556  
FGUS61 KRHA 281611  
ESGRHA  
 
SPRING RIVER FLOOD POTENTIAL OUTLOOK  
NATIONAL WEATHER SERVICE MIDDLE ATLANTIC RIVER FORECAST CENTER  
STATE COLLEGE, PA  
12:13 PM EDT WED MAR 28 2018  
 
OUTLOOK NUMBER 18-07 - MARCH 28, 2018  
 
THIS SPRING RIVER FLOOD POTENTIAL OUTLOOK IS VALID FOR THE TWO-WEEK  
PERIOD MARCH 29-APRIL 12, 2018.  
 
THIS OUTLOOK ESTIMATES THE POTENTIAL FOR RIVER FLOODING (NOT FLASH  
FLOODING) TO DEVELOP DURING THE NEXT TWO WEEKS ACROSS THE MIDDLE  
ATLANTIC RIVER FORECAST CENTER'S (MARFC) AREA OF RESPONSIBILITY (MID-  
ATLANTIC REGION) BASED ON A CURRENT ASSESSMENT OF  
HYDROMETEOROLOGICAL FACTORS WHICH CAN CONTRIBUTE TO RIVER FLOODING.  
ACROSS THE MARFC AREA THESE FACTORS INCLUDE FUTURE WEATHER  
CONDITIONS, RECENT PRECIPITATION, SOIL MOISTURE, SNOW COVER AND SNOW  
WATER EQUIVALENT, RIVER ICE, STREAMFLOW, AND OTHERS. 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 - VARIABLE. THE RIVER FLOOD  
POTENTIAL RANGES FROM SOMEWHAT ABOVE AVERAGE ACROSS ABOUT THE  
NORTHERN THIRD OF THE MARFC SERVICE AREA, TO AVERAGE ACROSS THE  
MIDDLE THIRD, TO SOMEWHAT BELOW AVERAGE ACROSS THE SOUTHERN THIRD.  
FACTORS WHICH CONTRIBUTE TO THIS ASSESSMENT OF RIVER FLOOD POTENTIAL  
ARE DISCUSSED IN SOME DETAIL BELOW.  
 
CURRENT FLOODING - NONE.  
 
RECENT PRECIPITATION - VARIABLE. DURING THE LAST 30 DAYS (FEBRUARY  
25-MARCH 26) PRECIPITATION WITHIN THE MARFC SERVICE AREA RANGED FROM  
AVERAGE TO MUCH ABOVE AVERAGE ACROSS MOST OF NY, EASTERN PA, NJ AND  
DE. ACROSS THE REMAINDER OF THE REGION PRECIPITATION WAS BELOW  
AVERAGE TO MUCH BELOW AVERAGE, INLCUDING CENTRAL PA, MOST OF MD, WV,  
VA AND THE SOUTHERN DELMARVA PENINSULA. PRECIPITATION OVER THE LAST  
30 DAYS RANGED FROM 3-7 INCHES ACROSS THE NORTHEAST (WETTEST IN NJ)  
TO 1.0-3.5 INCHES ACROSS THE DRY SOUTH (DRIEST IN NORTHERN VA).  
PLEASE VISIT WWW.WEATHER.GOV/MARFC/PRECIPITATION_DEPARTURES.  
 
SNOW CONDITIONS - VARIABLE. SIMILAR TO TWO WEEKS AGO, PORTIONS OF  
THE DELAWARE AND SUSQUEHANNA RIVER BASINS STILL HAVE SIGNIFICANT  
SNOW ON THE GROUND. WITHIN THE MARFC SERVICE AREA, THIS INCLUDES  
PORTIONS OF NY AND NORTHEASTERN PA AND PERHAPS THE HIGHEST  
ELEVATIONS OF NORTHWESTERN NJ. IN THIS REGION SNOW DEPTHS GENERALLY  
RANGE FROM 1-12 INCHES, WITH SNOW WATER EQUIVALENT VALUES OF  
GENERALLY 0.5-3.0 INCHES. LOCALLY GREATER SNOW DEPTHS AND WATER  
EQUIVALENT VALUES EXIST IN THIS AREA, ESPECIALLY ACROSS THE HIGHEST  
ELEVATIONS AND IN WOODED/SHADED AREAS. MEANWHILE VALLEY LOCATIONS  
HAVE MUCH LESS SNOW. IN THIS REGION SNOW CONDITIONS ARE ABOVE  
AVERAGE FOR LATE MARCH. ELSEWHERE, GENERALLY LIGHT AND PATCHY SNOW  
REMAINS ACROSS PORTIONS OF PA, MD, WV AND VA, AGAIN MAINLY IN  
HIGHER, SHELTERED LOCATIONS. MOST OF THIS SNOW IS HYDROLOGICALLY  
INSIGNIFICANT. CURRENT SNOW INFORMATION CAN BE FOUND AT  
WWW.WEATHER.GOV/MARFC/SNOW AND WWW.NOHRSC.NOAA.GOV.  
 
