FGUS61 KRHA 071828
ESGRHA

FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC)
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 128 PM EST THU MAR 07 2013 

WINTER/SPRING RIVER FLOOD POTENTIAL OUTLOOK
NWS MIDDLE ATLANTIC RIVER FORECAST CENTER

OUTLOOK NUMBER 13-05 - MARCH 7, 2013

THIS OUTLOOK IS VALID FOR THE ONE-WEEK PERIOD MARCH 7-14, 2013.

THIS OUTLOOK ESTIMATES THE POTENTIAL FOR RIVER FLOODING (NOT FLASH
FLOODING) TO DEVELOP ACROSS THE MARFC AREA OF RESPONSIBILITY
(MID-ATLANTIC REGION) BASED ON A CURRENT ASSESSMENT OF
HYDROMETEOROLOGICAL FACTORS WHICH CONTRIBUTE TO RIVER FLOODING.
ACROSS THE MARFC AREA THESE FACTORS INCLUDE RECENT PRECIPITATION, SOIL
MOISTURE, SNOW COVER AND SNOW WATER EQUIVALENT, RIVER ICE, STREAMFLOW,
FUTURE WEATHER CONDITIONS, AND OTHERS.  THIS OUTLOOK DOES NOT ADDRESS
THE SEVERITY/EXTENT OF ANY FUTURE RIVER FLOODING.

REMEMBER, IN THE MID-ATLANTIC REGION HEAVY RAINFALL IS THE PRIMARY
FACTOR WHICH LEADS TO RIVER FLOODING.  HEAVY RAINFALL CAN RAPIDLY
CAUSE RIVER FLOODING ANY TIME OF THE YEAR, EVEN WHEN OVERALL RIVER
FLOOD POTENTIAL IS CONSIDERED TO BE LOW OR BELOW AVERAGE.

ONE-WEEK RIVER FLOOD POTENTIAL - AVERAGE TO BELOW AVERAGE.  THE RIVER
FLOOD POTENTIAL ACROSS THE MARFC SERVICE AREA FOR THE WEEK THROUGH
MARCH 14, 2013 IS STILL CONSIDERED SOMEWHAT BELOW AVERAGE ACROSS MOST
OF THE NORTHERN HALF OF THE REGION AND ABOUT AVERAGE ELSEWHERE.
FACTORS WHICH CONTRIBUTE TO RIVER FLOOD POTENTIAL ARE ADDRESSED
INDIVIDUALLY BELOW.

CURRENT FLOODING - NONE.

RECENT PRECIPITATION - VARIABLE.  PRECIPITATION WITHIN THE MARFC
SERVICE AREA DURING THE LAST 30 DAYS (FEBRUARY 5-MARCH 6, 2013) WAS
BELOW AVERAGE (50-75 PERCENT OF NORMAL) ACROSS MOST OF THE NORTHERN
HALF OF THE MARFC SERVICE AREA.  THIS INCLUDES NY, PA AND NORTHWESTERN
NJ WHERE ONLY 1.5-2.5 INCHES OF PRECIPITAITON FELL.  FURTHER SOUTH,
PRECIPITATION DURING THE LAST 30 DAYS RANGED FROM BELOW AVERAGE TO
AVERAGE (50-100 PERCENT OF AVERAGE) ACROSS THE APPALACHIAN REGION AND
ACROSS MOST OF MD AND NORTHERN DE.  THIS REGION RECEIVED 2-3 INCHES OF
PRECIPITATION.  FINALLY, PRECIPITATION WAS ABOUT AVERAGE (75-125
PERCENT OF NORMAL) ACROSS CENTRAL VA, INCREASING TO MUCH ABOVE AVERAGE
(150-250 PERCENT OF NORMAL) ACROSS SOUTHEASTERN VA, THE SOUTHERN HALF
OF THE DELMARVA PENINSULA AND EXTREME SOUTHEAST NJ.  THIS REGION
RECEIVED 3-7 INCHES OF PRECIPITATION.  PLEASE VISIT
WWW.ERH.NOAA.GOV/ER/MARFC.

