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Hydrometeorological Discussion
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AGUS76 KPTR 241736
HMDPTR
HYDROMETEOROLOGICAL DISCUSSION
NORTHWEST RIVER FORECAST CENTER PORTLAND OR
10:35 AM PDT FRI MAY 24 2013

...LINGERING HIGH WATER IS EXPECTED LATE THIS WEEK AND AGAIN OUT TOWARDS
NEXT WEEKEND LOCALLY MAINLY THROUGH NORTHEAST TO NORTH-CENTRAL WASHINGTON...
NORTHERN IDAHO...AND NORTHWEST MONTANA. BY NEXT WEEKEND THE FLATHEAD RIVER
AT COLUMBIA FALLS POTENTIALLY EXCEEDS FLOOD STAGE.

...HYDROMETEOROLOGICAL CONDITIONS...PAST 24 HOURS...4 AM - 4 AM...

A PERSISTENT LOW PRESSURE SYSTEM WITH UPPER LEVEL ATMOSPHERIC
DISTURBANCES BROUGHT SCATTERED PRECIPITATION TO MUCH OF THE REGION
WITH THE HEAVIEST ACCUMULATIONS OVER THE NORTHERN ROCKIES...
NORTHWEST OREGON.. AND SOUTHWEST WASHINGTON.
FREEZING LEVELS RANGED FROM 5300 FEET OVER THE OLYMPICS... TO 4500
FEET AT SALEM... AND TO 5100 FEET AT MEDFORD. FREEZING LEVELS EAST
OF THE CASCADES RANGED FROM 6300 FEET OVER SOUTHERN CANADA...6600
FEET AT SPOKANE... AND 8100 FEET AT BOISE.
DAYTIME TEMPERATURES AVERAGED 11 DEGREES BELOW NORMAL ACROSS THE
REGION.

...OBSERVED HYDROLOGIC CONDITIONS...

RECENT MODERATE PRECIPITATION BROUGHT RISES TO SEVERAL NORTHWEST
OREGON SITES. MOST OF THE REMAINDER OF THE REGION HAD ONLY MINOR
FLOWS MONTANA. FLAT TO RECEDING FLOWS DOMINATED FLOWS ELSEWHERE TOWARD OUR SOUTH-
EASTERN TIER SNAKE RIVER BASINS

...HYDROMETEOROLOGICAL FORECAST...MAY 24 - MAY 28...

THE PERSISTENT LOW PRESSURE SYSTEM THAT BROUGHT HEAVY RAINFALL TO
MUCH OF NORTHWEST OREGON IS FORECAST TO SLOWLY MOVE TO THE NORTHERN
ROCKIES. ASSOCIATED WITH THIS SYSTEM WILL BE AN UNSTABLE AIRMASS THAT
WILL BRING SCATTERED SHOWERS AND A FEW THUNDERSTORMS EAST OF THE
CASCADES. THE REGION WILL BE MAINLY UNDER THE INFLUENCE OF A TROUGH
OF LOW PRESSURE AND A COLD AIR MASS THROUGHOUT THE PERIOD. EXPECT
OCCASIONAL ATMOSPHERIC DISTURBANCES TO BRING SCATTERED PRECIPITATION
MAINLY WEST OF THE CASCADES AND THE NORTHERN ROCKIES. DAYTIME
TEMPERATURES 8 DEGREES BELOW NORMAL TODAY... THEN GRADUALLY MODERATE
OVER THE COMING DAYS TO AROUND 3 DEGREES BELOW NORMAL BY TUESDAY.

...HYDROLOGIC CONDITIONS...

DUE TO RECENT RAINFALL ACROSS THE NORTHWEST PORTION OF THE REGION...
MAINLY IN OREGON... EXPECT RISES TO CREST TODAY AND TRANSITION TO
RECESSIONS. DUE TO COOLER THAN NORMAL TEMPERATURES... EXPECT MOST
SITES TO HAVE STEADY TO MINOR RISES DUE MAINLY TO SNOW-MELT RUNOFF
THAT TEND TO PICK AS WE NEAR MID WEEK NEXT WEEK.

...6-10 DAY OUTLOOK...MAY 29 - JUN 02...

THIS PERIOD TENDS TO BE DOMINATED BY A PROGRESSIVE TROUGHY PATTERN OVER US THAT
RESULTS IN OCCASIONAL RAIN SCATTERING ACROSS THE REGION AND GENERALLY NEAR
TO SLIGHTLY BELOW NORMAL TEMPERATURES. THERE IS ALSO THE POTENTIAL FOR SEVERAL
DECENT SURGES OF NORTH EASTERN TIER HEAVIER PRECIPITATION ENHANCED BY SOME
MONSOONAL INTERIOR MOISTURE MIXING INTO THE REGION FROM THE SOUTHEAST.

AO/KB/CO/TD/RF/BA/JS

VISIT US ON THE WEB AT HTTP://WWW.NWRFC.NOAA.GOV FOR DETAILED
GRAPHICAL PRECIPITATION...FREEZING LEVEL...AND TEMPERATURE FORECASTS.


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National Weather Service Weather Forecast Office
