000
FGUS71 KBUF 211657
ESFBUF
NYC003-009-011-013-029-037-045-049-051-055-063-069-073-075-117-
121-071700-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
1157 AM EST THU FEB 21 2013

...NEAR NORMAL FLOOD POTENTIAL THROUGH EARLY MARCH...

THIS IS THE FOURTH WINTER / SPRING FLOOD POTENTIAL OUTLOOK OF THE
2012 SEASON. FLOOD OUTLOOKS WILL BE ISSUED EVERY TWO WEEKS INTO
EARLY SPRING TO SUMMARIZE BASIN HYDROMETEOROLOGICAL CONDITIONS AND
TO ASSESS THE POTENTIAL FOR FLOODING. THE OUTLOOKS ARE BASED ON
CURRENT AND FORECAST HYDROMETEOROLOGICAL CONDITIONS. THIS INCLUDES
SNOW COVER AND SNOW WATER EQUIVALENT...CREEK AND RIVER LEVELS AND
THE AMOUNT OF ICE COVER ON THEM...ALONG WITH THE EXPECTED
PRECIPITATION OVER THE NEXT TWO WEEKS.

...CURRENT CONDITIONS SUMMARY...

THE PAST TWO WEEKS BROUGHT FAIRLY SEASONABLE TEMPERATURES...AVERAGING
JUST A TAD BELOW NORMAL. HOWEVER...IT WAS A FAIRLY ACTIVE PERIOD
FOR LAKE SNOWS...WITH SEVERAL EVENTS ADDING MOISTURE TO THE BLACK
RIVER BASIN...AND PARTS OF THE ALLEGHENY AND BUFFALO CREEKS BASINS.

DESPITE THE ADDITIONAL SNOWS...WATER EQUIVALENT VALUES ARE STILL A
BIT BELOW NORMAL. MUCH OF THIS IS DUE TO A PAIR OF JANUARY
THAWS...WHICH MELTED MOST OF THE SNOW FROM EARLIER IN THE SEASON. ON
THE TUG HILL...SNOW DEPTHS ARE ABOUT NORMAL...BUT LOTS OF THIS IS
FROM FRESH SNOW WHICH HAS NOT COMPACTED YET. WATER EQUIVALENT
VALUES ABOUT 30 PERCENT BELOW NORMAL...AND RATIOS SUGGEST THE SNOW
PACK IS QUITE FAR FROM BEING RIPE. MOST OTHER LOCATIONS ARE BELOW
NORMAL IN WATER EQUIVALENT TOO...GENERALLY RANGING BETWEEN 25 AND
50 PERCENT BELOW NORMAL FOR THIS TIME OF YEAR.

THE JANUARY THAWS ALSO LEFT RIVER AND CREEK ICE BELOW NORMAL FOR
MOST WATERWAYS. ICE HAS STARTED TO REDEVELOP ON SMALLER CREEKS AND
TRIBUTARIES...WHILE MOST OF THE RIVERS AND LARGER CREEKS STILL
HAVE SIGNIFICANT OPEN AREAS. LAKE ERIE IS ONLY PARTIALLY
FROZEN. IT USUALLY FROZEN BY THIS TIME OF YEAR.

THE FOLLOWING IS A SUMMARY OF CONDITIONS AND OUTLOOK BY BASIN AS
OF THURSDAY MORNING ON FEBRUARY 21ST:

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........UP TO 6 INCHES LAKESHORE...8 TO 16 INCHES HEADWATERS.
.WATER EQUIVALENT....UP TO A HALF INCH LAKESHORE...1 TO 2 INCHES HEADWATERS.
.CREEK FLOWS.........NEAR NORMAL.
.CREEK ICE...........THIN.
.GROUND FROST........6 TO 12 INCHES.
.GROUND STATE........FROZEN.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........2 TO 8 INCHES.
.WATER EQUIVALENT....UP TO A HALF INCH...AN INCH UPPER GENESEE VALLEY.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER/CREEK ICE.....THIN.
.GROUND FROST........6 INCHES.
.GROUND STATE........FROZEN.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........6 TO 12 INCHES.
.WATER EQUIVALENT....1 TO 2 INCHES.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER CREEK ICE.....SOME.
.GROUND FROST........AROUND 12 INCHES.
.GROUND STATE........FROZEN.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........AROUND A FOOT...18 TO 36 INCHES ON TUG HILL.
.WATER EQUIVALENT....1 TO 2 INCHES...3 TO 6 INCHES ON TUG HILL.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER/CREEK ICE.....MODERATE.
.GROUND FROST........12 TO 18 INCHES.
.GROUND STATE........FROZEN.

