Flood Potential Outlook
Issued by NWS Buffalo, NY

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FGUS71 KBUF 191737
ESFBUF
NYC003-009-011-013-029-037-045-049-051-055-063-069-073-075-117-
121-021745-

WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
137 PM EDT THU MAR 19 2015

...ABOVE NORMAL FLOOD RISK THROUGH APRIL 2ND...

THIS IS THE SIXTH 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...
FOLLOWING ABOUT A TWO MONTH PERIOD OF PRIMARILY BELOW FREEZING
TEMPERATURES...THE PAST WEEK AND A HALF WAS NEAR TO A BIT ABOVE
NORMAL. THIS HAS MELTED A CONSIDERABLE PORTION OF THE SNOW PACK
SOUTH OF LAKE ONTARIO. IN THE BUFFALO CREEKS...AND GENESEE AND
ALLEGHENY RIVER BASINS SNOW WATER EQUIVALENT HAS BEEN REDUCED BY
ABOUT HALF FROM WHAT IT WAS TWO WEEKS AGO.

THIS HAS CAUSED SOME ICE TO BREAK UP ON THE BUFFALO CREEKS...WHILE
THERE ARE STILL SOME PATCHES OF THICK ICE. THIS HAS ALREADY
RESULTED IN SOME MINOR ICE JAM FLOODING WITH MANY OF THESE ICE
JAMS STILL IN PLACE. THERE ARE KNOWN ICE JAMS ON BUFFALO
CREEK...CAYUGA CREEK...AND CATTARAUGUS CREEK...AND THERE ARE
PROBABLY OTHER ICE JAMS WHICH HAVE NOT BEEN REPORTED. THESE ICE
JAMS ARE NOT CURRENTLY CAUSING ANY FLOODING...BUT IF FLOWS
INCREASE SIGNIFICANTLY THE WATER BEHIND THE ICE JAMS WILL RISE AND
THE EXISTING ICE JAMS RE-POSITION TO MORE PROBLEMATIC LOCATIONS.
THE RECENT RUN-OFF HAS ALSO INCREASED CREEK FLOWS TO ABOVE NORMAL
ON MOST BASINS...ESPECIALLY THE GENESEE BASIN WHERE TEMPERATURES
WERE THE WARMEST. IT IS ALSO IMPORTANT TO NOTE THAT DESPITE THE
RECENT SNOW MELT THAT SNOW PACK IS STILL MUCH ABOVE NORMAL FOR
THIS POINT IN THE SEASON. ON THE BUFFALO CREEKS SNOW WATER
EQUIVALENT IS STILL RUNNING 2 TO 3 TIMES NORMAL FOR THIS
DATE...AND THE SNOW PACK IN PLACE IS RIPE.

FOR THE BLACK RIVER BASIN...TEMPERATURES WERE NOT AS WARM AND
THERE WAS LESS SNOW MELT. SNOW WATER EQUIVALENT VALUES ARE NEAR
NORMAL...AND THE SNOW PACK IS STILL NOT FULLY RIPE...THOUGH IT HAS
BECOME CONSIDERABLY MORE DENSE SINCE THE LAST OUTLOOK.

THE FOLLOWING IS A SUMMARY OF CONDITIONS AND OUTLOOK BY BASIN AS
OF THURSDAY MORNING ON MARCH 19TH:

...BUFFALO AREA CREEKS / LAKE ERIE BASIN...
.SNOW COVER..........6 TO 12 INCHES.
.WATER EQUIVALENT....2 TO 5 INCHES.
.CREEK FLOWS.........ABOVE NORMAL.
.CREEK ICE...........PATCHY BUT THICK IN SPOTS...SOME ICE JAMS.
.GROUND FROST........ABOUT 18 INCHES.
.GROUND STATE........FROZEN.

...GENESEE RIVER BASIN / FINGER LAKES / ROCHESTER AREA...
.SNOW COVER..........3 TO 6 INCHES.
.WATER EQUIVALENT....1 TO 3 INCHES.
.RIVER/CREEK FLOWS...MUCH ABOVE NORMAL.
.RIVER/CREEK ICE.....PATCHY BUT THICK IN SPOTS.
.GROUND FROST........12 TO 18 INCHES.
.GROUND STATE........FROZEN.

...ALLEGHENY RIVER BASIN...
.SNOW COVER..........3 TO 6 INCHES...MAINLY ACROSS HIGHER TERRAIN.
.WATER EQUIVALENT....1 TO 3 INCHES...MAINLY ACROSS HIGHER TERRAIN.
.RIVER/CREEK FLOWS...ABOVE NORMAL.
.RIVER CREEK ICE.....PATCHY BUT THICK IN SPOTS.
.GROUND FROST........ABOUT 18 INCHES.
.GROUND STATE........FROZEN.

...BLACK RIVER BASINS / TUG HILL...
.SNOW COVER..........18 TO 30 INCHES.
.WATER EQUIVALENT....4 TO 7 INCHES...7 TO 10 INCHES HIGHER TERRAIN.
.RIVER/CREEK FLOWS...NEAR NORMAL.
.RIVER/CREEK ICE.....THICK.
.GROUND FROST........ABOUT 24 INCHES.
.GROUND STATE........FROZEN.

...TEMPERATURE AND PRECIPITATION OUTLOOK...
TEMPERATURES WILL AVERAGE BELOW NORMAL THROUGH THE PERIOD...BUT
THERE IS A SYSTEM FORECAST TO DEVELOP DURING THE MIDDLE PORTION OF
NEXT WEEK THAT BEARS WATCHING.

