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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KGYX 012011
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
411 PM EDT Fri Jul 1 2022

.SYNOPSIS...
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A very warm night is expected with showers and embedded
thunderstorms increasing in coverage well after midnight ahead
of an advancing cold front. This activity will continue through
early Saturday afternoon before the cold front passes south of
the area and much drier and cooler air returns for Saturday
night. Seasonably warm temperatures will continue under high
pressure for Sunday and Independence Day before another
disturbance brings our next chance for showers and thunderstorms
late Monday night and Tuesday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...

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High Impact Weather Potential: Low chance for an isolated strong
storm well after midnight with local downpours/ponding of water
possible.

Pattern: Early afternoon water vapor imagery shows a pinwheeling
upper low over Hudson Bay with a plume of moisture on it/s eastern
flank moving into the northeastern United States.  A cold front is
moving east in association with this moisture plume and is firing
convection over the eastern Great Lakes.  More convection is firing
along a pre frontal trough south and west of our area into the Mid
Atlantic. Tonight...as the cold front approaches...our focus will be
on the potential for overnight convention as a very warm and humid
airmass moves overhead.

Through this evening: A mix of sun and clouds with very warm
temperatures attm will continue through the evening. Visible
satellite imagery and area webcams showing convective towers
having a tough time standing up against strong deep layer shear
given modest instability with surface dewpoints still largely in
the 50s. While a shower or storm could clip the area along the
international border late this afternoon and into the
evening...expect the area to remain mostly dry with

Tonight: While the first half of the night is looking dry given
the short term ensemble consensus...there is an increasing
confidence that a convectively-induced vort lobe associated with
evening convection over western NY and PA will move into the
region well after midnight ahead of the surface cold front.
There remains substantial /500-1000 J/kg/ elevated instability
as this activity pushes through the region and thus expect
showers and embedded thunderstorms as it arrives. Can/t
completely rule out an isolated strong to severe storm as this
occurs given brisk mid level flow though MUCAPES will be falling
as the convection arrives. PWATs will near 1.5" with warm cloud
depths moving toward 12kft. However..convective activity should
have a pretty robust forward motion and will likely be in a
decaying state given the time of night so outside of localized
downpours/ponding...do not see a significant hydro threat
overnight.

The precipitation will lower temps some...but do expect a
rather warm night as temperatures south and east of a AFN-CON-
LEW-AUG line will likely struggle to fall below 70...and will
likely remain in the mid 70s for much of the night.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...

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High Impact Weather Potential: Isolated severe thunderstorm
possible over far southern NH and southwest ME through mid
afternoon Saturday.

Pattern:  Shortwave trough and associated cold front will be
entering the forecast area as this period opens daybreak Saturday.
This feature will cross the region through the morning and early
afternoon providing the impetus for shower and thunderstorm activity
which will be our forecast focus through the short term.  By late in
the day...drier air will filter in from the north and west bringing
clearing skies and quieter conditions that will persist through
Saturday night.

Saturday: Expect scattered showers and thunderstorms at daybreak
with the surface cold front just entering the area from the west.
Our severe convective potential will be tied to how much instability
we can regain ahead of the cold front as it looks to reach the coast
by early afternoon.  There will be ample deep shear /40-50kt at H5/
to support severe convection.  Clearly the best chance for
instability to rebound sufficiently to support new convective
activity will be over southern NH and far southwestern ME.  CAMs
support a glancing blow along the NH/MA border with more robust
activity to the south and thus the SPC Marginal Risk area looks
good.  Will continue to highlight this potential in the afternoon
Hazardous Weather Outlook...but feel that it is a small window in
space and time /11am-3pm/ where severe convection will be possible.
While temperatures will be cooler than today...dewpoints will be
much higher.  Would expect parts of SE NH and SW ME to push into the
mid 80s which may allow heat indices to near 90 for a time before
drier air returns in the afternoon.

