FLOOD POTENTIAL STATEMENT MIDDLE ATLANTIC RIVER FORECAST CENTER NATIONAL WEATHER SERVICE STATE COLLEGE PA 319 PM EST THU MAR 16 2006
LATE WINTER/EARLY SPRING RIVER FLOOD POTENTIAL OUTLOOK MIDDLE ATLANTIC RIVER FORECAST CENTER
OUTLOOK NUMBER 06-7 MARCH 16, 2006
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 TWO WEEK PERIOD MARCH 16-30, 2006 AND INCLUDES THE LATEST NWS EXTENDED-RANGE (6-10 DAY AND 8-14 DAY) WEATHER FORECASTS. FOR THE MARFC SERVICE AREA, THESE FORECASTS SUGGEST THAT BOTH TEMPERATURES AND PRECIPITATION AVERAGED OVER THE NINE-DAY PERIOD FROM MARCH 22-30, 2006 WILL BE BELOW NORMAL.
IN THE MID-ATLANTIC REGION, HEAVY RAINFALL IS THE PRIMARY FACTOR WHICH LEADS TO RIVER FLOODING. IT IS IMPORTANT TO NOTE THAT HEAVY RAINFALL CAN RAPIDLY CAUSE RIVER FLOODING ANY TIME OF THE YEAR, EVEN WHEN OVERALL RIVER FLOOD POTENTIAL IS CONSIDERED LOW OR BELOW AVERAGE.
CURRENT RIVER FLOOD POTENTIAL - MOSTLY BELOW AVERAGE. THE OVERALL POTENTIAL FOR RIVER FLOODING DURING THE NEXT TWO WEEKS IS CONSIDERED BELOW AVERAGE ACROSS MOST OF THE MARFC SERVICE AREA. THIS ASSESSMENT IS BASED ON THE FOLLOWING ANALYSIS OF HYDROMETEOROLOGICAL CONDITIONS:
CURRENT FLOODING - NONE.
RECENT PRECIPITATION - BELOW AVERAGE. THE ENTIRE MARFC SERVICE AREA RECORDED BELOW TO MUCH-BELOW AVERAGE PRECIPITATION DURING THE LAST 30 DAYS (2/14/06-3/15/06). MOST LOCATIONS OBSERVED 0.1-2.5 INCHES OF PRECIPITATION, WHICH WAS GENERALLY 20-95 PERCENT BELOW NORMAL. THE SOUTHERN HALF OF THE MARFC REGION WAS DRIEST, WHILE THE EXTREME NORTHERN PORTION OF THE REGION RECEIVED THE MOST PRECIPITATION. VISIT WWW.ERH.NOAA.GOV/ER/MARFC TO VIEW PRECIPITATION DEPARTURE MAPS.
SNOW CONDITIONS - BELOW AVERAGE TO AVERAGE. THERE IS CURRENTLY NO HYDROLOGICALLY SIGNIFICANT SNOW FOUND WITHIN THE MARFC SERVICE AREA. SNOW DATA SOURCES INCLUDE THE NOAA/NWS NATIONAL OPERATIONAL HYDROLOGIC REMOTE SENSING CENTER (WWW.NOHRSC.NOAA.GOV/), THE U.S. ARMY CORPS OF ENGINEERS, NWS COOPERATIVE OBSERVERS, THE NEW YORK CITY DEPARTMENT OF ENVIRONMENTAL PROTECTION, AND OTHERS.
RIVER ICE - BELOW AVERAGE TO AVERAGE. THERE IS CURRENTLY NO SIGNIFICANT RIVER ICE FOUND WITHIN THE MARFC SERVICE AREA.
STREAMFLOW CONDITIONS - MOSTLY BELOW MEDIAN. PRESENTLY, STREAMFLOW ACROSS MOST OF THE MARFC SERVICE AREA IS SUBSTANTIALLY BELOW MEDIAN FOR THE DATE. HOWEVER, DUE TO RECENT RAINFALL, STREAMFLOW ACROSS PORTIONS OF NORTHERN PA AND NY IS PRESENTLY NEAR MEDIAN TO ABOVE MEDIAN. 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 - AVERAGE TO MUCH ABOVE AVERAGE. THE LATEST PALMER DROUGHT SEVERITY INDEX CHART FOR THE WEEK ENDING MARCH 11, 2006, IMPLIES THAT SOIL MOISTURE CONDITIONS ACROSS NORTHEASTERN PORTIONS OF THE MARFC SERVICE AREA REMAIN UNUSUALLY MOIST TO EXTREMELY MOIST FOR THIS TIME OF YEAR. THIS INCLUDES MUCH OF PA, NJ AND NY, WHERE RECENT RAINFALL HAS BEEN CLOSER TO NORMAL. FURTHER SOUTH, SOIL MOISTURE IS ABOUT NORMAL FOR THIS TIME OF YEAR ACROSS MD, DE, WV AND VA. SOIL MOISTURE CONDITIONS CONTINUE TO SLOWLY DECREASE ACROSS MUCH OF THE SOUTHERN TWO-THIRDS OF THE MARFC REGION DUE TO THE DRY WEATHER OF THE LAST SEVERAL WEEKS. ADDITIONALLY, VEGETATION IS SLOWLY RE-EMERGING ACROSS THE SOUTH, AIDING IN DECREASING SOIL MOISTURE. SOIL MOISTURE MONITORING CHARTS FROM NOAA`S CLIMATE PREDICTION CENTER CAN BE FOUND AT WWW.CPC.NCEP.NOAA.GOV/SOILMST/. SOILS ARE NOT SIGNIFICANTLY FROZEN ANYWHERE WITHIN THE MARFC REGION.
