FGUS61 KRHA 062232
ESGRHA

FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 532 PM EST THU MAR 06 2008 
 
WINTER/SPRING RIVER FLOOD POTENTIAL OUTLOOK
MIDDLE ATLANTIC RIVER FORECAST CENTER

OUTLOOK NUMBER 08-5 MARCH 6, 2008

INTRODUCTION - THE MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC) IS
ONE OF 13 NATIONAL WEATHER SERVICE (NWS) RIVER FORECAST CENTERS
LOCATED ACROSS THE CONTINENTAL UNITED STATES.  MAJOR RIVER BASINS
LOCATED WITHIN THE MARFC AREA OF RESPONSIBILITY INCLUDE THE
SUSQUEHANNA, DELAWARE, RARITAN, PASSAIC, POTOMAC, SHENANDOAH,
RAPPAHANNOCK, JAMES AND APPOMATTOX.  STATES LOCATED WITHIN THE MARFC
AREA OF RESPONSIBILITY INCLUDE ALL/PORTIONS OF NEW YORK, PENNSYLVANIA,
NEW JERSEY, WEST VIRGINIA, MARYLAND, DELAWARE AND VIRGINIA.

THE FOLLOWING OUTLOOK ESTIMATES THE POTENTIAL FOR RIVER FLOODING (NOT
FLASH FLOODING) 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.

THIS OUTLOOK IS VALID FOR THE ONE WEEK PERIOD MARCH 6-13, 2008, AND
INCLUDES THE LATEST NWS EXTENDED-RANGE (6-10 DAY) WEATHER FORECAST.
FOR THE MARFC SERVICE AREA, THIS FORECAST SUGGESTS THAT TEMPERATURES
AVERAGED OVER THE FIVE-DAY PERIOD FROM MARCH 11-15, 2008 WILL LIKELY
BE BELOW NORMAL, WHILE PRECIPITATION AVERAGED OVER THE SAME FIVE DAYS
WILL LIKELY BE NORMAL TO BELOW NORMAL.  TO VIEW MEDIUM AND LONG-RANGE
WEATHER OUTLOOKS, PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV/.

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.

CURRENT RIVER FLOOD POTENTIAL - ABOVE AVERAGE ACROSS THE NORTHERN
TWO-THIRDS OF THE SERVICE AREA, INCLUDING THE POTOMAC, SUSQUEHANNA,
DELAWARE AND NEW JERSEY RIVER BASINS.  SOMEWHAT BELOW AVERAGE TO THE
SOUTH.

CURRENT FLOODING - PRESENTLY ABOUT 12 MARFC FORECAST POINTS STILL HAVE
WATER LEVELS ABOVE FLOOD STAGE, MAINLY IN THE SUSQUEHANNA BASIN.  MOST
OF THIS MINOR FLOODING WILL END DURING THE NEXT 24 HOURS, EXCEPT FOR
ONE OR TWO LOCATIONS WHERE FLOODING COULD LINGER INTO SATURDAY.

RECENT PRECIPITATION - VARIABLE.  DURING THE LAST 30 DAYS
(02/05/08-03/05/08) PRECIPITATION WAS MUCH ABOVE NORMAL ACROSS PA, NY
AND THE NORTHERN HALF OF NJ.  HEADING SOUTH, PRECIPITATION WAS NORMAL
TO ABOVE NORMAL ACROSS NORTHEASTERN WV, MOST OF MD, NORTHERN DE AND
THE SOUTHERN HALF OF NJ.  FURTHER SOUTH PRECIPITATION WAS ABOUT NORMAL
ACROSS NORTHERN VA, AND BELOW NORMAL ACROSS CENTRAL VA AND MUCH OF THE
DELMARVA PENINSULA.  PRECIPITATION WAS GENERALLY IN THE 5-10 INCH
RANGE ACROSS PA, NY AND THE NORTHERN HALF OF NJ.  HEAVIEST AMOUNTS OF
7-10 INCHES FELL ACROSS THE UPPER HALF OF THE DELAWARE RIVER BASIN.
ELSEWHERE, PRECIPITATION WAS GENERALLY IN THE 2-4.5 INCH RANGE.  THE
JAMES BASIN IN CENTRAL VA ONCE AGAIN RECEIVED THE LEAST AMOUNT OF
PRECIPITATION, 2-3 INCHES.  PLEASE VISIT WWW.ERH.NOAA.GOV/ER/MARFC TO
VIEW PRECIPITATION DEPARTURE MAPS.

