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afdcar

Area forecast discussion
National Weather Service Caribou ME
922 PM EST Tue Feb 21 2017

Synopsis...
a weak occluded front will cross the region tonight. High
pressure will be to our south Wednesday into Thursday as a small
low pressure system tracks to our north.

&&

Near term /through Wednesday/...
9:22 PM update...an occluded front is now into central Quebec
and will move east overnight. The front will fizzle out as it
approaches western Maine early Wed morning. The low level air
mass is very dry across the County Warning Area this evening with dew points in
the single digits across northern Maine, and this dry air was
very evident on the 00z kcar sounding below 600 millibars.
High and mid level clouds will continue to overspread the area
tonight from the west, and they will gradually lower overnight.
The regional radar mosaic which showed a more solid line of
showers early in the evening across western New York state shows some
returns moving into Vermont and NH, but most of this activity is high
based and not reaching the ground. A passing shower of snow or
sleet is possible later tonight, mainly across the higher
terrain in the west and across far northern Maine, but nothing
significant, with most areas to not receive anything measurable.
Made some tweaks to the ongoing forecast based mainly on the
latest observations as well as the radar and near term models.
Temperatures will likely not drop much more tonight as the
clouds thicken up and will tweak the hourly temps and lows up a
few degrees in most areas.

Previous discussion...
strong high pressure will continue to move to the east of New
England tonight as an occluded front approaches from the west.
The frontal passage is expected to be dry but clouds will
increase across the area as the front passes. Weak high pressure
is expected to build to the southeast of the region Wednesday.

&&

Short term /Wednesday night through Friday/...
sfc low currently sitting over the northern rockies will translate
east acrs the upr Midwest drg the near term pd. Srly flow wl be
drawing in warm air on Wed night with a wmfnt mvg thru the state.
Med range guidance agrees fairly well on location of sfc low by 12z
thur but differ on the details with regard to warm air aloft. NAM/ec
and CMC are all hinting at h9 temps abv +4c as far north as the St.
John Vly while GFS is running some 2-4 degrees colder. Hv backed off
on pops mvg in until closer to daybreak along wmfnt and hv indicated
patchy -fzra acrs the far north for a time thur mrng. Warm air mvg
up ovr snowpack wl lkly result in patchy fog drg the overnight hrs.

Lopres wl slide along bndry on thur crossing into the Maritimes thur
night. Hv bumped pops to lkly acrs the far north thur aftn with rain
expected as warm air conts to be drawn north ahd of system. Maxes on
thur wl lkly be approx 15f abv normal for this time of year.

Cdfnt crosses the County Warning Area thur ngt with lingering pcpn expected as the
bndry mvs south. Front wl lkly stall out acrs the waters Fri mrng
bfr being swept back north as a wmfnt at the start of the long
term.

&&

Long term /Friday night through Tuesday/...
aft a vry brief break in the pcpn thur ngt expect pcpn to be on the
increase early Fri aftn FM the southwest as strong 500 mb low digs thru
the nrn plains. Expect that rain wl occur Fri night as wmfnt lifts
back thru the area. May see a break in the steady rain on Sat as
area wl be in the wmsector but sfc low and assoc cld frnt wl mv thru
the region Sat night. Strong 800 mb jet wl lkly be present acrs the area
Sat ngt as County Warning Area wl be in right fnt quad of 300 mb jet streak. Precipitable water values
progged to be btwn 2-4 Standard deviations abv normal exceeding 1
inch late Sat ngt. May need to add in locally hvy rain at some point
Sat ngt/Sun morning.

Med range guidance certainly showing the potential for over 1+
inches of rain Sat and sun with the heaviest falling Sat night. This
may be enuf to get ice mvmnt on the rivers, especially acrs downeast
zones. Sat wl be the warmest day of the next 7 days with highs in
the M/u40s acrs the north to arnd 50f in the south. Cldr air then
mvs in Mon night in wake of departing system with weak trof mvg thru
on Mon with perhaps some isold snow showers.

&&

Aviation /02z Wednesday through Sunday/...
near term: expect VFR conditions this evening to lower to MVFR
at the northern terminals late tonight into Wednesday morning
with VFR conditions for the remainder of the day Wednesday. VFR
for the next 24 hours at the downeast terminals.

Short term: MVFR and eventually IFR expected late Wed night as
southerly flow draws in low-level moisture over the snowpack.
Expect this will continue thru thur with potential for -ra or-
fzra for northern terminals thur morning. Conds expected to
briefly improve to VFR acrs the south on Friday tho northern
sites may remain low MVFR/IFR into the afternoon. Conditions
deteriorate late Fri afternoon at bgr and bhb and Friday night
for remaining terminals through the end of the period.

&&

Marine...
near term: have used the NAM for sustained wind speed. For
waves: expect northeasterly wind wave (1-2 feet/7-8 seconds) to
be the primary wave system into this evening. Southwesterly wind
wave will develop early Wednesday. Will use the near shore wave
model to populate wave grids.

Short term: seas and winds will remain below Small Craft Advisory levels through
thur. Wind gusts will be marginal arnd 25kts thur evening as
cdfnt appchs the waters. Expect that seas wl rise above 5ft in
southerly swell on Sat ahead of next system continue through the
weekend.

&&

Car watches/warnings/advisories...
ME...none.
Marine...none.

&&

$$

Near term...cb/mignone

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