Saturday Night:  Robust dry advection will push PWATs to 0.5"
overnight as surface dewpoints fall back into the 50s and even upper
40s. Temperatures aloft will fall back towards +10C at H8 under
modest westerly winds.  Thus clear/mostly clear skies are expected
with lows falling back into the 50s for the mountains and
foothills...with 60s to the south and east.
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&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
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Overview... New England sits inbetween an upper level low over
Newfoundland and a broad, low amplitude ridge over the central US
through most of the extended period.  This brings several shortwaves
overhead in a broadly positive area of vorticity creating unsettled
conditions for the second half of the week.  One stronger shortwave
brings an area of low pressure on Tuesday with a chance of rain over
most areas of Maine and NH.

Details...

Independence Day: High pressure builds in behind the cold front
Sunday into Monday bringing drier air for the later part of the
holiday weekend. Mixing will set in both afternoons with a
comfortable breeze and highs in the low 70s up north and low 80s
in the south. Clouds and showers start moving in Monday evening
from the northwest as low pressure approaches for Tuesday.

Tuesday Onward: Low pressure starts tracking east across the
northern plains at the start of the week, slipping into New England
for Tuesday, bringing showers and some possible thunderstorms
throughout the day as it passes.  The structure of this low is
rather unorganized and has been difficult for the models to capture,
although a more consistent signal is finally starting to be
resolved.  Showers will fill in across the CWA over the morning,
moving offshore by Wednesday.  A broad area of positive vorticity
sits overhead for the remainder of the week with unsettled
conditions lingering behind the low.  Several chances of showers
swing through Thursday and Saturday under these unsettled
conditions.  No significant impacts are expected at this time.
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&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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Short Term...

Summary: Clouds will thicken and lower overnight as showers and
embedded thunderstorms arrive ahead of a cold front.  This cold
front will push through the region on Saturday with showers and
thunderstorms coming to an end and improving conditions arriving
Saturday night.

Restrictions: VFR conditions persist through 08Z Saturday.
Beyond this...a period of MVFR CIGS and possible MVFR VSBYS is
expected as an area of showers and embedded thunderstorms moves
through the area. Improvement to VFR is expected during the mid
to late morning Saturday with VFR Saturday afternoon and
Saturday night.

Winds: Southwest winds 12g20kts continue into this evening before
diminishing to less than 10kts overnight.  Southwest winds will
gradually veer westerly during the day on Saturday as the cold front
moves through...increasing to 10g18kts.  Westerly winds diminish to
less than 5kts Saturday night.

LLWS: 1.5kft winds increase to 30-35kts tonight along the
coast...with LLWS possible. Greatest threat is PWM-RKD and have
included it in this TAF package. Will have to watch for possible
need at PSM-AUG. Shear is weaker to the north and west of this.

Lightning: Isolated/scattered thunderstorm activity is expected
after midnight tonight with activity south of the mountains
persisting into the morning on Saturday.  A few strong to possibly
severe storms are possible late Saturday morning through mid
Saturday afternoon CON-MHT-PSM.

Long Term...VFR conditions prevail through Monday under high
pressure until ceilings thicken and lower Monday night into Tuesday
as low pressure brings SHRA to most terminals Tuesday.  Conditions
should return to VFR on Wednesday.  Unsettled conditions could bring
a few chances of lower ceilings and MVFR through the end of the week.
-- End Changed Discussion --

&&

.MARINE...
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Short Term...SCAs for winds and seas will continue into
Saturday given brisk southwesterly flow ahead of an approaching
cold front. This cold front will pass through the waters
Saturday afternoon with winds and waves subsiding into Saturday
night.

Long Term...Calm winds and seas are expected through next week with a
chance of showers on Tuesday. Seas will remain around 2-3 ft.
-- End Changed Discussion --

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 11 AM EDT Saturday for ANZ150>154.

&&

$$
SYNOPSIS...Arnott
NEAR TERM...Arnott
SHORT TERM...Arnott
LONG TERM...Thunberg
AVIATION...Arnott/Thunberg
MARINE...Arnott/Thunberg