000
FGUS71 KBUF 211720
ESFBUF
NYC003-009-011-013-029-037-045-049-051-055-063-069-073-075-117-
121-041730-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
119 PM EDT THU MAR 21 2013

...BELOW NORMAL FLOOD POTENTIAL THROUGH MARCH...
...INCREASING FLOOD POTENTIAL IN THE BLACK RIVER BASIN FOR APRIL...

THIS IS THE SIXTH 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...

OVER THE PAST TWO WEEKS THERE HAVE BEEN TWO EVENTS WHICH HAVE HAD A 
SIGNIFICANT IMPACT ON SNOW PACK ACROSS OUR REGION. THE FIRST WAS ON 
MARCH 10TH AND 11TH...WHEN WELL ABOVE NORMAL TEMPERATURES MELTED
NEARLY ALL THE SNOW PACK IN THE BUFFALO CREEKS...AND IN THE
GENESEE AND ALLEGHENY BASINS. DESPITE THIS WARM UP...THERE WAS NO
FLOODING BECAUSE RAINFALL WAS RELATIVELY LIGHT IN THE AREAS WHICH
HAD THE MOST SNOW MELT. THIS ALSO CLEARED OUT VIRTUALLY ALL OF THE
RIVER AND CREEK ICE...WITH ADDITIONAL ICE UNLIKELY TO FORM.

SNOWPACK WAS MUCH DEEPER EAST OF LAKE ONTARIO...AND EVEN THE TWO 
DAYS OF WARM TEMPERATURES WAS NOT ENOUGH TO COMPLETELY MELT SNOW ON 
THE TUG HILL. WHILE THIS PROBABLY TRIMMED THE WATER EQUIVALENT 
VALUES SOME...IT ALSO SERVED TO RIPEN THE SNOW PACK IN THE BLACK 
RIVER BASIN.

AFTER THIS...A PERSISTENT COLD PATTERN SET IN. THIS BROUGHT A 
SIGNIFICANT PERIOD OF SNOW AND LAKE EFFECT SNOW WHICH STARTED TO 
REESTABLISH SOME OF THE SNOW PACK LOST. WATER EQUIVALENTS REMAIN ON 
THE LIGHT SIDE IN MOST BASINS...WITH LITTLE IF ANY SNOW OUTSIDE OF 
THE LAKE EFFECT SNOW BELTS. FIRST CAME A SYNOPTIC SYSTEM WHICH
DROPPED ROUGHLY AN INCH OF FROZEN PRECIPITATION...THEN THIS WAS
FOLLOWED BY A FLUFFY SNOW WHICH DROPPED OVER TWO FEET ON SOME
PORTIONS OF THE TUG HILL. SNOW CORE MEASUREMENTS WERE LARGELY
TAKEN BEFORE MUCH OF THIS SNOWFALL...SO TAKING THIS INTO ACCOUNT
EXPECT WATER EQUIVALENT VALUES OF THE SNOW PACK ON THE TUG HILL
ARE SLIGHTLY ABOVE NORMAL...WITH SLIGHTLY BELOW NORMAL SNOW PACK
IN LOWER LYING AREAS.

ELSEWHERE IS BELOW NORMAL DUE TO SEVERAL COMPLETE THAWS THIS
WINTER. THERE IS VIRTUALLY NO ICE ON THE BUFFALO CREEKS...WITH
LITTLE CHANCE FOR ICE JAMS FOR THE REMAINDER OF THE SEASON.

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

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........TRACE...EXCEPT 6 TO 12 INCHES AT THE HEADWATERS.
.WATER EQUIVALENT....TRACE...EXCEPT AROUND AN INCH AT THE HEADWATERS.
.CREEK FLOWS.........BELOW NORMAL.
.CREEK ICE...........NONE.
.GROUND FROST........LESS THAN 6 INCHES.
.GROUND STATE........MOSTLY FROZEN.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........UP TO 3 INCHES.
.WATER EQUIVALENT....LESS THAN AN INCH.
.RIVER/CREEK FLOWS...BELOW NORMAL.
.RIVER/CREEK ICE.....NONE.
.GROUND FROST........LESS THAN 6 INCHES.
.GROUND STATE........MOSTLY FROZEN.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........6 TO 12 INCHES.
.WATER EQUIVALENT....1 TO 2 INCHES.
.RIVER/CREEK FLOWS...BELOW NORMAL.
.RIVER CREEK ICE.....VERY LITTLE.
.GROUND FROST........6 TO 12 INCHES.
.GROUND STATE........FROZEN.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........6 TO 18 INCHES...2 TO 4 FEET ON TUG HILL.
.WATER EQUIVALENT....1 TO 3 INCHES...5 TO 9 INCHES ON TUG HILL.
.RIVER/CREEK FLOWS...BELOW NORMAL.
.RIVER/CREEK ICE.....MODERATE.
.GROUND FROST........12 TO 18 INCHES.
.GROUND STATE........FROZEN.