GROUND WATER - GENERALLY NEAR TO ABOVE AVERAGE. CURRENT GROUND WATER LEVELS ARE GENERALLY ABOVE AVERAGE ACROSS THE NORTHERN PORTIONS OF THE MARFC SERVICE AREA AND ABOUT AVERAGE ACROSS SOUTHERN PORTIONS.
RESERVOIR CONDITIONS - AVERAGE/ABOVE AVERAGE. MOST LARGE WATER SUPPLY RESERVOIRS WITHIN THE MARFC SERVICE AREA ARE HOLDING AVERAGE OR ABOVE AVERAGE STORAGES FOR THIS TIME OF YEAR, WHILE MOST FLOOD CONTROL RESERVOIRS ARE GENERALLY CLOSE TO NORMAL LEVELS.
FUTURE WEATHER CONDITIONS - A WEAK WEATHER SYSTEM WILL PRODUCE SOME LIGHT SNOW AND RAIN ACROSS THE SOUTH DURING THE NEXT 24 HOURS. THEN, CHILLY BUT GENERALLY DRY WEATHER IS EXPECTED INTO EARLY NEXT WEEK. A SIGNIFICANT STORM SYSTEM COULD IMPACT PORTIONS OF THE MARFC REGION DURING THE TUESDAY/WEDNESDAY TIME FRAME OF NEXT WEEK. AT THIS EARLY DATE, THERE IS SOME INDICATION THAT THIS STORM COULD PRODUCE SOME SIGNIFICANT SNOW, EVEN RATHER FAR TO THE SOUTH. WIDESPREAD HEAVY RAIN SEEMS UNLIKELY, AT LEAST AT THIS TIME, DURING THE NEXT SEVEN DAYS. REPEATING THE NWS EXTENDED-RANGE OUTLOOK FOR THE NINE-DAY PERIOD MARCH 22-30, 2006 FOR THE MARFC REGION: BELOW NORMAL TEMPERATURES AND PRECIPITATION.
AHPS FLOOD FORECASTS - MOSTLY BELOW AVERAGE. ANOTHER TOOL USED TO ASSESS THE POTENTIAL FOR RIVER FLOODING IN THE MARFC AREA IS THE ADVANCED HYDROLOGIC PREDICTION SERVICE (AHPS). 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 THIS OUTLOOK PERIOD (MARCH 16-30, 2006) AHPS INDICATES THAT THE LIKELIHOOD OF RIVER FLOODING ACROSS THE ENTIRE MARFC REGION RANGES FROM ABOUT 5% TO ABOUT 35% BELOW WHAT HAS BEEN HISTORICALLY OBSERVED DURING THIS SAME TIME PERIOD. VISIT WWW.WEATHER.GOV/AHPS/ FOR DETAILED AHPS INFORMATION.
SUMMARY - WHEN ALL FACTORS ARE CONSIDERED, THE POTENTIAL FOR RIVER FLOODING WITHIN THE MARFC SERVICE AREA DURING THE NEXT TWO WEEKS (MARCH 16-30, 2006) IS MOSTLY BELOW NORMAL FOR THIS TIME OF YEAR. THERE IS NO APPRECIABLE SNOW COVER OR RIVER ICE, WHICH MEANS HEAVY RAINFALL WOULD BE REQUIRED FOR RIVER FLOODING TO DEVELOP. THE THREAT OF ANY WIDESPREAD HEAVY RAIN EVENTS DURING THE NEXT SEVEN DAYS APPEARS MINIMAL AT THIS TIME, ESPECIALLY ACROSS NORTHERN BASINS WHERE CHILLY TEMPERATURES WILL HOLD FOR QUITE SOME TIME.
WATER SUPPLY OUTLOOK - ASSUMING NEAR NORMAL PRECIPITATION OCCURS, NO MUNICIPAL WATER SUPPLY SHORTAGES ARE ANTICIPATED ANYWHERE WITHIN THE MARFC REGION DURING THE NEXT FIVE MONTHS. HOWEVER, CONDITIONS WILL NEED TO BE MONITORED THIS YEAR DUE TO THE LOW AMOUNT OF SNOW RECEIVED SO FAR THIS WINTER ACROSS MOST NORTHERN LOCATIONS, AS WELL AS THE BELOW NORMAL PRECIPITATION OBSERVED ACROSS SOUTHERN LOCATIONS. THE LATEST (MARCH 16, 2006) U.S. SEASONAL DROUGHT OUTLOOK, ISSUED BY NOAA`S CLIMATE PREDICTION CENTER (WWW.CPC.NCEP.NOAA.GOV), DOES INDICATE THAT DROUGHT CONDITIONS COULD DEVELOP/EXPAND ACROSS PORTIONS OF VIRGINIA DURING THE NEXT THREE MONTHS.
OTHER HYDROMETEOROLOGICAL INFORMATION CAN BE FOUND BY VISITING THE NWS MARFC INTERNET HOMEPAGE AT WWW.ERH.NOAA.GOV/ER/MARFC.
THE NEXT RIVER FLOOD POTENTIAL OUTLOOK WILL BE ISSUED BY THIS OFFICE ON THURSDAY, MARCH 30, 2006.
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