SNOW CONDITIONS - VARIABLE.  CURRENTLY WITHIN THE MARFC SERVICE AREA
THERE ARE TWO MAIN AREAS OF SNOW COVER.  THE FIRST IS ASSOCIATED WITH
THE RECENT SOUTHERN STORM WHICH DEPOSITED SIGNIFICANT SNOW ACROSS MUCH
OF CENTRAL AND NORTHERN VA, WESTERN AND CENTRAL MD, AND SOUTH-CENTRAL
PA.  MEANWHILE THE SECOND AREA EXISTS FURTHER NORTH WHERE SNOW REMAINS
ON THE GROUND ACROSS NORTHERN PA AND OUR NY BASINS.  IN BETWEEN THESE
TWO AREAS (CENTRAL PA) THE SNOW COVER IS MORE PATCHY IN NATURE,
EXISTING MOSTLY ACROSS JUST THE HIGHER ELEVATIONS.  THE SOUTHERN AREA
OF SNOW CONTAINS WATER EQUIVALENT VALUES GENERALLY IN THE 0.50-1.50
INCH RANGE, THOUGH BOTH LOWER AND HIGHER VALUES ARE ALSO SCATTERED
WITHIN THIS AREA.  SNOW DEPTHS HERE GENERALLY RANGE BETWEEN 3-18
INCHES, THOUGH AGAIN BOTH LOWER AND HIGHER DEPTHS EXIST.  THESE SNOW
CONDITIONS RANGE FROM ABOUT NORMAL TO PERHAPS A LITTLE ABOVE NORMAL IN
SOME AREAS FOR THE DATE.  UP NORTH, WATER EQUIVALENT VALUES IN
NORTHERN PA AND NY ARE GENERALLY IN THE 0.25-1.50 INCH RANGE, WITH
DEPTHS GENERALLY SIX INCHES OR LESS.  AGAIN, BOTH HIGHER AND LOWER
EQUIVALENT VALUES AND DEPTHS EXIST IN SCATTERED LOCATIONS.  SNOW
CONDITIONS IN THIS NORTHERN AREA ARE BELOW NORMAL.  LIKEWISE, THE
PATCHY SNOW CONDITIONS THAT CURRENTLY EXIST ACROSS CENTRAL PA ARE ALSO
BELOW NORMAL FOR THE DATE.  LITTLE OR NO SNOW REMAINS IN NJ.  PLEASE
VISIT WWW.NOHRSC.NOAA.GOV AND WWW.ERH.NOAA.GOV/ER/MARFC.

RIVER ICE - BELOW AVERAGE TO AVERAGE.  LITTLE OR NO SIGNIFICANT RIVER
ICE IS FOUND WITHIN THE MARFC SERVICE AREA.  THE RIVER ICE CONDITIONS
IN NY AND PA ARE BELOW NORMAL FOR THIS TIME OF WINTER.  ELSEWHERE,
RIVER ICE CONDITIONS ARE CLOSER TO AVERAGE.  AS THE WINTER OF
2012-2013 SLOWLY TRANSITIONS TO SPRING, RIVER ICE FORMATION IS NOW
UNLIKELY FOR THE REMAINDER OF THE SEASON.

STREAMFLOW CONDITIONS - VARIABLE.  ACCORDING TO THE U.S. GEOLOGICAL
SURVEY (USGS) THE CURRENT SNAPSHOT OF STREAMFLOW WITHIN THE MARFC
REGION SHOWS CONSIDERABLE VARIABILITY.  STREAMFLOW ACROSS THE NORTHERN
HALF OF THE MARFC REGION IS BELOW MEDIAN TO MEDIAN DUE TO RECENT DRY
WEATHER.  MEANWHILE FURTHER SOUTH STREAMFLOW IS MOSTLY MEDIAN TO ABOVE
MEDIAN THANKS TO THE RECENT SIGNIFICANT STORM THAT PASSED THROUGH THAT
REGION.  HOWEVER, STREAMFLOW REMAINS BELOW NORMAL ACROSS UPPER
PORTIONS OF THE JAMES RIVER BASIN IN VA.  REAL-TIME WATER DATA CAN BE
FOUND BY VISITING THE USGS WEB PAGES AT HTTP://WATER.USGS.GOV/.

