Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 302308

Area Forecast Discussion
National Weather Service Caribou ME
608 PM EST Mon Jan 30 2023

Low pressure will cross the region tonight. High pressure builds
across the region later Tuesday into Wednesday night. Low
pressure crosses the region Thursday then exits across the
Maritimes Friday drawing a strong Arctic cold front across the
region. High pressure builds toward the region Saturday.


6:08 PM Update: Light snow has overspread much of far northern
Maine to the north of Houlton early this evening. Snow will
develop across the remainder of the FA during the evening as
weak low pressure develops and tracks across the Gulf of Maine.
This looks to be a light snow event with an inch or two for most
areas. The best chance of a period of moderate snow may come
later tonight along the coast where locally a few inches could
accumulate. The ongoing forecast handles things very well with
only very minor tweaks to account for the current and expected
conditions tonight.

Previous discussion:
A weak area of low pressure will track across the Gulf of Maine
tonight, with a trof extending north to another weak low
crossing northern Maine. An upper level disturbance will also
begin to cross the region overnight. Expect light snow across
the region tonight, tapering to snow showers late. Snow
accumulations will generally range from 1 to 2 inches across
most of the region, though localized accumulations up to 3
inches are possible across both northern and Downeast areas.
Isolated/scattered snow showers could linger early Tuesday with
the exiting systems. Cloud cover will then decrease during the
afternoon with building high pressure. Low temperatures tonight
will generally range through the single digits above zero north,
to the upper teens to around 20 interior Downeast with lower
20s along the Downeast coast. High temperatures Tuesday will
range from around 10 to around 15 north, to the lower to mid 20s
interior Downeast with mid 20s along the Downeast coast.


For Tuesday night, all elements appear to be in place
for the coldest night of the season across most of the area.
H925 temps will be near -20C with a 1028mb surface high ridging
into the CWA. This should lead to calm winds, clear skies and a
very steep and shallow radiation inversion. As such, most
guidance appears too optimistic and have leaned towards a much
colder solution than our previous forecast package. With the
warm winter to date, bias-corrected and MOS guidance continues
to look way too high. The surface high remains in place
Wednesday with winds shifting more southwesterly ahead of
another arctic boundary to the north. Given the cold air mass in
place, little modification will occur and highs will still be
in the mid teens north and lower 20s for Bangor and Downeast.
Wednesday night presents another opportunity for strong
radiational cooling and steep shallow inversion as winds move
towards calm again. Once again, guidance seems too warm. The
reinforcing arctic boundary to the north will stall as a much
more powerful arctic front organizes in northern Ontario and
Quebec on Thursday. Thursday will be a bit milder as a warm
front sweeps through with near seasonable temps. Snow showers
will be possible in North Woods, mostly in the afternoon.


***Record Arctic Outbreak Friday and Saturday***

The severity of the cold air descending on northern and eastern
Maine on Friday and Saturday cannot be overemphasized. It`s
outside of model climate norms. The coldest air currently in
the Northern Hemisphere will be moving over the area Friday and
Saturday as measured by 925mb temps. 850mb temps may be the
coldest since 1982. We expect wind chills to drop as low as 45
to 55 below zero across the area later Friday night. As a
reference, Caribou has not measured a wind chill of 50 below (F)
or colder since 1988. -54F is the coldest ever recorded. The
grand ensemble model averages were predicting
minus 49F wind chills at Caribou and even the 95th percentile
was at minus 40F (on the warm side of statistical outcomes).
Wind chill advisories and warnings will be needed by Friday
morning and will continue through Saturday. Confidence is very
high on this event.

The wind chills will create extremely hazardous conditions for
anyone exposed to the cold. Frostbite can occur in just 5
minutes at these wind chills. While the wind gusts will top out
around 45 mph and do not suggest a lot of power outages, any
power outages could be particularly impactful given the cold.

Besides the brutal cold, the other threat will be blowing
snow, mostly in Aroostook County. There is a fresh coating of
powdery snow that will be blown around by winds gusting to 40
mph. In addition, low level instability and St Lawrence
streamers will add snow showers to the equation on Friday. The
warm winter to date and strength of this cold air advection
should maximize transport of St Lawrence moisture southward into
Aroostook County. The net result will be white-outs in the open
agricultural areas of Aroostook County for key roads such as US
Route 1 and 1A. This will be the first widespread blowing snow
event of the winter. It will develop Friday and continue Friday
night. Travel could be extremely hazardous in Aroostook County.

The arctic front crosses the area early Friday morning. Highs
on Friday will occur before daybreak for much of the area. By
Saturday, highs will remain below zero except on the coast where
low single digits may be realized. These will be record low
high temperatures.

Bitterly cold subzero temps renew Saturday evening as winds
finally decrease, but do not believe there will be a lot of
radiational cooling due to a return flow and increasing high
clouds. Light warm frontal snow seems likely for Sunday with
moderating temperatures as a clipper moves through the area.
Expect another arctic front Monday, but the magnitude of cold
air will not be anything like Friday and Saturday, but do expect
another round of subzero temps in northern zones by Monday


NEAR TERM: Across northern areas, MVFR/IFR with occasional LIFR
through early morning with light snow, then MVFR late with snow
tapering to snow showers. VFR/MVFR Tuesday morning with isolated
to scattered snow showers. VFR Tuesday afternoon. Across
Downeast areas, VFR/MVFR early tonight with snow developing.
MVFR/IFR, occasional LIFR, overnight with light snow. VFR/MVFR
Tuesday morning with isolated to scattered snow showers. VFR
Tuesday afternoon. Variable winds 5 to 10 knots tonight.
West/northwest winds around 10 knots, increasing to 10 to 20
knots with gusts up to around 25 knots Tuesday.

Tuesday night into Thursday morning...Predominantly VFR with
light winds.

Thursday afternoon...VFR tempo IFR in snowshowers north of GNR
and HUL.

Thursday night...Chance of MVFR cigs and tempo IFR in
snowshowers, mostly north of HUL and GNR.

Friday and Friday night...Tempo IFR in snowshowers and blowing
snow north of HUL. Mostly VFR for BGR and BHB. Northwest winds
gusting to 35 kt.

Saturday...Tempo IFR in blowing snow for FVE and CAR. Otherwise
predominantly VFR. Northwest winds gusting to 30 kt.


NEAR TERM: Winds/seas below small craft advisory levels tonight.
A Small Craft Advisory is then in effect starting Tuesday
morning. Snow tonight. Scattered snow showers Tuesday morning.
Light freezing spray Tuesday afternoon.

SHORT TERM: SCA conditions continue Tuesday night with light
freezing spray. SCA conditions return Thursday afternoon and
ramp up into a strong gale for Thursday night into late
Saturday. Moderate to heavy freezing spray can be expected
Friday through Saturday with an advisory or warning likely.


The coldest air mass so far this winter is expected at the end
of the week. Although record low temperatures do not look likely
at this time due to wind, record low high temperatures are possible
across the area on Saturday.  Here are the forecast highs on
Saturday, 2/5 along with the record low highs:

Caribou: -8F, record -4F, in 1963
Houlton: -7F, record -2F, in 1963
Millinocket: -7F, record 0F, in 1963
Bangor: -2, record +4, in 1963

It has been over 5 years since Bangor has had a day where the
high temperature failed to reach zero. The last sub-zero high
was -1F on January 6, 2018.


MARINE...Small Craft Advisory from 10 AM Tuesday to 1 AM EST Wednesday
     for ANZ050>052.



Near Term...CB/Norcross
Short Term...MCW
Long Term...MCW
Climate...CB is the U.S. government's official web portal to all federal, state and local government web resources and services.