FGUS61 KRHA ddhhmm ESGRHA This is archived version of the product generated on Linux that was destined for SBN or WAN distribution FLOOD POTENTIAL STATEMENT MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC) NATIONAL WEATHER SERVICE STATE COLLEGE PA 109 PM EST THU FEB 07 2013 WINTER/SPRING RIVER FLOOD POTENTIAL OUTLOOK NWS MIDDLE ATLANTIC RIVER FORECAST CENTER OUTLOOK NUMBER 13-03 - FEBRUARY 7, 2013 THIS OUTLOOK IS VALID FOR THE TWO-WEEK PERIOD FEBRUARY 7-21, 2013. 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 - AVERAGE TO SOMEWHAT BELOW AVERAGE. THE RIVER FLOOD POTENTIAL ACROSS THE MARFC SERVICE AREA FOR THE NEXT TWO WEEKS THROUGH FEBRUARY 21, 2013 REMAINS SOMEWHAT BELOW AVERAGE ACROSS MOST OF THE NORTHERN HALF OF THE REGION AND CLOSER TO AVERAGE ELSEWHERE. 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 (JANUARY 7-FEBRUARY 5, 2013) RANGED FROM BELOW AVERAGE TO AVERAGE (50-125 PERCENT OF NORMAL) ACROSS NY, MUCH OF PA AND NJ, AND IN THE DELMARVA/CHESAPEAKE BAY REGION, WHERE GENERALLY 1.5-3.5 INCHES (WATER EQUIVALENT) WAS OBSERVED. FURTHER SOUTH, PRECIPITATION RANGED FROM AVERAGE TO MUCH ABOVE AVERAGE (80-200 PERCENT OF NORMAL). THIS INCLUDES WESTERN AND CENTRAL MD, NORTHEASTERN WV, NORTHERN DE, MOST OF VA, AND SOUTHERN PORTIONS OF THE DELMARVA PENINSULA. IN THIS AREA GENERALLY 3.0-6.5 INCHES FELL, WITH THE HEAVIEST AMOUNTS OBSERVED IN THE JAMES AND APPOMATTOX RIVER BASINS IN CENTRAL VA. PLEASE VISIT WWW.ERH.NOAA.GOV/ER/MARFC FOR ADDITIONAL PRECIPITATION INFORMATION. SNOW CONDITIONS - MUCH BELOW AVERAGE TO ABOUT AVERAGE. CURRENTLY WITHIN THE MARFC SERVICE AREA SNOW COVERS THE GROUND ACROSS THE MOUNTAINS OF MD AND WV, A GOOD PORTION OF PA, NY, AND EXTREME NORTHWESTERN NJ. THE AREAL EXTENT OF THE SNOW COVER IS BELOW NORMAL FOR THE DATE. ADDITIONALLY, THE AMOUNT OF WATER CONTAINED IN THE SNOW (WATER EQUIVALENT) IS GENERALLY MUCH BELOW AVERAGE TO BELOW AVERAGE FOR THIS TIME OF WINTER, ESPECIALLY ACROSS THE NORTHERN HALF OF THE MARFC REGION. ACROSS THE SOUTHERN HALF OF THE MARFC REGION WHERE LITTLE OR NO SNOW CURRENTLY EXISTS CONDITIONS ARE CLOSER TO AVERAGE SINCE THIS REGION RECEIVES MUCH LESS SNOW ON AVERAGE. WHERE SNOW DOES EXIST WATER EQUIVALENT VALUES ARE GENERALLY 0.5 INCHES OR LESS AND SNOW DEPTHS ARE GENERALLY 1-5 INCHES. THERE ARE OF COURSE A FEW ISOLATED HIGHER AMOUNTS WHERE EQUIVALENT VALUES REACH AN INCH AND DEPTHS REACH 10 INCHES. THE CURRENT SNOW CONDITIONS ARE BEST DESCRIBED AS BEING HYDROLOGICALLY INSIGNIFICANT. HOWEVER, ADDITIONAL SNOW IS PREDICTED DURING THE NEXT COUPLE OF DAYS ACROSS ABOUT THE NORTHERN HALF OF THE MARFC REGION. NORTHEASTERN SECTIONS OF THE MARFC REGION IN PARTICULAR ARE PREDICTED TO RECEIVE SIGNIFICANT SNOW ACCUMULATIONS FROM TOMORROW'S PREDICTED DEEP COASTAL STORM SYSTEM. PLEASE VISIT WWW.NOHRSC.NOAA.GOV AND