Flood Potential Outlook
Issued by NWS Portland, ME

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FGUS71 KGYX 161124

Winter/Spring Flood Potential Outlook
National Weather Service Gray ME
724 AM EDT Fri Mar 16 2018


The flood potential is above normal in western Maine and New

The potential for ice jam flooding is below normal for most of
western Maine except for the mountains where ice jam potential is
near normal.

The potential for ice jam flooding in New Hampshire is below

This is the sixth in a series of regularly scheduled flood
potential outlooks that are issued during the winter and spring
seasons. These outlooks will be issued every two weeks until the
end of the snow melt season, and will assess the potential for
flooding based on a number of factors.


The weather pattern for March has been one where troughing has
been prevalent over the eastern United States with a blocking
high pressure area over Greenland. This allowed some marginally colder
air to bleed south over New England and allowed for the rapid
development and slow movement of 3 very strong noreasters. This
active weather pattern is expected to continue through most of the
remainder of March. This will allow for colder air to filter into
New England with the associated storm track being near or through
New England.

The official National Weather Service 6 to 10 day and 8 to 14 day forecast
calls for below normal temperatures and near normal precipitation.



Snow depth across New Hampshire is quite variable and ranges from
10 to 20 inches in the lower Connecticut River Valley up to 1 to 3
feet across the rest of the State.

Snow water equivalent ranges from 2 to 5 inches across the lower
elevations of New Hampshire. Water equivalent increases rapidly to
5 to 10 inches in the higher elevations. A snow survey done by the
Corps of Engineers at an elevation of 1710 feet in the
Pemigewasset river basin recorded a water equivalent of 10.2
inches. Moose Falls near the Canadian border reported a snow depth
of 48 inches and a water equivalent of 10.0 inches.

Water equivalent is generally near normal for the time of year
except for northern New Hampshire where they are above normal.


Snow depth ranges 1 to 3 feet from the foothills south. North of
the foothill snow depth ranges from 2 to 4 feet. Both Moosehead
lake and Brassua Lake reported a snow depth of 48 inches this

Snow water equivalent ranges from 2 to 5 inches south of the
foothills. north of the foothills to the Canadian border snow
water equivalent ranges from 5 to 10 inches with locally higher
amounts. West Kennebago Mountain north of Rangeley reported a
snow water equivalent of 11.5 inches in 3 feet of snow.

Water equivalent is generally above normal for the time of year.


Soil moisture anomaly maps from March 14 indicate above normal
moisture conditions in western Maine and New Hampshire.

The long term Palmer Drought Severity Index from March 10
indicates unusually moist conditions across southern New Hampshire
and coastal Maine and normal conditions in central and northern
Maine and northern New Hampshire.

Reservoirs in the Androscoggin River basin are 50.6 percent full
which is 17.3 percent above normal.

All reservoirs in the Kennebec River basin are above normal for
the time of year.

Groundwater levels courtesy of the USGS show that monitoring
wells in western Maine and New Hampshire are mostly above


River flows are mostly above normal for the time of year in both
western Maine and New Hampshire.

Ice has decreased markedly over the past 2 weeks. The ice jam on
the Kennebec River at Augusta is now gone due to the help of the
Coast Guard and their ice breaking efforts. The ice jam that was
on the Saco River at Fryeburg has melted away. All other known
ice jams have melted away and are no longer a threat.

The only remaining ice is on headwater streams and rivers in the
mountains, like the Carrabassett and Sandy Rivers. While we don`t
anticipate any further issues with ice we will have to continue
to monitor these and other mountain rivers and streams as we move
into the spring season.


Based on the above information the flood potential is above normal
for all of western Maine and New Hampshire. This is due mainly to
an increasing snowpack which will likely increase further through
the remainder of March. Also we are reaching later into March and
as we approach April the chances of a rapid warmup increase.

The threat for ice jam flooding is below normal due to the rapid
decrease in ice cover. While ice remains on mountain streams and
river we do not anticipate any further ice jam flooding this
season. However the Sandy and Carrabassett Rivers will continue
to be monitored.

It is important to note that major flooding does not occur from
snowmelt alone. Rainfall, how much and in how short a period of
time is the most important factor in determining the severity of

Another Winter/Spring Flood Potential Outlook will be issued
March 29.



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