FGUS61 KRHA 021916
ESGRHA

FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC)
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 215 PM EST THU FEB 02 2012 

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

OUTLOOK NUMBER 12-03 - FEBRUARY 2, 2012

THIS OUTLOOK IS VALID FOR THE TWO-WEEK PERIOD FEBRUARY 2-16, 2012.
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
INCLUDES THE LATEST NWS EXTENDED-RANGE (6-10 AND 8-14 DAY) WEATHER
FORECASTS DISCUSSED BELOW IN THE FUTURE WEATHER CONDITIONS SECTION.
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 OUTLOOK - GENERALLY A LITTLE BELOW
AVERAGE.  THE RIVER FLOOD POTENTIAL ACROS THE MARFC SERVICE AREA FOR
THE NEXT TWO WEEKS (THROUGH FEBRUARY 16, 2012) IS NOW CONSIDERED
SOMEWHAT BELOW AVERAGE FOR MOST OF THE MARFC REGION.  FACTORS WHICH
CONTRIBUTE TO RIVER FLOOD POTENTIAL ARE ADDRESSED INDIVIDUALLY BELOW.

CURRENT FLOODING - NONE.

RECENT PRECIPITATION - ABOUT AVERAGE TO BELOW AVERAGE.  PRECIPITATION
WITHIN THE MARFC SERVICE AREA DURING THE LAST 30 DAYS (JANUARY
3-FEBRUARY 1, 2012) WAS AROUND AVERAGE (75-125 PERCENT OF NORMAL)
ACROSS ABOUT THE NORTHWESTERN HALF OF THE MARFC REGION, INCLUDING NY,
NORTHERN NJ, MOST OF PA, AND MOST OF THE APPALACHIAN MOUNTAIN REGION.
MEANWHILE, PRECIPITATION WAS BELOW AVERAGE (MUCH BELOW AVERAGE IN SOME
LOCATIONS) ACROSS ABOUT THE SOUTHEASTERN HALF, INCLUDING MUCH OF VA,
THE DELMARVA PENINSULA, EASTERN MD AND SOUTHERN NJ.  IN THIS REGION
PRECIPITATION WAS GENERALLY ONLY 30-75 PERCENT OF NORMAL.  PLEASE
VISIT WWW.ERH.NOAA.GOV/ER/MARFC FOR PRECIPITATION INFORMATION.

SNOW CONDITIONS - MUCH BELOW AVERAGE TO NEAR AVERAGE.  ALTHOUGH SOME
SNOW HAS FALLEN DURING THE LAST TWO WEEKS IN SOME AREAS, ALL OF IT HAS
MELTED.  PRESENTLY THERE IS NO HYDROLOGICALLY SIGNIFICANT SNOW ON THE
GROUND WITHIN THE MARFC SERVICE AREA.  THIS IS RARE FOR THIS TIME OF
YEAR ACROSS ABOUT THE NORTHWESTERN HALF OF THE MARFC SERVICE AREA
WHERE CURRENT SNOW CONDITIONS ARE BELOW AVERAGE TO MUCH BELOW AVERAGE.
MEANWHILE, FURTHER SOUTH AND EAST CURRENT SNOW CONDITIONS MAY BE
CONSIDERED CLOSER TO AVERAGE AS THIS AREA OFTEN HAS LITTLE OR NO SNOW
ON THE GROUND DURING MOST WINTERS.  PLEASE VISIT WWW.NOHRSC.NOAA.GOV
AND WWW.ERH.NOAA.GOV/ER/MARFC FOR SPECIFICS ON SNOW CONDITIONS.

RIVER ICE - MUCH BELOW AVERAGE TO NEAR AVERAGE.  NO HYDROLOGICALLY
SIGNIFICANT RIVER ICE EXISTS WITHIN THE MARFC SERVICE AREA.  THE
ABSENCE OF SIGNIFICANT RIVER ICE ACROSS THE NORTHWESTERN HALF OF THE
MARFC SERVICE AREA IS QUITE UNUSUAL FOR THIS TIME OF YEAR, HENCE
CURRENT RIVER ICE CONDITIONS THERE ARE MUCH BELOW AVERAGE.  FURTHER
SOUTH AND EAST, CURRENT RIVER ICE CONDITIONS ARE CLOSER TO AVERAGE AS
THIS AREA OFTEN HAS LITTLE OR NO RIVER ICE DURING MOST WINTERS.

