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afdcar

Area forecast discussion
National Weather Service Caribou ME
1205 PM EST Tue Nov 12 2019

Synopsis...
low pressure tracking along the coast of Maine will exit into
the Maritimes this afternoon and tonight. High pressure will
build in Wednesday through Thursday. A strong cold front will
cross the region later Friday followed by cold Canadian high
pressure on Saturday.

&&

Near term /through tonight/...
12 PM update...
low pressure will continue to track northeast through the
Canadian Maritimes this afternoon. Latest radar reflectivity/correlation
coefficient imagery/surface observations show mixed
precipitation is beginning to transition back to all snow from a
Caribou to Greenville line at this hour. As colder air
continues to wrap in behind the departing low, the trend toward
mixed precipitation changing back to all snow should continue
this afternoon before steady precipitation winds down late this
afternoon. No significant changes to going forecast at this
time.

Previous discussion:
a broad area of low pressure moving up along the Maine coast this
morning with multiple centers will deepen today and lift northeast
to a position just east of the gaspe Bay peninsula by this
evening. The low continues to deepen and should be near
southern Labrador by Wednesday morning.

As far as the sensible weather GOES, steady snow will continue
across far northern Maine this morning with the snow to mix of sleet
at times, especially from around Presque Isle/Caribou south. Across
the Saint John valley it should remain all snow. The down east area
is getting into the dry slot early this morning with a strong push
of milder air along the immediate coast where there will be spotty
light rain and drizzle and patchy fog. In the Bangor area and
interior downeast region, there will be a mix of mostly sleet
and freezing rain this morning. As the low pulls away and a cold
front sweeps across the region the snow in the north will
transition to snow showers by late in the day with rain showers
to perhaps mix with or change back to snow showers down east.

It will be breezy and turn colder tonight with isolated to scattered
snow showers. Temperatures will tumble back into the teens, but
with a northwest wind of 10 to 15 mph with a few higher gusts
the wind chills be make it feel closer to zero by daybreak
Wednesday. Along the coast any standing water/slush will freeze
solid.

&&

Short term /Wednesday through Thursday/...
Wednesday will be breezy and cold as a tight pressure gradient
passes overhead amid northwest flow. Blowing snow is likely given the
fresh snow on the ground across the north where damp mixing
didnt occur. Low level lapse rates around 9c/km could support
good mixing during the early afternoon for thin snow bands
across NE Maine. These could briefly reduce visibility,
especially combined with blowing snow, but otherwise dissipate
into later afternoon. Limiting factor could be positive
buoyancy, with only 20-30 j/kg in the bl. No accumulation is
anticipated from the snow showers/squalls,

Clearing skies Wednesday evening sets the stage for overnight
lows in the single digits across the north and lower teens
downeast. For record lows to be achieved: gradient winds will
need to fall off rapidly and potential cloud cast moving in from
the west towards early morning will need to be high. Forecast
values for this update can be found in the climate section
below. Otherwise, nearly perfect setup for record lows given the
strong cold air advection during the day, recent snowfall, center of high
pressure moving right over central Maine overnight, and clear
skies early on. Return flow from the south sets up Thursday
morning, advecting some moisture into the region ahead of
approaching shortwave. Two areas of precip are possible with
convergence zone draping across coastal Hancock and
interior/coastal Washington counties. This region is forecast to
have greater chance to see measurable precip into Thursday
night. Temperatures would support mostly a rain/snow mix along
the coast, with snow showers inland. As warm temps push in along
the immediate coast, low snow ratios indicate snow will be wet
with little accumulation forecast. The other area of precip will
be the chance of snow showers in the north Thursday afternoon
and evening.

&&

Long term /Thursday night through Monday/...
the shortwave passes Friday afternoon and evening, setting off
a few snow showers in the north along with lingering rain/snow
showers along coastal downeast. With the passing front,
temperatures will again drop into the single digits Friday night
in the North Woods. High pressure pushes in Saturday with dry
conditions through the weekend, albeit chilly. Single digit lows
will be more widespread Saturday night as the high passes
overhead.

Next chance of precip comes Monday and Tuesday as systems track
near the East Coast. Not much guidance consistency leaves much
to be desired confidence wise. Overall pattern suggests a upper
trough crossing the plains and potential low pressure system in
the open Atlantic off the mid-Atlantic coast. For Maine, this
would translate to SW flow in the early week with temperatures
rebounding in the 30s and 40s for highs to start the week.

&&

Aviation /18z Tuesday through Sunday/...
near term: IFR and at times LIFR this afternoon. Conditions
will improve to MVFR by this evening at the Aroostook County
terminals and to VFR at the downeast terminals.

Short term: wednesday: downeast terminals likely to be VFR with
MVFR possible in passing snow showers Wed afternoon in the
north. Localized low IFR at fve, car and pqi in blowing snow. West
winds 5-15 kts becoming NW and gusty by Wed morning with gusts
20-30kts.

Wed night - Thu: VFR. Light W winds becoming south on Thu.

Thu night: MVFR/IFR for downeast terminals, otherwise VFR.
Light S winds.

Fri: MVFR/IFR over north terminals in snow showers ahead of cold
front. S-SW winds 5-10kts gusting to 20kts.

Sat: VFR. Northwest winds 5-10kts turning S on Sunday.

&&

Marine...
near term: a Small Craft Advisory is in effect on the intra-coastal
waters into early Wednesday afternoon. A Small Craft Advisory is in
effect on the coastal waters until midnight tonight with a Gale
Warning from midnight tonight until early afternoon Wednesday.

Short term:
gale conditions slacken to below Small Craft Advisory criteria early thurs
morning with winds becoming light and seas 1 to 3 feet. SW winds
increase thurs night with seas responding 5 to 7 feet. Small Craft Advisory may
be needed through Saturday night with gale possible Friday
night.

&&

Climate...
record lows possible Thursday morning, 11/14:

Caribou: record, +4f in 1986 (current forecast +2f)
houlton: record, +5f in 1996 (current forecast +5f)
millinocket: record +8f in 1986 (current forecast +9f)
bangor: record +11f in 1986 (current forecast +10f)

&&

Car watches/warnings/advisories...
ME...Winter Storm Warning until 6 PM EST this evening for
mez001>004-010.
Winter Weather Advisory until 6 PM EST this evening for mez005-
006-011-015>017-031-032.
Marine...Small Craft Advisory until 1 PM EST Wednesday for anz052.
Small Craft Advisory until midnight EST tonight for anz050-051.
Gale Warning from midnight tonight to 1 PM EST Wednesday for
anz050-051.

&&

$$

Near term...cb/duda

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