SNOW CONDITIONS - MUCH BELOW AVERAGE TO ABOUT AVERAGE.  SNOW COVER IS
PRESENTLY LIMITED TO ABOUT THE NORTHERN THIRD OF THE MARFC SERVICE
AREA, FROM THE VICINITY OF INTERSTATE ROUTE 80 IN PENNSYLVANIA
NORTHWARD.  IN THIS REGION SNOW WATER EQUIVALENT VALUES ARE GENERALLY
IN THE 0.5-2.0 INCH RANGE, EXCEPT IN THE CATSKILL MOUNTAINS WHERE SOME
VALUES OF 2-3 INCHES EXIST.  SNOW DEPTHS IN THIS SAME REGION ARE
GENERALLY LESS THAN SIX INCHES, EXCEPT IN THE HIGHER ELEVATIONS WHERE
DEPTHS OF 6-18 INCHES ARE FOUND.  WHERE SNOW EXISTS, THE CURRENT SNOW
CONDITIONS ARE GENERALLY BELOW AVERAGE FOR EARLY MARCH WHICH IS
CONSIDERED TO BE THE PEAK OF THE SNOW SEASON WITHIN THE MARFC SERVICE
AREA.  HOWEVER, THERE ARE AREAS WHERE SNOW WATER EQUIVALENT VALUES ARE
CLOSE TO NORMAL FOR THIS TIME OF YEAR, INCLUDING UPPER PORTIONS OF THE
WEST BRANCH SUSQUEHANNA BASIN, AND UPPER PORTIONS OF THE DELAWARE
BASIN.  AT THE SAME TIME, THERE ARE AREAS WHERE CONDITIONS ARE MUCH
BELOW AVERAGE FOR LATE WINTER, INCLUDING MUCH OF THE UPPER SUSQUEHANNA
RIVER BASIN IN NY AND NORTHERN PA.  SNOW CONDITIONS ARE ALSO BELOW
AVERAGE ACROSS MUCH OF CENTRAL PA AND ACROSS THE APPALACHIAN MOUNTAINS
OF SOUTHWEST PA, NORTHEAST WV AND WESTERN MD.  FINALLY, FOR THE
SOUTHERN HALF OF THE MARFC SERVICE AREA WHERE LITTLE OR NO SNOW
CURRENTLY EXISTS, SNOW CONDITIONS ARE ABOUT AVERAGE SINCE THESE AREAS
DO NOT TYPICALLY RECEIVE OR KEEP AS MUCH SNOW ANYWAY.  BASIN-AVERAGE
WATER EQUIVALENT ESTIMATES CAN BE SEEN AT WWW.ERH.NOAA.GOV/ER/MARFC.
IT SHOULD BE NOTED THAT A STORM SYSTEM THIS WEEKEND MAY PRODUCE SOME
MODERATE AMOUNTS OF SNOW ACROSS MAINLY NORTHWESTERN PORTIONS OF THE
SERVICE AREA.

RIVER ICE - BELOW AVERAGE TO AVERAGE.  CURRENTLY, LITTLE OR NO RIVER
ICE EXISTS WITHIN THE MARFC SERVICE AREA.  FOR THE NORTHERN THIRD OF
THE REGION, RIVER ICE CONDITIONS ARE BELOW AVERAGE FOR THIS TIME OF
YEAR.  ELSEWHERE, RIVER ICE CONDITIONS ARE CLOSER TO NORMAL FOR THIS
TIME OF YEAR SINCE THESE RIVERS DO NOT TYPICALLY DEVELOP OR KEEP AS
MUCH ICE ANYWAY.  THIS LATE IN THE WINTER, NEW RIVER ICE FORMATION OF
ANY SIGNIFICANCE IS VERY UNLIKELY.

