National Weather Service Text Product Display

Flood Potential Outlook
Issued by NWS Burlington, VT
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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE BURLINGTON VT
1046 AM EST FRI FEB 5 2010

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK /3/...

THIS IS THE THIRD WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR THE 2010
SNOW MELT 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 SNOWPACK MELT AND
BREAKUP OF RIVER ICE ACROSS CENTRAL AND NORTHERN VERMONT...AS WELL
AS NORTHERN NEW YORK.

...OVERVIEW...

THE WINTER/SPRING FLOOD POTENTIAL FOR NORTHERN AND CENTRAL VERMONT
AND NORTHERN NEW YORK IS BELOW NORMAL. THIS IS PRIMARILY DUE TO
THE LACK OF DEEP SNOW COVER ACROSS THE REGION. THE SNOWPACK IS
RUNNING WELL BELOW NORMAL THE USUAL EARLY FEBRUARY NUMBERS...AS
IS THE SNOW WATER EQUIVALENT CONTAINED IN THAT SNOW. IN SOME
PLACES...THE SNOWPACK AND ASSOCIATED WATER EQUIVALENT ARE HALF OF
WHAT THEY SHOULD BE FOR THIS TIME OF YEAR. IN ADDITION...WITH NEAR
TO BELOW NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION
EXPECTED OVER THE WEEK TO 10 DAYS...IT IS VERY UNLIKELY ANY
SIGNIFICANT RUNOFF WILL BE PRODUCED. AREA RIVERS THAT EXPERIENCED
BREAK UP ICE JAMS LAST WEEK HAVE BEGUN TO REFREEZE WHILE THE JAMS
THEMSELVES HAVE STABILIZED IN PLACE AS RIVER LEVELS HAVE RECEDED.
THE SHORT TERM THREAT OF ICE JAMS IS LOW...BUT THE LONGER TERM
POTENTIAL FOR ICE JAM FLOODING WILL REMAIN ABOVE NORMAL UNTIL
THESE OLD JAMS RELEASE.

...SNOW DEPTHS AND WATER EQUIVALENT...

AS MENTIONED ABOVE...SNOW DEPTHS AND SNOW WATER EQUIVALENTS ARE
RUNNING BELOW TO MUCH BELOW NORMAL FOR THIS TIME OF YEAR. IN
CENTRAL VERMONT...10 INCHES OR LESS COVERS THE GROUND WITH SOME
BARE SPOTS EVIDENT. THESE AMOUNTS INCREASE SLIGHTLY ABOVE 1500 FT
WHERE 10 TO 20 INCHES OF SNOW HAS BEEN OBSERVED. THE SNOW WATER
EQUIVALENT...OR AMOUNT OF WATER CONTAINED IN THE SNOW...AVERAGES
BETWEEN A TRACE TO AS MUCH 3 INCHES AT LOWER ELEVATIONS. THIS
INCREASES TO 3 TO 4 INCHES IN THE HIGHER TERRAIN. IN NORTHERN
VERMONT...A BIT MORE SNOW REMAINS. THE PACK IS 8 TO 16 INCHES IN
THE VALLEYS HERE WITH 1 TO 2.5 FEET ABOVE 1500 FT. MORE WATER IS
BEING HELD IN THIS DEEPER SNOW WITH VALUES OF 2 TO 4 INCHES IN THE
VALLEYS. AT HIGHER ELEVATIONS 3 TO 6 INCHES OF SNOW WATER
EQUIVALENT EXISTS.

THE STORY IS MUCH THE SAME ACROSS NORTHERN NEW YORK. THE
ADIRONDACKS HAVE 6 TO 12 INCHES OF SNOW ON THE GROUND...WITH 1 TO
2 FEET ABOVE 1500 FT. SNOW WATER EQUIVALENTS HERE ARE 1 TO 3 INCHES
AT LOWER ELEVATIONS WHILE 2 TO 5 INCHES OF LIQUID HAS BEEN
REPORTED ABOVE 1500 FT. IN FACT...ACROSS THE HIGHER TERRAIN OF THE
ADIRONDACKS...SNOW WATER EQUIVALENTS ARE RUNNING JUST 50 TO 75
PERCENT OF NORMAL FOR MID-WINTER. IN THE SAINT LAWRENCE RIVER
VALLEY...SNOW DEPTHS ARE 10 INCHES OR LESS WITH A TRACE TO 2
INCHES OF WATER IN THE SNOWPACK.


...RIVER AND SOIL MOISTURE CONDITIONS...