RIVER ICE - AVERAGE. THE RIVER ICE SEASON IS OVER.  
 
STREAMFLOW CONDITIONS - VARIABLE. THE LATEST DATA FROM THE UNITED  
STATES GEOLOGICAL SURVEY (USGS) INDICATE NORMAL TO ABOVE-NORMAL  
STREAMFLOW CONDITIONS IN NJ AND IN/NEAR THE APPALACHIANS. ACROSS  
MOST OF THE REMAINDER OF THE REGION, STREAMFLOW CONDITIONS RANGE  
FROM NEAR NORMAL TO MUCH BELOW NORMAL. PLEASE VISIT  
HTTPS://WATERDATA.USGS.GOV/NWIS/RT FOR CURRENT STREAMFLOW DATA.  
 
SOIL MOISTURE CONDITIONS - NORMAL/BELOW NORMAL. THE LONG-TERM  
PALMER DROUGHT SEVERITY INDEX IS USED TO INFER DEEP SOIL MOISTURE  
CONDITIONS. THE MARCH 24, 2018 CHART (FOUND AT  
WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/  
REGIONAL_MONITORING/PALMER.GIF) SUGGESTS DEEP SOILS ACROSS MUCH OF  
THE MARFC SERVICE AREA CONTAIN MOISTURE THAT IS NORMAL/ABOVE NORMAL  
FOR THIS TIME OF YEAR, WITH THE WETTEST SOILS LOCATED ACROSS THE  
NORTH. HOWEVER, OTHER DETAILED SOIL MOISTURE INFORMATION (GO TO  
WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING AND THEN CLICK ON  
U.S. MONITORING) INDICATES SOIL MOISTURE DEFICITS STILL REMAIN  
ACROSS SOUTHERN AREAS. THESE CHARTS ALSO INDICATE THAT SOILS ACROSS  
THE WESTERN HALVES OF PA AND NY HAVE DRIED SOME OVER THE LAST MONTH.  
 
GROUNDWATER - VARIABLE. USGS GROUNDWATER MONITORING WELLS ARE  
CURRENTLY INDICATING NORMAL/ABOVE-NORMAL GROUNDWATER LEVELS ACROSS  
ABOUT THE NORTHERN HALF OF THE REGION, AND NORMAL/BELOW-NORMAL  
LEVELS ELSEWHERE. PLEASE VISIT HTTPS://GROUNDWATERWATCH.USGS.GOV.  
 
RESERVOIR CONDITIONS - NEAR AVERAGE. MOST MAJOR RESERVOIRS WITHIN  
THE MARFC REGION ARE HOLDING STORAGES THAT ARE ABOUT AVERAGE FOR  
THIS TIME OF YEAR.  
 
FUTURE WEATHER CONDITIONS - A FAIRLY TYPICAL EARLY SPRING WEATHER  
PATTERN IS EXPECTED DURING THE NEXT TWO WEEKS. FLUCTUATING  
TEMPERATURES AND PERIODS OF MOSTLY LIGHT-MODERATE PRECIPITATION ARE  
EXPECTED. WHILE CURRENTLY THERE ARE NO STRONG INDICATIONS OF  
WIDESPREAD HEAVY RAINFALL DURING THE NEXT WEEK, ENOUGH RAIN MAY FALL  
AND ENOUGH SNOW MAY MELT IN NY AND NORTHERN PA THAT SOME RIVER  
FLOODING COULD STILL DEVELOP THERE. MEANWHILE, LONGER RANGE WEATHER  
OUTLOOKS FOR THE MARFC REGION STILL SUGGEST A GOOD CHANCE OF  
TEMPERATURES AVERAGING BELOW NORMAL AND PRECIPITATION AVERAGING  
ABOVE NORMAL DURING MUCH OF THIS TWO-WEEK OUTLOOK PERIOD. VIEW LONG-  
RANGE OUTLOOKS AT WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/610DAY.  
 
