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FGUS61 KRHA 221905
ESGRHA

FLOOD POTENTIAL STATEMENT
MIDDLE ATLANTIC RIVER FORECAST CENTER (MARFC)
NATIONAL WEATHER SERVICE STATE COLLEGE PA
 205 PM EST THU JAN 22 2015

WINTER/SPRING RIVER FLOOD POTENTIAL OUTLOOK
NWS MIDDLE ATLANTIC RIVER FORECAST CENTER

OUTLOOK NUMBER 15-02 - JANUARY 22, 2015

THIS OUTLOOK IS VALID FOR THE TWO WEEKS JANUARY 22-FEBRUARY 5, 2015.

THIS OUTLOOK ESTIMATES THE POTENTIAL FOR RIVER FLOODING (NOT FLASH
FLOODING) TO DEVELOP DURING THE NEXT TWO WEEKS ACROSS THE 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.  AN EXAMPLE
OF THIS OCCURRED LAST SUNDAY, JANUARY 18, WHEN 1.0-2.5 INCHES OF RAIN
FELL IN SIX HOURS IN NJ AND RESULTED IN RIVER RISES TO NEAR/ABOVE FLOOD
STAGE AT SEVERAL FORECAST POINTS.

TWO-WEEK RIVER FLOOD POTENTIAL - BELOW AVERAGE TO AVERAGE.  THE
POTENTIAL FOR RIVER FLOODING TO DEVELOP DURING THE NEXT TWO WEEKS
WITHIN THE MARFC SERVICE AREA IS CONSIDERED BELOW AVERAGE ACROSS THE
THE NORTHWESTERN HALF OF THE REGION AND ABOUT AVERAGE ELSEWHERE.
FACTORS WHICH CONTRIBUTE TO RIVER FLOOD POTENTIAL ARE ADDRESSED BELOW.

CURRENT FLOODING - NONE.

RECENT PRECIPITATION - VARIABLE.  PRECIPITATION DURING THE LAST 30 DAYS
(DECEMBER 23, 2014-JANUARY 21, 2015) WAS BELOW NORMAL ALONG AND EAST OF
THE APPALACHIANS AND ACROSS CENTRAL AND NORTHERN PA INTO SOUTHERN NY.
FURTHER SOUTH AND EAST RECENT PRECIPITATION WAS NORMAL TO ABOVE NORMAL
ACROSS THE CHESAPEAKE BAY REGION, THE DELMARVA PENINSULA AND MUCH OF
NJ.  IN GENERAL 1-3 INCHES OF PRECIPITATION FELL DURING THE LAST 30
DAYS ACROSS MOST REGIONS WHICH RANGES FROM 0-60 PERCENT BELOW NORMAL,
DEPENDING ON LOCATION.  BUT EAST OF A LINE FROM ABOUT FARMVILLE, VA TO
WASHINGTON, D.C., TO THE CATSKILL MOUNTAINS OF SOUTHEASTERN NY, 3-6
INCHES OF PRECIPITATION FELL, WHICH IS IS 0-60 PERCENT ABOVE AVERAGE.
VISIT WWW.ERH.NOAA.GOV/ER/MARFC FOR ADDITIONAL INFORMATION.

SNOW CONDITIONS - SOMEWHAT BELOW NORMAL TO NORMAL.  CURRENTLY WITHIN
THE MARFC SERVICE AREA THERE IS LITTLE IN THE WAY OF HYDROLOGICALLY
SIGNIFICANT SNOW.  SNOW EXISTS ON THE GROUND ACROSS ABOUT THE
NORTHERN TWO THIRDS OF THE REGION.  LITTLE OR NO SNOW EXISTS ACROSS
CENTRAL AND SOUTHERN VA, CENTRAL AND LOWER PORTIONS OF THE DELMARVA
PENINSULA, AND ACROSS THE NORTHERN HALF OF NJ.  WHERE SNOW COVERS THE
GROUND DEPTHS ARE GENERALLY A FEW/SEVERAL INCHES WITH ISOLATED
HIGHER AMOUNTS.  SNOW WATER EQUIVALENT VALUES, OR THE AMOUNT OF WATER
CONTAINED IN THE SNOW IF IT WERE MELTED, ARE LIMITED TO GENERALLY
A HALF INCH OR LESS.  HOWEVER, VALUES OF A HALF INCH TO AN INCH ARE
FOUND ACROSS HIGHER ELEVATIONS IN CENTRAL PA, AND IN PORTIONS OF THE
UPPER SUSQUEHANNA AND DELAWARE BASINS IN NY.  AGAIN, ISOLATED HIGHER
VALUES EXIST.  FOR THIS TIME OF YEAR THESE SNOW CONDITIONS ARE
CONSIDERED SOMEWHAT BELOW NORMAL FOR THE NORTHWESTERN HALF OF THE MARFC
REGION, AND ABOUT NORMAL ELSEWHERE.  FOR DETAILED SNOW INFORMATION
PLEASE VISIT WWW.NOHRSC.NOAA.GOV AND WWW.WEATHER.GOV/MARFC.