...TEMPERATURE AND PRECIPITATION OUTLOOK...
AS HAS BEEN THE CASE FOR THE MAJORITY OF THE PAST MONTH AND A 
HALF...THE REGION IS FORECAST TO BE UNDER THE INFLUENCE OF A 
PERSISTENT UPPER LEVEL TROF. MODEL CONSENSUS IS FAIRLY STRONG IN 
PLACING OUR REGION ON THE BACK OF THIS TROF...WHICH WOULD LEAD TO A 
CONTINUED COOL PATTERN. THIS WOULD LEAD TO BELOW NORMAL TEMPERATURES
THROUGH THE NEXT 10 DAYS. WHILE PRECIPITATION WILL BE FREQUENT IN
THIS PATTERN...IT WILL PROBABLY BE MOSTLY IN THE FORM OF LAKE
EFFECT SNOW SHOWERS. THIS PATTERN IS NOT FAVORABLE FOR HEAVY
RAINFALL.

LOOKING AHEAD INTO EARLY APRIL...THE 8 TO 14 DAY FORECAST IS FOR A 
COOL BUT SLIGHTLY DRIER PATTERN TO CONTINUE. THIS WOULD ALSO NOT BE 
FAVORABLE FOR HEAVY RAIN...HOWEVER FORECAST CONFIDENCE TENDS TO 
DIMINISH IN THIS TIMEFRAME...ESPECIALLY CONSIDERING THE TIME OF 
YEAR. AS THE CALENDER TURNS TO APRIL...CLIMATOLOGY GROWS 
WARMER...AND THE LIKELIHOOD OF A SIGNIFICANT WARM UP INCREASES.

...FLOOD POTENTIAL OUTLOOK...
THERE CONTINUES TO BE A BELOW NORMAL FLOOD POTENTIAL FOR THE REGION 
THROUGH THE END OF MARCH. THERE IS A FAIRLY HIGH FORECAST CONFIDENCE 
THAT THE REGION WILL REMAIN IN A COOL PATTERN...WHICH IS UNLIKELY TO 
PRODUCE MUCH RAINFALL. ALSO...SNOW PACK IS BELOW NORMAL IN MOST
BASINS...WITH THE BLACK RIVER BASIN A NOTABLE EXCEPTION. THERE IS
LITTLE TO NO RISK FOR ICE JAMS ON THE BUFFALO CREEKS.

ONE POTENTIAL CAUSE FOR CONCERN IS THAT THE SNOWPACK CONTINUES TO 
GROW ON THE TUG HILL. IF THIS TREND CONTINUES...THERE WILL BE
QUITE SIGNIFICANT WATER EQUIVALENT VALUES OF SNOW IN THE BLACK
RIVER BASIN AT THE START OF APRIL. WHILE SNOW PACK ALONE RARELY
RESULT IN FLOODING...IT IS LIKELY THAT AT SOME POINT THE WEATHER PATTERN
WILL SHIFT. THIS WOULD LEAVE THE BLACK RIVER BASIN VULNERABLE IF
THERE IS A SIGNIFICANT AND WARM RAINFALL. THIS WILL BE THE MAIN
AREA TO WATCH IN APRIL...SINCE SNOW PACK IN THE OTHER BASINS IS
MINIMAL.

...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
APRIL 4TH. THANKS TO ALL THE OBSERVERS AND AGENCIES WHICH HAVE
HELPED GATHER DATA IN SUPPORT OF THIS OUTLOOK.

$$

APFFEL