Cornish, New Hampshire Weather Forecast Discussion

318
FXUS61 KGYX 060708
AFDGYX
Area Forecast Discussion
National Weather Service Gray ME
308 AM EDT Sat Sep 6 2025
.SYNOPSIS...
A very summer like day is on tap today, with temperatures well
into the 80s and high humidity. That will lead to showers and
thunderstorms erupting as a cold front moves into the area
during the afternoon. Some of thunderstorms may be severe with
damaging winds and large hail possible. Showers may linger near
the coast through Sunday before clearing out. Then another
stretch of dry weather is anticipated through the end of next
week.
&&
.NEAR TERM /TODAY/...
Key Message...The latest round of CAM and available machine
learning guidance has remained relatively consistent over the
past 24 hours with the severe weather threat this afternoon.
SPC maintains a Slight Risk across southern NH into SW Maine and
a Marginal Risk across the mountains through central Maine with
all severe hazards possible near the Slight Risk.
Details...Latest water vapor imagery shows a short wave over
Wisconsin rotating through the base of closed low near James
Bay. This short wave will track towards the St Lawrence Valley
today and help push a cold front across northern New England
this afternoon into tonight. All the while, an upper jet streak
will strengthen over SE Canada aiding in favorable dynamics for
ascent over the region as the cold front crosses.
Steady southwest flow over the forecast area has allowed for
mostly clear skies early this morning with mostly clear skies
expected to prevail south of the mountains into early this
afternoon. Solar insolation will allow for temperatures to
climb well into the 80s along the coastal plain with dew points
pushing to near 70 degrees. The approaching cold front will
trigger showers and storms across the mountains and north early
this afternoon. As the front slides east additional storms will
develop near the lakes region of NH and foothills and will
track towards the coast between 2 PM and 7 PM. It is within this
corridor where ML CAPE will approach 1500 J/kg along with 0-6
km bulk shear around 50 kts. This environment will be
supportive of organized updrafts and potential for super cell
structures. Model soundings also show veering low level winds
increasing with height that will also support rotating storms.
CAMs generally suggest semi discrete modes at convective
initiation over central NH and interior western Maine around 2
PM with storm mergers leading to more linear structures as
activity pushes towards the coast. Damaging winds have the
highest probability of occurrence followed by large hail and
perhaps a brief tornado or two. Despite the ongoing dry
conditions some training of storms will bring the potential for
urban and poor drainage issues across the higher population
centers of southern NH and SW Maine.
The severe threat will diminish around 8 PM this evening as
instability wanes.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
The cold front will stall near the coast tonight and provide a
focus for additional showers over the region into Sunday. Lows
tonight will range from the upper 40s across the north to mid
50s across the south.
Most model solutions keep the cold front near the coast through
the day Sunday with a wave of low pressure tracking along the
front. Models then diverge on how close this low will track to
the area with some keeping the heaviest rainfall offshore. The
going forecast call for rain showers to continue along and south
of the mountains Sunday morning with a NW to SE drying trend
Sunday afternoon. Highs on Sunday will be in the upper 60s to
low 70s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Key Message: Another extended period of dry weather is forecast
as high pressure dominates the region. Temps will average near
to below normal.
Impacts: Little drought relief is anticipated. Some northern
valleys may experience frosty mornings under high pressure.
Forecast Details: Any lingering showers over the coastal waters
Sun night will give way to dry conditions as high pressure
builds into the region. The center of the surface high does not
quite move overhead until Mon night however. Right now there are
no strong signals for colder than normal weather...but ensemble
guidance hints at some coolish temps. Overall I anticipated
things average near to slightly below normal. If trends hold
some overnight temps may need to be adjusted down under ideal
radiational cooling conditions. I did also add some fog to Mon
night in the major river valleys.
Otherwise it is another extended period of dry weather. Little
drought relief is anticipated. The only thing that may stave off
significant expanding drought conditions will be the rainfall
Sat.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Steady south to southwest flow will likely keep
conditions VFR early this morning into early this afternoon. A
cold front will trigger showers and thunderstorms this afternoon
starting between 14Z and 18Z across northern and western NH with
showers and storms progressing towards the coast around 23Z.
Some storms may become severe with damaging winds and hail with
greatest chance for severe storms from KCON to KAUG to the coast
between 18Z and 23Z. Low cigs and showers will persist over the
area tonight through Sunday morning with periods of IFR possible
for all site. Conditions improve from NW to SE Sunday afternoon.
Long Term...Largely VFR conditions expected thru the extended.
Beginning Mon night high pressure settles over the region and
will promote valley fog. LEB and HIE will likely experience IFR
or lower conditions each night while high pressure remains
overhead. Long term dry conditions may keep fog from forming
down the Merrimack Valley.
&&
.MARINE...
Short Term...A cold front approaches from the west today with
southerly winds increasing to 30 kts and seas building greater
than 5 feet. Storms that form over land this afternoon may
maintain severe strength as they track into the waters this
evening. The front stall over the waters tonight into Sunday
while winds and seas drop below SCA thresholds by Sunday
morning.
Long Term...High pressure is forecast to be in control of the
waters thru most of the extended. Winds and seas are expected to
remain below SCA thresholds.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ150-
     152>154.
&&
$$
NEAR TERM...Schroeter
SHORT TERM...Schroeter
LONG TERM...Cornwell/Legro
AVIATION...Legro/Schroeter
MARINE...Legro/Schroeter

NWS GYX Office Area Forecast Discussion