Note that if drought conditions are not being experienced, or in the case of river flooding or heavy rain, this statement may be used to indicate river flows or flood potential.
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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
940 AM EDT FRI MAR 19 2010
...WINTER/SPRING FLOOD OUTLOOK...NUMBER 6 (FINAL)
...SLIGHTLY ABOVE NORMAL FLOOD POTENTIAL REMAINS...
THIS IS THE SIXTH AND LAST IN A SERIES OF ANNUAL WINTER/SPRING FLOOD
POTENTIAL STATEMENTS INTENDED TO PROVIDE INSIGHT INTO THE LIKELIHOOD
OF RIVER FLOODING (NOT FLASH FLOODING) ACROSS THE BLACKSBURG
HYDROLOGIC SERVICE AREA (HSA). THE HSA INCLUDES ALL OR PARTS OF THE
JAMES ...ROANOKE...UPPER YADKIN...GREENBRIER...NEW ...CLINCH AND
HOLSTON RIVER BASINS IN WESTERN VIRGINIA...SOUTHEAST WEST VIRGINIA
AND NORTHWEST NORTH CAROLINA.
THESE STATEMENTS PROVIDE INFORMATION ON FLOOD THREAT CONDITIONS
SUCH AS RECENT PRECIPITATION...SOIL MOISTURE...SNOW COVER AND ITS
WATER EQUIVALENT...RIVER ICE CONDITIONS...STREAMFLOW...FUTURE
PRECIPITATION AND OTHERS FACTORS. THIS OUTLOOK IS VALID FOR THE
PERIOD THROUGH APRIL 2 2010.
FOR THE BLACKSBURG HSA THE POTENTIAL FOR FLOODING DURING THE
OUTLOOK PERIOD IS NOW CONSIDERED NEAR OR SLIGHTLY ABOVE AVERAGE
BASED PRIMARILY WET SOIL CONDITIONS AND HIGHER THAN NORMAL
STREAMFLOWS NOW IN PLACE. SNOW COVER IS NO LONGER A SIGNIFICANT
FACTOR IN THE FLOOD OUTLOOK...UNLESS HEAVY RAINS WERE TO
MOVE ACROSS THE UPPER GREENBRIER RIVER BASIN IN WHICH CASE
SNOWMELT COULD AGGRAVATE FLOODING SOMEWHAT. THE AREA MOST AT
RISK FOR FLOODING AT THE CURRENT TIME WOULD BE SOUTHEAST
WEST VIRGINIA AND FAR WESTERN VIRGINIA...AREAS STILL RECOVERING
FROM SEVERE FLASH FLOODING ONLY LAST WEEKEND.
IN THIS PART OF THE MID-ATLANTIC REGION...IT IS HEAVY RAINFALL THAT
IS THE PRIMARY FACTOR LEADING TO RIVER FLOODING. HEAVY RAINFALL CAN
RAPIDLY CAUSE RIVER FLOODING AT ANY TIME OF THE YEAR...EVEN WHEN
OVERALL RIVER FLOOD POTENTIAL IS CONSIDERED LOW.
CURRENT FLOODING...
NONE.
RECENT PRECIPITATION...
THE MARCH 12-13 STORM PRODUCED ABOUT 1 TO 3 INCHES OF RAIN
ACROSS THE HSA WITH THE HIGHEST AMOUNTS IN THE NEW RIVER BASIN.
FLOODING AND FLASH FLOODING FROM THIS EVENT WAS SEVERE IN
SEVERAL WESTERN COUNTIES INCLUDING MERCER...GREENBRIER...GILES AND
PULASKI. THERE HAS BEEN LITTLE SIGNIFICANT PRECIPITATION OUTSIDE OF
THIS EVENT HOWEVER AND MARCH TOTAL PRECIPITATION IS NOW RUNNING
SOMEWHAT BELOW NORMAL ACROSS MUCH OF THE REGION WITH THE EXCEPTION
OF SOUTHEAST WEST VIRGINIA AND FAR WESTERN COUNTIES IN VIRGINIA.
