000
FGUS71 KPBZ 071741
ESFPBZ
MDC023-OHC013-019-029-031-059-067-081-111-119-121-157-PAC003-005-
007-019-031-051-053-059-063-065-073-085-121-125-129-WVC009-029-
049-051-061-069-077-093-103-211745-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
1241 PM EST THU MAR 7 2013

 ...FLOOD POTENTIAL IS EXPECTED TO BE NEAR NORMAL...

THE FLOOD POTENTIAL FOR THE PITTSBURGH HYDROLOGIC SERVICE AREA IS
NEAR NORMAL THROUGH MARCH 21. NORMAL FLOOD POTENTIAL MEANS AT
LEAST MINOR FLOODING IS POSSIBLE.

FOR THE LONG-RANGE RIVER OUTLOOKS AND THE PROBABILITY OF
EXCEEDING FLOOD STAGE OR THE CHANCES OF FLOODING RELATIVE TO
NORMAL AT SPECIFIC FORECAST POINTS DURING THE NEXT 90-DAYS...
REFER TO WWW.WEATHER.GOV/OHRFC AND CLICK ON THE 90-DAY RIVER
OUTLOOK IN THE LEFT HAND COLUMN. CLICK ON FLOOD CHC VS. NORMAL TO
SEE THE RISK OF FLOODING WITH RESPECT TO NORMAL.

FLOOD OUTLOOKS ARE ISSUED BI-WEEKLY BY THE NATIONAL WEATHER
SERVICE DURING WINTER AND EARLY SPRING TO SUMMARIZE BASIN
HYDROMETEROLOGICAL CONDITIONS AND TO ASSESS THE POTENTIAL FOR
WINTER/SPRING FLOODING. THE OUTLOOKS ARE BASED ON CURRENT AND
EXPECTED CONDITIONS ACKNOWLEDGING THAT ACTUAL CONDITIONS COULD
CHANGE DURING THE OUTLOOK PERIOD.

IN ADDITION...90-DAY WATER RESOURCES OUTLOOKS ARE ISSUED MONTHLY.
FACTORS CONSIDERED IN ASSESSING FLOOD POTENTIAL ARE...

ANTECEDENT CONDITIONS

PAST PRECIPITATION 
OVER THE PAST 30 DAYS...PRECIPITATION HAS BEEN 40% TO 55% OF NORMAL 
IN ALLEGHENY RIVER BASIN...50% TO 95% OVER THE MONONGAHELA AND CHEAT 
RIVER BASINS AND 50% TO 100% ACROSS THE UPPER OHIO AND MUSKINGUM 
BASINS.

OVER THE PAST 60 DAYS...PRECIPITATION HAS BEEN 50% TO 75% OF NORMAL 
IN ALLEGHENY RIVER BASIN...75% TO 125% OVER THE MONONGAHELA... 
CHEAT...UPPER OHIO AND MUSKINGUM RIVER BASINS.

OVER THE PAST 90 DAYS...PRECIPITATION HAS BEEN 60% TO 125% OF NORMAL 
IN ALLEGHENY RIVER BASIN...95% TO 200% OVER THE MONONGAHELA AND 
CHEAT RIVER...AND 95% TO 190% OVER THE UPPER OHIO AND MUSKINGUM 
BASINS.

SOILS ARE CURRENTLY MOIST TO WET ACROSS MUCH OF THE REGION DUE TO 
CONSISTENT LIGHT TO MODERATE PRECIPITATION ACROSS THE REGION.
 
SNOW COVER AND SNOW WATER CONTENT
A RECENT STORM SYSTEM HAS PUT DOWN A SNOW PACK ACROSS MOST 
WATERSHEDS NORTH OF THE MAINSTEM OF THE OHIO WITH A WATER EQUIVALENT 
OF 1/2 TO 3/4 INCH WATER EQUIVALENTS. SNOW WATER EQUIVALENTS ARE  
HIGHEST IN THE MOUNTAINOUS TERRAIN OF THE UPPER MONONGAHELA AND 
CHEAT BASINS OF WEST VIRGINIA AS WELL AS THE HEADWATERS OF THE 
ALLEGHENY BASIN WHERE 1+ INCH WATER EQUIVALENTS EXIST.

STREAMFLOW CONDITIONS 
STREAM FLOWS FOR THE PAST 30 DAYS ARE NORMAL TO ABOVE NORMAL FOR THE 
AREA.

ICE CONDITIONS 
A RIVER RISES IN EARLY FEBRUARY REMOVED NEARLY ALL ICE COVERAGE
ACROSS ALL MAJOR RIVERS IN THE REGION. CURRENTLY THE ONLY LOCATIONS 
REPORTING SOME ICE ARE IN THE TRIBUTARIES OF THE UPPER REACHES OF 
THE ALLEGHENY ABOVE RIMER PENNSYLVANIA. ICE COVERAGE IS BELOW 
NORMAL FOR THIS TIME OF THE YEAR.

RESERVOIR CAPACITIES
MOST RESERVOIRS IN THE USACE PITTSBURGH DISTRICT WERE GRADUALLY
INCREASING THOUGH MOST ARE STILL USING 7 PERCENT OR LESS OF THEIR
STORAGE CAPACITY. THERE WERE THREE RESERVOIRS THAT WERE USING
BETWEEN 11% AND 30%. THESE VALUES ARE UP FROM THE PAST TWO WEEKS
AS THE USACE PREPARES FOR SPRING. THE RESERVOIRS IN THE HUNTINGDON 
USACE DISTRICT ARE AT NORMAL WINTER POOL TO ALERT POOL LEVELS.
THIS IS UNCHANGED OVER THE PAST TWO WEEKS.

WEATHER AND PRECIPITATION OUTLOOK
THE OUTLOOK FOR THE NEXT 2 WEEKS HAS A MODERATELY ACTIVE STORM TRACK 
OVER THE AREA WITH TEMPERATURES AVERAGING NEAR NORMAL FOR THIS TIME 
OF THE YEAR.  THE WEATHER PATTERN HAS EXPECTATIONS FOR RELATIVELY 
SMALL STORMS. SOME OF THE PRECIPTATION MAY BE IN THE FORM OF SNOW OR 
MIXED PRECIPITATION BUT THE MAJORITY OF THE PRECIPITATION SHOULD 
MOSTLY BE IN THE FORM OF RAIN THROUGH MARCH 21. THE FLOOD POTENTIAL 
WILL REMAIN NEAR NORMAL.

SUMMARY...
RAINFALL IS THE PRIMARY FACTOR LEADING TO FLOODING. HEAVY OR
EXCESSIVE RAINFALL CAN CAUSE FLOODING ANY TIME OF THE YEAR...EVEN
WHERE THE FLOOD POTENTIAL IS BELOW NORMAL.

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED BY
MARCH 21.

$$