Flood Potential Outlook
Issued by NWS State College, PA

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
230 PM EDT THU MAR 12 2015

...2015 WINTER/SPRING FLOOD POTENTIAL OUTLOOK NUMBER 6...

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 MARCH 12TH 2015 THROUGH THURSDAY
MARCH 26TH 2015.

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 NEAR AVERAGE.

CURRENT FLOODING...ICE JAM FLOODING.
ICE MOVEMENTS ON RIVERS AND STREAMS HAVE INCREASED ACROSS THE
REGION...SEVERAL SMALL ICE JAMS HAVE BEEN REPORTED.  WITH THE MILDER
TEMPERATURES...MORE ICE MOVEMENT AND POTENTIAL ICE JAMS AREA EXPECTED
IN THE COMING DAYS.

RECENT PRECIPITATION...BELOW AVERAGE. PRECIPITATION WITHIN THE STATE
COLLEGE FORECAST AREA DURING THE LAST 30 DAYS (FEBRUARY 12TH 2015
- MARCH 11TH 2015) IS BELOW AVERAGE ACROSS THE REGION...RANGING FROM
50 TO 90 PERCENT OF AVERAGE.

SNOW CONDITIONS...ABOVE AVERAGE.
WARMER TEMPERATURES AND RECENT RAINFALL HAS LED TO SNOW MELT
MAINLY SOUTH OF INTERSTATE 80. THE SNOW ACROSS THE HIGHER ELEVATIONS AND
HEADWATERS OF THE ALLEGHENY AND SUSQUEHANNA RIVER BASINS ARE ABOVE
AVERAGE FOR MID MARCH WITH LIQUID WATER EQUIVALENTS RANGING
FROM 2 TO 4.5 INCHES.

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...ABOVE AVERAGE.
RIVER ICE IS STILL SUBSTANTIAL ACROSS A LARGE PORTION OF THE AREA...BUT
INDICATIONS ARE THAT RIVER ICE IS DECREASING QUICKLY AND MOVEMENT IS
EXPECTED ON THE SUSQUEHANNA RIVER IN THE NEXT SEVERAL DAYS. WITH THE ICE
MOVEMENT WILL BE THE THREAT OF ICE JAMS. WHILE MOST ICE JAMS ARE SMALL
AND DISLODGE QUICKLY...THERE IS ALWAYS THE THREAT THAT AN ICE JAM MAY
ALLOW WATER LEVELS TO RISE QUICKLY AND PRODUCE FLOODING. THE ICE JAM THREAT
IS EXPECTED TO DECREASE IN THE NEXT ONE TO TWO WEEKS.

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 ABOVE AVERAGE ACROSS SOUTHERN AREAS AND BELOW
AVERAGE FOR NORTHERN AREA. WITH THE INCREASE IN SNOW MELT OVER THE NEXT WEEK EXPECT
STREAM FLOWS TO INCREASE ACROSS ALL OF THE AREA.

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 EXCEPTION IS ACROSS
THE SOUTHEAST WHERE AVERAGE VALUES ARE OBSERVED.

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...BELOW AVERAGE TO AVERAGE.
MONITORING WELLS INDICATE  THAT CURRENT GROUND WATER LEVELS ARE VARIABLE
WITH NORMAL OR BELOW NORMAL ACROSS PORTIONS OF THE AREA. WITH THE INCREASE
IN SNOW MELT AND RAINFALL GROUND WATER LEVELS ARE EXPECTED TO INCREASE
SUBSTANTIALLY THIS SPRING.

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 WEATHER SYSTEM WILL BRING A PERIOD OF RAIN TO THE REGION FRIDAY NIGHT
AND SATURDAY. A COOLER AND RATHER DRY WEATHER PATTERN IS EXPECTED LATE
IN THE WEEKEND THROUGH MUCH OF NEXT WEEK.

THE 6 TO 10 DAY OUTLOOK FOR THE PERIOD MARCH 17 - MARCH 21 IS FOR
NEAR AVERAGE TEMPERATURES AND BELOW AVERAGE PRECIPITATION. THE 8 TO
14 DAY OUTLOOK FROM MARCH 19 - MARCH 25 IS FOR BELOW AVERAGE
TEMPERATURES AND BELOW AVERAGE PRECIPITATION.

ADVANCED HYDROLOGIC PREDICTION SERVICE (AHPS)...AVERAGE. 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. RIVER
INFORMATION CAN BE FOUND WEATHER.GOV/AHPS

SUMMARY OF FLOOD POTENTIAL MARCH 12 TO MARCH 26 2015: THE REGIONAL
FLOOD POTENTIAL IS AVERAGE FOR THE NEXT COUPLE OF WEEKS.

OVERVIEW:
CURRENT FLOODING...ISOLATED ICE JAM FLOODING.
RECENT PRECIPITATION...BELOW AVERAGE.
SNOW CONDITIONS...ABOVE AVERAGE.
RIVER ICE...ABOVE AVERAGE.
STREAM FLOW CONDITIONS...AVERAGE.
SOIL MOISTURE CONDITIONS...BELOW AVERAGE.
GROUND WATER...BELOW AVERAGE TO AVERAGE.
RESERVOIR CONDITIONS...AVERAGE.
AHPS...AVERAGE.
OVERALL  FLOOD POTENTIAL...AVERAGE.

THE NEXT FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON THURSDAY
MARCH 26TH.

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

$$

CR



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