STREAMFLOW CONDITIONS - VARIABLE.  COMPARED TO MEDIAN FOR THIS TIME OF
YEAR, STREAMFLOW IS VERY HIGH ACROSS NY, PA AND NORTHERN NJ, WHERE IT
IS CURRENTLY MUCH ABOVE NORMAL.  IN THIS REGION SOME LOCATIONS ARE
OBSERVING RECORD HIGH FLOWS FOR THE DATE.  HEADING SOUTHWARD,
STREAMFLOW DROPS OFF TO ABOVE NORMAL ACROSS THE POTOMAC BASIN, TO
ABOUT NORMAL ACROSS THE REST OF CENTRAL VA.  STREAMFLOW IS SOMEWHAT
BELOW MEDIAN IN THE CHESAPEAKE BAY REGION, ACROSS THE DELMARVA
PENINSULA, AND IN THE SOUTHERN HALF OF NJ.  REAL-TIME WATER DATA CAN
BE FOUND BY VISITING THE U.S. GEOLOGICAL SURVEY (USGS) WEB PAGES AT
HTTP://WATER.USGS.GOV/.

SOIL MOISTURE CONDITIONS - VARIABLE.  THE MARCH 1, 2008, PALMER
DROUGHT SEVERITY INDEX CHART (FOUND BY NAVIGATING THE WEBSITE:
WWW.CPC.NOAA.GOV/PRODUCTS) CONTINUES TO INDICATE WET TO EXTREMELY WET
SOIL MOISTURE CONDITIONS ACROSS NY, MOST OF PA AND THE NORTHERN HALF
OF NJ.  ELSEWHERE THE CHART INDICATES NEAR AVERAGE SOIL MOISTURE
CONDITIONS FOR THIS TIME OF YEAR.  ACTUAL PALMER INDEX VALUES,
HOWEVER, AS WELL AS OTHER SOIL MOISTURE AND DROUGHT-RELATED DATA
INDICATES PORTIONS OF VA, MD AND DE STILL HAVE BELOW AVERAGE SOIL
MOISTURE CONDITIONS FOR THIS TIME OF YEAR.  SOIL MOISTURE AND DROUGHT
RELATED DATA AND CHARTS CAN BE SEEN AT WWW.CPC.NCEP.NOAA.GOV/SOILMST/
AND WWW.DROUGHT.GOV.

GROUND WATER - VARIABLE.  SIMILAR TO OTHER CONDITIONS, CURRENT GROUND
WATER LEVELS ARE ABOVE NORMAL ACROSS THE NORTH, NEAR NORMAL ACROSS THE
CENTRAL REGION, AND BELOW NORMAL ACROSS THE SOUTH.

RESERVOIR CONDITIONS - VARIABLE.  RESERVOIR CONDITIONS ARE CURRENTLY
ABOVE AVERAGE ACROSS THE FAR NORTH, AND BELOW AVERAGE ACROSS PORTIONS
OF VA.

FUTURE WEATHER CONDITIONS - ANOTHER SIGNIFICANT STORM SYSTEM WILL
TRACK NORTHEASTWARD ALONG OR JUST EAST OF THE APPALACHIAN MOUNTAINS
THIS WEEKEND.  THIS SYSTEM WILL LIKELY PRODUCE MODERATE-HEAVY
PRECIPIATION OF 0.75-1.50 INCHES ACROSS MOST OF THE MARFC REGION, WITH
A CHANCE FOR GREATER THAN 2 INCHES ACROSS EXTREME EASTERN PA, PORTIONS
OF NJ AND SOUTHEASTERN NY.  SOME MIXED PRECIPITATION SEEMS PROBABLE
ACROSS NORTHERN AND WESTERN PORTIONS OF THE MARFC SERVICE AREA, WITH A
CHANCE FOR SIGNIFICANT SNOW ACROSS THE NORTHERN APPALACHIANS.
OTHERWISE, MOSTLY RAIN IS EXPECTED.  CHILLY BUT MAINLY DRY WEATHER
STARTS THE WORK WEEK OUT, WITH A GRADUAL MID-WEEK WARMING TREND
ACCOMPANIED BY SOME LIGHT PRECIPITATION.  A COLD FRONT WILL BE
APPROACHING THE REGION AS THIS ONE-WEEK OUTLOOK PERIOD ENDS NEXT
THURSDAY.  IN SUMMARY, A WET WEEKEND TO START THIS OUTLOOK OUT
FOLLOWED BY FAIRLY TYPICAL EARLY-MID MARCH WEATHER.  REPEATING THE
EXTENDED RANGE WEATHER OUTLOOK FOR THE FIVE-DAY PERIOD MARCH 11-15:
BELOW NORMAL TEMPERATURES AND NORMAL TO BELOW-NORMAL PRECIPITATION.

