Extended Streamflow Guidance
Issued by NWS Middle Atlantic RFC

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FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC)
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 1222 PM EDT THU MAR 19 2015

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

OUTLOOK NUMBER 15-07 - MARCH 19, 2015

THIS SEVENTH OUTLOOK IS VALID FOR THE TWO-WEEK PERIOD MARCH 19-APRIL 2,
2015.

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

TWO-WEEK RIVER FLOOD POTENTIAL - THE RIVER FLOOD POTENTIAL DURING THE
NEXT TWO WEEKS IS ABOUT AVERAGE FOR WEEK ONE AND SOMEWHAT ABOVE AVERAGE
FOR WEEK TWO ACROSS ABOUT THE NORTHERN THIRD OF THE MARFC REGION.
ELSEWHERE THE RIVER FLOOD POTENTIAL DURING THE NEXT TWO WEEKS IS NEAR
AVERAGE.  FACTORS WHICH CONTRIBUTE TO RIVER FLOOD POTENTIAL ARE
DISCUSSED BELOW.

CURRENT FLOODING - NONE.

RECENT PRECIPITATION - BELOW/MUCH-BELOW NORMAL NORTH, NEAR/ABOVE NORMAL
ESLEWHERE.  PRECIPITATION (LIQUID EQUIVALENT) DURING THE LAST 30 DAYS
(FEBRUARY 16-MARCH 17, 2015) WAS BELOW NORMAL TO MUCH-BELOW NORMAL
ACROSS NY, MUCH OF PA, NORTHERN NJ, WESTERN MD, PORTIONS OF
NORTHEASTERN WV AND A SMALL AREA IN EXTREME SOUTHEASTERN VA.  IN THIS
REGION GENERALLY 0.75-2.75 INCHES OF PRECIPITATION FELL WHICH WAS
10-70 PERCENT BELOW NORMAL.  MEANWHILE PRECIPITATION DURING THE LAST 30
DAYS ACROSS THE REMAINDER OF THE MARFC SERVICE AREA WAS NEAR NORMAL TO
MUCH-ABOVE NORMAL.  THIS INCLUDES SOUTHEASTERN PA, CENTRAL AND SOUTHERN
NJ, THE DELMARVA PENINSULA, CENTRAL MD, PORTIONS OF NORTHEASTERN WV AND
MOST OF VA.  IN THESE AREAS GENERALLY 2.5-6.0 INCHES OF PRECIPITATION
FELL, WHICH WAS 0-85 PERCENT ABOVE NORMAL.  THE HEAVIEST PRECIPITATION
WITH RESPECT TO NORMAL FELL ACROSS SOUTHERN AND EASTERN PORTIONS OF THE
MARFC REGION.  PLEASE VISIT WWW.ERH.NOAA.GOV/ER/MARFC.

SNOW CONDITIONS - ABOVE NORMAL ACROSS FAR NORTHERN AREAS, NEAR NORMAL
ELSEWHERE.  CURRENTLY WITHIN THE MARFC SERVICE AREA SNOW COVERS THE
GROUND ACROSS THE HIGHER ELEVATIONS OF THE WEST BRANCH SUSQUEHANNA
BASIN IN PA, ACROSS MOST OF THE NY BASINS, AND ACROSS NORTHEASTERN PA
AND NORTHWESTERN NJ.  OUTSIDE OF THESE AREAS, THE SNOW COVER QUICKLY
BECOMES PATCHY IN NATURE AND ESSENTIALLY HYDROLOGICALLY INSIGNIFICANT.
THE GREATEST SNOW DEPTHS ARE STILL FOUND ACROSS PORTIONS OF NY WHERE
GENERALLY 2-18 INCHES WITH LOCALLY GREATER DEPTHS EXIST.  ACROSS THE
REMAINDER OF THE SNOW COVERED AREAS IN PA AND NJ DEPTHS OF 1-10 INCHES
ARE COMMON, AGAIN WITH LOCALLY HIGHER AMOUNTS.  SNOW WATER EQUIVALENT
VALUES OF 2.0-4.5 INCHES WITH LOCALLY HIGHER AMOUNTS EXIST IN THE
NORTH BRANCH SUSQUEHANNA BASIN IN NY, WHILE VALUES IN THE REMAINING
SNOW-COVERED AREAS ARE GENERALLY 0.5-2.5 INCHES WITH LOCALLY HIGHER
AMOUNTS.  SNOW CONDITIONS ARE ABOVE NORMAL FOR LATE WINTER IN MAINLY
JUST THE UPPER PORTIONS OF THE SUSQUEHANNA AND DELAWARE BASINS IN NY.
OTHERWISE, SNOW CONDITIONS ARE FAIRLY TYPICAL FOR LATE WINTER.  SOME
ADDITIONAL MODERATE SNOW ACCUMULATIONS ARE POSSIBLE DURING THE NEXT 48
HOURS ACROSS PORTIONS OF THE MARFC SERVICE AREA, BUT MUCH OF THIS
PREDICTED NEW SNOW WILL MELT WITH LITTLE IMPACT IN JUST A FEW DAYS.
MEANWHILE, MEANINGFUL MELT IN THE NORTH BRANCH SUSQUEHANNA BASIN MAY
HAVE TO WAIT ANOTHER WEEK OR SO BASED ON CURRENT PREDICTIONS OF
TEMPERATURES IN THAT REGION.  FOR DETAILED SNOW INFORMATION PLEASE
VISIT WWW.NOHRSC.NOAA.GOV AND WWW.WEATHER.GOV/MARFC.