RIVER ICE - ABOUT AVERAGE.  IN GENERAL RIVER ICE CONDITIONS REMAIN
FAIRLY TYPICAL FOR THE DATE.  THERE ARE CURRENTLY NO KNOWN MAJOR ICE
JAMS, AND MOST RIVERS STILL HAVE AT LEAST CHANNELS OF OPEN WATER FLOWING
THROUGH THE ICE.  NORTHERN/WESTERN REGIONS, AS EXPECTED, CONTINUE TO
OBSERVE MORE RIVER ICE THAN SOUTHERN/EASTERN AREAS.  DUE TO LESS FRIGID
TEMPERATURES ACROSS THE ENTIRE REGION DURING THE LAST WEEK OR SO, AND
RECENT HEAVY RAIN IN NJ, RIVER ICE CONDITIONS HAVE DECREASED IN MANY
SOUTHERN/EASTERN BASINS FROM TWO WEEKS AGO.  WITH LONGER-RANGE WEATHER
OUTLOOKS INDICATING A GOOD LIKELIHOOD OF BELOW-NORMAL TEMPERATURES
ACROSS THE MARFC REGION DURING THIS OUTLOOK PERIOD, SOME ADDITIONAL
RIVER ICE FORMATION CAN BE EXPECTED.  OCCASIONALLY ICE JAMS CAN FORM
DURING RIVER FREEZE-UP PERIODS AND CAN RARELY RESULT IN WHAT IS
TYPICALLY MINOR LOCALIZED FLOODING.

STREAMFLOW CONDITIONS - VARIABLE.  ACCORDING TO THE U.S. GEOLOGICAL
SURVEY (USGS) THE CURRENT STREAMFLOW ACROSS THE MARFC REGION VARIES
FROM BELOW MEDIAN ALONG AND EAST OF THE APPALACHIANS, TO NEAR MEDIAN
ACROSS FAR EASTERN PORTIONS OF THE REGION.  ABOVE MEDIAN STREAMFLOW
LINGERS ACROSS PORTIONS OF NJ AS A RESULT OF THE HEAVY RAIN EVENT OF
LAST SUNDAY, JANUARY 18.  MEANWHILE, STREAMFLOW IS MUCH BELOW MEDIAN
IN THE APPOMATTOX BASIN OF CENTRAL VA.  QUITE A FEW STREAM GAGES
CONTINUE TO BE AFFECTED BY RIVER ICE AND THEREFORE ARE NOT
REALLY REPRESENTATIVE OF ACTUAL CONDITIONS.  REAL-TIME WATER DATA CAN
BE FOUND BY VISITING THE USGS AT WWW.USGS.GOV/WATER.

SOIL MOISTURE CONDITIONS - MOSTLY ABOUT NORMAL.  THE LONG-TERM PALMER
DROUGHT SEVERITY INDEX IS WIDELY USED TO INFER DEEP SOIL MOISTURE
CONDITIONS.  THE MOST RECENT (JANUARY 17, 2015) INDEX CHART
(WWW.CPC.NOAA.GOV/PRODUCTS) SUGGESTS SOILS ACROSS MOST OF THE MARFC
SERVICE AREA CONTAIN MOISTURE THAT IS NEAR NORMAL FOR THIS TIME OF
YEAR.  WETTER THAN NORMAL SOILS ARE INDICATED IN PORTIONS OF NY, SOUTH-
CENTRAL PA, CENTRAL MD AND SOUTHERN NJ.  DRIEST SOILS ARE ACROSS
PORTIONS OF THE DELMARVA PENINSULA.  SOIL MOISTURE CONTINUES TO SLOWLY
DECREASE ACROSS MUCH OF THE MARFC REGION.  PLEASE VISIT
WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US FOR ADDITIONAL
SOIL MOISTURE INFORMATION.

