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Area forecast discussion
National Weather Service Gray ME
1115 am EST Mon Feb 27 2017

Synopsis...
low pressure will pass north of the region today allowing
somewhat warmer temperatures to stream in from the south and
west. A weak cold front pushes south but will weaken and stall
over the region before moving north Wednesday as a warm front.
Much warmer temperatures arrive behind this warm front on
Wednesday, but they will not last long. A cold front moves
through Wednesday night with much colder air arriving behind it
and lasting through the weekend.

&&

Near term /until 6 PM this evening/...
11 am update...
cold front slowly sagging south out of southern Quebec currently
pushing clouds into northern zones and this boundary will
continue to slowly move south through the afternoon bringing
variable clouds into southern and central areas. Have adjusted
temp/TD/sky grids based on current obs/Sat pics. No other
changes to current forecast planned attm.



843am update...quick update this morning to account for current
temperature trends. Forecast package remains largely intact
except for a few very minor tweaks.



650 am update...
only minor changes to the forecast early this Morning. Sun and
a dry airmass in place will allow for quick warming today.

Previous discussion...
water vapor imagery shows broad zonal flow over the region with
a few clouds affecting the Connecticut River valley and
northern zones as a frontal system approaches the international
border. Light rain and snow showers will develop today mainly
over just the northern third of the region. Quantitative precipitation forecast amounts will be
light but there could be some light accumulations. Westerly
winds will help boost temperatures into the mid to upper 50s
south with mid to upper 40s for the foothills. Across the
mountains cloud cover will keep readings near 40.

&&

Short term /6 PM this evening through 6 PM Tuesday/...
we will have some lingering cloud cover across the north
tonight with the boundary stalling in the area. This could keep
the odd shower in the region overnight but forcing for ascent
will be weak and without daytime heating not expecting much to
come of it. Again we are looking at very warm weather for
Tuesday. Showers will begin over southern New Hampshire and coastal Maine
in the late afternoon as a warm front lifts north. Any
measurable precipitation amounts will arrive after sunset.

&&

Long term /Tuesday night through Sunday/...
we will see quite the Topsy-turvy temperature trend this week
as our region will be within an active zone of the westerlies
caught in between impressive warmth to the south and building
cold to the north. The temperatures will reach its peak on hump
day before taking a tumble Thursday into the weekend.
Temperature differences across this time period could be 50
degrees or more.

It all begins with a warm front lifting north across the area
Tuesday night into Wednesday morning. Ahead of this front expect
some cold air damming in an east-southeast pressure gradient.
Although this will be a briefly dammed flow, temperatures in the
cold sector ahead of the warm front are not all that cold. So
even in the cold air dammed areas, temperatures may be near or
just above freezing. Warm advection precipitation will begin
Tuesday night and spread north as the warm front lifts across
the area. It is possible that some areas of northern New
Hampshire and interior western Maine could see a brief period of
freezing rain if temperatures can drop to around the freezing
point before the warm front lifts through overnight. If this
does occur any icing will be very light and temporary as
temperatures quickly warm well above freezing by Wednesday
morning behind the warm front.

Very warm air venting from the southern portion of the continent
will stream north into the area behind the warm front on
Wednesday. We will again see 850 mb temperatures near +10c
which, if mixed fully to the surface, would translate to
temperatures in the 70s. There is some uncertainty as to whether
any of our area will see full mixing as there may be a fair
amount of cloud cover. Low level winds will have more of an
onshore component to them across Maine which should temper the
warmth there a bit. But it does appear likely that we will see a
break in the precipitation and possibly a few breaks in the
cloud cover as well on Wednesday as the warm front lifts well to
the north and the cold front presses eastward through the Great
Lakes. Some of the models (ex. Gfs) paint quantitative precipitation forecast across the entire
northeast for a full 24 hours as subtle features advance
through the southwesterly flow, but this may be a bit
unrealistic. A solution more similar to the NAM seems more
likely with precipitation focused along and ahead of the warm
front Wednesday morning and then along and ahead of the cold
front Wednesday evening. In between there will be a period of
southwesterly flow which will promote better mixing especially
over southeastern New Hampshire. This is where the best chance
exists to see 70 degrees. It is Worth noting that Concord still
had 10 inches of snow on the ground as of yesterday morning, but
this snow depth will have very little effect on temperatures
during this period especially considering the majority of this
warmth is achieved through advection/mixing of the warm air
venting out of the southern half of the country. The record high
temperature on Wednesday, March 1 in Concord is 65 degrees and
this will be in jeopardy.

A cold front will swing east out of the Great Lakes and into New
England Wednesday night. Expect a chance of showers as this
moves through, and considering how deep we will be in the warm
sector it is possible that there could be a few thunderstorms as
the front moves through. Temperatures will come crashing down
behind the front, falling through the 40s by Thursday morning.
High temperatures on Thursday may occur in the morning hours as
cold advection will be strong all day. This cold advection will
allow for efficient mixing of stronger winds aloft down toward
the surface with gusts to 35 mph possible.

Cold air should last into the weekend, with most of the area
seeing at least two full days below freezing. A weak impulse
will move around the back side of the upper trough through
southern New England on Friday. Models disagree on the placement
of this feature, but there is an outside chance it could
provide a quick shot of snowfall as it moves by. The coldest day
will be Saturday before a warm up begins again on Sunday.

&&

Aviation /16z Monday through Friday/...
short term...expect VFR conditions throughout the period. Gusty
westerly flow will allow winds to gust to around 20-25 kts at
all terminals before diminishing tonight.

Long term...IFR conditions will be possible Tuesday night as a
warm front moves through bringing light rain and low clouds.
Should see mostly VFR conditions during the day Wednesday before
showers and a possible thunderstorm move through Wednesday
evening ahead of a cold front. Winds behind the front on
Thursday could gust to 30kt.

&&

Marine...
short term...Small Craft Advisory has been expanded to go ahead and include the
bays as opposed to later since seas are increasing this morning.
Winds diminish tonight but seas remain high so will leave the
end time this evening so it can be converted to a small craft
for hazardous seas if desired.

Long term...southwesterly flow behind a warm front on Wednesday
could reach advisory levels. A cold front crossing the waters
Wednesday night into Thursday morning will bring cold advection
and gale force northwest winds on Thursday.

&&

Hydrology...
the Flood Watch has been cancelled as almost all rivers have
crested and the flooding potential has diminished. Warmer
temperatures today may start ice moving again so we will
continue to monitor it closely.

More warm temperatures this week could cause another round of
snow melt allowing any remnant ice on the rivers to start moving
again. This will increase the chance of flooding especially on
Wednesday into early Thursday. Colder weather arriving late in
the week should cut off the snow melt and allow river levels to
recede again.

&&

Gyx watches/warnings/advisories...
ME...none.
New Hampshire...none.
Marine...Small Craft Advisory until 7 PM EST this evening for

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