WWW.ERH.NOAA.GOV/ER/MARFC FOR SPECIFICS ON SNOW CONDITIONS. RIVER ICE - MUCH BELOW AVERAGE TO AVERAGE. AS OF THIS MORNING, RIVER ICE HAS DECREASED FROM LATE JANUARY LEAVING LITTLE OR NO SIGNIFICANT RIVER ICE WITHIN THE MARFC SERVICE AREA. IN NY AND PA RIVER ICE OBSERVERS ARE GENERALLY REPORTING WIDE OPEN CHANNELS WITH JUST SOME SCATTERED BORDER ICE AND SOME FRAZIL ICE PANS MOVING DOWN RIVERS. THESE CONDITIONS ARE MUCH BELOW NORMAL TO BELOW NORMAL FOR THIS TIME OF WINTER. ELSEWHERE, RIVER ICE CONDITIONS ARE CLOSER TO AVERAGE FOR THIS TIME OF WINTER SINCE SIGNIFICANT RIVER ICE OCCURS WITH MUCH LESS FREQUENCY ACROSS SOUTHERN AND FAR EASTERN PORTIONS OF THE MARFC REGION. NO SIGNIFICANT INCREASE IN RIVER ICE IS EXPECTED FOR AT LEAST THE NEXT WEEK. STREAMFLOW CONDITIONS - NEAR MEDIAN TO ABOVE MEDIAN. ACCORDING TO THE U.S. GEOLOGICAL SURVEY (USGS) STREAMFLOW FOR MOST STREAMS AND RIVERS WITHIN THE MARFC REGION CURRENTLY RANGES FROM NEAR MEDIAN TO ABOVE MEDIAN. NORTHERN AREAS ARE CURRENTLY OBSERVING HIGHER STREAMFLOW COMPARED TO MEDIAN AT THAN SOUTHERN AREAS. REAL-TIME WATER DATA CAN BE FOUND BY VISITING THE USGS WEB PAGES AT HTTP://WATER.USGS.GOV/. SOIL MOISTURE CONDITIONS - NORMAL TO EXTREMELY MOIST. THE LONG-TERM PALMER DROUGHT SEVERITY INDEX IS WIDELY USED TO INFER DEEP SOIL MOISTURE CONDITIONS. THE FEBRUARY 2, 2013 INDEX CHART (WWW.CPC.NOAA.GOV/PRODUCTS WEBSITE) INDICATES SOILS ACROSS THE MARFC SERVICE AREA CONTAIN MOISTURE THAT RANGES FROM NEAR NORMAL TO EXTREMELY MOIST FOR THIS TIME OF YEAR. THE WETTEST SOILS ARE CURRENTLY FOUND ACROSS PA. FOR ADDITIONAL SOIL MOISTURE INFORMATION VISIT WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING. GROUND WATER - VARIABLE. USGS GROUND WATER MONITORING WELLS ACROSS MOST OF THE MARFC REGION ARE INDICATING NEAR NORMAL TO ABOVE NORMAL LEVELS. HOWEVER, FURTHER SOUTH SOME MONITORING WELLS LOCATED IN THE CHESAPEAKE BAY REGION CONTINUE TO INDICATE BELOW NORMAL LEVELS. PLEASE VISIT HTTP://GROUNDWATERWATCH.USGS.GOV. 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 - A MAJOR WINTER STORM WILL BRING SIGNIFICANT SNOW TO NORTHEASTERN PORTIONS OF THE MARFC REGION DURING THE NEXT COUPLE OF DAYS. THE AREA MOST LIKELY TO RECEIVE SIGNIFICANT SNOW INCLUDES THE NY BASINS, NORTHERN AND NORTHEASTERN PA, AND NORTHERN NJ. LESSER AMOUNTS OF SNOW ARE EXPECTED FURTHER SOUTH. RAINFALL ASSOCIATED WITH THE STORM WILL GENERALLY BE LIGHT-MODERATE. ANOTHER MILDER WEATHER SYSTEM WILL LIKELY BRING WHAT CURRENTLY LOOKS LIKE LIGHT TO MODERATE MIXED PRECIPITATION TO THE REGION EARLY NEXT WEEK. THE REMAINDER OF THIS OUTLOOK PERIOD ALSO LOOKS RATHER ACTIVE WITH SEVERAL ADDITIONAL STORMS POSSIBLE, SOME OF WHICH MAY BRING ADDITIONAL SIGNIFICANT PRECIPITATION. WEATHER FORECASTS SHOULD BE MONITORED OFTEN DURING THIS OUTLOOK PERIOD. THE LATEST (FEBRUARY 6, 2013) NWS 6-10 DAY AND 