-- Discussion containing changed information from previous version are highlighted. --
365
FXUS61 KGYX 290308
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1108 PM EDT Fri Jun 28 2024

.SYNOPSIS...
High pressure over the region tonight will push south and east
of New England on Saturday with a warm front lifting through the
area by late in the day. This will result in increasing chances
for showers by late Saturday with rain and embedded
thunderstorms Saturday night. Rain will taper off early Sunday
ahead of an approaching cold front with the potential for
additional showers and thunderstorms Sunday afternoon. High
pressure arrives early next week bringing a period of quiet
weather and seasonable temperatures.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
1100 PM Update... Minor changes to reflect latest observational
trends. Cirrus will continue to increase overnight with lows
into the 40s and 50s.

Previously...
715 PM Update... A rather pleasant Summer evening continues
across the region with mainly clear skies and warm temperatures.
Latest satellite imagery indicates the cirrus shield is still
rather far away in VT and Quebec and therefore given the low dew
points and weakening winds, temperatures will likely fall
rather abruptly over the next few hours. Will continue to
monitor these cloud trends and the associated impacts to
overnight lows.

Previously...
High Impact Weather Potential: None.

Pattern: The shortwave trough responsible for ushering in a much
cooler and drier airmass is now moving east of the region as seen on
early afternoon GOES 16 water vapor imagery.  Surface high pressure
now over southern New England will slowly sag south and east
offshore with the flow aloft slowly backing ahead of the next
shortwave arriving into the Great Lakes region. Overall this spells
a quiet night weather-wise with the focus of the forecast being on
cloud cover and overnight lows.

Through this evening: Temperatures should quickly drop in the dry
airmass with some high clouds overhead.  8pm temperatures will dip
below 60 in the mountains while remaining in the 60s to the south.

Tonight: High pressure settles south and east of the area overnight
as warm advection pattern sets up in the return flow as the H8 ridge
axis passes to our east.  The result will be top-down saturation
with mid and upper level cloudiness increasing.  The result will be
somewhat warmer temperatures with lows generally in the 50s across
the area under light winds.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
High Impact Weather Potential: Locally heavy rain possible Saturday
night.

Pattern: Low pressure north of the western Great Lakes early
Saturday will move north and east through the short term forecast
period remaining well north of New England through Saturday night.

Saturday: Southwesterly flow continues to strengthen during the day
as surface warm front approaches the region from the southwest. Top
down saturation will continue through the morning with ample dry air
remaining below H85. By late in the day...there is good short term
mesoscale ensemble agreement that some showers will work into the
northern zones given continued isentropic ascent in the area of
deepest moisture.  No convection expected with no instability to
work with through evening.  Despite warm advection...the southerly
marine-influenced flow along with increasing clouds will not yield
any significant warming of surface temperatures with highs again
around 70 in the mountains and in the lower 70s to the south. Some
of the mesoscale guidance is hinting at the midcoast through the
Capitol region also struggling to reach 70.

Saturday Night: Robust...broad LLJ at H8 crosses the New England
Saturday night with MUCAPE plume overspreading the region as the
warm front finally drives through northern New England. This occurs
in the presence of significant deep moisture...with PWATs around 2"
pushing above the 30 year climatology values.  Deep forcing is a bit
more questionable.  There is a weak mid level vort max in the
presence of weak height falls with modest right entrance region jet
forcing moving overhead overnight in advance of the surface cold
front. Thus...despite increasing warm cloud depths in the presence
of significant moisture...the overall ensemble signals for heavy
rainfall have decreased over the past 24 hours...favoring areas
across northern New York. A consensus forecast approach favors basin-
wide average QPF of 0.5 to 1"...which also lines up well with the
most recent runs of the HRRR and NAM Nest.  Certainly some potential
for locally heavy downpours given the environment focused over the
mountains matching well with the day 2 marginal excessive rainfall
outlook from WPC.  Temperatures will be much warmer than the night
previous as the warm front lifts through the region with southern NH
likely to remain in the upper 60s...with upper 60s to lower 60s
elsewhere across northern New Hampshire and western Maine.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
I suppose its safe to say we have worked our way into a typical
summer pattern as 500 MB ridging take residence S of the Mason-
Dixon line, and troughs in north-shifted jet stream. Are
generally flatter and more mobile. We start off a little on the
cool side but the trend will be fore warming to near and above
normal 850 MB temps by mid to late week. The tricky part is what
becomes of the closed low that shifts to our SE late in the
week and whether it acts as a block to allow S_SW flow to
settle, making for another round of hot/humid weather or keep
flow more zonal which will lead to more typical summer wx. As
for chances of shra/tsra, beyond Sunday, we do see some of wave
move to our N around Wed-Thu.

On Sunday will see a cold front, trailing fro low pressure
moving just N of the St. Lawrence valley cross the CWA. 12Z Euro
shows a generally less dynamic system aloft associated with the
front, but there should be a surge in low level moisture and
instability ahead of it Sunday morning, so cannot rule out
SHRA/TSRA, although less certainty about the potential for
severe that day. Behind the front, we do a surge of cooler air,
and very dry air at least for Mon-Tue, with highs a little below
normal on Monday, but nice otherwise, and warming back to near
normal on Tuesday. Wed will be warmer still with a bit of
increase in humidity, but should stay dry most of the day.
Wednesday night and Thursday are the next chance of precip, but
theres still a lot of uncertainty with this weaker system.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Short Term...

Summary: High pressure builds south and east of the region tonight
with southerly winds strengthening on Saturday as clouds slowly
lower. A warm front crosses Saturday evening with deteriorating
conditions in rain and embedded thunderstorms.

Restrictions: VFR conditions expected to dominate through the day
Saturday.  Showers with embedded thunderstorms arrive Saturday night
with conditions deteriorating to MVFR/IFR CIGS and MVFR VSBYS.

Winds: Northwest winds 10g18kts will diminish through this evening
before going calm/light-variable for the overnight.  For the day on
Saturday winds turns southerly and strengthen to 10g18kts for the
day.  Winds remain southerly around 10kts for Saturday night.

LLWS: LLWS is not expected through Saturday.  Saturday night...a
strengthening low level jet will result in LLWS throughout the
region.

Lightning: No lightning is expected through Saturday.  Showers with
embedded thunderstorms are expected across the terminals Saturday
night.

Long Term...Mainly VFR Sun-Wed, although some restrictions
possible in SHRA/TSRA Sunday. Also valley fog possible at
KHIE/KLEB Sun and Mon night.

&&

.MARINE...
Short Term...Quiet conditions over the waters through early
Saturday as high pressure crests over the waters. Southerly
winds strengthen Saturday afternoon and Saturday night with SCAs
likely necessary for this period.

Long Term...SW flow ahead of cold front will allow for SCA conds
on Sunday, but these4 drop off Sun night, and stay below SCA
levels through mid-week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from noon Saturday to 4 PM EDT Sunday for
     ANZ150>154.

&&

$$

NEAR TERM...Tubbs