Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
417 am EST Thursday Feb 11 2016
weak low pressure will cross the region today in advance of an
Arctic front that will cross the region this afternoon...followed
by very cold air at the end of the week. Another low with a
second Arctic cold front will cross the region Saturday...followed
likely by the coldest daytime high temperatures for the season
so far on Sunday.
Near term /through tonight/...
whats left of this current batch of snow showers is crossing into New Brunswick
prov as a weak cold front crosses the region. Additional scattered snow
showers is possible this afternoon into Erly evening ahead of a secondary
Arctic front. With only MDT 925-700mb instability...conditions
will be marginal for snow sqls...but we cannot rule out a few
stronger segments of heavier snow showers resulting in localized half
to full inch of additional light fluffy snfl for some lctns.
Hi temperatures today will be a little Erly today given the tmg of the Arctic
front...ranging from late morng over he far northwest along the qb border to
midday to Erly afternoon further east. Temperatures will then fall fairly quickly
later this afternoon into Erly evening behind the front. Any remaining
narrow band St Lawrence sea way effect snow showers will taper to scattered
flurries by late tonight as the low level air becomes to cold to hold any
moisture...with flurries ending last over the far NE by daybreak
Friday. Wind chills will be an issue especially across the northwest late
tonight into Friday morning...potentially requiring a wind chill advection.
Short term /Friday through Saturday night/...
high pressure builds Friday with sunshine across the
area and decreasing winds...but high temperatures will only be in
the single digits north and low teens south. On Friday
night...the high is over the area with light winds. This means
temperatures will drop off quickly in the evening...but will
likely level out due to increasing clouds ahead of a clipper
system. Subzero readings are forecast for the northern 2/3 of the
forecast area and single digits towards Bangor. Temperatures could
drop much lower in northern zones if these clouds do not
A classic norlun type 2 will set up late Friday night as the
clipper low transfers energy to a low well south of Cape Cod and
leaves an inverted trough along the coast. There will be a fairly
deep unstable layer moving east along the coast late Friday night
through Saturday and it could produce some impressive snowfall
rates. As is always the case with norlun troughs...the big
question will be where it sets up. Guidance has trended further
west in the past 24 hours towards the more climatologically
favored areas towards the midcoast. These troughs are often an
all-or-nothing proposition with a high bust potential. For
now...have taken a composite approach with amounts reaching 8-9
inches in coastal Hancock County with a sharp cutoff east of
Machias due to high snow ratios along the narrow surface
convergence line. The concern is that it will end up on the other
side of Penobscot Bay as the nam12 has been showing with minimal
snow along the down East Coast.
Elsewhere...some snow can be expected inland along the narrow inverted
trough axis...but dry elsewhere with highs in the upper single
digits towards the Saint John valley and low 20s on the coast.
Winds pick up late day and continue through the night as the
coldest air of the season advects into the forecast area. A Wind
Chill Advisory is likely as wind chills drop to -20 to -30f by
Long term /Sunday through Wednesday/...
highs on Sunday will be even colder than Saturday
with highs around zero north and low single digits everywhere
else. The wind continues Sunday with Wind Chill Advisory headlines
highly likely. High pressure builds Sunday night. Have taken a
conservative approach to temperatures with this forecast due to
the narrow ridge...but if it crests Sunday night...temperatures
could go much lower. The entire area will be below zero Sunday
night. Strong warm advection follows later Monday and Monday
night with a good southerly flow. Highs rebound on Monday to the
teens. The coast will warm to the low 20s.
On Monday night...the initial overrunning snow from a major storm
event will start. Low pressure will move out of the southeastern
US in the southern branch and move up the coast as the upper
trough develops some negative tilt. The exact track remains
uncertain. Our gridded forecast took an ensemble approach from
multiple models and brought the low into the midcoast towards
Houlton on Tuesday night. This means several inches of overrunning
snow followed by a changeover to heavy rain except towards the
Allagash where snow could hold through the event.
There is potential for this to be one of the biggest events of the
winter as it pulls a very rich flow of moisture north from the
Bahamas with very strong frontogentical forcing. The potential
impacts include significant flooding with a more western track or
heavy snow with a more eastern track. A corridor of freezing rain
is another concern on the west side of trough extending north from
The storm is forecast to move out Wednesday with a flash freeze
possible as colder air returns.
Aviation /08z Thursday through Monday/...
near term: msly MVFR clg conditions will prevail across the taf
sites today into this evening...with intervals of VFR clgs and brief periods
of IFR visibilities with heavier snow showers. All sites should then become
predominate VFR late tonight.
Short term: mostly VFR through the period. IFR conditions at bhb
and bgr on Saturday due to snow are possible.
near term: initially no hdlns for today with long period swell running
at or below 5 feet over the outer waters and at or below 3 feet for the inner
Bay/Harbor waters. Winds will increase later this afternoon behind an
Arctic cold front to Small Craft Advisory gusts over all waters beginning by Erly
this evening...continuing through midday Friday. Kept close to ww3 WV guidance
for forecast WV heights for the near term. Air temperatures will be cold enough
late tonight into Friday morning for the potential of MDT fzg spy...
requiring a fzg spy advection over all of our waters during this tm.
Short term: a strong gale is expected Saturday night into Sunday
morning with freezing spray. An Small Craft Advisory will follow Sunday afternoon
into Monday morning. A new gale is possible Tuesday.
Marine...Small Craft Advisory from 6 PM this evening to 1 PM EST Friday
Freezing spray advisory from midnight tonight to noon EST
Friday for anz050>052.