Area Forecast Discussion
Issued by NWS Portland, ME-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KGYX 220832
Area Forecast Discussion
National Weather Service Gray ME
332 AM EST Wed Feb 22 2017
A weak cold front will stall over the area today...with rain
showers along it drying up. Low pressure moving east through
southern Canada will drag the boundary back north as a warm
front...leading to a mild night and even warmer temperatures Thursday.
Highs will climb into the 50s to near 60 across New Hampshire...with
40s to near 50 over western Maine. A cold front will cross the
area with rain showers Thursday evening. Once more that boundary
lifts north as a warm front Friday night as we await a stronger
cold front and more widespread precipitation over the weekend.
.NEAR TERM /TODAY/...
An area of rain showers along a decaying cold front is pushing
thru Srn and central NH and extreme SWrn ME this morning. Temps
have very slowly slipped down towards freezing thru the
night...but most areas remain above 32. However...dewpoints are
generally below 30...so some wetbulb cooling or pockets of near
surface sub-freezing air is possible and could lead to localized
freezing rain. The biggest hinderance to icing this morning may
be that the rain showers are just too light to coat surfaces.
Otherwise...we will warm up again nicely today. Temps should
climb into the 40s for most areas...and maybe even a few low 50s
across Srn NH.
.SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
The washed out cold front begins to drift back Nwd tonight as a
warm front...ahead of a fast moving s/wv trof moving thru Srn
Canada. We will have to keep an eye on dewpoints climbing thru
the night...as it could lead to some fog over the colder snow
pack. Also behind the advancing warm front will be some of the
very warm air mass that could be responsible for several more
broken records over the Midwest today. Steep lapse rates aloft
within this air mass will advect in overnight. Much like the
late spring and early summer...the arrival of this steep lapse
rate air may be enough for some WAA type showers late tonight or
SW flow behind the warm front and the moderating Midwest air
mass will lead to very warm temps Thu. 50s should be pretty
widespread across Wrn portions of the forecast area...with a few
low 60s possible in favored Srn NH downslope areas. Those steep
lapse rates remain in place Thu...and within the warm sector
ahead of approaching cold front. I expect a convective line of
showers to develop along the front as it advances Ewd Thu
afternoon. Model CAPE forecasts are fairly meager at this
time...but it would not surprise me to see a few stronger cells
lead to a graupel shower or clap of thunder even. The showers
will lose some punch with loss of daytime heating...but lapse
rates aloft should sustain them to the coast thru early evening.
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The models are in decent agreement on the longwave pattern through
late next week. While we`ll see some brief intrusions of colder
air into the region...ridging and above normal temperatures are
expected to dominate the extended period. In the dailies...a weak
impulse will cross the area Thursday night with an associated
surface low passing down the Saint Lawrence and a trailing cold
front crossing the area with a few rain or snow showers in the
higher terrain. High pressure briefly builds by to our north on
Friday. However...warm air advection clouds and light
precipitation should spread north and east across the area during
the afternoon and evening hours. The warm front will lift north
across the area on Saturday as an impulse over the upper Midwest
pushes a surface low northward across the Great Lakes. This low
will drive a strong cold front across the area Saturday night with
more seasonable air and upslope snow showers to follow for
Sunday. Another quick moving impulse will race eastward along the
U.S. Canadian border and drive a second cold front across the area
on Monday accompanied by a second round of upslope snow showers.
A weak ridge follows for Monday night. By Tuesday, warmer air
returns in broad west- southwest flow aloft. Both clouds and pops
will increase in warm air advection ahead of a disturbance
expected to track to our north and west down the Saint Lawrence
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Some local MVFR possible this morning near decaying
cold front edging towards the coast. It will lift back N tonight
as a warm front...and increasing dewpoints over the snow cover
may lead to some fog development. Confidence is low in
occurrence at this time. Tonight into Thu morning some -SHRA
are possible along the advancing warm front...though low
probability precludes mentioning in the TAFs just yet. Late Thu
afternoon a cold front approaching the CT River may bring -SHRA
to LEB...HIE...and CON before reaching the coast around or just
after 00z Fri.
Fri AM...Sct MVFR psb in mtn -shra/-shsn.
Fri PM - SAT...MVFR in -shra with areas of IFR in drizzle and
fog. SE sfc wnd Sat gusting to 30 kt.
Sun...Sct MVFR in mtn -shsn. NW sfc wnd gusting to 25 kt.
Short Term...A few gusts just below SCA thresholds this morning
ahead of the cold front will diminish by afternoon. A warm front
lifts N across the waters tonight...with winds and seas
remaining below SCA conditions. SWly flow Thu will begin to
build seas to near 5 ft by evening.
Fri AM...SCA`s likely outside the bays.
Sat - Sun...SCA`s likely...wth gusts approaching gale
outside the bays.