Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
944 am EST Thursday Feb 11 2016
cloudy weather with a few snow showers is expected ahead of an
approaching cold front set to cross the area today. Snow showers
will be likely along and ahead of that front...before colder air
arrives. We have a brief break in store Friday...but then a strong
cold front drives through the region and the coldest air of the
season settles in for the weekend. While the actual air
temperatures will be quite cold...combined with gusty winds...the
wind chills will become dangerous for a time this weekend.
Near term /until 6 PM this evening/...
935 am...other than some changes in the very near term term based
on latest observation...did make some changes to probability of precipitation though the
afternoon today...but nothing significantly different than previous
forecast. Based on latest mesoscale models...including latest
hrrr/rap/12z NAM have focused probability of precipitation a little better across southern New Hampshire
and coastal ME. Went with scattered coverage...as its likely some shsn
will form ac the front moves through...but not everyone will see one.
Some of the showers could approach squalls at times...given steep
lapse rates and particular good height falls as the 500mb trough
swings through. Not convinced this will be widespread yet, but
certainly Worth keeping an eye on.
Previous discussion...a secondary cold fnt is already pushing
towards the area from the west. Ahead of it some snow showers will be
possible...and along it any snow shower may be briefly heavy. Lapse
rates will be quite steep during the day...and could support
localized areas of strong lift even if only in the lowest couple
thousand feet. Hi-res model guidance favors southern zones for
that...and the highest pop was placed in these areas. If the heavy
snow showers or squalls develop in this manner...an increase in pop
is likely and special weather statements may be needed.
Short term /6 PM this evening through 6 PM Friday/...
a brief break in the action is expected tonight...with very weak
shortwave ridging set to cross the area. The cold air advection today will have set
the stage for some chilly temperatures relative to the winter so far.
Readings should fall below zero in the north...with single digits down
to the coast. Recovery will be tough going Friday...with teens and
20s doing it for high temperatures.
Will keep an eye towards the latter part of the day...as lobe of
polar vortex pinwheels down across Hudson Bay. Ahead of it snow
showers should become more widespread as rapidly cooling air aloft
creates an unstable column. Though the bulk of the snowfall should be
Friday night into Sat.
Long term /Friday night through Wednesday/...
low pressure crossing northern New England Friday night forecast to
weaken and open into an inverted trough over central Maine
by Saturday morning. Arctic front behind this system will kick
off snow showers and squalls as it swings in from the west after
midnight. Expect an area of steadier snow to develop generally
east of the trough axis in downeast and midcoast areas toward
daybreak Saturday morning. Snowfall amounts overnight should be
on the light side across most of the forecast area...mainly an
inch or less but midcoast areas may see several inches by
Saturday morning. Lows overnight will range through the single
numbers north and lower teens south.
Inverted trough will remain parked over downeast Maine on Saturday
and will likely back snowfall west into western Maine and
possibly eastern New Hampshire during the day. GFS depositing an inch
or more of quantitative precipitation forecast over downeast sections through Saturday evening but
mainly in caribou's area. May need advisories or possibly warnings
for far eastern middle coast zones where a good fluff factor will
contribute to snow accumulations of 3 to possibly 6 inches. At
this point looks like western Maine will escape the worst of this
one with just light accumulations during the day. Expect
northwest winds to increase rapidly during the late morning and
early afternoon producing a lot of blowing and drifting of the
light powdery snow. High temperatures will range through the single
numbers north and teens south.
Expect snow to linger into Saturday evening as surface trough slowly
pivots over downeast Maine...especially in central and
midcoast locations where several more inches will be possible
before snow tapers off after midnight. Expect at least partial
clearing after midnight. Tight northwest gradient will persist
through the night producing a lot blowing and drifting and
dangerous wind chills. Wind chill warnings will likely be needed
for most if not all of the forecast area for overnight and into
Sunday morning. Low temperatures will range from 10 to 20 below north
and 5 to 10 below south.
High pressure will build in from the west on Sunday. Expect winds to
remain strong during the morning before tapering off in
the afternoon. Should see mostly sunny skies but this will hardly
budge temperatures with readings barely climbing above zero in the north
and remaining in the single numbers south.
High pressure will crest over the region Sunday night producing
another very frigid night with lows ranging from around zero
south to 10 below north.
High pressure will slide offshore on Monday with return flow bringing
warmer air back into the region. Broad area of over-running ahead
of next shortwave will bring increasing clouds in the morning and
possibly a few snow showers in the afternoon. Expect high temperatures to
get back closer to normal with readings in the middle teens to
lower 20s north and lower to middle 20s south.
Plenty of uncertainty in forecast Monday night through Tuesday as
models still converging on the exact track of low pressure moving up
the East Coast. Seeing the GFS gradually moving toward the
warmer European model (ecmwf) forecast from last night...bringing low pressure
farther west. This would likely start precipitation as a mix after
midnight Monday night gradually transitioning to rain on Tuesday
across much of the forecast area with a mix possibly hanging on
for much of the event in far western zones.
Low pressure forecast to pull away on Wednesday although
tight pressure gradient will persist for much of the day with
strong northwest flow delivering another shot of Arctic air.
Aviation /15z Thursday through Monday/...
short term...localized MVFR ceilings remain across the forecast area.
One over the midcoast associated with gradually lifting
fg/stratus...and another in the mountains of northern New Hampshire. Otherwise
generally VFR expected. Exception will be with the passage of a
secondary cold fnt. Shsn will be possible along and ahead of the
fnt...with local IFR or lower conditions. Behind the fnt VFR
conditions return to all terminals except hie...and gusty northwesterly
winds are possible.
Long term...areas of MVFR/IFR ceilings and visibility Friday night
through Saturday night. VFR Sunday. MVFR/IFR ceilings developing
Monday afternoon and persisting through Tuesday.
short term...seas are building again as first cold fnt is crossing
the waters. A stronger secondary fnt crosses later this afternoon.
This will bring gales to southern waters...and strong Small Craft Advisory conditions north
of Portland. As temperatures fall overnight and winds/seas remain
up...freezing spray will be likely and an advisory has been issued
for all waters into Friday morning.
Long term...gales likely Saturday through Sunday.
some of the coldest air of the season will arrive over the
weekend with bitter cold wind chill values. However...overnight
low records for this time of the year are particularly cold and
records are not expected to be broken.
Marine...Small Craft Advisory until 8 am EST Friday for anz150>153.
Freezing spray advisory from 10 PM this evening to 10 am EST
Friday for anz150>154.
Gale Warning from 3 PM this afternoon to 10 PM EST this
evening for anz154.