913
FXUS61 KGYX 152258
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
658 PM EDT Mon Jul 15 2024

.SYNOPSIS...
Heat and humidity build for the next few days as high pressure
strengthens off the Eastern Seaboard, with chances for
scattered afternoon showers and thunderstorms each day. A cold
front moves through late Wednesday through Thursday, bringing
drier and somewhat cooler conditions for the end of the week and
going into the weekend with high pressure building in from the
west.

&&

.NEAR TERM /THROUGH TUESDAY/...
7 PM Update...Convection that has be ongoing across Mass has
remained well south of the NH border and have trimmed back PoPs
in the near term across southern NH. Latest satellite shows CU
fields have started to dissipate across the forecast area with
mostly fair skies prevailing and therefore have also decreased
the sky cover forecast. The main item of interest is an MCS
marching across the Finger Lakes region of NY. Recent runs of
the HRRR and the 18Z NamNest maintain good agreement that this
MCS will weaken as it crosses the Hudson Valley and moves into
VT around Midnight tonight. Models suggest this feature will
continue to weaken as it crosses into NH after midnight with few
rumbles of thunder possible and some brief heavy rain. Will
continue to monitor this feature through the evening, while the
overall threat for strong thunderstorms is on the downward trend
based on the latest model guidance.

Previously...


Visible satellite imagery this afternoon shows some diurnally
driven cumulus across the area with some cirrus streaming over
southern NH. The latest RAP13 pressure analysis shows a sfc
trough moving across southern New England, which is helping to
spark scattered showers and thunderstorms over Central
Massachusetts. Latest CAMs suggest most of this activity should
drift east and south of NH over the next couple of hours but it
is possible some additional storms develop within the outflow
boundaries associated with the ongoing convection. It will
otherwise continue to be a hot and humid afternoon and early
evening with just an isolated shower or storm. Any storm will be
capable of producing locally gusty winds and briefly heavy
rainfall.

Our attention tonight will be focused on a gradually weakening
MCS/MCV that is currently moving across western NY state. This
system is progged to continue moving east-northeastward this
evening and through tonight before arriving towards VT within an
hour or so either side of 10 PM. Latest CAMs indicate a
continued weakening trend as it arrives in our area by or a
little after midnight with the main focus moving into southern
Quebec. The environment will remain somewhat favorable though
through the night for strong to locally severe storms as the h8
LLJ strengthens, increasing the 0-6km shear to around 35 kts
with around 1500 J/KG of MUCAPE to work with. As a result, while
the threat for overnight convection and possible strong to
severe storms is low it cannot be completely ruled out as CAMs
tend to struggle with these types of setups. Strong to locally
damaging winds, heavy rainfall, and frequent lightning would be
the primary threats.

It will otherwise be a warm and muggy night with lows into the
upper 60s to lower 70s. Patchy fog will be possible overnight as
well.

&&

.SHORT TERM /TUESDAY NIGHT/...
Hot and humid conditions will persist on Tuesday with high
temperatures into the lower to middle 90s south of the
mountains. Cooler temperatures will be common across the far
north, mountains, and along the Mid-Coast/islands. A Heat
Advisory has been issued for most locations south of the
mountains and away from the Mid-Coast with heat indices into the
95-100 degree range during the afternoon. Additional scattered
showers and storms are possible during the afternoon and evening
as a s/w crosses over the region. Any storms will be capable of
becoming strong to severe with damaging winds the primary
threat. The Storm Prediction Center has placed most of NH into a
MRGL risk for severe storms.

Storms diminish Tuesday night paving the way to another warm and
muggy night with lows primarily into the 70s. Fog will be
possible once again, especially in locations the receive earlier
rainfall.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Models have been fairly consistent over the last few days for
breaking the heat wave come Wed night and Thursday as a more
localized -NAO sets up over Greenland and the Atlantic poleward
of 50 N. This does help break down the ridge, but there is so
much warm over central and western Canada that there really
isn`t much of source to cool things down, but itll be more
along the lines of less warm, with temps running normal or a
little above. However, once we clear the hot air out, it will be
mainly dry Friday into early next week, with daytime temps
mostly in the 80s, and overnight light in the mid 50s to mid
60s.

Wednesday shot be the last hot and humid days, and while we
will probably need another heat advisory in S NH and SW ME,
there are still questions as to how quickly clouds/SHRA/TSRA
move in ahead of the front, and thus, how will warm it will be
in points N and E. As for the front, there still questions with
its timing as we will have to see how it reacts to the wave
interacting with it Tuesday night, and then again a second wave
that moves through late Wed night or Thu, and where and when the
second one develops will be dependent on the first. So, while
some SHRA/TSRA will be possible Wed afternoon, especially in the
mtns, the bulk of any convection will likely be Wed night, and
precip amts will depend on what happens with the front. Its
unlikely that we will clear the high humidity out of here Wed
night, although mins will be a little lower especially in the
mtns, generally in the 60s.

Thu will also depend on what happens with the front, but, as we
often see with cold fronts in the summer, if it doesnt get
through before dark, it will likely not mix down until nest
morning, and because we may rain overnight into Thu morning, may
not see the drier air mix down until later in the day, so,
while it ill not be as hot but itll still be humid. The good
news is, we should see the effect of that cold front by Thu
night with clearing and lower humidity, with mins in the mid 50s
in the mtns to 60 to 65 in the S.

Friday through the weekend will be dry and sunny. More
comfortable RH are expected Fri with highs 75-80 in the mtns and
low to mid 80s in the S and lows Sat morning in the mid 50s to
low 60s. Sat and Sunday will be a few degrees warmer, with highs
mostly in the 80, but will start to see the RH creep up a bit by
Sunday. Monday looks dry and warm as well.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions dominate tonight through Tuesday
night outside of any FG, which could result in IFR to LIFR
restrictions. The greatest potential for this will be at KHIE,
KLEB, and KRKD. Scattered SHRA and TSRA are possible late
tonight and again Tuesday afternoon and evening with locally
strong winds and +RA the primary threats. No LLWS is expected
outside of any TSRA.

Long Term...Some valley fog possible lingering into Wed morning,
but should return to VFR through the rest of the day. Sct TSRA
will develop inland during the afternoon as a front approaches
and move through Wed night. This is the best to see several
hours or more of flight restrictions as fog settles in behind
any rain that does fall. Flight restrictions could linger into
Thu morning, but should see improvement to VFR during the
afternoon. Thu night through the weekend will be mainly VFR, the
only exception being late night valley fog.

&&

.MARINE...
Short Term...South-southwesterly winds will persist through
Tuesday night. Although winds will primarily remain below 25
kts, a few gusts to near 25 kts will be possible at times.
Scattered showers and storms will remain possible, some of which
will contain locally stronger winds. Seas will be at 2-4 ft,
highest outside of the bays. Marine fog will be possible at
times.

Long Term...Generally winds/seas stay below SCA levels through
the coming week, but could approach SCA gusts/seas Wed night
into early Thu.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory until 8 PM EDT this evening for MEZ012-018>020-
     023-033.
     Heat Advisory from noon to 8 PM EDT Tuesday for MEZ012-018>024-
     033.
NH...Heat Advisory until 8 PM EDT this evening for NHZ004-006-
     008>010-012>015.
     Heat Advisory from noon to 8 PM EDT Tuesday for NHZ004-006-
     008>015.
MARINE...None.

&&

$$

SYNOPSIS...Tubbs
NEAR TERM...Schroeter/Tubbs
SHORT TERM...Tubbs
LONG TERM...Cempa