STREAMFLOW CONDITIONS - NEAR MEDIAN TO ABOVE MEDIAN.  SIMILAR TO TWO
WEEKS AGO, STREAMFLOW IS CURRENTLY IN THE MEDIAN TO ABOVE MEDIAN RANGE
ACROSS MUCH OF THE MARFC REGION.  ACCORDING TO THE U.S. GEOLOGICAL
SURVEY (USGS) MOST STREAMGAGES ACROSS THE MARFC REGION ARE REPORTING
FLOWS THAT ARE 80-500 PERCENT OF MEDIAN FOR THIS TIME OF YEAR.
STREAMFLOW IS HIGHEST WITH RESPECT TO MEDIAN ACROSS THE NORTHERN HALF
OF THE MARFC SERVICE AREA, WHILE FURTHER SOUTH STREAMFLOW IS LOWER
WITH RESPECT TO MEDIAN.  SOMEWHAT BELOW MEDIAN FLOW (ABOUT 50 PERCENT
OF MEDIAN) CURRENTLY EXISTS ACROSS THE APPOMATTOX BASIN IN VA AND
ACROSS LOWER PORTIONS OF THE DELMARVA PENINSULA.  REAL-TIME WATER DATA
CAN BE FOUND BY VISITING THE USGS WEB PAGES AT HTTP://WATER.USGS.GOV/.
SOIL MOISTURE CONDITIONS - NORMAL TO MUCH ABOVE NORMAL.  THE LONG-TERM
PALMER DROUGHT SEVERITY INDEX IS WIDELY USED TO INFER DEEP SOIL
MOISTURE CONDITIONS.  THE JANUARY 28, 2012 INDEX CHART
(WWW.CPC.NOAA.GOV/PRODUCTS WEBSITE) INDICATES EXTREMELY MOIST SOILS
ACROSS THE NORTH, WITH NEAR NORMAL TO VERY MOIST SOILS ACROSS THE
SOUTH.  PLEASE SEE WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING
FOR INFORMATION.

GROUND WATER - GENERALLY NORMAL TO ABOVE NORMAL.  MOST USGS GROUND
WATER MONITORING WELLS CONTINUE TO INDICATE ABOVE NORMAL (IN SOME
AREAS MUCH ABOVE NORMAL) LEVELS ACROSS THE NORTHERN TWO-THIRDS OF THE
MARFC SERVICE AREA, WHILE FURTHER SOUTH GROUND WATER CONDITIONS ARE
CLOSER TO NORMAL.  HOWEVER, SOME MONITORING WELLS ACROSS PORTIONS OF
THE CHESAPEAKE BAY REGION AND SOUTHEASTERN VA ARE SHOWING BELOW NORMAL
LEVELS.  PLEASE VISIT HTTP://GROUNDWATERWATCH.USGS.GOV/.

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

FUTURE WEATHER CONDITIONS - SIX MORE WEEKS OF WINTER WAS PREDICTED
THIS MORNING BY THE GROUNDHOG IN PA, THOUGH THE WINTER OF 2011-12 HAS
SO FAR BEEN ANYTHING BUT SEVERE WITHIN THE MARFC AREA OF
RESPONSIBILITY.  A WEAK STORM SYSTEM WILL BRING MOSTLY LIGHT-MODERATE
PRECIPITATION TO MAINLY SOUTHERN PORTIONS OF THE MARFC REGION THIS
WEEKEND.  FOLLOWING THIS SYSTEM, COOLER (THOUGH STILL NOT COLD)
TEMPERATURES ARE EXPECTED MUCH OF NEXT WEEK ALONG WITH GENERALLY ONLY
LIGHT PRECIPITATION EVENTS.  AT THE PRESENT TIME THERE ARE NO
INDICATIONS OF ANY WIDESPREAD HEAVY RAIN EVENTS AFFECTING THE MARFC
REGION FOR AT LEAST THE NEXT SEVEN DAYS (THROUGH FEBRUARY 9).  THE
LATEST (FEBRUARY 1, 2012) NWS 6-10 DAY AND 8-14 DAY WEATHER FORECASTS
FOR THE MARFC REGION SUGGEST BOTH TEMPERATURES AND PRECIPITATION WILL
MOST LIKELY BE ABOUT NORMAL WHEN AVERAGED OVER THE NINE-DAY PERIOD
FEBRUARY 7-15, 2012.  THE NWS OUTLOOK FOR THE MARFC REGION FOR THE
REST OF THE WINTER AND INTO EARLY SPRING (THROUGH APRIL, 2012)
SUGGESTS NORMAL TO ABOVE NORMAL TEMPERATURES AND PRECIPITATION.
PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV.

AHPS RIVER FORECASTS - NORMAL TO A LITTLE 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 (FEBRUARY 2-16, 2012) AHPS RIVER FORECASTS
INDICATE THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC
SERVICE AREA IS NEAR TO SLIGHTLY BELOW AVERAGE.  PLEASE VISIT
WWW.WEATHER.GOV/AHPS/.

