Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 210232

Area Forecast Discussion
National Weather Service Caribou ME
932 PM EST Mon Jan 20 2020

High pressure will cross the region through Tuesday. A warm
front will cross the region Wednesday. A cold front will cross
the area Thursday into Friday. Low pressure will approach the
area Saturday night.


930 PM Update: Sfc obs from KFVE indicate lgt sn flurries with a
SC cld street originating from the St Lawrence seaway. This
band of cldnss is slowly dropping SE, so will cvr with isolated
flurries thru the remainder of the eve across the N hlf of
Aroostook county.

Otherwise, cld cvr and impact on temps, particularly low temps
across the N, will be the greatest challenge ovrngt, with winds
xpctd to become lgtr with tm, spcly ovr vly areas late tngt.
Most model layer RH progs do show a trend toward drier
conditions late tngt into erly tue morn across the N, so we will
be looking at fcst lows here closely for possible chgs by next
update, but for now, will cont to hold the course, using latest
sfc obs to adjust fcst hrly temps/dwpts into the late ngt.

Prev Disc: Surface high pressure will build east toward the
region tonight through Tuesday. Aloft, an upper level
disturbance will cross northern areas tonight. Another upper
level disturbance will approach the region later Tuesday.
Satellite imagery indicates an area of clouds expanding across
northern Maine in advance of the upper disturbance.
Partly/mostly cloudy skies are expected across northern Maine
through the early morning hours, with partly cloudy skies late.
Mostly clear skies are expected across the remainder of the
forecast area tonight. Generally expect partly cloudy skies
across northern areas Tuesday. Expect a mostly sunny start
across the remainder of the region Tuesday morning with clouds
in advance of the approaching upper disturbance producing a
partly sunny afternoon. Low temperatures across northern areas
tonight will be dependent on the extent of cloud cover.
Generally expect low temperatures to range from around 10 below
to around 15 below zero. However, lesser cloud cover could allow
colder temperatures. Expect low temperatures to range from
around 5 below to around 10 below zero across central and
interior Downeast areas, with around zero to 5 below along the
Downeast coast with locally colder readings possible across both
areas. High temperatures Tuesday will range from around 10
above north, to the mid to upper teens Downeast.


Quiet weather is expected for the middle of the week with a
couple weak disturbances leading to cloud cover and a chance of
flurries. A shortwave trough will cross Maine Tuesday night.
Moisture will be confined mainly below 700mb, limiting the risk
for measurable precipitation. Expanded the area of flurries to
include more of the western part of the CWA where PVA will be
most pronounced. Much of the forecast sounding below 700mb is
within the DGZ, so it should not take much lift and moisture to
generate some flakes.

By Wednesday the shortwave exits, but scattered cloud cover will
linger due to an approaching warm front. Warm advection aloft
and a building ridge will result in a strong subsidence
inversion forming around 925mb. A transition from below normal
to above normal temperatures is expected Wednesday through
Thursday behind the warm front. Overall, it will be a nice break
for backs and snow removal equipment.


A weak cold front will cross the region early Friday with
limited impact as the primary low and mid/upper level forcing
pass well to the north. Temperatures behind the front will only
cool slightly to near or just above average. High pressure will
build in behind the front Friday night into Saturday, with some
high level clouds possible Saturday as the next significant
system approaches the area.

There is much better model agreement this afternoon for the late
weekend system. The 12z Euro, which was previously well to the
south of the CWA, is now much closer to the 12z CMC and GFS
solutions both in northward extent and timing. In fact, the Euro
has shifted farther north with the precipitation shield compared
to the CMC and GFS. Current thinking is that guidance may still
be too fast and too far north with the precipitation shield
moving in due to the separation of the feature from the polar
jet, dry air on its northern fringes, and an area of high
pressure over eastern Quebec. PoPs were held to chance across
the north and increased to likely across coastal and Downeast
Maine where greater confidence exists. PoPs over the south are
higher than the NBM that did not have the 12z Euro data ingested
yet. Given that the system is an upper level low and detached
from the polar jet, erratic movement is possible with subtle
changes to northern stream troughs and ridges influencing its
track. Therefore current model consensus may be unrepresentative
of the overall forecast confidence/uncertainty, limiting more
significant increases in PoPs along the coast for now.

More uncertainty emerges with how quickly the upper low will
eject eastward into the Maritimes. The Euro and CMC show the
system interacting with a 500mb shortwave diving southeastward
from Quebec, causing precipitation to linger farther to the
north on Monday. Meanwhile, the GFS is more progressive and ends
precipitation Monday morning. Kept chance PoPs through most of
the day given the GFS progressive bias. The system should
finally exit Monday night, ushering in cooler air to end the
forecast period.


NEAR TERM: Generally expect VFR conditions across the region
tonight through Tuesday. However, occasional MVFR ceilings are
possible across northern areas through the early morning hours.

Tuesday night through Thursday night...Mostly VFR. MVFR CIGs
possible for a brief period across the north Tuesday night, then
again Wednesday into Wednesday night. SW winds of 15-20kts
Thursday afternoon.

Friday through Saturday...VFR.


NEAR TERM: A Small Craft Advisory remains in effect until 7 PM
for the intracoastal waters. The Small Craft Advisory for the
remainder of the waters has been extended through 1 AM.
Conditions are expected to be below small craft advisory levels
later tonight through Tuesday. Light freezing spray will occur
tonight through Tuesday morning.

SHORT TERM: Winds and seas will likely remain below small craft
advisory levels through Friday. There is a chance for small
craft criteria on the outer waters Friday night into Saturday as
an area of low pressure approaches the waters.


MARINE...Small Craft Advisory until 1 AM EST Tuesday for ANZ050-051.



Near Term...VJN
Short Term...Strauser
Long Term...Strauser
Marine...VJN/Strauser is the U.S. government's official web portal to all federal, state and local government web resources and services.