATION...FREEZING LEVEL...AND TEMPERATURE FORECASTS. $$ $$

US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Northwest River Forecast Center (NWRFC)
5241 NE 122nd Avenue
Portland, Oregon 97230-1089
Telephone: 503-326-7401

Last Modified: November 23, 2009
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