AHPS FLOOD FORECASTS - VARIABLE.  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.  FOR THE NEXT WEEK AHPS INDICATES THAT THE
LIKELIHOOD OF RIVER FLOODING IS HIGHEST ACROSS ABOUT THE NORTHERN HALF
OF THE MARFC SERVICE AREA WHERE THE CHANCES ARE NORMAL TO SOMEWHAT
ABOVE NORMAL FOR THIS TIME OF YEAR.  THIS INCLUDES MOST OF THE
SUSQUEHANNA BASIN, THE DELAWARE BASIN, AND THE CENTRAL AND NORTHERN NJ
BASINS.  ELSEWHERE, AHPS INDICATES THE CHANCES OF RIVER FLOODING
DURING THE NEXT TWO WEEKS IS NEAR NORMAL TO SOMEWHAT LESS THAN NORMAL
THAN WHAT HAS BEEN HISTORICALLY OBSERVED.  HEAVY RAINFALL CAN RESULT
IN FLOODING ANYWHERE WITHIN THE MARFC REGION, EVEN WHEN OVERALL RIVER
FLOOD POTENTIAL IS CONSIDERED TO BE LOW OR BELOW AVERAGE.  PLEASE
VISIT WWW.WEATHER.GOV/AHPS/ FOR DETAILED AHPS INFORMATION.

SUMMARY - THE RIVER FLOOD POTENTIAL FOR THE NEXT WEEK IS ABOVE NORMAL
FOR THE SUSQUEHANNA, DELAWARE AND NEW JERSEY RIVER BASINS, AND
SOMEWHAT ABOVE NORMAL FOR THE POTOMAC RIVER BASIN.  VERY HIGH
STREAMFLOW AND VERY WET SOILS, ALONG WITH A FAIRLY HIGH CHANCE OF SOME
HEAVY RAINFALL THIS WEEKEND, ARE THE FACTORS CAUSING THE ELEVATED
FLOOD RISK.  ELSEWHERE, THE RIVER FLOOD POTENTIAL IS NORMAL TO
SOMEWHAT BELOW NORMAL.  WHETHER OR NOT ANY NEW RIVER FLOODING DEVELOPS
DURING THE NEXT WEEK WILL DEPEND ENTIRELY ON THE TYPE, AMOUNT AND
DISTRIBUTION OF PRECIPITATION ASSOCIATED WITH THIS WEEKEND'S STORM.
THIS STORM SHOULD BE MONITORED CLOSELY.

WATER SUPPLY OUTLOOK - MILD-SEVERE DROUGHT CONDITIONS LINGER ACROSS
MUCH OF VA, MD AND THE DELMARVA REGION.  AS SUCH, WATER SUPPLY
SHORTAGES REMAIN POSSIBLE FOR THE SOUTHERN THIRD OF THE MARFC REGION
DURING THE NEXT FEW MONTHS UNLESS PRECIPITATION AVERAGES ABOVE NORMAL.
THE LATEST SEASONAL DROUGHT OUTLOOK (WWW.DROUGHT.GOV) RELEASED ON
MARCH 6, 2008, DOES SUGGEST CONTINUED SLOW IMPROVEMENT ACROSS THE
DROUGHT AREA DURING THE NEXT THREE MONTHS.  ELSEWHERE, ASSUMING NEAR
NORMAL PRECIPITATION OCCURS, NO WATER SUPPLY SHORTAGES ARE ANTICIPATED
ANYWHERE WITHIN THE MARFC REGION DURING THE NEXT FIVE MONTHS.  THE NWS
LONG-RANGE WEATHER OUTLOOK FOR THE MONTH OF MARCH SUGGESTS NORMAL TO
ABOVE NORMAL TEMPERATURES AND PRECIPITATION FOR THE MARFC SERVICE
AREA.

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

THE NEXT OUTLOOK WILL BE ISSUED BY MARFC IN ONE WEEK ON MARCH 13,
2008.

SK
$$

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