Flood Potential Outlook
Issued by NWS Portland, ME

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Winter/Spring Flood Potential Outlook
National Weather Service Gray ME
743 PM EDT Thu May 2 2019

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

The flood potential is above normal across the mountains of
northwest Maine and northern New Hampshire. In the remainder of
western Maine and southern New Hampshire the flood potential is
normal.

The threat of flooding due to ice jams is is over for the season.

This is the ninth 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.

...CLIMATOLOGICAL GUIDANCE...

March ended colder than normal with average temperatures ranging
between 0.5 to 2 degrees below normal. Precipitation was around
1.5 to 3 inches below normal for March. Snowfall was below normal
in March also.

Due to the very active pattern during the last 2 weeks of April,
the month ended with above normal precipitation. Temperatures were
below normal in central and northern areas and near to above
normal in southern locations. The active pattern is expected to
continue for the next 2 weeks.

The official National Weather Service 6 to 10 day and 8 to 14 day
forecast calls for temperatures to be near or below normal.
Precipitation is expected to be above normal.

...OBSERVED SNOW DEPTH AND WATER EQUIVALENT...

...NEW HAMPSHIRE...

the ground is bare across much of the State. The only remaining
snow exists in the higher wooded terrain from the White Mountains
north to the Canadian border. Snow depth in these locations ranges
from just a few inches up to 1 to 2 feet with water equivalent of
1 to 8 inches.

Snow readings taken by the Corps of Engineers this week showed a
snow depth of 14 inches at the Flume and 9 inches at Breezy Point
at an elevation of 2500 feet. Snow water equivalent was 2.4 and
5.6 inches respectively. Farther north snow readings taken by
Great River Hydro showed a snow depth at Moose Falls of 21 inches
and at Second Connecticut Lake 65 percent coverage with a depth of 8
inches. Water equivalent was 8.9 and 2.9 inches respectively.

...WESTERN MAINE...

The ground is bare across much of western main with the exception
of the higher wooded terrain in northwest Maine. Snow depth in
these areas ranges for just a few inches up to 1 to 2 feet in the
higher wooded elevations. Snow water equivalent ranges from 1 to 8
inches.

...SOIL MOISTURE AND WATER SUPPLY CONDITIONS...

Soil moisture anomaly maps from May 1 continue to indicate above
normal moisture conditions in western Maine and New Hampshire.

The long term Palmer Drought Severity Index from April 27
indicates very moist conditions in southern New Hampshire and
coastal Maine. Unusually moist conditions exist in central and
northern Maine as well and northern New Hampshire.

Reservoirs in the Androscoggin and Kennebec River basins continue
to rise due to rain and melting snow. Reservoirs in the
Androscoggin River basin are now 88.6 percent full as of April
29, which is 23.2 percent above normal.

In the Kennebec River basin, Moosehead, Brassua, and Flagstaff
Lakes are all above normal for the time of year.

Lake Winnipesaukee in New Hampshire is 0.7 feet above normal for
the time of year.

Groundwater levels courtesy of the USGS are mostly above normal.
Recharge is occuring across the area.

Water supply shortages are not expected this spring as there was
plenty of water in the snowpack and rain to bring groundwater
levels to above normal.

...RIVER AND ICE CONDITIONS...

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

The threat of ice jam flooding is over for the season.

...IN CONCLUSION...

Based on the above information the flood potential is above
normal across the mountains of northwest Maine and northern New
Hampshire. The flood potential is normal across southern New
Hampshire and the remainder of western Maine.

The threat of flooding due to ice jams is over for the season.

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
flooding.

This will be the last Winter/Spring Flood Potential Outlook of the
season.

$$

TFH



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