Flood Potential Outlook
Issued by NWS Blacksburg, VA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
326 PM EST THU JAN 22 2015

...WINTER/SPRING FLOOD OUTLOOK...NUMBER 2

...DRY JANUARY REDUCES RIVER FLOOD POTENTIAL TO BELOW NORMAL...

THIS IS THE SECOND 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 FEBRUARY 5TH 2015.

FOR THE BLACKSBURG HSA THE POTENTIAL FOR FLOODING DURING THE OUTLOOK
PERIOD IS BELOW NORMAL BASED ON INCREASINGLY DRY ANTECEDENT
CONDITIONS...ESPECIALLY THE VERY DRY JANUARY.

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...

JANUARY HAS BEEN VERY DRY TO DATE WITH LESS THAN 25 UP TO ONLY 50
PERCENT OF NORMAL PRECIPITATION ACROSS THE BASINS OF THE
HYDROLOGIC SERVICE AREA (HSA). MONTHLY RAIN GAGE TOTALS THROUGH
12Z (7AM) THIS MORNING RANGE FROM LESS THAN 0.25 INCHES AT A FEW
REPORTING STATIONS UP TO ALMOST 2 INCHES...BUT MOST SITES ARE
REPORTING FROM 0.50 TO 1.00 INCH FOR THE MONTH SO FAR.

DECEMBER 2014 PRECIPITATION AT 62 NWS COOP STATIONS WAS 2.85 INCHES
OR 86 PERCENT OF THE 1981-2010 NORMAL OF 3.32 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 HAVE PERSISTED IN A SMALL PORTION OF
SOUTHSIDE VIRGINIA AND ADJACENT PIEDMONT COUNTIES IN NORTH CAROLINA.

SNOW COVER..

SNOW COVER IS BASICALLY NON-EXISTENT.

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

RIVER ICE...

RIVER ICE IS NON-EXISTENT AT THIS TIME.

STREAMFLOW...

STREAMFLOWS ARE RUNNING WELL BELOW NORMAL IN NEARLY THE ENTIRE
HSA DUE TO THE VERY DRY JANUARY. THE LOWEST STREAMFLOWS ARE IN
PARTS OF THE LOWER ROANOKE RIVER BASIN WHERE A FEW SITES ARE BELOW
THE 10TH PERCENTILE OF ALL FLOWS FOR THIS DATE.

FOR MORE DETAILED INFORMATION ON STREAMFLOW CONDITIONS SEE THE USGS
WATERWATCH SITE BELOW.

HTTP://WATERDATA.USGS.GOV/WATERWATCH

SOIL MOISTURE...

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

FOR ADDITIONAL INFORMATION FROM CPC: HTTP://WWW.CPC.NCEP.NOAA.GOV

THE UNIVERSITY OF WASHINGTON EXPERIMENTAL SOIL MOISTURE ANALYSIS
CONFIRMS THE GENERAL PATTERN OF DECLINING SOIL MOISTURE
CONDITIONS ACROSS PARTS OF THE HSA.

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...

A STORM SYSTEM IS FORECAST TO AFFECT THE HSA FRIDAY INTO SATURDAY
WITH MIXED PRECIPITATION EXPECTED AND A LIQUID EQUIVALENT OF
ABOUT 0.50 TO 1.00 INCH ACROSS THE BASINS. NO SIGNIFICANT STORMS
ARE EXPECTED FOR THE REMAINDER OF THE 7-DAY FORECAST PERIOD.

LONGER TERM OUTLOOKS (6-10 AND 8-14 DAY) FROM THE CLIMATE PREDICTION
CENTER VALID THROUGH FEBRUARY 1 AND FEBRUARY 5 SHOW A HIGHER PROBABILITY
OF BELOW NORMAL PRECIPITATION IN THE 6-10 DAY PERIOD AND HIGHER
PROBABILITY OF NEAR NORMAL IN THE 8-14 DAY PERIOD. THERE IS A
HIGHER PROBABILITY OF BELOW NORMAL TEMPERATURES DURING BOTH
PERIODS. THE EXTENDED OUTLOOK FOR PRECIPITATION IN THE MONTH OF
FEBRUARY SHOWS EQUAL CHANCES OF ANY CATEGORY (BELOW...NEAR NORMAL
OR ABOVE) OCCURRING.

REPEATING THE CURRENT FLOOD POTENTIAL OUTLOOK: BELOW NORMAL.

THE NEXT SCHEDULED UPDATE OF THE WINTER/SPRING FLOOD OUTLOOK WILL
BE FEBRUARY 5TH 2015.

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

$$

PC



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