Flood Potential Outlook
Issued by NWS Buffalo, NY

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FGUS71 KBUF 051931
ESFBUF
NYC003-009-011-013-029-037-045-049-051-055-063-069-073-075-117-
121-191945-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
231 PM EST THU MAR 5 2015

...BELOW NORMAL FLOOD RISK THROUGH MARCH 12TH...
...ABOVE NORMAL FLOOD RISK MARCH 13TH THROUGH MARCH 19TH...

THIS IS THE FIFTH WINTER / SPRING FLOOD POTENTIAL OUTLOOK OF THE
2015 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 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 REGION HAS BEEN IN A DEEP FREEZE FOR JANUARY AND FEBRUARY WITH
FEBRUARY TEMPERATURES IN BUFFALO THE COLDEST ON RECORD. THIS COLD
WEATHER RESULTED IN LITTLE IF ANY SNOW MELT...WITH ANY
PRECIPITATION SIMPLY ADDING TO THE EXISTING SNOW PACK.

TYPICALLY THE BUFFALO CREEKS BASIN WILL EXPERIENCE ONE OR TWO
WARM-UPS DURING THE WINTER MONTHS WHICH TEND TO LIMIT SNOW PACK.
THIS WAS NOT THE CASE THIS YEAR...WITH SNOW WATER EQUIVALENT
VALUES IN THE BUFFALO CREEKS RUNNING 2 TO 3 TIMES NORMAL FOR THIS
TIME OF YEAR.

SNOW WATER EQUIVALENT IS ALSO SIGNIFICANTLY ABOVE NORMAL IN THE
ALLEGHENY AND GENESEE BASINS...WITH THE MOST SIGNIFICANT SNOW PACK
IN THE GENESEE BASIN ACROSS LOWER PORTIONS WHICH ARE CLOSER TO
LAKE ONTARIO. SNOW PACK IS ALSO DEEP IN THE BLACK RIVER
BASIN...BUT WATER EQUIVALENT VALUES ARE ONLY ABOUT 10 PERCENT
ABOVE NORMAL SINCE SINCE DEEP SNOW PACKS ARE MORE TYPICAL FOR THAT
BASIN THIS TIME OF YEAR.

A VERY IMPORTANT NOTE...THE SNOW PACK IS FAR FROM RIPE. SNOW DEPTH
TO WATER EQUIVALENT RATIOS AVERAGE 5 TO 1...AND WITH A DEEP SNOW
PACK IT WILL TAKE QUITE A BIT OF WARM WEATHER TO RIPEN THIS. SNOW
DEPTHS FOR THE BUFFALO CREEKS BASIN ARE NEAR RECORD LEVELS...BUT
SNOW WATER EQUIVALENT VALUES ARE NOT.

THE COLD TEMPERATURES HAVE CAUSED CREEK AND RIVER ICE TO THICKEN.
OUTSIDE OF FAST FLOWING AREAS VIRTUALLY ALL THE CREEKS AND RIVERS
ARE FROZEN... WITH A VERY THICK ICE PACK IN PLACE. ICE EXCEEDS A
FOOT IN MANY SLOW FLOWING AREAS. IT WILL PROBABLY TAKE MORE
THAWING DEGREE HOURS THAN NORMAL TO BREAK THIS ICE UP...BUT THERE
COULD BE SIGNIFICANT ICE JAMS IF THE ICE DOES BREAK UP.

THE FOLLOWING IS A SUMMARY OF CONDITIONS AND OUTLOOK BY BASIN AS
OF THURSDAY MORNING ON MARCH 5TH:

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........20 TO 30 INCHES.
.WATER EQUIVALENT....4 TO 7 INCHES.
.CREEK FLOWS.........NEAR NORMAL.
.CREEK ICE...........THICK
.GROUND FROST........ABOUT 18 INCHES.
.GROUND STATE........FROZEN.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........12 TO 24 INCHES.
.WATER EQUIVALENT....2 TO 4 INCHES.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER/CREEK ICE.....THICK.
.GROUND FROST........12 TO 18 INCHES.
.GROUND STATE........FROZEN.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........16 TO 24 INCHES.
.WATER EQUIVALENT....3 TO 5 INCHES.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER CREEK ICE.....THICK.
.GROUND FROST........ABOUT 18 INCHES.
.GROUND STATE........FROZEN.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........24 TO 42 INCHES.
.WATER EQUIVALENT....5 TO 7 INCHES...7 TO 10 INCHES ON THE TUG.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER/CREEK ICE.....THICK.
.GROUND FROST........ABOUT 24 INCHES.
.GROUND STATE........FROZEN.