GROUND WATER - VARIABLE.  USGS GROUND WATER MONITORING WELLS ACROSS
THE MARFC REGION ARE INDICATING RATHER VARIABLE WATER LEVELS.  MANY OF
THE LONGER-TERM WELLS SUGGEST GROUND WATER LEVELS ARE NEAR NORMAL
ACROSS MUCH OF THE MARFC REGION.  PA SEEMS TO BE SHOWING THE GREATEST
NUMBER OF WELLS WITH BELOW-NORMAL WATER LEVELS, BUT THERE ARE WELLS
WITH BOTH VERY LOW AND VERY HIGH WATER LEVELS SCATTERED ACROSS THE
ENTIRE MARFC REGION, MAKING IT RATHER DIFFICULT TO GENERALIZE.  PLEASE
VISIT HTTP://GROUNDWATERWATCH.USGS.GOV FOR MONITORING INFORMATION.

RESERVOIR CONDITIONS - GENERALLY ABOUT AVERAGE.  IN GENERAL, MOST
MAJOR RESERVOIRS WITHIN THE MARFC REGION ARE HOLDING STORAGES THAT ARE
FAIRLY CLOSE TO AVERAGE FOR THIS TIME OF YEAR.

FUTURE WEATHER CONDITIONS - A PAIR OF STORM SYSTEMS WILL IMPACT THE
MARFC REGION DURING THE NEXT SEVERAL DAYS.  THE FIRST ONE WILL TRACK
FROM THE GULF COAST REGION FRIDAY TO NOVA SCOTIA SATURDAY NIGHT.  THIS
WILL BRING LIGHT TO MODERATE PRECIPITATION, MIXED IN FORM, TO MUCH OF
THE MARFC REGION FRIDAY NIGHT THROUGH MIDDAY SATURDAY.  ANY HEAVY RAIN,
IF IT OCCURS, WILL LIKELY BE LIMITED TO EXTREME SOUTHERN AND EASTERN
PORTIONS OF THE MARFC SERVICE AREA.  THIS SYSTEM SHOULD BE MONITORED
IN NJ, PARTICULARLY IF THE STORM TRACK SHIFTS WESTWARD.  THE NEXT
SYSTEM WILL BE A COLDER SYSTEM AND WILL LIKELY BRING LIGHT-MODERATE
SNOW TO MUCH OF THE NORTHERN TWO-THIRDS OF THE MARFC REGION SUNDAY
NIGHT INTO MONDAY NIGHT.  FAIRLY COLD BUT DRY WEATHER FOLLOWS
THIS SECOND STORM THROUGH MIDWEEK NEXT WEEK, WITH A SLIGHT WARM UP
LATER NEXT WEEK AHEAD OF A COLD FRONT.  QUITE COLD WEATHER THEN SEEMS
LIKELY FOR MUCH OF THE SECOND WEEK OF THIS OUTLOOK PERIOD.  THE BEST
CHANCE OF HEAVY RAINFALL DURING THIS OUTLOOK PERIOD, SMALL AS IT IS, IS
IN ASSOCIATION WITH THE FIRST STORM SYSTEM THIS WEEKEND.  THE LATEST
(JANUARY 21, 2015) 6-10 AND 8-14 DAY EXTENDED WEATHER OUTLOOKS ISSUED
BY THE NWS CLIMATE PREDICTION CENTER (CPC) AND VALID FOR THE NINE-DAY
PERIOD JAN 27-FEB 04, STRONGLY SUGGEST BELOW NORMAL TEMPERATURES AND
NEAR-NORMAL/ABOVE-NORMAL PRECIPITATION FOR THE MARFC REGION, WHEN
AVERAGED OVER THE ENTIRE NINE-DAY PERIOD.  PLEASE VISIT
WWW.CPC.NCEP.NOAA.GOV TO VIEW THESE OUTLOOKS.

