Winter/Spring Potential Flood Outlook For Northern & Eastern Maine

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
313 PM EST Thu Mar 5 2020

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

This is the fifth Winter/Spring Flood Potential Outlook for 2020,
issued by the National Weather Service in Caribou, Maine. This
outlook is for Northern, Central, and Downeast Maine for the
two-week period of March 5th through March 19th, 2020.

The flood potential for open water flooding and flooding due to
ice jams, remains near normal for this time of year, with the
exception of Northwest Maine, where the flood potential is
slightly above normal.

...CLIMATOLOGICAL GUIDANCE...

A few storm systems affected the region over the last two weeks
bringing measurable snow and rain to the region. The most
significant storm system came across the region on February 27th
and 28th. This storm system delivered anywhere from 6 to 11 inches
across Northern and Northwest Maine, with 2 to 9 inches across
the Maine Central Highlands into the Downeast region. This storm
helped to increase the snowpack across the region. Mild
temperatures and some rain arrived on the 3rd into the 4th across
the entire region. This system helped to reduce the snowpack,
especially across the Maine Central Highlands into the Downeast
region.

Temperatures over the last two weeks continued to average above
normal. Temperatures warmed into the upper 40s and mid 50s across
the region on March 3rd. Bangor set a record high temperature of
56 degrees on the 3rd. This broke the previous record high
temperature of 53 degrees set back in 1964. Over the last two
weeks, there were a few mornings, where temperatures dropped to a
range of 10 to 25 below zero across the region. The NWS in Caribou
recorded a low temperature on February 21st of 17 below zero,
while Bangor came in with 11 below zero. Houlton recorded a low
temperature of 11 below on March 2nd.

The weather pattern over the next 5 to 10 days will start out
quiet with temperatures averaging near to slightly above normal
across northern areas, while from the Maine Central Highlands
into the Downeast region, temperatures are expected to be above
normal. The pattern looks like it will become more active by the
by the middle of second week of March. There is potential for a
significant storm to affect the region on the 10th and 11th. This
system could bring more snow, especially across the northern and
central regions, while a mixed bag of precipitation could fall
across the Downeast. Once again, the storm track will determine
the amount and type of precipitation.

The official National Weather Service 6 to 14 day outlook
is calling for near to slightly above normal temperatures and
above normal precipitation.

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

As of 7 AM this morning, snow depths ranged from 26 to 40 inches
across Northern and Northwest Maine, with Allagash Maine reporting
40 inches of snow on the ground. The NWS office in Caribou
reported 26 inches of snow depth. Chimney Pond in the Baxter State
Park region, reported a snow depth of a whopping 56 inches. Snow
depths across the Maine Central Highlands decreased a bit over the
last 48 hours, given the milder temperature and some rainfall.
Snow depths in this region ranged from 9 to 16 inches, with a few
sites coming around 20 inches. Snow depths from the Bangor
area to the Interior Downeast region ranged from 1 to 5 inches
with some bare ground. Along the coast, snow depths ranged from a
trace to perhaps an inch or two.

Snow depths across Northern Maine averaged near to slightly above
normal for early March, while across the Maine Central Highlands,
snow depths remained near normal. From Bangor to the coast, snow
depths continued to be below normal.

The snow water equivalent, or the amount of water contained in
the snowpack increased across the region over the last two weeks.
Northern and Northwest Maine recorded 8 to 11 inches of water in
the snowpack. Across the Maine Central Highlands, snow water
equivalents were in the range of 3 to 6 inches. Across the Bangor
region to the coast, 1 to 2 inches of water was measured in the
snowpack.

The snow water equivalent is near normal across the Northeast
Maine, while Northwest Maine is now above normal. Across the
Maine Central Highlands, water equivalents remain near normal.
Water equivalents from Bangor to the coast, continue below
normal.

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

Soil moisture continue to be near to slightly above normal for
the entire region. The latest Palmer Drought Severity Index, which
measures soil moisture in the longer term, continues to show
normal conditions.

A look at the groundwater levels, courtesy of the USGS, shows levels
are near normal across northern and central areas, while from
Bangor to the Downeast region, levels are slightly above normal.

...RIVER AND ICE CONDITIONS...

River flows are near normal across the entire regions. The exception
to this continues to be across Washington County along the St.
Croix River basin, where flows are above normal.

As of 7 AM this morning, ice covers about 100% of the rivers and
streams across Northern and Northwest Maine. There are a few open
stretches on the St. John, Aroostook Rivers, Allagash and Fish
Rivers. The Piscataquis River and Penobscot Rivers had ice on them
with 90 ice coverage. There are open sections on the Penobscot
River from just north of Bangor to Old Town. In downtown Bangor,
where the Kenduskeag meets the Penobscot River, solid ice is in
place. However, just west of the city, there are open channels on
the Kenduskeag Stream. Across the Downeast region which includes
the St. Croix River, ice coverage was reduced to about 70%. There
are large sections of the St. Croix River with with open water.

Ice thicknesses ranged from 20 to 25 inches along the Aroostook
River with 18 to 25 inches of ice thickness on the St. John and
Allagash River. Ice thickness on the St. John River at Nine Mile
Bridge remains near 25 inches, while Big Black River in Northwest
Maine ice thickness was close to 30 inches. Ice thickness along
the Piscataquis River and Penobscot River, is 6 to 10 inches. The
exception to this was along the East Branch of the Penobscot
River at Grindstone, where the ice thickness remained at 15
inches. The Kingsbury Stream at Abbot in Piscataquis County hung
on to an ice thickness measured at 15 inches. The ice thickness
along portions of the St. Croix River was estimated to be 4 to 8
inches in spots.

An ice jam remains in place on the Aroostook River in Fort
Fairfield. This ice jam is one mile long and remained in place
just upstream from the Fort Fairfield bridge. There were some
bunches of ice locked in place on the Aroostook River in the
vicinity of Washburn. Ice remains bunched up on the St. John
River from the town of St. John to St. Francis.

Ice coverage and thicknesses are near normal across the St. John
and Aroostook River basins, while ice thicknesses further south
along the Penobscot, Piscataquis and the St. Croix river basins,
are below normal.

...IN CONCLUSION...

Based on the above information, the flood potential for open water
and ice jam flooding remains normal, with the exception of
Northwest Maine, as the flood potential is now slightly above
normal.

As always, 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 Outlook will be issued on Thursday,
March 19th.

$$

Hewitt