Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Caribou ME
645 am EST Fri Jan 19 2018
high pressure will build across the region through this evening.
A warm front will approach late tonight. Low pressure will
track north of the region Saturday. High pressure will build
across the region Sunday into Monday.
Near term /through tonight/...
630am update...increased pops this morning for the Bangor area
as well as the down east region as the upper trough crosses. A
quick half inch of snow could fall at locations such as
Ellsworth and Bar Harbor.
the area remains in a col today between ridges in
Quebec and the southeastern US. A weakening cold frontal
boundary will sag southward this morning across the area and
bring isolated snow showers in the southern half of the forecast
area. A rather compact upper trough will aid in the development
of these showers. No accumulation is expected. The upper trough
will quickly move east of the area by this afternoon and the
frontal boundary will start returning northward as a warm front
tonight. This will result in some clearing this afternoon in the
southern half of the forecast area while northern zones remain
mostly cloudy. Temperatures today will be slightly warmer than
readings recorded on Thursday and lows tonight will likely be
recorded in the evening. Temperatures will remain steady or even
rise through the rest of the night. A fast-moving low will
speed out of Ontario into Quebec tonight accompanied by
shortwave trough. This shortwave impulse will energize the warm
frontal boundary late tonight with snow developing in northern
zones. Up to 2-3 inches could fall in the Saint John valley with
amounts quickly tapering to less than an inch south of northern
Aroostook County. The energy with shortwave is sufficient to
generate high confidence in the snowfall forecast. With a warm
layer aloft, trace amounts of sleet and freezing rain could fall
towards daybreak Saturday around Bangor and the down east
region...possibly as far north as Lincoln and Millinocket.
Short term /Saturday through Sunday night/...
low pressure will track north of Maine Saturday. Light snow is
expected across northern portions of the forecast area early
Saturday with up to around an inch of additional accumulation
possible. Could also have the chance of a light wintry mix
across central/downeast portions of the forecast area early
Saturday. Could still have a chance of snow showers across
northern areas Saturday afternoon in advance of an approaching
cold front, with decreasing clouds downeast. The cold front will
cross the region Saturday night through early Sunday with a
chance of snow showers across mostly the north and mountains.
Otherwise, generally expect partly cloudy skies across the
region Saturday night with partly/mostly cloudy skies Sunday.
High pressure then builds across the region Sunday night with
partly cloudy skies. Temperatures will be at above normal levels
Long term /Monday through Thursday/...
high pressure exits across the Maritimes Monday while low
pressure crossing the Great Lakes draws a cold/occluded front
toward New England. Cloud cover will increase Monday, with
increasing snow chances Monday night. However, uncertainty still
exists regarding how rapidly precipitation is able to expand
against retreating high pressure. The primary Great Lakes low
will track northwest of the region Tuesday drawing the
cold/occluded front across the region. Uncertainty also exists
regarding the timing of the cold/occluded front Tuesday into
Tuesday night along with whether a secondary low develops along
the front. Expect snow across the region early Tuesday. Warmer
air being drawn north could then allow the snow to begin
transitioning to a wintry mix across downeast areas later
Tuesday. The transition from snow to a wintry mix should expand
northward Tuesday night, with a transition to rain possible
along the downeast coast. However, how rapidly the transition to
a wintry mix occurs and the northern extent of the transition
remain uncertain. If a secondary low were to develop along the
front and limit the northern extent of warm air, precipitation
across northern areas could remain mostly snow. Exact
precipitation types/amounts Tuesday remain uncertain at this
time. The initial cold/occluded front will exit across the
Maritimes early Wednesday, with a secondary cold front crossing
the region later Wednesday. Expect a chance of snow north, with
a chance of a wintry mix downeast, early Wednesday with
precipitation then tapering to snow showers. High pressure will
build toward the region later Thursday. Expect partly cloudy
skies along with a slight chance of snow showers across the
north and mountains Thursday, with partly/mostly sunny skies
downeast. Temperatures will be at near normal levels Monday and
Thursday. Temperatures Tuesday/Wednesday will be dependent on
the eventual timing of the cold/occluded front and whether a
secondary low develops.
Aviation /12z Friday through Tuesday/...
near term: bhb and bgr will be mostly VFR through the period.
MVFR cigs will affect sites north of hul at times through
tonight. IFR vis in snow is expected north of pqi after midnight
into early Saturday morning.
Short term: MVFR/IFR conditions are expected across northern
areas early Saturday, with occasional MVFR conditions possible
downeast. Occasional MVFR conditions are possible across the
north and mountains Saturday night into Sunday, with generally
VFR conditions downeast. VFR conditions are expected across the
region Monday, with MVFR/IFR conditions developing Monday night.
IFR/LIFR conditions are expected across the region Tuesday.
near term: a Small Craft Advisory has been issued starting after midnight as a
warm front crosses the waters. There is a good pressure gradient
and some mixing in the low levels, so confidence is pretty
Short term: Small Craft Advisory conditions are expected
Saturday into Saturday night. Conditions are expected to be
below Small Craft Advisory levels Sunday through Sunday night.
Marine...Small Craft Advisory from 2 am to 7 PM EST Saturday for