RIVER FLOWS ARE ABOVE NORMAL ACROSS MOST OF VERMONT AND NORTHERN
NEW YORK. A MAJOR RAIN AND THAW EVENT DURING LAST WEEK RESULTED IN
SEVERAL BREAKUP ICE JAMS ACROSS THE NORTH COUNTRY. THESE ICE JAMS
SHOULD FREEZE IN PLACE AS RIVER FLOWS DECLINE AND COLD AND MAINLY
DRY CONDITIONS CONTINUE. ON THOSE RIVERS ON WHICH THE ICE
COMPLETELY MOVED OUT...ICE COVER IS STARTING TO REFORM. CONDITIONS
WILL BE FAVORABLE FOR CONTINUED ICE FORMATION OVER THE NEXT
SEVERAL DAYS. HOWEVER...THE SHORT TERM THREAT OF ICE JAM FLOODING
IS BELOW NORMAL AS LITTLE TO NO RUNOFF IS EXPECTED. LONGER
TERM...WHERE OLD ICE JAMS REMAIN FROZEN IN PLACE...FLOODING
POTENTIAL IS ABOVE NORMAL AND WILL REMAIN SO UNTIL THEY RELEASE.

LONG TERM ANTECEDENT SOIL MOISTURE STATES REMAIN AT OR ABOVE
NORMAL ACROSS THE REGION. SOME OF THIS IS DUE TO THE LARGE SCALE
RAIN AND SNOWMELT EVENT THAT OCCURRED THE LAST WEEK IN JANUARY.
SOME DRY CONDITIONS ARE DEVELOPING INTO PORTIONS OF NORTHERN NEW
YORK. THE LACK OF A DEEP SNOWPACK HAS ALLOWED FROST TO EASILY WORK
INTO THE SOIL. FROST DEPTHS ARE RUNNING SOME 8 TO 14 INCHES ACROSS
THE AREA.

...WEATHER OUTLOOK...

THE CURRENT FORECAST CALLS FOR COLD AND MAINLY DRY CONDITIONS TO
REIGN ACROSS THE NORTH COUNTRY. FORECAST MODELS INDICATE THAT THE
STORMIEST WEATHER WILL REMAIN ACROSS SOUTHERN NEW ENGLAND AND
POINTS SOUTH THROUGH THE NEXT WEEK TO 10 DAYS. CONFIDENCE IS
HIGHER THAN AVERAGE IN TEMPERATURES TO BE NEAR TO BELOW NORMAL
WHILE PRECIPITATION IS BELOW NORMAL ACROSS NEW ENGLAND AND NEW
YORK STATE.

...SUMMARY...

THE WINTER/SPRING FLOOD POTENTIAL IS BELOW NORMAL ACROSS NORTHERN
AND CENTRAL VERMONT AND NORTHERN NEW YORK. EVEN THOUGH RIVER FLOWS
ARE ABOVE NORMAL AND SOIL MOISTURE ARE AT OR ABOVE NORMAL...SNOW
DEPTHS AND WATER EQUIVALENTS ARE BELOW TO WELL BELOW SEASONAL
AVERAGES. THIS COMBINED WITH A COLD AND RELATIVELY DRY FORECAST
MEANS ANY SIGNIFICANT RUNOFF IS HIGHLY UNLIKELY. THEREFORE...THE
THREAT FOR FLOODING IS ALSO BELOW NORMAL.

ICE JAM FLOODING POTENTIAL IS NEAR TO BELOW NORMAL. ALTHOUGH
WIDESPREAD BREAKUP JAMS WERE SEEN LAST WEEK...THESE JAMS HAVE NOW
FROZEN IN PLACE AND ARE EXPECTED TO STABILIZE OVER THE NEXT WEEK OR
TWO. THOSE RIVERS THAT LOST ALL OF THEIR ICE COVER ARE NOW SEEING
THE REFORMATION OF ICE WHICH WILL CONTINUE OVER THE NEXT SEVERAL
DAYS. HOWEVER...DECREASING RIVER FLOWS AND LITTLE TO NO EXPECTED RUNOFF
MEANS WIDESPREAD ICE JAM FLOODING IS UNLIKELY THROUGH THE SHORT
TERM. HOWEVER...THE OLD ICE JAMS WILL HAVE THE POTENTIAL TO CAUSE
FLOODING IN THE LONG TERM.

IT IS IMPORTANT TO REMEMBER THAT HEAVY RAINFALL CAN STILL PRODUCE
FLOODING AT ANY TIME OF YEAR...EVEN IN AREAS THAT HAVE A BELOW
NORMAL POTENTIAL FOR FLOODING.

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

THE NEXT WINTER/SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON
FRIDAY FEBRUARY 19 2010.

$$

MB
National Weather Service Weather Forecast Office
