Extended Streamflow Guidance
Issued by NWS Middle Atlantic RFC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1
000
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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.