Flood Potential Outlook
Issued by NWS State College, PA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1245 PM EST THU JAN 5 2017

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK ISSUED JANUARY 5 2017...

INTRODUCTION.

DURING THE WINTER AND SPRING...THE NATIONAL WEATHER SERVICE
ISSUES A SERIES OF WINTER AND SPRING FLOOD POTENTIAL OUTLOOKS.
THESE OUTLOOKS ESTIMATE THE POTENTIAL FOR RIVER FLOODING (NOT
FLASH FLOODING) ACROSS CENTRAL PENNSYLVANIA BASED ON A CURRENT
ASSESSMENT OF HYDROMETEOROLOGICAL FACTORS WHICH CONTRIBUTE TO
RIVER FLOODING. ACROSS CENTRAL PENNSYLVANIA 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 OR EXTENT
OF ANY FUTURE RIVER FLOODING.

THIS OUTLOOK COVERS THE SUSQUEHANNA RIVER BASIN INCLUDING THE
WEST BRANCH...JUNIATA...AND MUCH OF THE MIDDLE AND LOWER
SUSQUEHANNA VALLEY. ALSO COVERED ARE PORTIONS OF THE UPPER AND
LOWER ALLEGHENY BASINS...INCLUDING AREAS FROM WARREN AND MCKEAN
COUNTIES IN THE NORTH...THROUGH CAMBRIA AND SOMERSET COUNTIES IN
THE SOUTH.

THIS OUTLOOK IS VALID THURSDAY JANUARY 5TH 2017 THROUGH THURSDAY
JANUARY 19TH 2017.

IN CENTRAL PENNSYLVANIA...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.

DETAILED DISCUSSION.

TWO WEEK RIVER FLOOD POTENTIAL...THE CURRENT POTENTIAL FOR RIVER
FLOODING IS BELOW AVERAGE.

CURRENT FLOODING...NONE.
NO FLOODING IS OCCURRING IN THE REGION AT THIS TIME.

RECENT PRECIPITATION...VARIABLE.
PRECIPITATION WITHIN THE STATE COLLEGE FORECAST AREA DURING THE LAST
30 DAYS (DECEMBER 6TH - JANUARY 4TH ) IS VARIABLE ACROSS THE ACROSS
THE REGION...WITH THE NORTHERN AND EASTERN HALF OF THE AREA
REPORTING BELOW AVERAGE PRECIPITATION...WHILE THE WESTERN AND
SOUTHERN HALF OF THE AREA HAS SEEN ABOVE AVERAGE PRECIPITATION.
SNOW CONDITIONS...BELOW AVERAGE.
SNOW COVERS THE LAKE EFFECT AREAS ACROSS NORTHERN PENNSYLVANIA BUT
THE REST OF THE REGION IS REPORTING JUST SPOTTY TO NO SNOW COVER.
AREAS SUCH AS THE LAUREL HIGHLANDS WHICH NORMALLY HAVE A SIGNIFICANT
SNOWPACK BY NOW REPORTS JUST SPOTTY SNOW COVER. SNOW WATER
EQUIVALENTS IN THE SNOW COVERED AREAS ARE LESS THAN ONE INCH.

SNOW DATA AND INFORMATION SOURCES INCLUDE THE NOAA/NWS
OPERATIONAL HYDROLOGIC REMOTE SENSING CENTER
(WWW.NOHRSC.NOAA.GOV)...THE U.S. ARMY CORPS OF ENGINEERS...NWS
COOPERATIVE OBSERVERS...THE COMMUNITY RAIN, HAIL AND SNOW NETWORK
(COCORAHS) AND OTHERS. SNOW DEPTH AND BASIN AVERAGE WATER
EQUIVALENT ESTIMATES CAN BE SEEN AT WWW.ERH.NOAA.GOV/ER/MARFC
(LOWER CASE) AND WWW.NOHRSC.NOAA.GOV (LOWER CASE).

RIVER ICE...BELOW AVERAGE.
ALL RIVERS AND STREAMS ARE OPEN AND RUNNING...WHICH IS UNUSUALLY FOR
EARLY JANUARY.  FOLLOW RIVER ICE CONDITIONS AT
HTTP://ERH.NOAA.GOV/CTP/HYDRO/RIVERICE/INDEX.PHP (LOWER CASE)

STREAM FLOW CONDITIONS...AVERAGE.
IN GENERAL STREAM FLOWS ARE VERY CLOSE TO AVERAGE ACROSS THE REGION
DUE TO RECENT SNOW MELT AND RAINFALL.

REAL TIME WATER DATA IS AVAILABLE FROM THE UNITED STATES GEOLOGICAL
SURVEY BY VISITING HTTP://WATER.USGS.GOV (LOWER CASE) ON THE
INTERNET.