8-14 DAY WEATHER FORECASTS FOR THE MARFC REGION SUGGEST NORMAL TO BELOW NORMAL TEMPERATURES ALONG WITH ABOVE NORMAL PRECIPITATION WHEN AVERAGED OVER THE NINE-DAY PERIOD FEBRUARY 12-20, 2013. PLEASE VISIT WWW.CPC.NCEP.NOAA.GOV. AHPS RIVER FORECASTS - NORMAL TO SOMEWHAT 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 7-21, 2013) AHPS RIVER FORECASTS INDICATE THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC SERVICE AREA RANGES FROM A LITTLE BELOW NORMAL ACROSS THE NORTHERN THIRD TO ABOUT AVERAGE ACROSS THE REMAINDER. THE NORTHERN THIRD OF THE MARFC SERVICE AREA INCLUDES THE NY, NORTHEASTERN PA AND NORTHERN NJ BASINS. PLEASE VISIT WWW.WEATHER.GOV/AHPS/ FOR ADDITIONAL INFORMATION. ENSEMBLE RIVER FORECASTS - MINIMAL RIVER FLOOD THREAT DURING THE NEXT WEEK. A RELATIVELY NEW TOOL DEVELOPED BY THE NWS NOW AIDS 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 LONG-RANGE FORECASTS SHOULD BE USED WITH CAUTION AND UTILIZED AS ANOTHER TOOL TO ASSESS RIVER FLOOD POTENTIAL FOR UP TO ONE WEEK INTO THE FUTURE. WITH THIS IN MIND, THE MOST RECENT RUNS (FEBRUARY 7, 2013) OF THE ENSEMBLE RIVER FORECASTS INDICATE ONLY A MINIMAL THREAT OF RIVER FLOODING WITHIN THE MARFC SERVICE AREA DURING THE NEXT SEVEN DAYS (THROUGH FEBRUARY 14, 2013). PLEASE VISIT WWW.ERH.NOAA.GOV/MMEFS TO VIEW THESE ENSEMBLE RIVER FORECASTS. SUMMARY - THE RIVER FLOOD POTENTIAL DURING THE NEXT TWO WEEKS THROUGH FEBRUARY 21, 2013 IS SOMEWHAT BELOW NORMAL ACROSS THE NORTH AND CLOSER TO NORMAL ACROSS THE SOUTH. WITH MINIMAL SNOW AND RIVER ICE PRESENTLY, RIVER FLOOD POTENTIAL DURING THE NEXT TWO WEEKS WILL BE ALMOST TOTALLY DEPENDENT UPON FUTURE WEATHER CONDITIONS. WHILE THE RISK OF WIDESPREAD HEAVY RAIN SEEMS LOW DURING THE FIRST WEEK OF THIS OUTLOOK, AN ACTIVE AND HIGHLY CHANGEABLE WEATHER PATTERN DOES APPEAR LIKELY. AS SUCH, WEATHER FORECASTS SHOULD BE MONITORED OFTEN DURING THIS OUTLOOK PERIOD. WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (FEBRUARY 5, 2013) U.S. DROUGHT MONITOR, A SMALL AREA OF ABNORMALLY DRY CONDITIONS PERSISTS ACROSS THE UPPER JAMES RIVER BASIN IN VIRGINIA AND A DROUGHT WATCH ADVISORY CONTINUES FOR PORTIONS OF VIRGINIA AT THIS TIME. ELSEWHERE, THE DROUGHT MONITOR SHOWS NO DROUGHT OR DRY CONDITIONS WITHIN THE MARFC SERVICE AREA. ASSUMING NEAR NORMAL PRECIPITATION DURING THE NEXT FEW MONTHS, NO WATER SUPPLY SHORTAGES ARE EXPECTED IN VIRGINIA OR ANYWHERE ELSE WITHIN THE MARFC REGION THROUGH AT LEAST MAY, 2013. THE LATEST (FEBRUARY 7, 2013) NOAA U.S. SEASONAL DROUGHT OUTLOOK SUGGESTS THE RESIDUAL DRY CONDITIONS ACROSS PORTIONS OF VIRGINIA COULD SHOW ADDITIONAL IMPROVEMENT DURING THE NEXT COUPLE OF 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. THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY THIS OFFICE IN TWO WEEKS, ON FEBRUARY 21, 2013. SK $$ ....END MARFC.... NNNN