807
FXUS61 KGYX 191626
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1226 PM EDT Wed Jun 19 2024

.SYNOPSIS...
High pressure will remain east of New England through much of
this week, continuing our period of hot and humid conditions
through Thursday. Record high temperatures and potentially
dangerous heat index values are likely. A cold front will
slowly cross through the region on Thursday and Friday with an
increasing chance for scattered strong thunderstorms and cooler
temperatures starting on Friday.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
1224 PM Update...
Latest update was to add shower and thunderstorm pops for the
early afternoon period. This includes storms developing and
heading towards the Concord, New Hampshire region.

1055 AM Update...
A large dome of high pressure aloft remain situated over the
Northeast. Around the periphery of this anticyclone hot and
humid air continues to enter the forecast area from the west,
southwest.

Warm overnight lows with plenty of low level moisture allow for
some record minimax temperatures across portions of Maine this
morning. Temperatures have soared this morning under mainly
sunny skies. Expect this trend to continue, therefore rare
Excessive Heat Warnings will remain in effect today across
southern interior sections of Maine and New Hampshire as
temperatures continue to be unfettered moving through the mid
and upper 90s with surface dew points in the 70s. This is
oppressive situation for this part of the CONUS.

Specifically as of 15Z, webcams have shown the sea breeze
developing and entering shoreline areas during the last half
hour in the Old Orchard Beach area. Although cooling is
occurring at area beaches, the inland penetration of the sea
breeze will be limited, so communities just a few miles inland
will continue with the hot, hazy and humid conditions.

Otherwise, at 15Z...
Portland ME 90 degrees with a dew point of 75 (sea breeze has
just kicked in)
Sanford ME 91 degrees with a dew point of 76
Fryeburg ME 92 with a dew point 75
Rockester NH 93 with a dew point of 75

These temperatures and dew points already place many areas
quickly closing in on Excessive Heat Warning criteria.

The only item that has a chance of tempering the heating will
be debris cloudiness in western New England stemming from
convection which is tracking east. However, this cloud cover
will likely arrive too late before the Warning Area exceeds the
apparent temperature thresholds during the midday and afternoon
hours today. Outside the warning area, Heat Advisories will
remain in place.

The next threat will be for convection this afternoon. While the
HRRR remains uneventful for today, the latest NamNest solution
allows for convection to begin to form by 18Z over the higher
terrain before spreading south and  east. We will continue with
gusty winds in the forecast in storms for this afternoon and
evening and SPC has placed our forecast area in a Marginal Risk
for severe weather. A high CAPE and low shear environment will
continue with storms producing locally strong, gusty winds.

Prev Disc - - 645 AM Update... Minor changes to reflect latest
observational trends. Still expecting hazy, hot, and humid
conditions today with perhaps a few interior spots approaching
the 100 degree mark.

Previously...
Nighttime microphysics satellite imagery early this morning
shows some passing cirrus overhead along with some valley and
coastal marine fog that is beginning to develop. Current
temperatures are into the 60s and 70s and they will likely drop
another degree or so prior to sunrise. It will otherwise
continue to be a warm and humid morning.

Surface high pressure will remain anchored east of New England
today, allowing for southwesterly flow over our region. Warm
temperatures aloft combined with afternoon mixing will result in
high temperatures into the middle 90s across most interior
locations with 70s/80s along the coast and in the mtns. Surface
dew points will be into the upper 60s and lower 70s, which will
push heat indices into the middle 90s across areas covered under
the heat advisory with readings up to around 105F within the
excessive heat warning.

Latest CAMS continue to show the potential for a few afternoon
and evening thunderstorms to develop as a s/wv crosses southern
Quebec. Forecast soundings indicate a high CAPE and low shear
environment with bulk shear of only around 15 kts. Despite this,
inverted-v soundings combined with precip loading and high DCAPE
introduces a locally strong wind threat within any stronger
storms. Coverage is expected to be spotty though due to fairly
weak forcing and a mid-level CAP. The Storm Prediction Center
has placed much of our area under a MRGL risk for severe storms
this afternoon.

Any remaining showers and thunderstorms will diminish this
evening, leaving behind another warm and muggy night. Lows will
primarily be into the 70s. Fog may develop overnight, especially
across the valleys.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Clouds will increase from north to south on Thursday ahead of a
sfc cold front that will cross during the afternoon and evening
hours. Ahead of this front, it will be another hot and humid
day with high temperatures into the lower to middle 90s away
from the coast with 80s in the mtns and the coast. Heat indices
will climb up to around 100 degrees for a few hours, which will
likely necessitate additional heat advisories.

