NWS Gray, Maine Area Forecast Discussion



000
FXUS61 KGYX 270329 AAB
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1129 PM EDT Tue Oct 26 2021

.SYNOPSIS...
A strong coastal storm system will track in a loop tonight
through early Wednesday just southeast of Nantucket Island.
Periods of rain and strong northeast winds can be expected
through Wednesday. Quieter weather is then expected for both
Thursday and Friday before another potential storm system
approaches from the south this weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Update...Core of the LLJ is approaching the South Shore of MA at
this time...as the intensity reaches its peak in the next
several hours. Already seeing a few gusts top 70 to 80 mph on
the Outer Cape and over 60 mph at PYM and on Cape Ann. As that
LLJ backs into the coast over the next couple of hours winds
should ramp for the Seacoast as well as farther N along the Wrn
ME coastline. Forecast looks to be largely on track...though I
did have to tamp down wind gusts over the far interior where
stable air is just not allowing for much mixing of the strong
winds aloft.

The biggest question remains how do winds unfold across interior
zones. Taking a look at Bufkit soundings across that area it
looks like a lot of gusts around 35 kt. For now I will hold off
on expanding headlines and see how things evolve. Given wind
direction more or less parallel to the coast I think that there
will be a large gradient between high gusts near the coast and
relative run of the mill gusts over the interior.

Previous discussion...Rapid cyclogenesis is underway as surface
pressures continue to quickly drop southeast of Cape Cod this
afternoon. Lightning strikes are more persistent as well around
and near a tightly clustered area of convection per latest radar
imagery.

Ensemble and operational runs as well as a suite of latest mesoscale
models continue to bring rain into the region tonight. The expected
storm track brings the system near the 40N/70W benchmark early this
evening before performing a loop near Nantucket Island overnight.

An increasing  gradient embedded within this retrograding storm will
allow for strong gusty winds, especially along the coastline. Wind
advisories will continue for this region with models suggesting
gusts up to 50 mph mixing down to the surface. GYX probabilistic
data continues to show a few locations may gust slightly higher,
particularly in coastal Rockingham County where a High Wind
Warning has been issued. Expect scattered power outages and
downed power lines with isolated downed trees which is very
close to high wind warning criteria.

Rain will be heaviest over southern areas where minor flooding is
possible due to clogged storm drains.

Patchy is expected with overnight lows in the upper 30 north to the
40s south.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Strong gusty winds continue Wednesday morning along with rain as the
storm completes its loop near the benchmark. During the day, winds
will gradually back and gradually begin to slowly diminish a little
during the afternoon.

With the low cloud cover and precipitation, temperatures will not
recover much from the overnight lows. Readings will be limited to
the upper 40s and lower 50s which is a very small range for our
forecast area.

Any precipitation Wednesday night will be limited to the coastline
and also limited to the evening hours. Thereafter, skies will begin
to clear from northwest to southeast as the low exits out to sea.
There is some indication that this system may become tropical or
subtropical as it moves away from our region.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Thursday and Friday continue to be the bright spots of the week
as high pressure moves in behind the exiting early week storm.
With the center of the high located just south of the Hudson
Strait, the northerly winds ahead of the high wont offer a
bigger push of the coastal storm out to sea. The result will be
moisture sticking around in the lower levels along the immediate
coast. With dry air expected to be plentiful aloft and at the
surface, the only tracer of this moisture may be a cloud deck
out to sea. A breezy morning will become lighter during the day,
with temperatures returning to around normal for both daytime
highs and overnight lows. Friday morning will be chilly as mid-
30s make it down to the coast, with upper 20s possible in the
northern/western mtn valleys. Areas of frost will develop and
push into the foothills.

Friday night, a very broad area of low pressure over the
Tennessee Valley will begin to track north. Model guidance
depicts a mid level jet strengthening off the Mid Atlantic coast
with energy being transferred to a low level jet along the New
England coast Saturday. Perhaps the biggest takeaway from the
setup is a large fetch of moisture potentially angled into the
region, resulting in higher than normal confidence of rain
Saturday at this range. Duration/timing still needs to be
refined over the coming forecasts, but the positioning of a LLJ
beneath a 250 jet along with a 90th percentile NAEFS PW feature
is indicative of a potential burst of heavy rainfall in the
afternoon.

An additional aspect would be wind. Both ECMWF and GFS guidance
angle a SE 25-50 kt low level jet along the Maine Midcoast. If
heavy rain does materialize, it could be another windy storm for
the coast, this time with a more easterly or southeasterly
component.

On the other side, the beginning of next week begins dry with
seasonable temperatures within a period of zonal flow into
southern New England and the Ohio Valley.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...It will be windy with widespread IFR and LIFR
conditions tonight into Wednesday. Conditions gradually begin to
improve late in the day and Wednesday night from northwest to
southeast as the storm moves out to sea.

Long Term...VFR conditions expected Thursday and Friday ahead of
another storm system that will cause IFR ceilings Saturday and
possibly lingering Sat night. This storm may contain heavy rain
and gusty winds for the coast.

&&

.MARINE...
Short Term...Will continue with storm warnings through early
Wednesday. GYX probabilistic data brings very high wind speeds
along the coastal waters with MISM1 having an 80% chance of
hurricane force wind gusts overnight.

Long Term...Gale conditions appear to be a threat through early
Thursday morning, mainly for the outer coastal waters. Northerly
winds will keep a bit of wind fetch over the waters, with wave
heights very slowly backing down. SCA conditions, in particular
wave heights, may well remain over a portion of the waters
until the weekend. Another low pressure system may develop near
the Gulf of Maine waters this weekend with gusty winds and heavy
rain.

&&

.HYDROLOGY...
Locally heavy rain is expected over southern NH and southwestern
ME today through Wednesday. A couple rivers may approach
bankfull and there could be some minor poor drainage flooding,
especially where fallen leaves clog storm drains.

&&

.TIDES/COASTAL FLOODING...
Forecast guidance indicates the possibility of splash-over and
beach erosion beginning tonight and lasting through Wednesday
despite low astronomical tides. Large waves will combine with
storm surge values of 2-3 feet over southern areas.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Wind Advisory until noon EDT Wednesday for MEZ023>028.
     Coastal Flood Advisory until 5 PM EDT Wednesday for MEZ023.
NH...High Wind Warning until noon EDT Wednesday for NHZ014.
     Coastal Flood Advisory until 5 PM EDT Wednesday for NHZ014.
MARINE...Storm Warning until 11 AM EDT Wednesday for ANZ150>154.

&&

$$

NEAR TERM...Legro

NWS GYX Office Area Forecast Discussion