ENSEMBLE RIVER FORECASTS - A LIMITED THREAT OF RIVER FLOODING  
DEVELOPING. THE MOST RECENT RUNS (MARCH 28, 2018) OF THE ENSEMBLE  
RIVER FORECASTS, WHICH TAKE INTO ACCOUNT ANTICIPATED FUTURE WEATHER  
CONDITIONS INCLUDING PRECIPITATION AND TEMPERATURES, DO SHOW SOME  
CHANCE OF RIVER FLOODING DEVELOPING WITHIN THE MARFC REGION DURING  
THE FIRST WEEK OF THIS OUTLOOK PERIOD. THE THREAT IS HIGHEST ACROSS  
UPPER PORTIONS OF THE SUSQUEHANNA AND DELAWARE RIVER BASINS IN NY  
AND NORTHERN PA, AND IS ASSOCIATED WITH PREDICTED RAIN AND SNOWMELT  
IN THOSE REGIONS DURING THE NEXT THREE DAYS. LONGER-RANGE ENSEMBLE  
FORECASTS ALSO SHOW AN ABOVE-AVERAGE CHANCE OF RIVER FLOODING  
DEVELOPING IN THIS SAME AREA DURING THE NEXT TWO WEEKS. PLEASE  
VISIT WWW.WEATHER.GOV/ERH/MMEFS FOR ENSEMBLE RIVER FORECASTS.  
 
SUMMARY - FOR THE NEXT TWO WEEKS THE RIVER FLOOD POTENTIAL FOR  
RIVERS IN THE MARFC REGION IS SOMEWHAT ABOVE AVERAGE ACROSS ABOUT  
THE NORTHERN THIRD OF THE REGION, AND SOMEWHAT BELOW AVERAGE ACROSS  
THE SOUTHERN THIRD. THE THREAT FOR RIVER FLOODING IS HIGHEST IN NY  
AND NORTHERN PA, WITHIN THE UPPER SUSQUEHANNA AND UPPER DELAWARE  
RIVER BASINS. HERE, POCKETS OF SIGNIFICANT SNOW STILL REMAIN ON THE  
GROUND, AND SNOWMELT COMBINED WITH PREDICTED RAINFALL COULD RESULT  
IN SOME RIVER FLOODING DEVELOPING IN THIS REGION DURING THE NEXT  
THREE DAYS, AND/OR LATER ON IN THIS OUTLOOK PERIOD AS WELL.  
 
WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (MARCH 20, 2018) U.S.  
DROUGHT MONITOR (HTTP://DROUGHTMONITOR.UNL.EDU), SOUTHERN PORTIONS  
OF THE MARFC SERVICE AREA CONTINUE TO SHOW CONDITIONS THAT RANGE  
FROM ABNORMALLY DRY TO MODERATE DROUGHT. VISIT WWW.DROUGHT.GOV,  
WWW.CPC.NCEP.NOAA.GOV AND WWW.WEATHER.GOV/MARFC/WRO_NORTH FOR  
ADDITIONAL DROUGHT AND WATER SUPPLY INFORMATION. IN GENERAL NO  
WATER SUPPLY CONCERNS CURRENTLY EXIST FOR ABOUT THE NORTHERN HALF OF  
THE MARFC REGION. FURTHER SOUTH, PERSISTENT DRY CONDITIONS SINCE  
LAST FALL ARE CAUSE FOR WATER SUPPLY CONCERNS THIS SPRING AND  
SUMMER. ABOVE-NORMAL PRECIPIATION IS NEEDED TO ALLEVIATE THOSE  
CONCERNS ACROSS THE SOUTH.  
 
PLEASE VISIT THE NWS MARFC HOMEPAGE AT WWW.WEATHER.GOV/MARFC OR FIND  
US ON FACEBOOK AT WWW.FACEBOOK.COM/NWSMARFC/?REF=AYMT_HOMEPAGE_PANEL  
AND ON TWITTER @NWSMARFC.  
 
THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY THIS OFFICE  
IN TWO WEEKS, IF NEEDED, ON APRIL 11 OR 12, 2018.  
 
SK  

 
   
...END MARFC.
 
 
NNNN  
 
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