NWS Forecast Discussion

For Fremont, NH

706
FXUS61 KGYX 200444 AAB
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1144 PM EST Mon Feb 19 2018

.SYNOPSIS...
A warm front will enter northern New England tonight, before
becoming nearly stationary along the New Hampshire and
Massachusetts borders on Tuesday. The front will move north of
the region Wednesday morning before a cold front sweeps through
during the afternoon and early evening hours. Canadian high
pressure will then follow through Thursday. A series of waves
moves across the area this weekend with light rain and snow
possible.

&&

.NEAR TERM /THROUGH TUESDAY/...
Update...Minor changes to reflect latest observational trends. I
have dropped the winter wx advisory in Oxford and Franklin based
on temps warming above freezing.

Previous discussion...Initial shot of light precipitation
arrives tonight in a warm air advection pattern. Atmosphere will
be relatively dry at the start. This may lead to some
evaporational cooling for a period over northern areas. This
will likely be sufficient enough to produce some pockets of
light mixed precipitation. There will be some light freezing
rain and sleet into early Tuesday morning in the cooler
locations. Have therefore issued a Winter Weather Advisory for
the mountains of Maine for tonight into early Tuesday morning.

There will be pockets of mixed precipitation in northern New
Hampshire as well. However, this precipitation will mainly be
confined almost exclusively to the higher terrain. Will handle
this in the recreation forecast.

With increasing dew points across the region as a warm front
enters southern areas, expect areas of fog to develop over the
colder snowpack.

&&

.SHORT TERM /TUESDAY NIGHT/...
Any effort for the warm front to march north will be relatively
futile on Tuesday as a cool drainage flow develops. Therefore,
we have backed off on the high forecasts with plenty of cloud
cover in the region. However, it will still be well above normal
for this time of the year.

Areas of fog will be slow to mix out in the morning. The
exception will be the coastline where the fog may linger the
entire day.

Pockets of freezing rain in the north will change to rain as
temperatures climb above freezing.

This is similar to a typical spring onshore pattern. As is the
case with these patterns, southwest New Hampshire has the chance
for the warm front to be situated in the region. Therefore,
there could be large temperature ranges for highs in the
vicinity of areas such as Keene.

Dew points increase further Tuesday night. This will allow for
large areas of fog to develop with the cold snowpack still in
place.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Wicked warm weather Wednesday...
As mentioned previously, a typically spring-like weather
situation is unfolding for the middle of the week. Very warm air
is being vented out of the south central part of the country and
through New England around a broad flat-topped ridge of high
pressure in the western Atlantic. While a preceding stationary
front will keep most of the area from feeling the extreme warmth
on Tuesday, this will not be the case on Wednesday. As low
pressure moves east into Quebec and a cold front heads east
through the eastern Great Lakes and Saint Lawrence Valley, it
will turn winds to the southwesterly helping to shove that front
all the way north into northern Maine by Wednesday morning,
putting our entire forecast area in the warm sector. While it is
typical in spring for coastal Maine to stay cooler due to the
cooling influences of the Gulf of Maine, this is not the case
when low level wind flow is out of the west as it is projected
to be on Wednesday. This will keep the sea breeze from being
able to have much of an effect in southwest Maine, allowing this
area to get in on the extreme warmth that southern New Hampshire
will be experiencing. Being that it is February, we cannot
expect the low levels to mix much further than about the 925 MB
level with the westerly downsloping winds doing the heavy
lifting on the mixing. Even temperatures at this level will
support high temperatures in the warm areas reaching to about 70
degrees. With the westerly low level flow expected, have brought
coastal New Hampshire and southwest Maine into the extreme
warmth.

This will meet or exceed all time February record high temperatures
at our primary climate stations, likely on par with what was
experienced last February 24 and 25. Note that although we do
have a snow cover, this will not have much cooling effect given
top down mixing of this warm air. In fact the snow cover will be
a victim of this warmth. Remember the record warmth last
February occurred with 12 inches of snow on the ground after
all! The all time record high temperatures for the month of
February are listed below, all of which are under threat of
being broken Wednesday.

***Warmest February Temperatures***
Portland            Concord             Augusta
64 - Feb 26, 1957   69 - Feb 24, 2017   60 - Feb 18, 1981

The cold front will drop in from the northwest Wednesday
afternoon and evening. Could see some showers along the front,
but support for this is weakening as the front moves through the
area, so the best chance for rain is in the north. Given the
lack of significant rainfall in the forecast, have decided not
to go with a Flood Watch, though the extreme warmth will melt a
good deal of the snow pack and could lead to ice movement and
jamming on area rivers. But without the rainfall, any ice jam
flooding will likely be isolated.

Cool high pressure moves in from the west Thursday and Thursday
night. High temperatures Thursday will likely be in the morning
as we are still cooling behind the front. With high pressure
over the area Thursday night we could see good radiational
cooling conditions, but low level dewpoints in the teens suggest
that low temperatures will only fall into the teens and 20s.

High pressure moves offshore on Friday with a warm southerly
flow returning on the back side of it. The warm upper ridge will
be backing up westward into Florida with the storm track
bringing systems from west to east across New England. The first
in a series of waves will be Friday night, bringing some light
rain or snow on the leading edge of warm advection. The next
wave moves through southern New England on Saturday, leaving
southern parts of New Hampshire and Maine on the northern
periphery of any precipitation associated with it. Although
this positioning would favor some light snowfall, temperatures
will still be quite warm even on the northern side and should
result in most of this falling as rain. The last and strongest
of the waves moves through on Sunday into Sunday night, tracking
south of New England. This one will be strong enough to pull in
enough cold air for snowfall for just about all of New
Hampshire and Maine.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions across the region will come to an
end late this evening as increasing clouds and showers move in
and a warm front enters the region. Increasing dewpoints over
the snowpack will result in fog overnight dropping conditions to
IFR and locally LIFR across the region. Tuesday will have a
gradual improvement for all but the immediate coastline where
IFR in low ceilings may remain throughout the day. Fog becomes
widespread once again Tuesday night.

Long Term...Should see VFR conditions on Wednesday with a cold
front moving through in the evening. A series of waves moves
through the region this weekend, each possibly bringing some
light rain or snow and IFR conditions possible.

&&

.MARINE...
Short Term...A south to southwest flow will continue over the
region through Wednesday. SCAs have been extended for the outer
waters through Tuesday with SCAs for the bays tonight.

Long Term...Southwest flow ahead of the front Wednesday could
reach up to about 25 KT with the flow behind the front Wednesday
night also reaching up to about that range. High pressure moves
through Thursday into Friday with light winds.

&&

.HYDROLOGY...
With the warm weather expected, some melting of the snow pack is
expected. This will lead to increased flows in the rivers and
may lead to a few ice jams. However, with the sustained warmth
and lack of significant rainfall, any ice jam flooding will
likely be isolated.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 10 AM EST Tuesday for MEZ009.
NH...None.
MARINE...Small Craft Advisory until 5 PM EST Tuesday for ANZ150-152-154.
     Small Craft Advisory until 6 AM EST Tuesday for ANZ151.

&&

$$

NEAR TERM...Legro

NWS GYX Office Area Forecast Discussion