FGUS61 KRHA 151453
ESGRHA

FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC)
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 1053 AM EDT THU MAR 15 2012 

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

OUTLOOK NUMBER 12-07 (FINAL) - MARCH 15, 2012

THIS OUTLOOK IS VALID FOR THE TWO-WEEK PERIOD MARCH 15-29, 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 - BELOW AVERAGE.  THE RIVER
FLOOD POTENTIAL ACROS THE MARFC SERVICE AREA FOR THE NEXT TWO WEEKS
(THROUGH MARCH 29, 2012) IS CONSIDERED TO BE GENERALLY BELOW NORMAL.
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 13-MARCH 13, 2012) WAS
BELOW AVERAGE (25-75 PERCENT OF NORMAL) ACROSS THE NORTHEASTERN
PORTION OF THE REGION, INCLUDING NORTHEASTERN MD, NORTHERN DE, MUCH OF
SOUTHEASTERN AND FAR EASTERN PA, MOST OF NJ AND SOUTHEASTERN NY.
ELSEWHERE, PRECIPITATION WAS FAIRLY CLOSE TO AVERAGE (70-130 PERCENT
OF NORMAL).  PLEASE VISIT WWW.ERH.NOAA.GOV/ER/MARFC FOR PRECIPITATION
INFORMATION.

SNOW CONDITIONS - MUCH BELOW AVERAGE TO NEAR AVERAGE.  CURRENTLY THERE
IS NO SNOW ON THE GROUND WITHIN THE MARFC SERVICE AREA.  ACROSS THE
NORTHERN HALF OF PA, NY AND EXTREME NORTHWESTERN NJ, CURRENT SNOW
CONDITIONS ARE CONSIDERED BELOW AVERAGE TO MUCH BELOW AVERAGE FOR MID
MARCH.  ELSEWHERE, THE LACK OF SNOW IS NOT AS UNUSUAL AND THEREFORE
SNOW CONDITIONS ARE NEAR AVERAGE.  PLEASE VISIT WWW.NOHRSC.NOAA.GOV
AND WWW.ERH.NOAA.GOV/ER/MARFC FOR SPECIFICS ON SNOW CONDITIONS.

RIVER ICE - BELOW AVERAGE TO NEAR AVERAGE.  NO RIVER ICE EXISTS WITHIN
THE MARFC SERVICE AREA.  THESE CONDITIONS ARE BELOW AVERAGE ACROSS
NORTHERN PA AND NY, BUT CLOSER TO AVERAGE ACROSS MOST OF THE REMAINDER
OF THE MARFC SERVICE AREA.

STREAMFLOW CONDITIONS - BELOW MEDIAN TO NEAR MEDIAN.  ACCORDING TO THE
U.S. GEOLOGICAL SURVEY (USGS) STREAMFLOW FOR RIVERS WITHIN THE MARFC
REGION CURRENTLY RANGES FROM BELOW MEDIAN TO NEAR MEDIAN.  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 MARCH 10, 2012 INDEX CHART
(WWW.CPC.NOAA.GOV/PRODUCTS WEBSITE) INDICATES UNUSUALLY MOIST TO
EXTREMELY MOIST SOILS ACROSS THE NORTH, WITH NEAR NORMAL TO UNUSUALLY
MOIST SOILS ACROSS THE SOUTH.  FOR ADDITIONAL SOIL MOISTURE
INFORMATION VISIT WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING.

GROUND WATER - GENERALLY AROUND NORMAL.  MOST USGS GROUND WATER
MONITORING WELLS WITHIN THE MARFC REGION ARE INDICATING NEAR NORMAL
LEVELS.  HOWEVER, MANY MONITORING WELLS LOCATED IN THE CHESAPEAKE BAY
REGION AND SOUTHEASTERN VA CONTINUE TO SHOW BELOW NORMAL LEVELS.
PLEASE VISIT HTTP://GROUNDWATERWATCH.USGS.GOV FOR CURRENT GROUNDWATER
LEVELS.