RIVER ICE - ABOVE AVERAGE TO AVERAGE.  PORTIONS OF BOTH THE SUSQUEHANNA
AND DELAWARE RIVER BASINS IN NY, PA AND NORTHWESTERN NJ STILL HAVE
ENOUGH RIVER ICE THAT ISOLATED ICE JAMS/ICE JAM FLOODING COULD STILL
OCCUR.  THIS THREAT WILL CONTINUE FOR ANOTHER WEEK OR SO WHILE SLOWLY
DECREASING AS THE REMAINING RIVER ICE CONTINUES TO DECAY AND WEAKEN.
RIVER ICE CONDITIONS ARE SOMEWHAT ABOVE AVERAGE UP NORTH FOR THIS LATE
IN WINTER.

STREAMFLOW CONDITIONS - GENERALLY NEAR NORMAL TO ABOVE NORMAL.  LATEST
DATA FROM THE U.S. GEOLOGICAL SURVEY (USGS) INDICATES THAT STREAMFLOW
ACROSS MOST OF THE MARFC SERVICE AREA IS IN THE MEDIAN TO ABOVE MEDIAN
RANGE THANKS TO RECENT SNOWMELT.  SOME GAGES IN NY AND PA CONTINUE TO
BE AFFECTED BY RIVER ICE AND THEREFORE DO NOT REPRESENT ACTUAL
STREAMFLOW CONDITIONS.  PLEASE VISIT WWW.USGS.GOV/WATER FOR REAL-TIME
STREAMFLOW DATA.

SOIL MOISTURE CONDITIONS - NORMAL TO ABOVE NORMAL.  THE LONG-TERM
PALMER DROUGHT SEVERITY INDEX IS WIDELY USED TO INFER DEEP SOIL
MOISTURE CONDITIONS.  THE MOST RECENT (MARCH 14, 2015) INDEX CHART
(WWW.CPC.NOAA.GOV/PRODUCTS) SUGGESTS SOILS ACROSS MOST OF THE MARFC
SERVICE AREA CONTAIN MOISTURE THAT RANGES FROM NEAR NORMAL TO ABOVE
NORMAL FOR THIS TIME OF YEAR.  FOR ADDITIONAL SOIL MOISTURE INFORMATION
PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US.

GROUND WATER - NEAR NORMAL TO BELOW NORMAL.  USGS GROUND WATER
MONITORING WELLS ACROSS THE MARFC REGION ARE CURRENTLY INDICATING THAT
GROUND WATER LEVELS ARE GENERALLY IN THE NORMAL TO BELOW NORMAL RANGE.
MANY WELLS WITHIN THE MARFC REGION HAVE SHOWN, OR ARE BEGINNING TO SHOW
RECOVERY DUE TO RECENT SNOW AND FROST MELT ALONG WITH RAIN IN SOME
AREAS.  PLEASE VISIT HTTP://GROUNDWATERWATCH.USGS.GOV FOR MONITORING
INFORMATION.

RESERVOIR CONDITIONS - GENERALLY ABOUT AVERAGE.  IN GENERAL, MOST
MAJOR RESERVOIRS WITHIN THE MARFC REGION ARE HOLDING STORAGES THAT ARE
FAIRLY CLOSE TO AVERAGE FOR THIS TIME OF YEAR.  RESERVOIR STORAGE IN
THE UPPER DELAWARE RIVER BASIN IS CURRENTLY BELOW MEDIAN FOR THE DATE
BUT IS EXPECTED TO RECOVER ONCE SIGNIFICANT SNOWMELT OCCURS.

FUTURE WEATHER CONDITIONS - A WEATHER SYSTEM WILL LIKELY RESULT IN
LIGHT TO MODERATE ACCUMULATIONS OF SNOW ACROSS ABOUT THE NORTHERN
TWO-THIRDS OF THE MARFC REGION DURING THE NEXT 36 HOURS.  RAIN WILL
FALL TO THE SOUTH.  A COLD FRONT WILL CROSS THE MARFC REGION SATURDAY,
FOLLOWED BY COLDER AND RELATIVELY DRY WEATHER.  MILDER TEMPERATURES
OVERSPREAD THE REGION MIDWEEK NEXT WEEK WITH ANOTHER COLD FRONTAL
PASSAGE AROUND NEXT THURSDAY.  AT THE PRESENT TIME THERE ARE NO
INDICATIONS OF ANY WIDESPREAD HEAVY RAIN EVENTS FOR ABOUT THE NEXT
WEEK.  THERE ARE ALSO NO STRONG INDICATIONS OF ANY SIGNIFICANT WARM
PERIODS THAT MIGHT RAPIDLY MELT THE REMAINING SNOW ACROSS NORTHERN
PORTIONS OF THE REGION DURING ABOUT THE NEXT WEEK.  IN FACT,
TEMPERATURES FOR MOST OF THE MARFC REGION ARE PREDICTED TO BE IN THE
BELOW-NORMAL TO NORMAL RANGE FOR MOST OF THE NEXT TWO WEEKS, WHILE
PRECIPITATION IS PREDICTED TO BE IN THE NORMAL TO ABOVE-NORMAL RANGE.
PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV FOR LONGER-RANGE WEATHER OUTLOOKS.

