Flood Potential Outlook
Issued by NWS Burlington, VT

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BURLINGTON VT
245 PM EDT THU APR 16 2015

...SPRING FLOOD POTENTIAL OUTLOOK /9/...

...ABOVE NORMAL POTENTIAL FOR SNOW MELT FLOODING IN THE NORTHEAST
KINGDOM, NEAR NORMAL ELSEWHERE...

THIS IS THE NINTH FLOOD OUTLOOK FOR THE 2015 WINTER/SPRING
SEASON. FLOOD OUTLOOKS ARE ISSUED BI-WEEKLY THROUGH THE WINTER AND
SPRING BY THE NATIONAL WEATHER SERVICE IN BURLINGTON VERMONT TO
SUMMARIZE THE FLOOD POTENTIAL DUE TO SNOW MELT AND BREAK UP OF
RIVER ICE ACROSS CENTRAL AND NORTHERN VERMONT, AND NORTHERN NEW
YORK.

...OVERVIEW...

THE SPRING FLOOD THREAT IS ABOVE NORMAL FOR THE NORTHEAST KINGDOM
OF VERMONT BASED ON ABOVE NORMAL SNOWPACK AND THE PROSPECT FOR
ABOVE FREEZING TEMPERATURES AND RAINFALL. ELSEWHERE ACROSS
VERMONT AND NORTHERN NEW YORK THE SPRING FLOOD THREAT IS NORMAL.
RIVER ICE HAS CLEARED FROM AREA RIVERS, ENDING THE THREAT FOR ICE
JAMS.

...SNOW DEPTHS AND WATER EQUIVALENT...

THE SNOW PACK HAS SEEN SIGNIFICANT LOSSES OVER THE PAST TWO WEEKS
WITH THE RETURN OF WARM DAYTIME TEMPERATURES AND ABOVE FREEZING
OVERNIGHT LOWS. VALLEY BOTTOMS WERE BARE OF SNOW, WITH SOLID SNOW
COVER IN THE HIGHER TERRAIN. THE EXCEPTION OF THE NORTHEAST
KINGDOM OF VERMONT WHERE SNOW COVER WAS MORE EXTENSIVE OVER LOWER
ELEVATIONS.

IN NORTHERN NEW YORK THE GROUND WAS BARE BELOW 1500 FEET
ELEVATION, AND SNOW COVER ONLY REMAINING IN THE ADIRONDACKS. SNOW
DEPTHS WERE THREE TO EIGHT INCHES ABOVE 1500 FEET, AND THE HIGH
PEAKS REGION OF THE ADIRONDACKS HAD ONE TO TWO FEET OF SNOW OVER
THE HIGHEST ELEVATIONS.

IN VERMONT, GROUND WAS BARE AT LOWER ELEVATIONS, WITH INCREASING
SNOW DEPTH HEADING INTO THE HIGHER TERRAIN OF THE GREEN MOUNTAINS
AND REACHING A MAXIMUM IN COVERAGE ACROSS THE NORTHEAST KINGDOM. SNOW
DEPTHS IN THE NORTHEAST KINGDOM WERE EIGHT TO EIGHTEEN INCHES AT
LOWER ELEVATIONS AND ONE TO TWO FEET OVER THE HIGHER TERRAIN.
ACROSS THE REST OF VERMONT GROUND WAS BARE BELOW ABOUT 1000 FEET
ELEVATION, AND SNOW DEPTHS WERE SIX INCHES TO A FOOT BETWEEN 1000
AND 2000 FEET ELEVATION. SNOW WAS AS DEEP AS 18 INCHES TO TWO FEET
NEAR 2000 FEET ELEVATION, AND THE SUMMITS RETAINED THREE TO FOUR
FEET OF SNOW.

SNOW WATER EQUIVALENT, OR THE AMOUNT OF LIQUID WATER HELD IN THE
SNOWPACK, WAS ONE TO THREE INCHES IN NORTHERN NEW YORK AND VERMONT
BETWEEN 1000 AND 2000 FEET ELEVATION. ABOVE 2000 FEET THE SNOW
HELD THREE TO SIX INCHES OF WATER, AND EIGHT TO TWELVE INCHES AT
THE SUMMITS.

...RIVER AND SOIL CONDITIONS...

RIVERS HAVE RESPONDED TO SNOWMELT AND RAINFALL OVER THE PAST TWO
WEEKS, RISING TO ABOVE NORMAL FLOWS. RIVERS WILL CONTINUE TO RUN
HIGH AS THE REMAINING HIGHER ELEVATION SNOW MELTS OUT AND SPRING
RAINS ADD TO THE RUNOFF. ICE WAS GONE FROM AREA RIVERS, ENDING THE
ICE JAM THREAT.

FROST WAS COMING OUT OF THE GROUND AS TEMPERATURES WARMED. SOILS
WERE SATURATED BY THE RELEASE OF THE WATER HELD IN STORAGE IN SNOW
DURING THE WINTER.

...WEATHER OUTLOOK...

THE NORTHEAST WILL TREND TOWARD A MORE UNSETTLED BUT COOLER
PATTERN. THE BELOW NORMAL PRECIPITATION SEEN IN MARCH AND EARLY
APRIL WILL GIVE WAY TO MORE NORMAL PRECIPITATION AMOUNTS.
TEMPERATURES WILL TREND A LITTLE BELOW NORMAL, ALTHOUGH STILL
ABOVE FREEZING TO ALLOW SNOW MELT TO CONTINUE. TEMPERATURES OVER
THE HIGHER TERRAIN WILL BE THE COOLEST, WHICH SHOULD HELP TO SLOW
THE MELT OF THE DEEPER SNOW PACK.

...SUMMARY...

THE RISK FOR SNOWMELT FLOODING IS ABOVE NORMAL IN THE NORTHEAST
KINGDOM OF VERMONT WHERE THE DEEPEST SNOW PERSISTS, AND NEAR
NORMAL ELSEWHERE. ALTHOUGH SNOW WAS ABSENT FROM THE LOWER
ELEVATIONS, A SUFFICIENT SNOW PACK EXISTS IN THE HIGHER TERRAIN TO
POSE A FLOOD RISK IF SNOWMELT COMBINES WITH RAINFALL.

THE PROBABILITY FOR LAKE CHAMPLAIN FLOODING IS LOW BASED ON MELT
OF THE EXISTING SNOW COMBINED WITH NORMAL PRECIPITATION. THE LAKE
LEVEL REMAINS BELOW NORMAL AND HAS THE CAPACITY TO ABSORB THE
COMING SNOWMELT.

ICE COVER HAS CLEARED FROM AREA RIVERS, ENDING THE ICE JAM THREAT
FOR 2015.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED ON THURSDAY
APRIL 30.

ACCESS CURRENT WEATHER CONDITIONS AND FORECASTS ON OUR WEB SITE
AT WWW.ERH.NOAA.GOV/BTV.

$$

HANSON



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