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 - UNSEASONABLY MILD WEATHER WILL PERSIST FOR
ALL OF THE MARFC REGION FOR ALL OF THE FIRST WEEK OF THIS OUTLOOK
PERIOD AND WELL INTO THE SECOND WEEK.  CURRENTLY, THERE ARE NO
INDICATIONS OF ANY WIDESPREAD HEAVY RAIN EVENTS FOR AT LEAST THE NEXT
WEEK.  RATHER, GENERALLY ONLY LIGHT-MODERATE RAIN IS ANTICIPATED,
THOUGH ISOLATED HEAVY RAIN IS STILL A POSSIBILITY IN THIS VERY
SPRING-LIKE WEATHER PATTERN.  THERE IS SOME INDICATION THAT A
SIGNIFICANT RAIN EVENT COULD DEVELOP IN THE MARFC REGION DURING THE
SECOND WEEK OF THE OUTLOOK PERIOD, AROUND MARCH 23-25, 2012.  THE
LATEST (MARCH 14, 2012) NWS 6-10 DAY AND 8-14 DAY WEATHER FORECASTS
FOR THE MARFC REGION STILL SUGGEST TEMPERATURES WILL MOST LIKELY BE
ABOVE NORMAL WHEN AVERAGED OVER THE NINE-DAY PERIOD MARCH 20-28, 2012,
WHILE PRECIPITATION WILL MOST LIKELY BE BELOW NORMAL FOR THE SAME
PERIOD.  FINALLY, THE MOST RECENT (RELEASED MARCH 15, 2012) NWS
LONG-RANGE WEATHER OUTLOOKS SUGGEST TEMPERATURES WILL REMAIN GENERALLY
ABOVE NORMAL WHEN AVERAGED OVER THE PERIOD APRIL-JUNE, 2012.
MEANWHILE, THE MARFC REGION HAS NEARLY EQUAL CHANCES OF SEEING BELOW
NORMAL, NORMAL, OR ABOVE NORMAL PRECIPITATION DURING THE NEXT THREE
MONTHS.  PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV.

AHPS RIVER FORECASTS - GENERALLY 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 15-29, 2012) AHPS RIVER FORECASTS
INDICATE THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC
SERVICE AREA IS GENERALLY BELOW AVERAGE.  PLEASE VISIT
WWW.WEATHER.GOV/AHPS/.

EXPERIMENTAL ENSEMBLE RIVER FORECASTS - NO RIVER FLOOD THREAT DURING
AT LEAST 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 (MARCH
14-15, 2012) OF THE EXPERIMENTAL ENSEMBLE RIVER FORECASTS INDICATE
ESSENTIALLY NO THREAT OF RIVER FLOODING WITHIN THE MARFC SERVICE AREA
DURING THE NEXT 7-8 DAYS (THROUGH MARCH 22, 2012).  PLEASE VISIT
WWW.ERH.NOAA.GOV/MMEFS TO VIEW THESE EXPERIMENTAL FORECASTS.

SUMMARY - THE RIVER FLOOD POTENTIAL DURING THE NEXT TWO WEEKS THROUGH
MARCH 29, 2012 IS CONSIDERED GENERALLY BELOW NORMAL THROUGHOUT THE
MARFC SERVICE AREA.  WITH THE EXCEPTION OF SOIL MOISTURE, MOST FACTORS
THAT CONTRIBUTE TO RIVER FLOOD POTENTIAL ARE PRESENTLY IN THE NORMAL
TO BELOW NORMAL RANGE WITHIN THE MARFC REGION.  THIS MEANS THAT FOR
RIVER FLOODING TO DEVELOP, AT LEAST ONE (BUT MORE LIKELY TWO)
WIDESPREAD HEAVY RAIN EVENTS WOULD BE REQUIRED.  AT THIS TIME THERE
ARE NO INDICATIONS OF ANY WIDESPREAD HEAVY RAIN EVENTS FOR AT LEAST
THE FIRST WEEK OF THIS OUTLOOK PERIOD.  SIGNIFICANT RAINFALL MAY OCCUR
IN THE SECOND WEEK, BUT BY NO MEANS IS THIS A CERTAINTY.

WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (MARCH 13, 2012)
U.S. DROUGHT MONITOR, A SMALL AREA OF MODERATE DROUGHT CONDITIONS
PERSISTS OVER A PORTION OF THE DELMARVA PENINSULA, AND IT CONTINUES TO
BE ABNORMALLY DRY ACROSS A LARGER AREA THAT INCLUDES SOUTHEASTERN VA,
MUCH OF THE REST OF THE DELMARVA PENINSULA AND EXTREME 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 MAY, 2012.  THE LATEST (MARCH 15, 2012) NOAA
U.S. SEASONAL DROUGHT OUTLOOK SUGGESTS THE ABNORMALLY DRY CONDITIONS
ACROSS THE DELMARVA REGION MAY IMPROVE DURING THE NEXT THREE MONTHS.
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.

THIS WILL BE THE FINAL WINTER/SPRING FLOOD OUTLOOK ISSUED BY THIS
OFFICE FOR THE 2011-2012 SEASON, UNLESS CONDITIONS WARRANT OTHERWISE.

SK
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