...TEMPERATURE AND PRECIPITATION OUTLOOK...
THERE IS INCREASING FORECAST CONFIDENCE THAT THE COLD PATTERN WE
HAVE BEEN IN FOR THE PAST TWO MONTHS WILL END SOON. MODEL GUIDANCE
SUGGESTS THAT THERE WILL BE A GRADUAL WARMING TREND THROUGH
THURSDAY MARCH 12TH. TEMPERATURES WILL INITIALLY START OFF BELOW
NORMAL BUT RISE TO NEAR OR SLIGHTLY ABOVE NORMAL BY NEXT WEEK.
DESPITE THE WARM UP...THERE IS GOOD FORECAST CONFIDENCE THAT IT
WILL BE A RELATIVELY DRY PATTERN DURING THIS TIME. THERE MAY BE
SOME LIGHT PRECIPITATION...BUT THIS WILL COME FROM WEAK CLIPPER
SYSTEMS.

AFTER THIS...THE 8 TO 14 DAY OUTLOOK SUGGESTS TEMPERATURES ARE
LIKELY TO AVERAGE ABOVE NORMAL. MODEL GUIDANCE SUGGESTS A RIDGE
WILL BUILD INTO THE UPPER PLAINS...WHICH IS LIKELY TO RESULT IN
ABOVE NORMAL TEMPERATURES FOR WESTERN NEW YORK. THE BIG FORECAST
QUESTION IS IF A SIGNIFICANT ROUND OF PRECIPITATION WILL ACCOMPANY
THIS WARM UP. AT THIS POINT...GUIDANCE DOES LIFT A SYSTEMS INTO
THE SOUTHEASTERN STATES...BUT IT IS UNCERTAIN IF THIS WILL REACH
OUR REGION OR STAY TO THE SOUTH. IF THIS DOES HAPPEN IT WOULD BE TOWARD
THE END OF THE OUTLOOK PERIOD.

...FLOOD POTENTIAL OUTLOOK...
THE OUTLOOK PERIOD IS BROKEN INTO TWO SECTIONS SINCE IT IS
IMPORTANT TO HIGHLIGHT THAT THERE IS A BELOW NORMAL FLOOD RISK FOR
THE FIRST WEEK OF THE OUTLOOK PERIOD THROUGH MARCH 12TH. THIS IS
BECAUSE THE SNOW PACK IS STILL FAR FROM RIPE...AND ALTHOUGH
TEMPERATURES ARE FORECAST TO WARM ABOVE FREEZING THIS ALONE WILL
NOT BE ENOUGH TO CAUSE FLOODING. THIS WILL...HOWEVER...RIPEN THE
SNOW PACK FOR THE LATTER PORTIONS OF THE OUTLOOK PERIOD.

AFTER THIS...THERE IS AN ABOVE NORMAL RISK FOR FLOODING IN THE
MARCH 13TH THROUGH MARCH 19TH TIMEFRAME. ONE REASON FOR THIS IS
BECAUSE THE SNOW PACK IS LIKELY TO BE MORE RIPE...ESPECIALLY IN
THE BUFFALO CREEKS...ALLEGHENY...AND GENESEE BASINS.
ALSO...TEMPERATURES ARE FORECAST TO BE ABOVE NORMAL AND THERE IS A
CHANCE THAT A SYSTEM WILL BRING STEADY RAIN WITH THIS WARM UP TOWARD
THE END OF THE OUTLOOK PERIOD. IF THIS DOES OCCUR...THERE COULD BE
SIGNIFICANT FLOODING ISSUES IN THESE BASINS FROM SNOW MELT...RUN-
OFF...AND ICE JAMS.

AGAIN...IT IS STILL FAR FROM CERTAIN THAT SUCH A SYSTEM WILL
IMPACT OUR REGION WITH A SIGNIFICANT PORTION OF MODEL GUIDANCE
KEEPING THE WARMEST AND MOST MOIST AIR TO OUR SOUTH. DESPITE THE
HEIGHTENED RISK...IT IS POSSIBLE THAT A PROLONGED PERIOD OF WARM
AND DRY WEATHER WILL GRADUALLY MELT THE SNOW PACK. THOSE LOCATED
IN AREAS VULNERABLE TO FLOODING SHOULD CONTINUE TO MONITOR THE
LATEST WEATHER SERVICE PRODUCTS.

...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 SCHEDULED OUTLOOK WILL BE ISSUED ON MARCH 19TH. THANKS TO
ALL THE OBSERVERS AND AGENCIES WHICH HAVE HELPED GATHER DATA IN
SUPPORT OF THIS OUTLOOK.

$$

APFFEL







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