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000 
FXUS61 KGYX 101450 AAA
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
950 AM EST Tue Dec 10 2019

.SYNOPSIS...
A cold front will approach from the west today with a chance of
showers. However, the main story will be temperatures well above
normal with highs in the 50s at most locations. Cold temperatures
return tonight with some light snow likely late tonight into 
Wednesday for southern New Hampshire and the coastal plain of 
Maine. An active weather pattern looks to continue this weekend 
with low pressure moving up the coast delivering another chance 
of heavy rainfall.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
F-gen ahead of the approaching cold front is helping to keeping
a band of showers fairly focused this morning. SW flow aloft is
transporting this into SW parts of the forecast area. I have
bumped PoP up about a category in most places to highlight more
in the way of showery wx today that previous forecast. Showers
will be light...but I do expect many areas to see some
measurable today. Otherwise no major changes.

Previous discussion...Mainly dry conditions are expected today 
behind a departing shortwave trough contributing to synoptic 
subsidence along with dry intrusion aloft. Meanwhile a long wave
trough digs and rotates through the Plains into the Great Lakes
region today, strengthening a 300 mb jet to 170+ kts over the 
northeast. At the surface, warm advection continues amid 
southwest flow, to near-record values over some parts of 
southern NH and coastal Maine. Late this afternoon into the 
evening, a lagging surface cold front crosses with an uptick in 
PoP mainly over the mountains. Cold advection marks a change in 
airmass behind the front with some showers switching over to 
snow before drying out.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Update...Early look at the 10.12z NWP shows continued evidence
of deep dry air below saturated layer aloft tonight. Depending
on the model lift is generally thru or above the snow growth
zone...so I expect snow to be generated. But the dry air will
help evaporate that...and Wly flow will help advect that snow 
Ewd as it falls. To me that screams a sharp NW cut off to snow
accumulation...and likely very light totals if any at all in our
Srn and coastal zones. I have really trimmed back snow amounts
to generally less than an inch thru Wed morning.

Previous discussion...The aforementioned strong jet aloft 
NEward allowing broad synoptic ascent and favorable bands of 
FGEN and deformation to develop along the eastern seaboard 
tonight into Wednesday morning. With a cool airmass now in 
place, precipitation that does fall would fall as snow - 
although it would be tough to accumulate with recent warm, wet 
conditions. In spite of very strong forcing coinciding with DGZ 
humidity in the upper levels, dry air in the mid- and low- 
levels will inhibit at least a portion of QPF from reaching the 
ground, so overall expected a light snowfall evening on the 
order of 1-2 inches over southern NH and along the coast of 
Maine. One caveat to the minor event is that snow could impact 
the morning commute on Wednesday with strong forcing fully 
capable of producing a burst of snow in an organized band. An 
approaching short wave trough from the west pushes any banded 
snow off shore by the evening, as will strengthening surface 
high pressure. Continued cold advection limits temperatures to 
the 20s over the north and in much of western Maine, low- 30s 
across the south.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Strong high pressure at the surface will move across the
forecast area Wednesday night through Thursday. This should
allow for colder than normal temperatures. The pattern remains
quite progressive and most of the 00z guidance agrees that the
next system to affect northern New England will come from the
southern stream and displace our cold air mass quite quickly.
So while we may have a brief period of mixed precipitation at 
the onset late Friday or Friday night, the vast majority of the 
forecast area is expected to see rain, heavy at times, on 
Saturday. A brief period of strong winds will be possible on the
coast as well. Thereafter, snow showers are possible with the 
passage of a short wave trough on Sunday along with gusty NW 
winds.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
Short Term /Through Wednesday/...TAF sites see gradual
improvements this morning with prevailing VFR visibilities and
ceilings improving from southwest to northeast, from IFR to
MVFR. LLWS also diminishes this morning as a LLJ continues to
track away from the region. A brief period of IFR could develop
again in the pre- dawn, but without confidence to include in the
forecast. Today, MVFR ceilings prevail while occasionally 
scattering to VFR with unrestricted visibilities. A cold front 
crosses this evening, shifting southwest winds northwesterly with
a few 15-20kt gusts, and improvements to VFR to follow except
for in upslope areas.

Long Term...VFR conditions outside of the mountains are 
expected Wednesday night into Thursday morning. VFR for all for 
the balance of Thursday through Friday. Conditions quickly 
become IFR Saturday in rain or mixed precipitation with LLWS a 
possibility.

&&

.MARINE...
Short Term /Through Wednesday/...The core of strong winds 
responsible for sporadic gusts last evening has moved off to the
east with diminishing winds this morning over the waters. SCA 
winds and seas continue through today with seas possibly 
continuing into Wednesday before winding down, before a cold 
front enters from the west.

Long Term...Strong cold air advection is expected on the waters 
Wednesday night and will result in SCA conditions. Some low-end 
gales will be possible for a brief time as well. SCA conditions 
or gales will be possible over the weekend in association with 
low pressure moving up the east coast.

&&

.HYDROLOGY...
Warm temperatures combined with rain will result in runoff and 
modest rises on area rivers. While snow loss is expected, it is
unlikely the entire snowpack will go over to runoff which will 
spare most locations from flooding. The most likely areas for 
minor flooding include southern New Hampshire with the Warner 
River at Davisville and the Suncook at North Chichester expected
to near action stage. Across the northern mountains, the snow 
density is lower, as are the QPF amounts and the combination 
will likely result in most of the rain being absorbed into the 
snowpack with low chance of any of the rivers meeting action 
stage.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for 
     ANZ150>154.

&&

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