...TEMPERATURE AND PRECIPITATION OUTLOOK...
THROUGH EARLY NEXT WEEK...IT LOOKS TO BE A FAIRLY QUIET
PATTERN...WITH A LOW CHANCE FOR ANY HYDROLOGICAL ISSUES. THERE
WILL LIKELY BE A SIGNIFICANT RAIN OR SNOW EVENT ON TUESDAY AND
WEDNESDAY OF NEXT WEEK. A SLOW MOVING LOW IS FORECAST TO
DEVELOP...WITH THIS SYSTEM LIKELY TO HAVE A SIGNIFICANT AMOUNT OF
MOISTURE WITH IT. IT IS TOO EARLY TO DETERMINE IF THIS WILL
PRODUCE RAIN OR SNOW...OR WHERE THE GREATEST AMOUNTS WILL FALL.
THIS SYSTEM HAS A POTENTIAL TO PRODUCE GREATER THAN AN INCH OF
PRECIPITATION...HOWEVER TEMPERATURES SHOULD NOT BE TOO MUCH ABOVE
FREEZING WHICH WOULD MITIGATE SNOW MELT POTENTIAL.

THIS SYSTEM IS FORECAST TO EVOLVE INTO A BROAD UPPER LOW WHICH WILL
LIKELY BE ACROSS OR JUST EAST OF OUR REGION. THIS PATTERN
TYPICALLY BRINGS FREQUENT SNOW SHOWERS FOR THE FIRST WEEK OF MARCH...BUT
WITH ONLY MODEST WATER EQUIVALENT VALUES. WHEN ADDED
UP...PRECIPITATION MAY BE SLIGHTLY ABOVE NORMAL...HOWEVER THIS
PATTERN IS NOT CONDUCIVE TO A SIGNIFICANT RAINFALL EVENT.
TEMPERATURES SHOULD AVERAGE NEAR TO BELOW NORMAL DURING THIS
PERIOD...WITH MOST PRECIPITATION LIKELY TO FALL AS SNOW.

...FLOOD POTENTIAL OUTLOOK...

THE FLOOD POTENTIAL OUTLOOK FOR FLOODING IS NEAR NORMAL THROUGH
EARLY MARCH. THE MAIN RISK FOR FLOODING WILL COME DURING THE
MIDDLE PART OF NEXT WEEK. A SLOW MOVING AREA OF LOW PRESSURE IS
FORECAST TO DEVELOP ACROSS THE UPPER MIDWEST...AND THIS WILL
LIKELY SET UP A MOIST FLOW ACROSS THE REGION. WHILE THIS PATTERN
IS FAVORABLE FOR HEAVY RAIN SOMEWHERE IN THE GENERAL REGION...IT IS
TOO EARLY TO TELL EXACTLY WHEN OR WHERE THIS MAY OCCUR. IT IS ALSO
POSSIBLE IT WILL BE COLD ENOUGH FOR THIS TO FALL AS SNOW...WHICH
WOULD ADD TO SNOWPACK IN SOME LOCATIONS...BUT NOT PRODUCE ANY FLOODING.

BASED ON CURRENT CONDITIONS...THE BUFFALO CREEKS BASIN IS THE MOST
RIPE...AND WOULD BE VULNERABLE TO RAINFALL AMOUNTS IN EXCESS OF AN
INCH AND A HALF. THE BLACK RIVER BASIN IS FAR FROM RIPE...AND MORE
LIKELY TO HOLD QUITE A BIT OF MOISTURE BEFORE MELTING AND RUNNING
OFF. GENERALLY THIN ICE COVER WOULD SUGGEST THE RISK FOR ICE JAMS
IS BELOW NORMAL.

AS AN UPPER LOW ASSOCIATED WITH THE MID-WEEK SYSTEM SETTLES
ACROSS AND EAST OF OUR REGION IN EARLY MARCH...THE PATTERN WILL
BECOME UNFAVORABLE FOR ANY FLOODING. PRECIPITATION SHOULD BE
FREQUENT...BUT SPACED OUT...AND MUCH WILL PROBABLY FALL AS SNOW
RATHER THAN RAIN.

...ADDITIONAL INFORMATION...

REAL TIME RIVER INFORMATION AND PROBABILISTIC FORECASTS FOR
SPECIFIC LOCATIONS ALONG RIVERS ACROSS WESTERN NEW YORK CAN BE
FOUND ON THE INTERNET AT WWW.WEATHER.GOV/BUF BY CLICKING ON THE
RIVERS AND LAKES AHPS LINK ON THE LEFT SIDE OF THE PAGE. SINCE
CONDITIONS CAN CHANGE PLEASE REFER TO THE LATEST FLOOD
WARNINGS...WATCHES...AND STATEMENTS FOR ADDITIONAL INFORMATION.

THE NEXT REGULARLY SCHEDULED OUTLOOK WILL BE ISSUED BY THURSDAY
MARCH 7TH. THANKS TO ALL THE OBSERVERS AND AGENCIES WHICH HAVE
HELPED GATHER DATA IN SUPPORT OF THIS OUTLOOK.

$$

APFFEL