Saturday, February 08, 2020

Winter/Spring Potential Flood Outlook For Northern & Eastern Maine

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK...Corrected
NATIONAL WEATHER SERVICE CARIBOU ME
506 PM EST Thu Feb 6 2020

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

This is the third 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 February 6th to February 20th, 2020.

The flood potential for open water flooding and flooding due to
ice jams remains near normal for this time of year.

...CLIMATOLOGICAL GUIDANCE...

The last week of January into the first week of February turned
out to be rather tranquil. The only significant system came into
the region on January 26th and 27th which brought 2 to 6 inches
of snow across northern and western areas, while rain occurred
from the Maine Central Highlands to the coast. Heavy rainfall
occurred from the Bangor area to the coast with 1 to 2 inches of
rain. This rainfall basically wiped out any snowpack that was in
place, especially along the coast.

Temperatures over the last two weeks averaged above normal. There
was a stretch from late January into the first day of February
where morning low temperatures across the north and west were
below zero.

The weather pattern will become more active over the next 5 to 10
days with a series of storm systems affecting the region. The
first storm system is expected hit the region through Friday
night. This is a major storm system with the potential for
snowfall amounts of 14 to 20 inches across positions of Northern
Maine, while a mix of snow, sleet and freezing rain is expected
across the Maine Central Highlands into the Downeast region.
Another storm system is expected on Monday with another round of
snow for the region.

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 15 to 26 inches
across Northern and Northwest Maine. Allagash came in with a snow
depth of 27 inches, while Caribou had 15 inches as of 7 AM this
morning. Chimney Pond in the Baxter State Park region reported a
snow depth of 37 inches this morning. Snow depths across the Maine
Central Highlands ranged from 7 to 14 inches. Snow depths from the
Bangor area to the coast ranged from 1 to 3 inches with a snow fresh
snow cover on account of this latest system. Snow depths across
Northern Maine were near near normal, while from the Maine Central
Highlands to the coast, snow depths were below normal.

The snow water equivalent, or the amount of water contained in
the snowpack, remains highest across northern areas with 4 to 8
inches of water being recorded. Across the Maine Central
Highlands, snow water equivalents were in a range of 2 to 4
inches. Across the Bangor region into the interior Downeast, 1 to
2 inches of water equivalents with trace amounts along the coast.

The snow water equivalent is near normal for this time of year
across the Northern Maine, while elsewhere, water equivalents are
below normal.

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

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

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

...RIVER AND ICE CONDITIONS...

River flows continue are near to slightly above normal for this
time of year across the region. The exception to this continues to
be across Washington County along the St. Croix River basin,
where flows are above normal.

Ice covers about 90% of the rivers and streams across Northern
and Northwest Maine. There are some open stretches on the St. John
and Aroostook Rivers. The Piscataquis River and Penobscot Rivers
had ice reforming on them, including in the Bangor region, with
about 85% coverage. The East Branch of the Penobscot River in
Grindstone was completely iced in. Across the Downeast region
which included the St. Croix River, ice had reformed with a good
section of the river still open.

Ice thicknesses ranged from 15 to 20 inches along the Aroostook
River with 16 to 25 inches of ice thickness on the St. John and 
Allagash River. According to the latest ice measurements done by
the USGS, ice thickness on the St. John River at Nine Mile Bridge
was measured to be around 24 inches. Big Black River had an ice
thickness close to 30 inches. Ice thickness along the Piscataquis
River and Penobscot River was generally 4 to 8 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 with an
ice thickness measured at 15 inches. Ice thickness along portions
of the St. Croix River was estimated to be 3 to 7 inches in spots.

An ice jam remains in place on the Aroostook River in Fort
Fairfield. This ice jam did break up over the last two weeks with
about one mile of this jam remaining in place. There were a few
small ice jams locked in place on the Aroostook River in the
vicinity of Washburn. Ice was also reported to be bunched up on
the St. John River downstream of the International Bridge in
Madawaska.

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
flooding remains near normal across the region at this time. The
threat for ice jam flooding continues near normal, especially
across the northern rivers.

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,
February 20th.

$$

Corrected for snow depths

Hewitt

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