TEMPERATURES SHOULD BE NEAR NORMAL FOR THE NEXT COUPLE DAYS...THEN
DROP OFF SHARPLY BY SUNDAY WHEN ANOTHER SHOT OF ARCTIC AIR IS
FORECAST TO DROP ACROSS THE REGION. THIS WILL RESULT IN A COOL AND
DRY PATTERN EARLY NEXT WEEK.

DURING THE MIDDLE PORTION OF NEXT WEEK MODEL CONSENSUS FORECASTS
A STRONG AREA OF LOW PRESSURE TO TRACK ACROSS THE GREAT LAKES
REGION. THIS LOW IS LIKELY TO TRACK TO THE NORTH OF THE AREA WHICH
WOULD BRING WARM AIR AND RAIN. A WESTERLY FLOW ALOFT SHOULD LIMIT
THE AMOUNT OF GULF MOISTURE THIS SYSTEM CAN TAP INTO...HOWEVER THE
SYSTEM MAY BE STRONG ENOUGH TO BRING AN INCH OF RAIN TO SOME AREAS
WITHOUT GULF MOISTURE. FORECAST CONFIDENCE IS MODERATE AT THIS
POINT...WITH A SYSTEM LIKELY TO DEVELOP...BUT THE SPECIFIC
TEMPERATURES AND AMOUNT OF RAIN UNCERTAIN.

AFTER THIS...A PERSISTENT TROUGH IS FORECAST TO REMAIN IN PLACE
ACROSS EASTERN CANADA WHICH IS LIKELY TO BRING MORE BELOW NORMAL
TEMPERATURES TO THE REGION. THIS MAY BRING ANOTHER WEAK SYSTEM OR
TWO WITH ONLY A SMALL CHANCE FOR A STRONGER SYSTEM. OVERALL...THIS
PATTERN IS NOT LIKELY TO PRODUCE A SINGULAR HEAVY RAIN EVENT...BUT
IT MAY BRING MULTIPLE LIGHT EVENTS WHICH HAVE A SMALL CHANCE TO
CAUSE HYDROLOGICAL ISSUES.

...FLOOD POTENTIAL OUTLOOK...
OVERALL THERE IS ABOVE NORMAL FLOOD RISK THROUGH APRIL 2ND.
THIS ELEVATED RISK IS MAINLY FOR THE POTENTIAL SYSTEM IN THE MARCH
25TH AND 26TH TIMEFRAME...WITH THE GREATEST RISK IN THE BUFFALO
CREEKS BASIN.

THE COMBINATION OF ABOVE NORMAL CREEK FLOWS...RIPE SNOW PACK...AND
ICE JAMS LEAVES THE BUFFALO CREEKS BASIN VULNERABLE TO FLOODING.
COLD TEMPERATURES THROUGH EARLY NEXT WEEK SHOULD LEAVE ICE JAMS
IN PLACE AND ONLY MELT A SMALL AMOUNT OF THE EXISTING SNOW PACK.
AFTER THIS...IT SIMPLY COMES DOWN TO THE MID- WEEK SYSTEM. IT IS
STILL POSSIBLE THAT THIS LOW WILL NOT DEVELOP...OR WILL TAKE A
COLDER TRACK...AND NOT CAUSE ANY HYDROLOGICAL ISSUES. HOWEVER...IF
SOME OF THE WARMER AND WETTER GUIDANCE VERIFIES THEN THIS COULD
RESULT IN MODERATE FLOODING FROM ICE JAMS AND HIGH FLOWS FROM SNOW
MELT. THE SNOW PACK AND FLOWS ARE ALSO ABOVE NORMAL IN THE ALLEGHENY
AND GENESEE BASINS SO THESE COULD ALSO EXPERIENCE ISSUES.

LOOKING BEYOND THE SYSTEM NEXT WEEK...THE COLDER THAN NORMAL PATTERN
NOT LIKELY TO PRODUCE A SINGULAR HEAVY RAIN EVENT. HOWEVER...GIVEN
THE CURRENT CONDITIONS...IT MAY NOT TAKE A PARTICULARLY STRONG
SYSTEM TO CAUSE FLOODING. IF THERE IS NOT AN EVENT BY EARLY APRIL...THE
NEXT TWO WEEKS WILL PROBABLY GO A LONG WAYS TOWARD MELTING THE
EXISTING SNOW PACK IN BASINS SOUTH OF LAKE ONTARIO AND HELP
DIMINISH THE FLOODING THREAT.

THE RISK FOR FLOODING IN THE BLACK RIVER BASIN IS CONSIDERABLY
LOWER...PROBABLY NEAR TO BELOW NORMAL. THE SNOW PACK IS NOT FULLY
RIPE AND THIS SYSTEM IS LESS LIKELY TO BRING WARM TEMPERATURES
INTO THIS BASIN. HOWEVER...CONTINUED BELOW NORMAL TEMPERATURES IS
LIKELY TO RIPEN BUT EXTEND THE SNOW PACK INTO APRIL. EXPECT THE
FLOOD RISK MAY INCREASE FOR THE BLACK RIVER BASIN IN APRIL.

...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 APRIL 2ND. THANKS
TO ALL THE OBSERVERS AND AGENCIES WHICH HAVE HELPED GATHER DATA IN
SUPPORT OF THIS OUTLOOK.


$$

APFFEL





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