-- Discussion containing changed information from previous version are highlighted. --
806
FXUS61 KGYX 061440
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1040 AM EDT Thu Jun 6 2024

.SYNOPSIS...
A warm front lifts into southern New England bringing chances
for showers this morning near the NH/MA border. Another front
crosses the area this evening for more widespread showers and
perhaps a few thunderstorms. An upper low slowly approaches
from the west tonight bringing more scattered showers Friday.
The upper low lingers over New England into early next week
keeping chances of showers in the forecast most days.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
1040 AM Update...Inherited forecast remains on track so changes
were minor and mostly to smooth trends based on latest obs.
Ample low level dry air as seen on the 12Z GYX sounding has
staved off the line of showers approaching western New Hampshire
early this morning, however with moisture now quickly
increasing as a warm front inches nearer, will keep low chance
PoPs for the remainder of the morning in southern and western
New Hampshire. While the bulk of the convection remains to our
south some is breaking off and moving north, this would be our
best chance to see a heavier shower or stronger thunderstorm
later this morning or early this afternoon in southern New
Hampshire and will be watched closely. Otherwise, the more
widespread showers associated with a cold front are still out in
western New York and won`t arrive until this evening.

635 AM Update...Have trimmed back PoPs across portions of NH
this morning. Recent runs of hi res guidance and radar trends
show areas of rain with embedded thunder will now track farther
south closer to the southern New England coast.

Previously...

Mid level ridge axis to the west of New England breaks down
today as a positively tilted trough/upper low treks east over
the Great Lakes region. A warm front responsible for convection
over the Mid Atlantic yesterday will lift into SW New England
this morning while a mid level perturbation tracks along the
southern New England coastline. Members of the 00Z HREF are in
good agreement that the warm front fails to lift farther north
than the Mass Pike. These model solutions keep instability as
well as a batch of rain with embedded thunder south of the NH/MA
border resulting in a downward trend in the QPF forecast for
today. This has also reduced the risk for isolated flooding. All
in all, there may be little in the way of rainfall across the
region for the better part of the day until a front and better
forcing arrives later this evening. It will be mostly cloudy
with low ceilings and fog may be persistent near the coast with
moist onshore flow. Highs will range from the upper 60s along
the coast to the mid 70s across northern and western zones.

Better forcing for ascent will arrive this evening as the upper
low nears and a front presses into Upstate NY and Vermont.
Instability will build ahead of this front while the axis of
best instability remains to the west of the forecast area. CAMs
indicate broken lines of thunderstorms will cross the Hudson
Valley this afternoon reaching the Green Mountains around 7 pm.
Thereafter, these storms look to weaken as they moving into NH.
However, some CAM solutions show a triple point tracking along
NH/MA with enough instability and shear for strong storms into
Cheshire County. SPC has issued a Marginal Risk for severe
storms just to the west of the CT Valley and subtle shifts in
the convective parameter space could lead to an expansion into
SW NH. Will also have to watch for the potential for heavy rain
as PWATs will be near 1.75 inches with warm cloud depths greater
than 12kft, although storm motion will be swift. The front will
continue to sweep across the region overnight with the
weakening line of thunderstorms crossing into Maine by Friday
morning. A well saturated boundary layer will also make patchy
fog likely tonight with lows in the upper 50s to low 60s.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
There will be slight drying trend early Friday behind the front
as winds briefly shift out of the WSW, particularly over NH.
Meanwhile, the approaching trough will attempt to spin up a
surface low in the Gulf of Maine that will likely maintain cool
and damp onshore flow along coastal Maine and into interior
central Maine. Modest height falls will lead to a few hundred
J/kg of CAPE to develop across the interior Friday afternoon
with CAMs develop showers and scattered thunderstorms across
the interior, particularly over VT into NH. The cool onshore
flow looks to limit instability near the coast and therefore
chances for showers here Friday afternoon and evening are lower.
Highs on Friday will range from the 60s across central Maine to
the upper 70s and low 80s across southern and western NH.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Overview: The 500 mb pattern continues to show a ridge blocking
the upper low over the Great Lakes through the weekend. The
block looks to break heading into next week, allowing the closed
low to move out of the region, however the pattern converts to
a parade of deep troughs swinging across the CONUS that will
continue our wetter stretch of weather.

Impacts:
*  No significant weather impacts expected

Details:
Surface low pressure continues to meander overhead Saturday as
a shortwave 500 mb trough also swings through. Would expect this
to be a wetter day with the added upper level forcing, but
again with not a great amount of synoptic forcing, would expect
storm mode to continue to be scattered, just more widespread,
convectively driven showers and maybe a thunderstorm. Highs and
lows will be similar to Friday, albeit a couple degrees cooler
as 850 temperatures are on a slight downward trend. The upper
low looks to be directly overhead on Sunday so, similar to
Saturday, there will be enough forcing for scattered showers and
a thunderstorm or two to develop in the afternoon.

The upper low departs overnight Sunday, but a well defined
trough will be hot on its heels for Monday. Depending on the
location of a cold front modeled to be in the area, showers
could be a lot more scattered to isolated on Monday, but with
the vorticity maxima rounding that trough being right overhead
we will have to watch trends in this time period closely as
changes in positions of frontal boundaries could make things
more interesting. The 500 mb pattern looks to become more zonal
for Tuesday, but again if we have a cold front near by as some
models suggest, scattered showers and an afternoon thunderstorm
or two remain in the table. As expected global models begin to
diverge greatly on timing of troughs going forward so for
Wednesday and beyond we will have to just continue to watch
trends. For now will be leaving in chances of showers as that
seems reasonable.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Short Term...Conditions will deteriorate through this morning as
cloud thicken and lower with IFR conditions likely for much of
the day from KCON to KAUG and points southward. SHRA will be
possible through this morning mainly at KMHT and KPSM. Another
round of showers moves into this evening with KHIE and KLEB
standing the best chance to see a TS. Low cigs and fog likely
bring widespread flight restrictions tonight. Some improvement
is likely Friday morning with most TAF sites seeing periods of
VFR by late morning, with the exception being KAUG and KRKD.

Long Term...Outside of scattered showers and an isolated
thunderstorm, or two, ceilings will be mainly VFR through
Monday. Winds also remain on the lighter side 5-10 kts with
gusts of 10- 15 kts.

&&

.MARINE...
Short Term...Winds and seas remain below SCA thresholds. Expect
marine fog and stratus to persist over the next 24 hours that
will reduce visibility with improving visibility Friday.

Long Term...Conditions hazardous to small craft are not
expected through Monday. Seas will generally be 3-4 ft with
winds 10-15 kts with gusts to 20kts. Winds will be shifting
southwesterly on Saturday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

UPDATE...Baron
NEAR/SHORT TERM...Schroeter
LONG TERM...Baron