SOIL MOISTURE CONDITIONS - NORMAL TO VERY MOIST.  THE LONG-TERM PALMER
DROUGHT SEVERITY INDEX IS WIDELY USED TO INFER DEEP SOIL MOISTURE
CONDITIONS.  THE MARCH 2, 2013 INDEX CHART (PLEASE VISIT THE
WWW.CPC.NOAA.GOV/PRODUCTS WEBSITE) INDICATES SOILS ACROSS THE MARFC
SERVICE AREA CONTAIN MOISTURE THAT RANGES FROM NEAR NORMAL TO VERY
MOIST FOR THIS TIME OF YEAR.  THE WETTEST SOILS WITH RESPECT TO NORMAL
ARE CURRENTLY FOUND ACROSS PA.  FOR ADDITIONAL SOIL MOISTURE
INFORMATION VISIT WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING.

GROUND WATER - GENERALLY NEAR NORMAL.  USGS GROUND WATER MONITORING
WELLS ACROSS MOST OF THE MARFC REGION ARE INDICATING NEAR NORMAL
LEVELS.  HOWEVER, SOME MONITORING WELLS LOCATED IN CENTRAL VA AND IN
THE CHESAPEAKE BAY REGION CONTINUE TO INDICATE BELOW NORMAL LEVELS.
PLEASE VISIT HTTP://GROUNDWATERWATCH.USGS.GOV.

RESERVOIR CONDITIONS - ABOUT AVERAGE.  IN GENERAL, MOST MAJOR
RESERVOIRS WITHIN THE MARFC REGION ARE HOLDING NEAR NORMAL STORAGES
FOR THIS TIME OF YEAR.

FUTURE WEATHER CONDITIONS - THE WEATHER DURING THE NEXT WEEK WILL
START OFF WITH A WEAK WEATHER SYSTEM THAT BRINGS SOME LIGHT-MODERATE
SNOW TO NORTHEASTERN PORTIONS OF THE MARFC REGION TONIGHT AND FRIDAY.
HIGH PRESSURE WILL THEN PROVIDE A DRY AND RELATIVELY MILD WEEKEND TO
THE ENTIRE REGION.  A RATHER SLOW-MOVING STORM SYSTEM MAY THEN BRING
WIDESPREAD MODERATE RAIN (POSSIBLY HEAVY) AND SNOWMELT TO MUCH OF THE
MARFC SERVICE AREA EARLY-MID WEEK NEXT WEEK (MARCH 11-13).

AHPS RIVER FORECASTS - NORMAL TO BELOW NORMAL.  THE ADVANCED
HYDROLOGIC PREDICTION SERVICE (AHPS) GENERATES PROBABILISTIC RIVER
FORECASTS BASED ON CURRENT BASIN CONDITIONS (RIVER LEVELS, SOIL
MOISTURE, EXTENT AND CONDITION OF ANY SNOWPACK) ALONG WITH 50 YEARS OF
HISTORIC TEMPERATURE AND PRECIPITATION DATA.  REMEMBER, AHPS RIVER
FORECASTS DO NOT TAKE INTO ACCOUNT ACTUAL FUTURE WEATHER CONDITIONS.
FOR THE NEXT TWO WEEKS (MARCH 7-21, 2013) AHPS RIVER FORECASTS
INDICATE THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC
SERVICE AREA IS IN THE NORMAL TO BELOW NORMAL RANGE.  PLEASE VISIT
WWW.WEATHER.GOV/AHPS/.

