Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 232324

Area Forecast Discussion
National Weather Service Gray ME
724 PM EDT Fri Mar 23 2018

High pressure over Hudson Bay will slide southeast into Quebec
on Saturday. As it does so, a back door front will push westward
across Maine and New Hampshire Saturday night. Some light snow
is possible as this moves through, with cloudy and cool weather
expected behind the front for Sunday. High pressure settles into
northern Maine for several days, bringing a period of dry
weather with cool nights and gradually warming days through


720 PM...TWeaked pops/temps a bit overnight but nothing
significant. A few very weak radar echoes moving N to S across
NH should pose no problem at all, and air mass remains dry so
upslope should not be an issue either. Temps wise, there are
lots of mid level clouds moving on the west side of the low
well to our east, and this should keep temps from falling too
much, so bumped up overnight mins by just abit, with lows
generally in the low to mid 20s inland, and upper 20s to around
30 along the coast and in more developed areas of srn NH.

Previously...Just some thin high clouds across the region this
afternoon, with much of the sunshine still making it to the
surface and allowing temperatures to rise to the mid 40s. There
is also a bit of convective cloud cover in the mountains as the
upper level low and cold air pool destabilizes slightly.

Overnight look for the thin high clouds to remain as the
instability driving cloud cover decreases. This modest cloud
cover should be enough to prevent temperatures from dropping as
low tonight as last night however have still gone a few degrees
colder than guidance in the mountain valleys, brining low temps
to the upper teens.


A trough of cold air aloft will remain over the region through
the start of the weekend. Within this trough a short wave will
push down from James`s bay. As it does, it will bring a backdoor
cold front down from northern Maine. This will mean a generally
cloudy day on Saturday with afternoon snow showers. While the
showers will likely reach the coast, accumulations will be
minimal and may not even stick to some warmer surfaces. Have
overall gone a bit lower on amounts of snow, expecting some to
melt on impact. Additionally have been a bit conservative in how
far south west the cold air and snow showers make it. Have
focused the majority of the effect on Central Maine. While there
is potential for the front to make it all the way through New
Hampshire it seems most likely to get hung up near the Maine/NH


Upper air pattern features a cut off low forming over the
western Atlantic southeast of Cape Cod and a building ridge over
the Great Lakes and central Canada, crashing northeastward
through Quebec this weekend. This ridge will cut off access to
the coldest air which will be locked in a trough over northwest
Canada. The ridge also draws in much more mild air out of
Texas. Northern New England will be positioned in between the
Atlantic cut off low and the Quebec ridge leading to a prolonged
period of subsident flow and dry weather with only the
leftovers of the warmth making it into our area. A series of
waves rotating around the northern Canadian trough during the
middle of next week will each take small bites out of the ridge
while the Atlantic low drifts southeast and fills.

On Sunday the back door front will have moved through the area
bringing cool and initially cloudy conditions behind it. Expect
highs only in the 30s with clouds breaking up as the day goes on
and drier air moves in. With the center of the high moving into
northern Maine and the axis remaining stretched southwestward
across our forecast area for several days, we should see a
prolonged stretch of dry conditions. Expect good radiational
cooling possible each night from Sunday night through Tuesday
night while daytime temperatures gradually warm as the air mass
modifies from a combination of daytime heating and increasing
access to warmer air from the ridge just to our west. By Tuesday
temperatures will be in the 40s again for most areas, finally
inching up toward what is normal for this time of year.

With the increasingly higher sun angle and gradually warming
temperatures, expect a gradual melt off of the remaining snow
pack, with southern areas possibly losing their snow pack by
midweek. With cold temperatures each night, the sap from the
maple trees will also be running.

By Wednesday the first significant wave in a series of
shortwave troughs rotate around the northern Canadian trough and
push back against the Quebec ridge. Although this wave passes by
to our northwest, it will send a cold front through our area
Wednesday into Wednesday night, with some rain showers possible
ahead of it. The best forcing will be north of our area, so the
best chance of showers will be to the north. The air mass
behind the front is not all that much cooler as the ridge fills
back in a bit behind the departing shortwave trough. So we
should still see mild temperatures through the end of the week,
with the next wave pushing closer to our area on Friday. Models
not in great agreement on whether this will go by a bit to our
west or a bit to our east, but it seems likely that there will
be another more substantial precipitation event late next week,
likely on Friday. Precipitation type may be mostly rain with
snow possible in parts of the area as well depending on the
track and availability of colder air.


Short Term...VFR conditions will continue overnight and into
Saturday. A back door cold front may bring some MVFR snow showers
to Central Maine.

Long Term...Clouds behind the back door front may keep MVFR or IFR
conditions into the day on Sunday before the overcast begins to
break up from northeast to southwest. Then expect a period of
dry and clear weather Sunday night through early Wednesday.


Short Term...High pressure will remain over the area with calm
winds and seas. A backdoor front will move west across the
waters Saturday night with increasing winds to near Gale force.

Long Term...Winds behind the back door front will gust into the
25 to 35 KT range, creating the potential for low end gales
especially on Sunday. The pressure gradient remains fairly
tight between the Atlantic low and the northern New England
high, so advisory level winds may continue through as late as




NEAR TERM...Cempa/Curtis
LONG TERM...Kimble
MARINE...Curtis/Kimble is the U.S. government's official web portal to all federal, state and local government web resources and services.