FEBRUARY PRECIPITATION WAS BELOW NORMAL...ENDING A 3-MONTH
STRING OF WELL ABOVE NORMAL PRECIPITATION. PRELIMINARY DATA FROM
73 COOPERATIVE WEATHER AND AIRPORT CLIMATE STATIONS SHOWED 2.78
INCHES FOR THE MONTH...VERSUS THE FEBRUARY MEAN VALUE OF 3.22
INCHES...OR 86 PERCENT OF NORMAL.
THE 3-MONTH PERIOD FROM NOVEMBER 1 THROUGH JANUARY 31 WAS
EXTRAORDINARILY WET ACROSS MOST OF THE HSA AND WAS THE WETTEST
COMBINED NOVEMBER-JANUARY PERIOD AT SEVERAL OBSERVING SITES.
SNOW COVER...
SNOW COVER IS CONFINED TO THE HIGHEST ELEVATIONS OF THE WESTERN HSA
MAINLY IN THE UPPER GREENBRIER RIVER BASIN IN POCAHONTAS COUNTY.
SNOW WATER EQUIVALENT IS ABOUT 1 TO 2 INCHES IN PARTS OF THE
BASIN.
FOR ADDITIONAL INFORMATION ON SNOW COVER AND SWE PLEASE SEE THE
WEBSITE OF THE NATIONAL OPERATIONAL HYDROLOGIC REMOTE SENSING
CENTER OF THE NATIONAL WEATHER SERVICE (SEE LINK BELOW). THIS SITE
PROVIDES EXTENSIVE INFORMATION ON SNOW COVER AND SNOW WATER
EQUIVALENT AND USES SATELLITE DATA TO SUPPLEMENT GROUND
MEASUREMENTS.
HTTP://WWW.NOHRSC.NWS.GOV
RIVER ICE...
THERE IS NO RIVER ICE.
STREAMFLOW...
STREAMFLOWS ARE NOW MOSTLY RUNNING AT ABOVE NORMAL LEVELS FOR
MID-MARCH IN ALL THREE STATES SERVED BY THE BLACKSBURG HSA.
FOR MORE DETAILED INFORMATION ON STREAMFLOW CONDITIONS SEE THE USGS
WATERWATCH SITE BELOW.
HTTP://WATERDATA.USGS.GOV/WATERWATCH
SOIL MOISTURE...
THE PALMER DROUGHT SEVERITY INDEX...USEFUL AS SOIL MOISTURE
INDICATOR...FOR MARCH 13 2010 SHOWS EITHER VERY MOIST OR EXTREMELY
MOIST SOIL CONDITIONS STILL EXISTING ACROSS THE ENTIRE BLACKSBURG
HSA.
FUTURE WEATHER CONDITIONS...
DRY WEATHER IS EXPECTED THROUGH THE WEEKEND BUT A STRONG UPPER
LEVEL LOW WILL MOVE TOWARD THE AREA LATE SUNDAY AND BRING CHANCES
FOR RAINFALL EARLY NEXT WEEK. CURRENT INDICATIONS ARE THAT RAINFALL
WILL BE FAIRLY MODERATE...GENERALLY CLOSE TO 1.00 INCH OVER
MOST OF THE AREA.
THE LONGER RANGE WEATHER FORECASTS FOR THE 6 TO 10 DAY PERIOD FROM
MARCH 24 THROUGH MARCH 28 CALLS FOR NEAR NORMAL TEMPERATURES AND
ABOVE NORMAL PRECIPITATION. FOR THE 8 TO 14 DAY OUTLOOK
PERIOD...MARCH 26 TO APRIL 1 THE PATTERN IS EXPECTED TO BE YIELD
NEAR NORMAL TEMPERATURES AND PRECIPITATION.
PLEASE SEE THE CPC WEBSITE FOR ADDITIONAL FORECAST
DETAILS: HTTP://WWW.CPC.NCEP.NOAA.GOV
REPEATING THE CURRENT FLOOD POTENTIAL FOR THE BLACKSBURG HYDROLOGIC
SERVICE AREA...SLIGHTLY ABOVE TO NEAR NORMAL.
THIS IS THE FINAL FLOOD OUTLOOK FOR THE 2010 WINTER/SPRING SEASON.
$$
PC
