Flood Potential Outlook
Issued by NWS Blacksburg, VA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
1257 PM EST THU MAR 5 2015

...WINTER/SPRING FLOOD OUTLOOK...NUMBER 5

...FLOOD POTENTIAL NEAR NORMAL AFTER CURRENT EVENT ENDS...

THIS IS THE FIFTH 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 MARCH 12TH 2015.

FOR THE BLACKSBURG HSA THE POTENTIAL FOR FLOODING DURING THE ONE-
WEEK OUTLOOK PERIOD IS NEAR NORMAL BASED EXISTING SNOW AND
PRECIPITATION OUTLOOKS. THIS DOES NOT INCLUDE THE CURRENT
FLOODING AFFECTING THE WESTERN AND NORTHERN BASINS.

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...

FLOOD WARNINGS ARE IN EFFECT FOR PARTS OF THE WESTERN HSA IN THE
OHIO AND TENNESSEE DRAINAGES AND SEVERAL LARGE STREAMS IN THE
JAMES BASIN ARE ABOVE FLOOD STAGE. ALL THIS FLOODING SHOULD
END WITHIN THE NEXT 24 HOURS AS SNOW AND COLDER WEATHER RETURNS.

RECENT PRECIPITATION...

FEBRUARY PRECIPITATION WAS SOMEWHAT BELOW NORMAL WITH 2.51 INCHES
VERSUS THE 30-YEAR MEAN OF 3.03 INCHES OR 83 PERCENT OF NORMAL.

WINTER (DEC-FEB) PRECIPITATION WAS 7.24 INCHES OR 74 PERCENT OF
THE SEASONAL NORMAL OF 9.72 INCHES

FALL 2014 (SEP-NOV) PRECIPITATION FALL WAS ALMOST EXACTLY NORMAL
WITH 10.54 INCHES VERSUS THE NORMAL OF 10.38 INCHES.

DROUGHT...

ABNORMALLY DRY (D0) CONDITIONS REMAIN ON THE LATEST WEEKLY U.S.
DROUGHT MONITOR MAP AND COVER NEARLY THE ENTIRE AREA WITH THE
EXCEPTION OF THE GREENBRIER BASIN IN WEST VIRGINIA AND PARTS OF
THE LOWER DAN AND LOWER ROANOKE BASINS. 60- TO 90-DAY
PRECIPITATION IN MUCH OF THE D0 AREAS IS ONLY 50 TO 75 PERCENT OF
NORMAL. THE DROUGHT MONITOR UPDATE CYCLE IS ONCE PER WEEK ENDING
AT 12Z ON TUESDAY...SO MUCH OF THE RECENT EVENT IS NOT
INCORPORATED INTO THE CURRENT MAP.

PLEASE SEE DROUGHTMONITOR.UNL.EDU FOR MORE INFORMATION ABOUT
DROUGHT.

SNOW COVER...

THE JUST-ENDED RAIN EVENT AND WARMER WEATHER ERASED A HUGE AMOUNT
OF SNOW ACROSS THE WESTERN AND SOUTHWESTERN BASINS...WITH 1 TO 3 INCHES
OF SNOW WATER EQUIVALENT MELTING OUT IN A MATTER OF HOURS AND
CONTRIBUTING TO SIGNIFICANT FLOODING. UP TO 1 FOOT OR MORE OF
SNOW REMAINS IN THE UPPER GREENBRIER AND JAMES RIVER BASINS WITH
SNOW WATER EQUIVALENT UP TO 2 INCHES.

PLEASE SEE WWW.NOHRSC.NOAA.GOV FOR MORE INFORMATION ON SNOW
COVER.

RIVER ICE...

MOST RIVER ICE HAS BROKEN UP IN THE PAST FEW DAYS ALTHOUGH A FEW
PARTS OF GREENBRIER AND BATH COUNTIES MAY HAVE

STREAMFLOW...

STREAMFLOWS ARE RUNNING WELL ABOVE NORMAL IN NEARLY ALL BASINS
WITH THE EXCEPTION OF A FEW GAGES IN THE PIEDMONT DUE TO THE
RECENT STORM.

PLEASE SEE WATERWATCH.USGS.GOV FOR MORE STREAMFLOW INFORMATION.

SOIL MOISTURE...

THE LATEST CPC SOIL MOISTURE ANALYSIS SHOW A SMALL AREA OF BELOW
NORMAL SOIL MOISTURE IN THE VIRGINIA AND NORTH CAROLINA PIEDMONT MOST
OF THE HSA WITH A BROAD AREA SHOWING A DEFICIT OF 20 MM OR NEARLY
ONE INCH.

PLEASE SEE WWW.CPC.NCEP.NOAA.GOV FOR MORE SOIL MOISTURE AND
CLIMATE INFORMATION.

THE UNIVERSITY OF WASHINGTON EXPERIMENTAL SOIL MOISTURE ANALYSIS
CONFIRMS THE GENERAL PATTERN OF BELOW NORMAL SOIL MOISTURE
CONDITIONS ACROSS PARTS OF THE HSA WITH PERCENTILES NEAR THE 20TH
OVER PARTS OF SOUTHWEST VIRGINIA AND NORTHWEST NORTH CAROLINA.

THIS DATA CAN BE ACCESSED AT:
HTTP://WWW.HYDRO.WASHINGTON.EDU/FORECAST/MONITOR/INDEX.SHTML

RESERVOIRS...

ALL MAJOR RESERVOIRS SERVING THE HSA REMAIN NEAR GUIDE CURVES
AND/OR CONSERVATION POOL LEVELS AT THIS TIME.

FUTURE WEATHER CONDITIONS...

NO SIGNIFICANT STORMS ARE FORECAST TO AFFECT THE HSA IN THE NEXT
7-DAY PERIOD.

REPEATING THE CURRENT FLOOD POTENTIAL OUTLOOK FOR THE NEXT WEEK:
NEAR NORMAL.

THE NEXT SCHEDULED UPDATE OF THE WINTER/SPRING FLOOD OUTLOOK WILL
BE MARCH 12TH 2015.

FOR ADDITIONAL WEATHER OR HYDROLOGIC INFORMATION...VISIT OUR
WEBSITE AT WWW.WEATHER.GOV/BLACKSBURG


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