This strong sfc heating will allow for steep low-level lapse
rates with MLCAPE increasing to around 2000 J/KG. This combined
with 20-30 kts of 0-6km bulk shear and PWATs nearing 2.00" once
again introduces the potential for scattered strong to severe
thunderstorms. The primary hazard will be locally damaging winds
with precip loading but the added shear could also allow for
some hail as well. Coverage is likely to be greater than today
due to the additional forcing from the passing cold front. The
storm Prediction Center has placed much of the CWA into a MRGL
risk with a SLGT risk in southwestern NH.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
The cold front will clear the coast Thursday night, bringing an
end to the showers and thunderstorms. Lows will range from
around 60 across the north to the 70s south.

It will be still be warm on Friday, especially over southern
NH, but will be much more manageable than the temps today-
Thursday with the post-frontal air coming in. Highs are forecast
to be in the mid- upper 80s for southern NH and the low-mid 80s
for the rest of the area. There will also be a tight moisture
gradient with the higher moisture across NH and this area has
30-50% chances for showers while chances decrease to the north
and east.

Although still running above normal for this time of year,
temperatures will follow a cooling trend over the upcoming
weekend as heights lower, flow aloft becomes more zonal, and
more in the way of clouds are expected. In addition to this,
dewpoints will also come down into the 50s for most of the area
on Saturday (except lower 60s in southern NH) before creeping
back upward into the 60s on Sunday. Highs on Saturday are
forecast to be in the upper 70s to lower 80s, and these may
increase by another couple of degrees by Sunday as southerly
flow starts increasing ahead of a cold front. This is certainly
good news after the hot weather this week. There is another
chance for shower late Saturday into Saturday night as energy
aloft moves overhead, but due to confidence have stuck with NBM
of 40-50% at this time.

A better chance for more widespread precip and possibly a few
storms arrives late Sunday and into Monday as a more potent
upper trough pushes a cold front through New England. Assuming
the front pushes through as advertised (decent agreement in the
models this far), we should see drying conditions by next
Tuesday or so.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Short Term...Patchy FG and low ceilings will continue to result
in the potential for IFR to LIFR restrictions through around
12Z, mainly at KLEB. Otherwise, VFR conditions will prevail
today with southwesterly winds at 10-15 kts. Scattered TSRA are
possible this afternoon and any storm may contain locally
strong winds and restrictions. Patchy FG will once again be
possible tonight, which will result in IFR to LIFR restrictions
through early Thursday morning. VFR conditions early Thursday
will be followed by a greater chance for scattered TSRA in the
afternoon and evening. Some LLWS is possible late tonight into
early Thursday.

Long Term...For Friday and Saturday, precip chances look lower
overall, but the better chances will be across the NH terminals.
A cold front approaches Sunday into Monday with chances for
widespread precip and restrictions.

&&

.MARINE...
Short Term...Southwesterly winds will prevail today through
Thursday with gusts between 15-20 kts. A few gusts to around 25
kts are possible across the outer waters. Seas will be at 3-4 ft
and marine fog will be possible, especially at night.

Long Term...Broad high pressure remains over the waters Friday
and Saturday before southerly flow potentially exceeds SCA
levels Sunday into Monday as a cold front approaches.

&&

.CLIMATE...
RECORD HIGHS FOR JUNE 19: Concord-98 in 1995; Augusta-98 in 1995
Portland-94 in 1995

RECORD WARM LOWS FOR JUNE 19: Concord-69 in 2017,1876;
Augusta-72 in 1995; Portland: 72 in 1995

RECORD HIGHS FOR JUNE 20: Concord-98, 1993 Augusta-95, 1953 Portland-
93, 2020

RECORD WARM LOWS FOR June 20: Concord-73 in 1931; Augusta-67 in
1974; Portland-69 in 2020

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory until 8 PM EDT this evening for MEZ007>009-
     022>028.
     Excessive Heat Warning until 8 PM EDT this evening for
     MEZ012>014-018>021-033.
NH...Heat Advisory until 8 PM EDT this evening for NHZ001>003-005-
     007-011-014.
     Excessive Heat Warning until 8 PM EDT this evening for NHZ004-
     006-008>010-012-013-015.
MARINE...None.

&&

$$

Cannon/Combs