984
FXUS61 KBTV 040242
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1042 PM EDT Mon Jun 3 2024

.SYNOPSIS...
Increasing moisture is expected. Isolated showers, coverage more
scattered over high terrain, will begin to develop with a few
rumbles of thunder. The weather pattern will begin to shift over the
later part of the week as an upper low approaches from the west.
This will bring cooler temperatures from 80s back to mid 70s and
lower 80s. The upper low will also bring more widespread rain
chances across the region.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1035 PM EDT Monday...Following a delightful early summer
day across North Country with low humidity and plentiful
sunshine, a quiet night of weather is on tap. With clear skies,
light winds and broad surface high pressure in place,
temperatures have fallen into the low to mid 60s, with the
exception of low 50s in colder hollows like SLK and around 70
for urban heat islands in the Champlain Valley like BTV. A
backdoor cool front associated with an upper low pressure system
off Nova Scotia has cleared the White Mountains, but appears
washed out across the Connecticut River Valley owing to the
strength of the subsidence inversion across our area. High
clouds associated with an approaching shortwave trough from the
Great Lakes should start overspreading the region from west to
east, but those have a higher probability of creating a vibrant
sunrise than stunting the radiational cooling. Overnight lows
are still on track to fall into the upper 40s to mid 50s, except
mid 40s in the typically colder hollows and upper 50s to low
60s in the immediate Champlain valley. Overall, forecast remains
in good shape.

PREVIOUS DISCUSSION...

Temperatures are running about 10 degrees above normal this
afternoon under very dry, subsident air beneath a broad upper
ridge. Outside some terrain driven cumulus, it`s mostly clear.
For tonight, dry conditions are expected, but radiational
cooling doesn`t appear as strong with slowly increasing
moisture. Cool hollows will likely still fall into the 40s, but
most locations should stay in the 50s with perhaps a few spot
readings of 60 in the Champlain Valley.

For tomorrow, 925 hPa temperatures are about a degree or two warmer,
and so the forecast is for max temperatures to creep just a bit
higher. BTV and MSS are forecast to reach 88 at present. Ensemble
forecasts are about 10 to 30 percent chance of reaching 90. So it`s
not out of the realm of possibility. In eastern Vermont, it appears
there could be a backdoor cold front that slides into the area,
which will be reinforced by a developing sea breeze, and that could
help keep temperatures somewhat cooler in far eastern Vermont. With
a bit more moisture on the ground, greater heating, and the presence
of a subtle boundary in eastern Vermont, there should be enough
forcing to break a capping inversion, at least across the mountain
ranges. Since there`s still plenty of dry air underneath the
upper ridge still in place with little to no shear present, only
garden variety showers are anticipated across the Adirondacks
and eastern Vermont. A rumble of thunder would be most likely in
the Dacks. Overnight, a subtle theta e ridge axis will shift
east in conjunction with the development of a weak surface
trough and tiny embedded upper trough. It`s not much, but it
appears to be enough with 300 to 500 J/kg of elevated CAPE that
high resolution guidance is developing hit-or-miss showers in
the Champlain Valley. The HREF paintball briefly shows several
members with this type of development. So have refined the
forecast to highlight some of those details with a 20 to 30 PoP
in and around the Champlain Valley overnight. Not anticipating
the activity will be strong enough for thunder at the moment.
Increasing south flow and additional moisture will result in a
humid conditions Tuesday night into early Wednesday with mid
50s to mid 60s.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
As of 300 PM EDT Monday...Wednesday will be another warm day
with highs reaching the mid to upper 80s. The humidity will also
be higher as dew points will be in the low 60s. Diurnal heating
will cause some instability to develop, but with minimal flow
aloft, it will be mostly terrain driven pulse-type thunderstorms.
Scattered showers and storms will likely develop in the
mountains during the early afternoon and may spread a bit into
the broad valleys later in the afternoon, but the coverage will
be more isolated there. Some guidance is suggesting up to 1500
J/KG of CAPE will be in place but with limited shear, there is
no severe threat with these storms. The showers will decrease in
coverage overnight without the diurnal heating but a cold front
will reach northern New York and cause some shower chances
there to increase there later in the night. With the increased
humidity and some lingering clouds, lows will only fall into the
60s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 300 PM EDT Monday...An unsettled pattern will be in place
during much of this period as a closed off low will be lingering for
several days. An initial cold front will come through Thursday into
Thursday night and bring some steadier rain. There is still high
model uncertainty with the exact timing of the front and how much
moisture it will be able to bring up into the area, but there is
good consensus that the front will be through by Friday morning.
However, there is no real consensus on QPF. Looking at a Euro, GEFS
and Canadian ensemble mixture, there is a roughly a 25 percent
chance that the region sees over an inch of rain while there is
around a 50 percent chance that the region sees under a half inch.
With model guidance trending toward slightly less precipitation,
conservatively went with around 0.25-0.50 inches for the region.
Areas that see heavier convective showers will see locally more. The
WPC put the region in a marginal risk ERO for flash flooding but
with dry antecedent conditions, that would likely require the higher
end synoptic-driven rain totals and training storms to occur in the
areas that see the most synoptic-driven rain. Therefore, flooding
looks unlikely at this time. After the front moves through, an upper
level low will be situated over the region and bring some shower
chances every day. There will be some embedded shortwaves that pivot
around it that will increase shower coverage during a few periods.
Temperatures will also drop back to or slightly below average with
the cooler airmass and increased clouds and showers. The shower
chances look to continue to the middle of next week at the moment.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...VFR conditions will continue at all
sites. Fair weather cumulus dissipate with sunset and mostly
clear skies are expected overnight tonight. Winds become light
and variable outside of southeast drainage flow at KRUT
overnight tonight. No fog is anticipated tonight. Winds will
become southeast to southwest after 13z around 5 knots. Mid-
level clouds of 5-8k ft increase towards the end of the TAF
period with the slight chance of showers after 18z Tuesday but
TAF conditions are expected to remain VFR.

Outlook...

Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Chance SHRA, Slight chance TSRA.
Wednesday Night: VFR. Chance SHRA, Slight chance TSRA.
Thursday: Mainly VFR, with local MVFR possible. Likely SHRA,
Slight chance TSRA.
Thursday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Friday: MVFR/IFR conditions possible. Chance SHRA, Slight chance
TSRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Haynes
NEAR TERM...Chai/Haynes
SHORT TERM...Myskowski
LONG TERM...Myskowski
AVIATION...Chai