National Weather Service Text Product Display

Hydrometeorological Discussion
Issued by NWS Northwest RFC
Versions: 1 2 3 4 5 6 7

000
AGUS76 KPTR 181916
HMDPTR
HYDROMETEOROLOGICAL DISCUSSION
NORTHWEST RIVER FORECAST CENTER PORTLAND OR
11:55 AM PDT SAT MAY 18 2013

...LOCAL FLOODING CONTINUES ON THE OKANOGAN RIVER. HIGH WATER
IS ALSO POTENTIALLY EXPECTED NEXT WEEK THROUGH NORTHEAST WASHINGTON, NORTHERN
IDAHO AND NORTHWEST MONTANA...

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

A WEAK ONSHORE TROUGHY PATTERN ACROSS THE WEST RESULTED IN A MIX OF WIDELY
SCATTERED OCCASIONAL LIGHT VALLEY RAIN SHOWERS AND MOUNTAIN SNOW ACROSS MUCH
OF OUR FORECAST AREA. FRIDAY TEMPERATURES TENDED TO BE GENERALLY AROUND 3 TO 7
DEGREES BELOW NORMAL. THIS MORNING FREEZING LEVELS RANGED BETWEEN 5500 FEET AT
QUILLAYUTE...TO 9000 FEET AT MEDFORD.

...OBSERVED HYDROLOGIC CONDITIONS...

NEAR THE U.S. CANADIAN BORDER A NUMBER OF FLOWS REMAIN NEAR TO ABOVE ACTION
LEVELS...WHILE ELSEWHERE RECESSIONS TENDED TO DOMINATE FLOWS.

...HYDROMETEOROLOGICAL FORECAST...MAY 18 - MAY 22...

SCATTERED LIGHT MIXED SHOWERS TRAIL OFF EASTWARD ACROSS THE REGION THIS WEEKEND
WITH MONDAY LOOKING TO BE MOSTLY DRY AS A TRANSIENT RIDGE WARMS UP MOST LOCA-
TIONS AROUND 4 TO 8 DEGREES ABOVE NORMAL. TUESDAY A COLD CORE GULF OF ALASKA LOW
WITH 2 TO 7 DEGREE BELOW NORMAL TEMPERATURES SAGS OCCASIONAL VALLEY RAIN AND
LOWERING MOUNTAIN SNOW INTO OUR NORTHWESTERN TIER TUESDAY. WEDNESDAY THE OCCLU-
SION OF THIS DAY-4 STORM ENTRAINS SOME GULF OF MEXICO MOISTURE INTO AN EASTWARD
SHIFTING RAIN PATTERN OVER THE UPPER COLUMBIA. EMBEDDED CONVECTION IN THIS UPPER
COLUMBIA DAY-5 FORECAST PROBLEM COULD RESULT IN LOCAL HEAVY RAIN IN SOUTH EAST-
ERN BRITISH COLUMBIA...NORTHWESTERN MONTANA...NORTHERN IDAHO...AND NORTH EASTERN
MONTANA.

...HYDROLOGIC CONDITIONS...

EXPECT EARLY TO MID PERIOD FLAT TO RECEDING FLOWS TO DOMINATE THE REGION...
BUT MINOR TUESDAY NORTHWESTERN TIER LOWER ELEVATION STREAM RISES ARE A PRELUDE
TO WHAT COULD BECOME LOCALLY SHARP NORTHEASTERN TIER UPPER COLUMBIA WEDNESDAY
RISES FROM POTENTIALLY HEAVY RAIN AT TIMES ACROSS SOUTHEASTERN BRITISH COLUMBIA
...NORTHWESTERN MONTANA...NORTHERN IDAHO...AND NORTHEASTERN WASHINGTON.

...6-10 DAY OUTLOOK...MAY 23 - MAY 27...

OUR REGION LOOKS LIKE ITS GOING TO BE DOMINATED BY THE SLOWLY DECAYING REMNANTS
OF AN UPPER LEVEL LOW CENTERED OVER OUR FORECAST AREA THAT CONTINUES PINWHEELING
GRADUALLY DIMINISHING SCATTERED MIXED SHOWERS OVER US THROUGH THIS FORECAST PER-
IOD. AS THIS LOW GRADUALLY OPENS UP WE SHOULD SEE TEMPERATURES START TO GRADUAL-
LY WARM UP...ENDING THE PERIOD NEAR NORMAL VALUES.

ML/RF/TD

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


$$
National Weather Service Weather Forecast Office
