Flood Potential Outlook
Issued by NWS

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
1207 PM EDT THU MAR 19 2015

* ...WINTER/SPRING FLOOD POTENTIAL OUTLOOK... *

THE FLOOD POTENTIAL IS ABOVE NORMAL OVER THE OHIO RIVER...

AN ABOVE NORMAL FLOOD POTENTIAL MEANS WIDESPREAD FLOODING COULD
OCCUR WITH WATER LEVELS HAVING SIGNIFICANT IMPACTS.

A NORMAL FLOOD POTENTIAL MEANS OCCASIONAL FLOODING COULD OCCUR WITH
WATER LEVELS HAVING MINOR IMPACTS.

FLOOD OUTLOOKS ARE ISSUED BIWEEKLY DURING THE WINTER AND SPRING TO
SUMMARIZE CURRENT CONDITIONS AND ASSESS THE POTENTIAL FOR FLOODING
ACROSS THE REGION.

FACTORS TO CONSIDER WHEN ASSESSING FLOOD POTENTIAL THIS TIME OF
YEAR ARE CURRENT RIVER AND RESERVOIR LEVELS...SNOW PACK DEPTH AND
WATER CONTENT...ICE COVERAGE ON AREA RIVERS AND THE LAKE...SOIL
MOISTURE...AND WIDESPREAD HEAVY RAINFALL POTENTIAL.

..OVERVIEW...
HE PREVAILING STORM TRACK DURING WINTER HAS RESEMBLED AN EL NINO
SIGNATURE ACROSS THE U.S...PREDICTED SINCE THE SUMMER OF 2014...WITH
STORM SYSTEMS HITTING THE WEST COAST...THEN MOVING ACROSS THE DEEP
SOUTH BEFORE CURVING UP THE EAST COAST OR OUT INTO THE WESTERN NORTH
ATLANTIC BASIN. THE LACK OF PHASING OF THE POLAR AND SUBTROPICAL JET
STREAMS HAS RESULTED IN MAINLY LIGHT TO MODERATE PRECIPITATION
EVENTS IN THE OHIO VALLEY/LAKE ERIE DRAINAGE.

FOR THE METEOROLOGICAL WINTER 2015...TEMPERATURES IN THE OHIO
VALLEY/LAKE ERIE DRAINAGE WERE BELOW NORMAL...AND PRECIPITATION
AVERAGED SLIGHTLY BELOW NORMAL WITH ISOLATED LOCATIONS IN THE UPPER
OHIO VALLEY HAVING SLIGHTLY ABOVE NORMAL PRECIPITATION.

...CURRENT RIVER AND RESERVOIR LEVELS...
STREAMFLOWS ARE CURRENTLY ABOVE NORMAL IN THE OHIO VALLEY/LAKE ERIE
DRAINAGE. MOST RESERVOIR LEVELS IN THE REGION ARE AT NORMAL WINTER
POOL LEVELS. RESERVOIR STORAGE FOR 10 OF THE 16 OF THE RESERVOIRS
IN THE REGION ARE AT 20 PERCENT TO 68 PERCENT OF CAPACITY. WATER
SUPPLY SHORTAGES ARE NOT ANTICIPATED.

STREAMFLOWS ARE CURRENTLY ABOVE NORMAL SOUTH OF THE OHIO RIVER WITH
WIDESPREAD FLOODING OCCURRING ACROSS WEST VIRGINIA/SOUTHWEST
PENNSYLVANIA. NEAR NORMAL STREAMFLOWS ARE OCCURRING NORTH OF THE
MAINSTEM.

...SNOW AND ICE COVERAGE...
SOILS ARE EXCESSIVELY WET SOUTH OF THE OHIO RIVER...AND NORMALLY
MOIST NORTH OF THE MAINSTEM.

SIGNIFICANT MELTING OF THE SNOWPACK HAS OCCURRED SINCE EARLY MARCH
RESULTING IN ELEVATED RIVER LEVELS...WITH NO SNOWPACK REMAINING.

THE FLOOD POTENTIAL ACROSS CENTRAL SECTIONS OF THE ALLEGHENY RIVER
IS ICE ACCUMULATION. IN ADDITION TO FLOODING DUE TO RUNOFF...ICE JAM
FLOODING REMAINS A CONCERN IN THE ICED-UP RIVER SECTIONS.


...PRECIPITATION AND TEMPERATURE FORECASTS...
THE TEMPERATURE FORECAST WILL BE NEAR NORMAL OVER THE
REGION THROUGH THE NEXT TWO WEEKS. THE CLIMATE PREDICTION CENTER`S
8-14 DAY OUTLOOKS SUGGESTS NORMAL TO SLIGHTLY ABOVE NORMAL
PRECIPITATION.

...LONG TERM OUTLOOKS...
THE WEATHER PATTERN APPEARS TO BE ON THE VERGE OF BREAKING THE EL
NINO SIGNATURE PERSISTING THIS PAST WINTER. FOR THE OHIO VALLEY AND
LAKE ERIE DRAINAGE...MILDER TEMPERATURES ALSO WILL BE ACCOMPANIED BY
A MORE ACTIVE STORM TRACK THIS SPRING WITH OCCASIONAL PHASING OF
THE SUBTROPICAL AND POLAR JET STREAMS.

...FLOOD POTENTIAL SUMMARY AND OUTLOOK...
BASED ON THE ABOVE INFORMATION...THE WINTER/SPRING FLOOD POTENTIAL
OVER THE NEXT 2 WEEKS IS ABOVE NORMAL. IN THE LONG TERM...THE FLOOD
POTENTIAL IS NEAR NORMAL.

THE WEATHER PATTERN HAS BROKEN THE EL NINO SIGNATURE PERSISTING THIS
PAST WINTER. FOR THE OHIO VALLEY AND LAKE ERIE DRAINAGE...MILDER
TEMPERATURES ALSO WILL BE ACCOMPANIED BY A MORE ACTIVE STORM TRACK
THIS SPRING WITH OCCASIONAL PHASING OF THE SUBTROPICAL AND POLAR
JET STREAMS PRODUCING HEAVY RAIN EVENTS.

HYDROLOGICALLY...THE RESULTING STREAMFLOWS WILL AVERAGE ABOVE
NORMAL...AND WIDESPREAD FLOODING IS POSSIBLE WITH WATER LEVELS
HAVING SIGNIFICANT IMPACTS.


THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED BY
APRIL 3 2015.


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