Flood Potential Outlook
Issued by NWS State College, PA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1220 PM EST THU JAN 19 2017

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK ISSUED JANUARY 19 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 19TH 2017 THROUGH THURSDAY
FEBRUARY 2ND 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 AVERAGE.

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

RECENT PRECIPITATION...BELOW AVERAGE.

PRECIPITATION WITHIN THE STATE COLLEGE FORECAST AREA DURING THE LAST
30 DAYS (DECEMBER 20TH - JANUARY 18TH ) IS VARIABLE ACROSS THE
ACROSS THE REGION...WITH MOST OF THE REGION SEEING BELOW AVERAGE
PRECIPITATION. THE EXCEPTION IS ACROSS THE NORTHWEST PORTION OF THE
AREA WHICH IS CLOSER TO AVERAGE.

SNOW CONDITIONS...WELL BELOW AVERAGE.

WITH RECENT WARM TEMPERATURES AND RAINFALL THERE WAS SUBSTANTIAL
SNOW MELT LAST WEEK. MANY AREAS THAT SHOULD HAVE A SIGNIFICANT PACK
IN THE HIGHER ELEVATIONS OF NORTHERN PENNSYLVANIA AND THE LAUREL
HIGHLANDS HAVE ONLY TRACE AMOUNTS OF SNOW ON THE GROUND.

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 WITH ONLY SPOTTY ICE COVERAGE...WHICH IS UNUSUALLY FOR LATE
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. ACROSS THE NORTHWEST STREAMFLOWS ARE ABOVE AVERAGE FROM
LAST WEEK BUT ARE RECEDING.

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...AVERAGE. THE LATEST SOIL MOISTURE REPORTS
SHOW THAT MOST OF THE REGION IS REPORTING NEAR AVERAGE MOISTURE
VALUES. THE DECEMBER 14, 2017 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 WITH SOIL MOISTURE LEVELS IMPROVING OVER THE NORTHERN HALF OF
PENNSYLVANIA. THE MOST RECENT VERSION (JANUARY 17, 2017) OF THE U.S.
DROUGHT MONITOR CHART DOES SHOW 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. A WARM AND UNSETTLED WEATHER PATTERN WILL
CONTINUE FOR THE NEXT WEEK.
A WEATHER SYSTEM WILL BRING RAIN TO THE REGION ON FRIDAY WITH ONLY
SMALL RISES IN WATER LEVELS.  A MORE SUBSTANTIAL PERIOD OF UNSETTLED
WEATHER IS EXPECTED EARLY NEXT WEEK. THE PATTERN WILL HAVE TO BE
MONITORED FOR THE POTENTIAL FOR HEAVY RAIN ESPECIALLY ACROSS THE
SOUTHEAST HALF OF THE AREA. THE LONGER-RANGE WEATHER OUTLOOKS
SUGGEST ABOVE AVERAGE TEMPERATURES AND PRECIPITATION FOR THE REGION
WHEN AVERAGED OVER THE NINE DAY PERIOD FROM JANUARY 26-FEBRUARY 1,
2017. LONGER-RANGE WEATHER OUTLOOKS CAN BE VIEWED AT
WWW.CPC.NCEP.NOAA.GOV.

ADVANCED HYDROLOGIC PREDICTION SERVICE (AHPS)...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 19 TO FEBRUARY 2 2017: THE
REGIONAL FLOOD POTENTIAL IS AVERAGE FOR THE NEXT COUPLE OF WEEKS...
DUE TO THE POTENTIAL FOR SIGNIFICANT RAINFALL TRIGGERING FLOODING.
THE LACK OF SNOW PACK LACK OF RIVER ICE AND RECENT DRY CONDITIONS
WORK AGAINST THE THREAT OF FLOODING.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...AVERAGE.
GROUND WATER...VARIABLE. RESERVOIR CONDITIONS...AVERAGE.
AHPS...AVERAGE. OVERALL  FLOOD POTENTIAL...AVERAGE.

THE NEXT FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON THURSDAY FEBRUARY
2ND.

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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