Area Forecast Discussion
Issued by NWS Caribou, ME-- Remove Highlighting --
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FXUS61 KCAR 212237
Area Forecast Discussion
National Weather Service Caribou ME
637 PM EDT Tue Mar 21 2017
A arctic cold front from Central Canada will approach the
region later tonight. Low pressure will develop and intensify
over the Bay of Fundy along the front as it crosses into the
Canadian Maritimes Wednesday. Strong high pressure will build
across the region later Wednesday night into Thursday.
.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --615 pm Update...No major changes made this update. Radar returns
showing between Katahdin and the coast appear to be almost
entirely not reaching the ground, as both obs and webcams don`t
show anything around the region. That said, will keep the Iso
to Sct POPs in across the southern half of the CWA through 00z,
with gradually increasing POPs overnight.
Latest model guidance from the 12z cycle is in pretty good
agreement with the synoptic pattern evolution tngt thru Wed, in
which an arctic cold front supported by a strengthening s/wv alf
from Cntrl Can will approach the region ovrngt, then cross on
Wed. Meanwhile, sfc low pres ovr S Cntrl QB will re-form near
the mouth of the Bay of Fundy by Wed morn, then deepen over the
Can Maritimes later Wed into Wed ngt.
This scenario will allow a band of sn shwrs from QB alg the
arctic front to evolve into a more organized area of steady
snfl crossing Nrn and Ern ptns of the region very late tngt thru
Wed. This snfl will also be accompanied by very strong NNW winds
accompanying llvl cold advcn on the back side of the
intensifying low by Wed aftn contg into the eve. So even though
most lctns will be receiving less than sn adv snfl from this
system, the concern is that powdery sn falling with strong winds
and a rapidly falling temp environment will produce a thin ice
layer due to initial sn melt then freeze, followed by blowing
and drifting of powdery snow. the delineation of the wntr wx adv
was based on total snfl accumulations of greater than 1.5
inches. Most models indicate the best snfl potential across
Cntrl and SE Aroostook county where lclzd max snfl amts could
reach 4 to 5 inches, but exactly where the best banding will
occur is still a little uncertain attm. Blowing in drifting will
intially greater impact E to W roadways with N winds late Wed
morn into erly aftn, then begin to impact N to S roads late Wed
aftn into eve as winds become more Wrly component.
The residence of the arctic air mass which begins in the deep
category over NE Ont prov modifies to mdt by late Wed aftn as
some of the cold air is utilized in the baroclinic intensification
of the secondary sfc low over the Can Maritimes.
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.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Snow showers move out for Wednesday night but cold air continues
to filter in from the northwest. Wind will be slow to die down,
and with temperatures around 0F later in the night in the
north, wind chills will be around -20F in the north and may need
a wind chill advisory.
Quiet for Thursday and Thursday night with high pressure
building in. Could be quite cold Thursday night except high
clouds streaming in from the northwest may keep it from getting
as cold as it could be.
Next potential system moves in Friday. Looks fairly weak and
would probably be a mix of precipitation types with a warmer
airmass moving in.
Overall, good model agreement through Friday.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Forecast confidence decreases into the weekend. Most models
bring the Arctic air back in early Saturday with the front
stalling out south of toward Southern New England, with
precipitation possible along the front south of our area and us
staying cold air dry into Monday. However, the possibility is
there that the Arctic front could not make it that far south.
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR conditions late this aftn and eve will begin to
lower MVFR/IFR late tngt in snfl...then to LIFR and VLIFR in
falling and blowing sn across Nrn TAF sites with MVFR/IFR ovr
SHORT TERM: MVFR improving to VFR Wednesday night as the system
moves out and blowing snow diminishes. VFR Thursday and Thursday
night. A weak system for Friday could bring MVFR/IFR conditions.
NEAR TERM: No chgs in the GLW slated to begin across all of our
waters late Wed morn...contg thru the remainder of the day Wed.
Fzg spray will begin to become an issue later Wed aft when
colder air begins to advect ovr the water but should be lgt
until later Wed eve. Kept close to WW3 wv guidance for fcst wv
hts thru the near term.
SHORT TERM: Freezing spray advisory issued for Wednesday night
with unseasonably cold air and strong gale force northwest winds
over the waters. Conditions gradually improve from gale
Wednesday night to below small craft Thursday night. Small
crafts likely with next system Friday.
ME...Winter Weather Advisory from 7 AM to 10 PM EDT Wednesday for
Winter Weather Advisory from 4 AM to 6 PM EDT Wednesday for
Wind Advisory from 2 PM Wednesday to 2 AM EDT Thursday for
MARINE...Freezing Spray Advisory from 10 PM Wednesday to 11 AM EDT
Thursday for ANZ050>052.
Gale Warning from 11 AM Wednesday to 8 AM EDT Thursday for