Flood Potential Outlook
Issued by NWS Caribou, ME

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
802 PM EST Wed Jan 17 2018

...SPRING FLOOD POTENTIAL OUTLOOK FOR NORTHERN...CENTRAL...AND
DOWNEAST MAINE...

This is the second Winter/Spring Flood Potential Outlook for
2018, issued by the National Weather Service in Caribou, Maine.
This outlook is for Northern, Central, and Downeast Maine for the
two-week period of January 18th to February 1st, 2018. 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 flood potential for open water flooding is near normal for
for this time of year. The potential for flooding due to ice jams
is above normal.

...CLIMATOLOGICAL GUIDANCE...

The arctic airmass in place early in the month was broken up by
sporadic significant warmups during the first two weeks of the
month. Colder than normal temperatures returned to the area after
January 14th. Average temperatures from January 1st to January
16th have ranged from 1 to 3 degrees below normal across the
region.

An intense noreaster on January 4th brought 12 to 24 inches of
snow, along with blizzard conditions, to the region. The
significant warmup after the 11th of January brought the snow
depths down to between 12 and 24 inches across the north with
bare spots along the Downeast coast. Snow depths across interior
Downeast ranged from 6 to 12 inches mainly in wooded areas.

The overall pattern looks to shift more toward ridging across the
east. This will allow for for slightly above normal temperatures
over the next two weeks, though not without sharp temperature
fluctuations.

The official National Weather Service 6 to 14 day outlook is
looking at above normal temperatures and precipitation.

...OBSERVED SNOW DEPTH AND WATER EQUIVALENTS...

Snow depths ranged from 12 to 24 inches across the far north. The
Downeast region from Bangor and points to the east recorded snow
depths between 2 and 5 inches.

The snow water equivalent, or the amount of water contained in
the snowpack, is the highest across northern areas with 2 to 4
inches of water being recorded. Across central areas to the interior
Downeast region to the coast, a trace to 3 inches of water was
common in the snowpack.

The snow water equivalent is below normal, to perhaps near
normal, for this time of year.

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

Soil moisture was above normal across the region. The latest
Palmer Drought Severity Index, which measures soil moisture in the
longer term, was showing above normal conditions.

Looking at the groundwater levels, courtesy of the USGS, we see
the levels have improved to near to above normal. Specifically
Kenduskeag, Amherst and Hadley Lake were carrying their highest
median groundwater levels for this time of year.

...RIVER AND ICE CONDITIONS...

River flows appeared to be above normal for this time of year
throughout the region.

After the brief January thaw, which allowed ice coverage to
decrease, the return to below normal temperatures helped bring
additional ice to area rivers. Across northern Maine rivers are
about 90 percent snow and ice covered. Portions of the St. John,
Aroostook and Penobscot Rivers reported a few open channels. The
Fish River in northern Aroostook has quite a bit of open water.

An ice jam remains on the Kenduskeag Stream in Bangor. It extends
from the mouth of the Penobscot River back to the bridge crossing
at Harlow St at the base of Drummond Hill. The Penobscot River in
downtown Bangor remains iced over with some open water on the
sides. Ice is locked up to near Eddington. Breakup/freeze up jams
are prevalent on the Piscataquis River and Kingsbury Stream. Ice
thicknesses ranged from 8 to 14 inches.

...IN CONCLUSION...

Based on the above information, the flood potential for open water
flooding is near normal across the region at this time. The
threat for ice jam flooding is above normal. It is important to
remember that a heavy rainfall event along with mild temperatures
can lead to an increased potential for flooding with snowmelt and
runoff. Ice breaking up and jamming can elevate the threat for
flooding in a short period of time.

The next winter/spring flood potential outlook will be issued by
the NWS in Caribou on February 1st.

$$

Farrar



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