Flood Potential Outlook
Issued by NWS Burlington, VT

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BURLINGTON VT
130 PM EDT THU MAR 17 2016

...SPRING FLOOD POTENTIAL OUTLOOK /6/...

THIS IS THE SIXTH FLOOD OUTLOOK FOR THE 2016 WINTER/SPRING
SEASON. FLOOD OUTLOOKS ARE ISSUED BI-WEEKLY BY THE NATIONAL
WEATHER SERVICE IN BURLINGTON VERMONT TO SUMMARIZE THE FLOOD
POTENTIAL DUE TO SNOWMELT AND BREAK UP OF RIVER ICE ACROSS CENTRAL
AND NORTHERN VERMONT...AND NORTHERN NEW YORK.

...OVERVIEW...

THE FLOOD OUTLOOK IS NEAR TO BELOW NORMAL FOR VERMONT AND
NORTHERN NEW YORK. ALTHOUGH THE SNOW PACK IS MOSTLY DEPLETED
ACROSS THE NORTH COUNTRY, RIVER FLOWS ARE HIGH AND SOILS ARE
SATURATED, AND THE WET CONDITIONS ENHANCE THE FLOOD THREAT. THE
ICE JAM THREAT HAS ENDED FOR THE SEASON.

...SNOW DEPTHS AND WATER EQUIVALENT...

SNOW COVER ACROSS NORTHERN NEW YORK AND VERMONT IS THIN TO NON-
EXISTENT. SNOW HAS MELTED ENTIRELY AT ELEVATIONS BELOW 1500 FEET,
WITH THIN COVERAGE OVER THE HIGHER TERRAIN AND IN FAR NORTHEAST
VERMONT. SNOW DEPTHS AT THE HIGHEST ELEVATIONS...AND IN FAR
NORTHEAST VERMONT IS 10 INCHES OR LESS. THE WATER CONTENT OF THE
REMAINING SNOW IS ONE TO THREE INCHES. THESE VALUES ARE JUST A
FRACTION OF THE NORMAL VALUES, AND REFLECT CONDITIONS COMMONLY
FOUND IN MID TO LATE APRIL.

...RIVER AND SOIL CONDITIONS...

RIVERS HAVE CLEARED OF ICE IN VERMONT AND NORTHERN NEW YORK,
ENDING THE ICE JAM THREAT FOR THIS SEASON.

SOILS REMAIN QUITE MOIST AS THE REGION FINDS ITSELF IN THE MIDST
OF AN EARLY MUD SEASON. WET SOIL CONTRIBUTES TO HIGHER RUNOFF AS
ANY RAINFALL OR SNOWMELT WILL FLOW DIRECTLY INTO RIVERS AND
STREAMS RATHER THAN BE ABSORBED INTO THE GROUND.

RIVER FLOWS ARE MUCH ABOVE NORMAL ACROSS THE REGION, RUNNING HIGH
FROM SNOWMELT EPISODES OVER THE PREVIOUS WEEKS. ADDITIONALLY,
RECENT PRECIPITATION HAS BEEN IN THE FORM OF RAIN, AND RAINFALL
RUNOFF ALSO CONTRIBUTES TO HIGHER RIVER FLOWS.

RECENT WARM TEMPERATURES HAVE BEGUN THE PROCESS OF THAWING THE
GROUND, WITH UNFROZEN GROUND EXTENDING DOWN 6 TO 9 INCHES. HOWEVER
A FROZEN LAYER REMAINS FURTHER DOWN IN THE SOIL, EXTENDING DOWN TO
10 TO 17 INCHES BELOW THE SURFACE. THE FROZEN SUBSURFACE LAYER
WILL CONTINUE TO BE A FACTOR IN RETAINING HIGH SOIL MOISTURE,
PREVENTING IT FROM SEEPING FURTHER INTO THE GROUND.

...WEATHER OUTLOOK...

A RETURN TO COOLER, MORE NORMAL TEMPERATURES IS IN STORE FOR THE
NEXT WEEK. DAILY HIGHS WILL BE ABOVE FREEZING WITH NIGHTTIME LOWS
BELOW FREEZING. A LOW PRESSURE SYSTEM WILL MOVE UP THE COAST THIS
WEEKEND, HOWEVER WILL BE TOO FAR EAST TO PRODUCE SNOW
ACCUMULATIONS OF ANY SIGNIFICANCE FOR VERMONT OR NORTHERN NEW
YORK. OTHER STORM SYSTEMS MID TO LATE NEXT WEEK COULD PRODUCE BOTH
RAIN AND SNOW.

HEADING INTO THE OUTLOOK PERIOD OF LATE MARCH THE OFFICIAL
NATIONAL WEATHER SERVICE OUTLOOK CALLS FOR TEMPERATURES AND
PRECIPITATION TO TREND BACK ABOVE NORMAL.

...SUMMARY...

THE SPRING FLOOD POTENTIAL IS NEAR TO BELOW NORMAL, BASED
PRIMARILY ON HIGH RIVER LEVELS AND SOIL MOISTURE. LITTLE SNOW
REMAINS TO CONTRIBUTE TO A FLOOD THREAT. RIVER ICE HAS CLEARED
FROM RIVERS AND THE ICE JAM THREAT HAS ENDED FOR THIS SEASON.

THE PROBABILITY FOR LAKE CHAMPLAIN FLOODING IS LOW BASED ON MELT
OF THE REMAINING SNOW COMBINED WITH THE PRECIPITATION OUTLOOK.
THE LAKE LEVEL IS OVER ONE AND A HALF FEET ABOVE NORMAL FOR EARLY
MARCH. HOWEVER GIVEN THE LACK OF SNOW REMAINING TO MELT, IT IS
POSSIBLE THAT LAKE CHAMPLAIN IS NEAR ITS HIGHEST LEVELS FOR THIS
SPRING. THE LAKE`S PEAK HEIGHT IS TYPICALLY REACHED IN LATE APRIL
TO EARLY MAY.

IT IS IMPORTANT TO NOTE THAT HEAVY RAINFALL ON TOP OF SNOWMELT IS
THE DRIVING FACTOR IN SPRING FLOODING. EVEN WITH THIS YEAR`S LOW
SNOW PACK, VERY HEAVY RAINFALL CAN RESULT IN FLOODING, EVEN IN
AREAS THAT HAVE LITTLE OR NO SNOW ON THE GROUND.

THE NEXT WINTER/SPRING FLOOD OUTLOOK WILL BE ISSUED ON MARCH 31.

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

$$

HANSON


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