EXPERIMENTAL ENSEMBLE RIVER FORECASTS - NO RIVER FLOOD THREAT DURING
ABOUT THE NEXT WEEK ACROSS THE MARFC SERVICE AREA.  A RELATIVELY NEW
TOOL IS CURRENTLY BEING TESTED BY THE NWS TO AID IN ASSESSING LONGER
TERM RIVER FLOOD POTENTIAL.  THE PROCESS USES PRECIPITATION AND
TEMPERATURE DATA DERIVED FROM NUMEROUS NUMERICAL WEATHER PREDICTION
MODELS DIRECTLY AS INPUT INTO HYDROLOGIC MODELS TO GENERATE RIVER
FORECASTS FOR UP TO ONE WEEK INTO THE FUTURE FOR LOCATIONS WITHIN THE
MARFC SERVICE AREA.  THE RIVER FORECASTS ARE AUTOMATICALLY GENERATED
FROM COMPUTER MODELS WITHOUT THE ADDED EXPERTISE AND EXPERIENCE OF
HUMAN FORECASTERS, AND SEVERAL ASSUMPTIONS ARE MADE IN THE GENERATION
OF THE FORECASTS.  SINCE EACH NEW RUN OF WEATHER PREDICTION MODELS CAN
GENERATE DRASTICALLY DIFFERENT FORECASTS OF PRECIPITATION AND
TEMPERATURES, THE RESULTANT RIVER FORECASTS MAY ALSO SHOW DRAMATIC
RUN-TO-RUN VARIABILITY, AS WELL AS VERY WIDE RANGES OF POSSIBILITIES.
THESE EXPERIMENTAL FORECASTS SHOULD BE USED WITH CAUTION AND TREATED
AS ANOTHER TOOL TO TRY TO ASSESS RIVER FLOOD POTENTIAL FOR UP TO ONE
WEEK INTO THE FUTURE.  WITH THIS IN MIND, THE MOST RECENT RUNS
(FEBRUARY 2, 2012) OF THE EXPERIMENTAL ENSEMBLE RIVER FORECASTS
INDICATE VIRTUALLY NO THREAT OF RIVER FLOODING WITHIN THE MARFC
SERVICE AREA DURING THE NEXT 6-7 DAYS (THROUGH FEBRUARY 9, 2012).
PLEASE VISIT WWW.ERH.NOAA.GOV/MMEFS TO VIEW THESE EXPERIMENTAL
FORECASTS.

SUMMARY - THE RIVER FLOOD POTENTIAL DURING THE NEXT TWO WEEKS THROUGH
FEBRUARY 16, 2012 IS NOW CONSIDERED SOMEWHAT BELOW NORMAL.  ALTHOUGH
SOILS IN MANY AREAS ARE STILL WET AND STREAMFLOW CONDITIONS STILL
ELEVATED, THERE IS STILL NO SIGNIFICANT SNOW ON THE GROUND AT THIS
TIME WITHIN THE MARFC REGION, NOR IS THERE ANY RIVER ICE.
ADDITIONALLY THERE ARE NO INDICATIONS OF ANY WIDESPREAD HEAVY RAIN
EVENTS FOR THE MARFC AREA FOR AT LEAST THE NEXT WEEK.  LONGER RANGE
WEATHER OUTLOOKS SUGGEST FAIRLY TYPICAL TEMPERATURES AND PRECIPITATION
DURING THE NEXT TWO WEEKS.  TAKEN ALL TOGETHER, DURING THE NEXT TWO
WEEKS RIVERS WITHIN THE MARFC SERVICE AREA WILL HAVE A SOMEWHAT BELOW
NORMAL CHANCE OF FLOODING FOR THIS TIME OF YEAR.

WATER SUPPLY OUTLOOK - NO DROUGHT CONDITIONS CURRENTLY EXIST WITHIN
THE MARFC REGION.  HOWEVER, IT IS GETTING INCREASINGLY DRIER ACROSS
SOUTHEASTERN VA, THE DELMARVA PENINSULA AND SOUTHERN NJ.  STILL,
ASSUMING NEAR NORMAL PRECIPITATION DURING THE NEXT FEW MONTHS, NO
WATER SUPPLY SHORTAGES ARE EXPECTED ANYWHERE WITHIN THE MARFC REGION
THROUGH AT LEAST APRIL, 2012.  HOWEVER, IF BELOW AVERAGE RAINFALL
CONTINUES ACROSS THE SOUTHEASTERN PORTIONS OF THE MARFC REGION SOME
DROUGHT CONDITIONS COULD DEVELOP THERE IN THE NEXT COUPLE OF MONTHS
WHICH COULD EVENTUALLY LEAD TO SOME WATER SHORTAGES IN THE SUMMER
MONTHS.  THE LATEST NOAA U.S. SEASONAL DROUGHT OUTLOOK (FEBRUARY 2)
SHOWS THIS POTENTIAL FOR DROUGHT DEVELOPMENT.  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 ON
THURSDAY, FEBRUARY 16, 2012.

SK
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