SOIL MOISTURE CONDITIONS...BELOW AVERAGE.
THE LATEST SOIL MOISTURE REPORTS SHOW THAT MOST OF THE REGION IS
REPORTING BELOW AVERAGE MOISTURE VALUES.  THE DECEMBER 31, 2016
CHART (FOUND AT
WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/
REGIONAL_MONITORING/PALMER.GIF) SUGGESTS DEEP SOILS ACROSS THE
AREA CONTAIN MOISTURE THAT IS FAIRLY CLOSE TO NORMAL FOR THIS TIME
OF YEAR.  HOWEVER, OTHER SOIL MOISTURE INFORMATION
(GO TO WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING
AND THEN CLICK ON THEN CLICK ON U.S. MONITORING) SHOWS CONSIDERABLE
SOIL MOISTURE DEFICITS REMAIN.  THIS SUPPORTS THE MOST RECENT VERSION
(JANUARY 3, 2017) OF THE U.S. DROUGHT MONITOR CHART WHICH SHOWS
PORTIONS OF THE AREA EXPERIENCING ABNORMALLY DRY TO SEVERE DROUGHT
CONDITIONS (HTTP://DROUGHTMONITOR.UNL.EDU).

MOISTURE MONITORING CHARTS FROM NOAA`S CLIMATE PREDICTION CENTER
CAN BE FOUND AT:
WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US/SOILMST/SOILMST.
SHTML

(LOWER CASE) AND WWW.DROUGHT.GOV.

GROUND WATER...VARIABLE.
MONITORING WELLS ARE ALL AT OR ABOVE NORMAL FOR WESTERN AREAS WHILE
SOUTHERN AND EASTERN ARES OF THE REGION ARE BELOW OR EVEN MUCH BELOW
AVERAGE...CORRESPONDING TO WHERE DROUGHT CONDITIONS ARE BEING
OBSERVED.

CURRENT GROUND WATER CONDITIONS BASED ON A 30 DAY MOVING AVERAGE
CAN BE FOUND AT HTTP://PA.WATER.USGS.GOV/MONITOR/GW/INDEX.HTML
(LOWER CASE)

RESERVOIR CONDITIONS...AVERAGE.
MOST WATER SUPPLY RESERVOIRS WITHIN CENTRAL PENNSYLVANIA ARE
HOLDING AVERAGE STORAGE FOR THIS TIME OF YEAR...AS ARE MOST FLOOD
CONTROL RESERVOIRS.

FUTURE WEATHER CONDITIONS.
THE NEXT SEVERAL DAYS WILL SEE BELOW AVERAGE TEMPERATURES WITH ONLY
LIGHT SNOW ACCUMULATIONS EXPECTED. A MORE ACTIVE AND WARMER WEATHER
PATTERN IS EXPECTED NEXT WEEK WITH RAINFALL AGAIN LIKELY.
THE LONGER-RANGE WEATHER OUTLOOKS SUGGEST ABOVE AVERAGE TEMPERATURES
AND PRECIPITATION FOR THE REGION WHEN AVERAGED OVER THE NINE DAY
PERIOD FROM JANUARY 10-18, 2017. LONGER-RANGE WEATHER OUTLOOKS CAN BE
VIEWED AT WWW.CPC.NCEP.NOAA.GOV.


ADVANCED HYDROLOGIC PREDICTION SERVICE (AHPS)...BELOW NORMAL.
ANOTHER TOOL USED TO ASSESS THE POTENTIAL FOR RIVER FLOODING IS THE
ADVANCED HYDROLOGIC PREDICTION SERVICE...AHPS. AHPS GENERATES
PROBABILISTIC RIVER FORECASTS BASED ON CURRENT BASIN CONDITIONS...
INCLUDING RIVER LEVELS...SOIL MOISTURE...EXTENT AND CONDITION OF ANY
SNOW PACK...ALONG WITH 50 YEARS OF HISTORIC TEMPERATURE AND
PRECIPITATION DATA. FOR THIS OUTLOOK PERIOD... AHPS INDICATES THAT
THE LIKELIHOOD OF RIVER FLOODING IS BELOW  AVERAGE COMPARED TO WHAT
HAS BEEN HISTORICALLY OBSERVED DURING THIS SAME TIME PERIOD ACROSS
SMALL RIVER BASINS ACROSS CENTRAL PENNSYLVANIA. RIVER INFORMATION
CAN BE FOUND AT WATER.WEATHER.GOV

SUMMARY OF FLOOD POTENTIAL JANUARY 5 TO JANUARY 19 2017:
THE REGIONAL FLOOD POTENTIAL IS BELOW AVERAGE FOR THE NEXT COUPLE OF
WEEKS... DUE MOSTLY TO THE LOW SNOW PACK LACK OF RIVER ICE AND
RECENT DRY CONDITIONS OVER MUCH OF THE AREA. HEAVY RAINFALL WOULD BE
REQUIRED TO CAUSE RIVER FLOODING.

OVERVIEW:
CURRENT FLOODING...NONE.
RECENT PRECIPITATION...VARIABLE.
SNOW CONDITIONS...BELOW AVERAGE.
RIVER ICE...BELOW AVERAGE.
STREAM FLOW CONDITIONS...AVERAGE.
SOIL MOISTURE CONDITIONS...BELOW AVERAGE.
GROUND WATER...VARIABLE.
RESERVOIR CONDITIONS...AVERAGE.
AHPS...BELOW AVERAGE.
OVERALL  FLOOD POTENTIAL...BELOW AVERAGE.

THE NEXT FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON THURSDAY
JANUARY 19TH.

OTHER HYDROMETEOROLOGICAL INFORMATION CAN BE FOUND BY VISITING
THE STATE COLLEGE INTERNET HOMEPAGE AT HTTP://WEATHER.GOV/CTP
(LOWER CASE).

$$

CR



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