Flood Potential Outlook
Issued by NWS Burlington, VT

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FGUS71 KBTV 151912

Winter/Spring Flood Potential Outlook
National Weather Service Burlington VT
312 PM EDT Thu Mar 15 2018

...Winter/Spring Flood Potential Outlook...

This is the sixth flood outlook for the 2018 winter/spring
season. Flood outlooks are issued bi-weekly 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.


The threat of open water flooding due to snow melt has been
increased to above normal while the threat for localized flooding
due to ice jams is now below normal.

...Snow Depths and Water Equivalent...

Recent nor`easters have brought prolific snows to much of the
North Country which has substantially increased the snow pack. In
Northern New York, snow depths along the Saint Lawrence Valley now
range from 6 to 12 inches with 1 to 2.5 feet of snow in the
Adirondacks. Liquid equivalents in these regions range from 1 to 4
inches in the Saint Lawrence Valley with upwards of 4 to 7 inches
of liquid equivalent in the higher mountains of the Adirondacks.
This represents near to above normal liquid equivalents for
northern New York for mid March.

The significant rises in snow depth and liquid equivalent have
also been seen across Vermont where the Champlain Valley has gone
from mostly bare ground to snow depths of 10 to 20 inches. In the
higher terrain, snow depths range from 2 to 4 feet with as much
as 7 feet of snow reported at Mt Mansfield. The snow water
equivalents are between 2 to 5 inches across most of the lower
elevation locations with a marked drop in the Champlain Valley
where less than 2 inches of liquid is being reported. The snow
depth is near normal for this time of the year, with the snow
water equivalents ranging from near normal across northern and
central Vermont and above normal water equivalents across
southern Vermont.

...River and Soil Conditions...

Very moist conditions are found across both Northern New York and
Vermont the combination of moderate to heavy snows and the thaw
from late February causing snow melt and run off. The only area
where soil moisture is slightly drier is along the northern
Champlain Valley.

In Vermont and Northern New York, below normal groundwater levels
are observed but with the significant increase in snow pack a
recharge should occur once the spring melt begins in earnest.

River flows are averaging above to well above normal across most
of the Northeast. This is mostly due to above normal precipitation
and above normal temperatures causing snow melt and considerable
ice breakup in February.

In Northern Vermont and far Northern New York State, ice
thicknesses continue to steadily decay. Most rivers are seeing
open water with only a few ice jams still remaining in place. Ice
jams still remain in the Missisquoi River near Swanton, Salmon
River near Fort Covington, and the Saint Regis River near
Hogansburg, however reports are that the ice has significantly
thinned and water is flowing over or around the jams.

...Weather Outlook...

The forecast of a negative NAO remaining in place favours a
continued delivery of colder than normal air over the next 6 to 14
days. Another potent nor`easter may bring moderate to heavy snows
to the North Country during the week of March 19-23 but exact
track and impacts are unknown as this moment. The climate
prediction center 6 to 14 day outlook from March 20-28 indicates
the potential for well below normal temperatures and near to
slight above normal precipitation.


Based on the above information, the threat for open water
flooding due to snowmelt and runoff is increased to above normal.
The threat is above normal in the Adirondacks, Northeastern,
Central, and Southern Vermont. The threat is near normal in the
Saint Lawrence and Champlain Valleys.

The potential for flooding due to ice jams is below normal across
Northern New York and Vermont. Ice coverage has continues to
steadily thin, although ice jams still exist across parts of
Northern New York and Vermont. The increasing sun angle will
continue to erode the ice which will gradually deteriorate with

It is important to note that heavy rainfall can result in
flooding at any time of the year, even in areas that have little
or no snow on the ground.

The next Winter/Spring Flood Outlook will be issued on Thursday,
March 29, 2018.

Access current weather conditions and forecasts on our web site
at www.weather.gov/btv.


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