775
FXUS61 KGYX 180728
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
328 AM EDT Tue Jun 18 2024

.SYNOPSIS...
High pressure will settle east of New England through much of
this week, setting the stage for hot and humid conditions.
Record high temperatures and potentially dangerous heat index
values are likely. A weak cold front will slowly cross through
the region on Thursday and Friday with an increasing chance for
scattered thunderstorms and cooler temperatures by this
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Nighttime microphysics satellite imagery early this morning
shows high level clouds continuing to stream from north to south
over western ME with a decaying MCS moving eastward over
Quebec. These clouds are riding along an h5 ridge axis that
continues to build over New England. Current temperatures are
primarily into the upper 50s and middle 60s but a few urban
locations remain in the upper 60s and even lower 70s.
Temperatures will remain nearly steady through daybreak.

Surface high pressure will build to our east today as the h5
ridge axis moves overhead, allowing for strong WAA aloft. This
will help to boost 925 mb temperatures up to around +25C today.
This places highs into the upper 80s to lower 90s across
interior western ME with lower to middle 90s in much of NH. The
exception will be at the coast as increasing southerly flow will
keep temperatures into the cool 60s and 70s. The latest HREF
does suggest high-level clouds could stick around for a good
portion of the day over western ME, which would keep highs a
few degrees cooler. Dew points during peak heating will be into
the 60s to near 70 degrees, which will help to push heat indices
up to around 95 degrees for a few hours. The existing heat
advisory remains in effect for the interior south of the
mountains.

Latest CAMS continue to indicate the potential for a few late
afternoon and early evening thunderstorms over the interior.
While coverage is expected to be spotty, any thunderstorm will
be capable of producing locally strong gusty winds given
inverted-v soundings. Bulk shear will be light (~15 kts) and
this combined with the warm airmass should prevent a hail
threat.

Any lingering thunderstorms will end by around 10pm this evening
with partly cloudy skies prevailing. It will be a warm and muggy
night with lows into the upper 60s but urban centers will likely
remain in the 70s.

&&

.SHORT TERM /WEDNESDAY/...
High pressure and upper level ridging will remain in control on
Wednesday, resulting in another hot and humid day. Skies will be
partly cloudy with the potential for additional afternoon
showers and thunderstorms. Any thunderstorm will once again be
capable of producing locally gusty winds along with briefly
heavy rainfall.

High temperatures will be similar to those of today, with
readings into the lower to middle 90s across the interior. A few
spots could reach the upper 90s provided adequate sunshine and a
lack of rain. One notable change will be that most coastal
locations will reach the middle to upper 80s as sfc winds become
more southwesterly. The exception will be the mid-coast which
will remain on the cooler side. Afternoon dew points into the
upper 60s/low 70s will help to push heat indices into the 95-100
degree range across the interior with some readings nearing 105.
Along the coast, heat indices could approach 95 except for the
mid-coast. The existing excessive heat watch remains in effect
and additional heat headlines can be expected.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...

Wednesday nighttime lows will be on the warm side again, mainly
in the lower 70s. This will cause cumulative heat stress.

The peak of the heat will arrive on Thursday as a strong upper level
ridge remains centered near Long Island New York. After a warm night
with patchy fog, temperatures will soar once again under a light
westerly flow aloft. Widespread mid to upper 90s can be expected
with a few communities, mainly in southern New Hampshire exceeding
100 degrees. Relatively high dew point values will allow for
apparent temperatures to climb into the 100 to 105 degree range,
very near to the Excessive Heat Thresholds. Scattered showers and
thunderstorms will once again rotate around the periphery of the
ridge and mainly be centered over northern areas.

A weak front will then be draped over the region on Friday. It
will be about 10 degrees cooler than on Thursday, mainly due to
the increased cloud cover and the scattered showers and storms
across the forecast area. Slightly lower dew points can be
expected which will be an ongoing trend into the weekend. A
nearly stationary front will allow for scattered showers and
thunderstorms throughout the weekend.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions will prevail today through at least
Wednesday. Patchy FG is possible at times at night, which could
result in localized restrictions. There is also the potential
for a scattered TSRA from roughly 18Z-02Z today and again on
Wednesday. The greatest potential for this is at KHIE, KLEB, and
KAUG. Light and variable winds early today will become southerly
at KPSM, KPWM, and KRKD behind a sea breeze. Winds will become
southwesterly on Wednesday. No LLWS is expected outside of any
TSRA.

Long Term...Additional scattered showers and thunderstorms are
likely with a cold frontal passage by late Thursday into Friday
with possible restrictions. Areas of IFR conditions are
possible as well during the night time period with patchy valley
fog and associated with more scattered showers and
thunderstorms throughout the weekend.


&&

.MARINE...
Short Term...A few southerly wind gusts across the outer waters
could approach 25 kts today and again on Wednesday out of the
southwest but winds will largely remain below SCA thresholds.
Seas will be at 2-4 ft.

Long Term...Winds and seas will primarily be out of the south-
southwest during the extended portion of the forecast and below
SCA thresholds. Highest wind gusts likely will be during the
afternoon hours as the sea breeze attempts to form. The winds
will briefly become westerly on Friday.

&&

.CLIMATE...
Record breaking high temperatures and warm overnight low
temperatures are likely today through Friday.

Here are the records...

RECORD HIGHS FOR June 18: Concord-98 in 1994; Augusta-93 in
1994; Portland-91 in 2018

RECORD WARM LOWS FOR JUNE 18: Concord-71 in 1994; Augusta-67 in
1995; Portland: 66 in 1994

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 from noon today to 8 PM EDT this evening for
     MEZ012>014-018>021-033.
     Excessive Heat Watch from Wednesday afternoon through Thursday
     evening for MEZ012-018>020-033.
NH...Heat Advisory from noon today to 8 PM EDT this evening for
     NHZ004>013-015.
     Excessive Heat Watch from Wednesday afternoon through Thursday
     evening for NHZ006-008>010-012-013-015.
MARINE...None.

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Tubbs
LONG TERM...Cannon
CLIMATE...Tubbs