AHPS RIVER FORECASTS - NORMAL TO SOMEWHAT ABOVE 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 19-APRIL 2, 2015) AHPS RIVER FORECASTS
INDICATE THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC SERVICE
AREA RANGES FROM NEAR NORMAL TO ABOVE NORMAL FOR MOST MARFC RIVER
BASINS.  KEEP IN MIND THAT THIS NEXT TWO-WEEK PERIOD IS, ON AVERAGE,
THE TIME OF YEAR WHEN FLOODING IS MOST LIKELY TO OCCUR WITHIN THE MARFC
SERVICE AREA.  PLEASE VISIT WWW.WEATHER.GOV/AHPS/.

ENSEMBLE RIVER FORECASTS - A MINIMAL THREAT OF FLOODING.  THE MOST
RECENT RUNS (MARCH 19, 2015) OF THE ENSEMBLE RIVER FORECASTS SHOW A
MINIMAL THREAT OF RIVER FLOODING DEVELOPING IN THE NORTH BRANCH
SUSQUEHANNA RIVER BASIN IN NY AROUND MIDWEEK NEXT WEEK.  THIS MINIMAL
THREAT IS ASSOCIATED WITH SOME POSSIBLE SNOWMELT AND RAINFALL DURING
THAT TIME PERIOD IN ADVANCE OF A COLD FRONT.  REMEMBER THAT ENSEMBLE
RIVER FORECASTS DO NOT ACCOUNT FOR RIVER ICE CONDITIONS AND THEREFORE
DO NOT PREDICT ICE JAMS/ICE JAM FLOODING.  PLEASE VISIT
WWW.ERH.NOAA.GOV/MMEFS.

SUMMARY - THE RIVER FLOOD POTENTIAL IN THE MARFC REGION DURING THE NEXT
TWO WEEKS IS GENERALLY NORMAL TO SOMEWHAT ABOVE NORMAL.  THE GREATEST
THREAT OF RIVER FLOODING (SOMEWHAT ABOVE NORMAL) DEVELOPING IS DURING
THE SECOND WEEK OF THIS OUTLOOK PERIOD, WHEN WARMER TEMPERATURES AND
RAINFALL MAY FINALLY ARRIVE ACROSS THE UPPER PORTIONS OF THE
SUSQUEHANNA AND DELAWARE RIVER BASINS IN NY WHERE SOME SIGNIFICANT SNOW
AND RIVER ICE REMAINS.  OTHERWISE, THE DEVELOPMENT OF RIVER FLOODING
DURING THE NEXT TWO WEEKS WILL DEPEND ALMOST ENTIRELY UPON SIGNIFICANT
RAINFALL OCCURING.  AT THE PRESENT TIME THERE ARE NO INDICATIONS OF A
WIDESPREAD HEAVY RAIN EVENT FOR ABOUT THE NEXT WEEK.  WEATHER
CONDITIONS BEYOND THE NEXT WEEK ARE UNCLEAR AT THIS TIME.

WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (MARCH 17, 2015) U.S.
DROUGHT MONITOR, ABNORMALLY DRY CONDITIONS ARE STILL FOUND ACROSS
PORTIONS OF THE MARFC SERVICE AREA.  THIS INCLUDES PORTIONS OF NY, NJ,
PA AND VA.  HOWEVER NO TRUE DROUGHT CONDITIONS CURRENTLY EXIST
WITHIN THE MARFC SERVICE AREA, NOR ARE ANY EXPECTED TO DEVELOP DURING
THE NEXT FEW MONTHS.  LIKEWISE ASSUMING NEAR-NORMAL PRECIPITATION
DURING THE NEXT FEW MONTHS, NO WATER SUPPLY SHORTAGES ARE EXPECTED
ANYWHERE WITHIN THE MARFC REGION THROUGH AT LEAST JUNE, 2015.  PLEASE
SEE WWW.DROUGHT.GOV, WWW.CPC.NCEP.NOAA.GOV AND
WWW.WEATHER.GOV/MARFC/WRO_UPDATE FOR ADDITIONAL DROUGHT AND WATER
SUPPLY INFORMATION.

FINALLY, PLEASE VISIT THE NWS MARFC HOMEPAGE AT
WWW.WEATHER.GOV/MARFC FOR OTHER HYDROMETEOROLOGICAL INFORMATION.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY THIS OFFICE IN
TWO WEEKS, ON THURSDAY, APRIL 2, 2015 IF CONDITIONS WARRANT.

SK
$$

....END MARFC....
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