ENSEMBLE RIVER FORECASTS - LIMITED RIVER FLOOD THREAT DURING THE NEXT
WEEK.  THE MOST RECENT RUNS (MARCH 7, 2013) OF THE ENSEMBLE RIVER
FORECASTS DO SHOW A LIMITED THREAT OF RIVER FLOODING DEVELOPING WITHIN
THE MARFC SERVICE AREA DURING THE NEXT SEVEN DAYS (THROUGH MARCH 14,
2013).  THIS THREAT IS ASSOCIATED WITH THE WEATHER SYSTEM EXPECTED TO
IMPACT THE REGION EARLY-MID WEEK NEXT WEEK, MARCH 11-13.  PLEASE VISIT
WWW.ERH.NOAA.GOV/MMEFS.

SUMMARY - THE RIVER FLOOD POTENTIAL DURING THE NEXT WEEK THROUGH MARCH
14, 2013 IS STILL CONSIDERED SOMEWHAT BELOW NORMAL ACROSS THE NORTH
AND ABOUT NORMAL ACROSS THE SOUTH.  UP NORTH, FACTORS CONTRIBUTING TO
THE LOWER FLOOD POTENTIAL FOR THIS TIME OF WINTER INCLUDE BELOW NORMAL
SNOW AND RIVER ICE CONDITIONS, AND RECENT BELOW NORMAL PRECIPITATION.
EVEN SO, THE WEATHER SYSTEM DURING THE FIRST PART OF NEXT WEEK WILL
NEED TO BE MONITORED FOR THE POSSIBILITY OF HEAVY RAIN.  FURTHER SOUTH
SNOWMELT FROM THE RECENT SNOWSTORM WILL OCCUR DURING THE NEXT FEW
DAYS.  NEXT WEEK'S RAIN EVENT WILL NEED TO BE MONITORED HERE AS WELL
SINCE IT WILL FOLLOW ON THE HEELS OF THE SNOWMELT.

WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (MARCH 5, 2013)
U.S. DROUGHT MONITOR, A SMALL AREA OF ABNORMALLY DRY CONDITIONS
PERSISTS ACROSS THE UPPER JAMES RIVER BASIN IN VIRGINIA AND A DROUGHT
WATCH ADVISORY CONTINUES FOR THIS AREA AT THIS TIME.  ELSEWHERE, THE
DROUGHT MONITOR SHOWS NO DROUGHT OR DRY CONDITIONS WITHIN THE MARFC
SERVICE AREA.  ASSUMING NEAR NORMAL PRECIPITATION DURING THE NEXT FEW
MONTHS, NO WATER SUPPLY SHORTAGES ARE EXPECTED IN VIRGINIA OR ANYWHERE
ELSE WITHIN THE MARFC REGION THROUGH AT LEAST MAY, 2013.  THE LATEST
(MARCH 7, 2013) NOAA U.S. SEASONAL DROUGHT OUTLOOK STILL SUGGESTS THE
RESIDUAL DRY CONDITIONS ACROSS PORTIONS OF VIRGINIA COULD SHOW
ADDITIONAL IMPROVEMENT DURING THE NEXT THREE MONTHS.  ADDITIONALLY,
THE OUTLOOK IS NOT INDICATING ANY NEW AREAS OF DROUGHT DEVELOPMENT
DURING THE NEXT THREE MONTHS WITHIN THE MARFC SERVICE AREA.  PLEASE
VISIT WWW.CPC.NCEP.NOAA.GOV AND WWW.DROUGHT.GOV FOR DROUGHT-RELATED
DATA AND CHARTS.

PLEASE VISIT THE NWS MARFC HOMEPAGE AT WWW.ERH.NOAA.GOV/ER/MARFC FOR
OTHER HYDROMETEOROLOGICAL INFORMATION.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY THIS OFFICE IN
ONE WEEK, ON MARCH 14, 2013.

SK
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