AHPS RIVER FORECASTS - MOSTLY NEAR 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 (JANUARY 22-FEBRUARY 5, 2015) AHPS RIVER FORECASTS INDICATE
THAT THE LIKELIHOOD OF RIVER FLOODING WITHIN THE MARFC SERVICE AREA IS
IN THE NORMAL TO BELOW-NORMAL RANGE.  PLEASE VISIT
WWW.WEATHER.GOV/AHPS/.

ENSEMBLE RIVER FORECASTS - VERY MINIMAL THREAT OF RIVER FLOODING DURING
THE NEXT WEEK LIMITED MAINLY TO NJ.  THE MOST RECENT RUNS (JANUARY 22,
2015) OF THE ENSEMBLE RIVER FORECASTS SHOW A VERY LIMITED THREAT OF
RIVER FLOODING DEVELOPING IN NJ DURING THE NEXT FEW DAYS.  THIS THREAT
IS RELATED TO THE RELATIVELY LOW PROBABILITY OF AN INCH OR MORE OF RAIN
DURING THE NEXT FIVE DAYS ACROSS PORTIONS OF NJ.  REMEMBER THAT
ENSEMBLE RIVER FORECASTS DO NOT ACCOUNT FOR RIVER ICE CONDITIONS AND
THEREFORE DO NOT PREDICT ICE JAMS/ICE JAM FLOODING.  PLEASE VISIT
WWW.ERH.NOAA.GOV/MMEFS FOR ADDITIONAL ENSEMBLE FORECAST INFORMATION.

SUMMARY - THE RIVER FLOOD POTENTIAL IN THE MARFC REGION DURING THE NEXT
TWO WEEKS IS BELOW AVERAGE ACROSS THE NORTHWESTERN HALF OF THE AREA AND
ABOUT AVERAGE ELSEWHERE.  IN GENERAL, HYDROLOGIC CONDITIONS AT THE
PRESENT TIME ARE PRETTY TYPICAL FOR THIS TIME OF YEAR, WITH THE
EXCEPTION OF SNOW CONDITIONS BEING SOMEWHAT BELOW NORMAL ACROSS THE
NORTH AND WEST.  THIS MEANS THAT SIGNIFICANT RAINFALL WOULD BE REQUIRED
TO INITIATE FLOODING.  THERE IS A VERY MINIMAL THREAT OF HEAVY RAIN
THIS WEEKEND ACROSS PORTIONS OF NJ IN ASSOCIATION WITH ANOTHER COASTAL
STORM SYSTEM.  THIS STORM SHOULD BE MONITORED FOR ANY ADDITIONAL
WESTWARD SHIFT IN ITS TRACK.  AFTER THIS STORM, THERE IS NO CURRENT
INDICATION OF WIDESPREAD HEAVY RAINFALL IN THE MARFC REGION FOR MOST OF
THE REMAINDER OF THIS OUTLOOK PERIOD.

WATER SUPPLY OUTLOOK - ACCORDING TO THE LATEST (JANUARY 20, 2015)
U.S. DROUGHT MONITOR, ABNORMALLY DRY CONDITIONS ARE STILL FOUND ACROSS
PORTIONS OF THE MARFC SERVICE AREA, MOST NOTABLY IN PA.  HOWEVER NO
TRUE DROUGHT CONDITIONS CURRENTLY EXIST WITHIN THE MARFC SERVICE AREA,
NOR ARE ANY EXPECTED TO DEVELOP DURING THE NEXT FEW MONTHS.  LIKEWISE
ASSUMING NEAR-NORMAL PRECIPITATION DURING THE NEXT FEW MONTHS, NO WATER
SUPPLY SHORTAGES ARE EXPECTED ANYWHERE WITHIN THE MARFC REGION THROUGH
AT LEAST MAY, 2015.  PLEASE SEE WWW.DROUGHT.GOV, WWW.CPC.NCEP.NOAA.GOV,
AND WWW.WEATHER.GOV/MARFC/WRO_UPDATE FOR ADDITIONAL DROUGHT AND WATER
SUPPLY INFORMATION.

FINALLY, PLEASE VISIT THE NWS MARFC HOMEPAGE AT
WWW.WEATHER.GOV/MARFC FOR OTHER HYDROMETEOROLOGICAL INFORMATION.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED BY THIS OFFICE IN
TWO WEEKS, ON FEBRUARY 5, 2015.

SK
$$

....END MARFC....
NNNN





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