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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 202302
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
702 PM EDT Sun Jun 20 2021

.SYNOPSIS...
Active weather is expected across the North Country
Monday afternoon and evening as the potential for strong to severe
thunderstorms are possible. Storms are expected to form over
northern New York in the afternoon and then move east into Vermont
during the late afternoon and evening hours. Gusty winds, hail,
heavy rain, and frequent lightning will be the main threats with any
of the thunderstorms. Above normal temperatures are expected on
Monday with highs in the mid 80s to lower 90s. Cooler and drier
weather is expected by the middle part of the week.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
-- Changed Discussion --
As of 651 PM EDT Sunday...Did make some adjustments to pops for
late tonight into Monday morning, based on expected warm frnt
and associated precip lifting from southwest to northeast acrs
our fa. Have mention chc across much of VT and northern NY with
low likely for the SLV btwn 10z-15z on Monday. Guidance
continues to show ribbon of deeper moisture, favorable synoptic
scale lift from 5h vort, and developing instability surging
north on southwest flow to support idea of showers with a few
embedded rumbles of thunder. We should experience a break in
precip with some clearing btwn 15z-20z on Monday, which wl
quickly help to destabilize atmosphere for next round of strong
to severe storms to develop. Pre-storm environmental parameters
still look very favorable for convection with some
organized/rotating cells possible, given the combination of
shear/instability and llvl convergence provided by pre-frontal
trof. General consensus is for convection to fire btwn 17z-19z
acrs the SLV and expand in areal coverage/intensity thru the
aftn/evening hours, with axis of best instability located over
the CPV around 21z. Should be an active and interesting day.

Previous discussion below:
Dry weather is expected for the first half of the night. As the
flow aloft turns to the southwest later tonight some showers
and isolated storms are expected during the early morning hours,
especially across northern New York. Lows will generally be in
the 60s with upper 50s in the mountains.

Forecast remains on track for Monday with the potential for strong
to severe thunderstorms during the afternoon and evening hours.
Clouds and some showers should be lifting north of the area just
before midday and sunshine should develop over most of the area.
Thermal axis at 850 millibars will be right over the area and thus
expecting highs in the mid 80s to lower 90s. Increasing south to
southwest flow in the low levels will bring dew points into the 60s
and this should result in an increasing unstable atmosphere
during the afternoon hours. Looking at CAPE values in the 1500
to 2000 J/kg range ahead of a pre-frontal trough moving into the
Saint Lawrence Valley of New York by mid-afternoon. This
feature plus differential heating along any areas just to the
east of more persistent cloud cover should also help to focus
convective development. At this time storms should form out near
Saint Lawrence and Franklin counties in New York in the 2-4 pm
time period. Favorable deep layer shear will be over this area
with strongest shear lagging back to the west. This should allow
for storms to become organized and have the potential to become
strong or severe. Strong wind gusts, hail, heavy downpours, and
frequent lightning will be the main threats as the storms move
across the northern Adirondacks during the mid-afternoon hours
and across the Champlain Valley and points east during the late
afternoon and evening hours. Threat of organized convection
should come to an end overnight Monday night, but showers should
still be rather prevalent.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 327 PM EDT Sunday...Have trended drier with the forecast
for Tuesday as models are now indicating the front almost
clearing our area by 12z. Have just a mention for chance of
showers Tuesday morning, then the pops drop off for the
afternoon and we`ll see increasing sunshine. High temperatures
on Tuesday will reach the 60s to around 70, warmest in the
Champlain valley. A large ridge of surface high pressure will
then build into the region and remain through much of the week.
Upper level trough will approach the region Tuesday night, but
will mainly just see a slight increase in clouds with this
feature. Minimum temperatures will be in the 40s to around 50.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 327 PM EDT Sunday...Dry weather is forecast from
Wednesday through Friday as large ridge of surface high pressure
settles over the region, but begins to slide eastward on
Thursday. Our weather will turn more active on Saturday and
Sunday as a low pressure system tracks from the Ohio river
valley northeastward towards our region. Warm front and
shortwave energy lifts across our area Saturday and spreads
showers across the region. Surface low, upper level trough and
another upper level shortwave moves across the area on Sunday
bringing more showers to the region.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
Through 00Z Tuesday...VFR conditions wl prevail for the next 6
to 12 hours acrs all our taf sites with south/southwest winds of
5 to 10 knots. Expect scattered showers with embedded rumbles of
thunder possible btwn 09z-15z on Monday with brief mvfr cigs/vis
possible in the heavier convection. Additional strong to severe
thunderstorms develop btwn 17z-19z acrs the SLV on Monday and
move thru northern NY/western VT thru 00z Tues. Expect localized
strong/gusty erratic winds, brief heavy down pours, and frequent
lighting, with areas of turbulence and shear likely in and
around any convection. Winds increase from the south/southwest
at 15 to 25 knots on Monday.

Outlook...

Monday Night: VFR. Likely SHRA, Chance TSRA.
Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
-- End Changed Discussion --

&&

.MARINE...
Active weather is expected across Lake Champlain Monday and
Monday night. First winds will be from the south at 15 to 25
knots, especially during the afternoon hours. Choppy conditions
are expected, especially over the northern portions of the lake.
From mid-afternoon through the evening hours showers and
thunderstorms will move from west to east across the lake and
any storms will have the potential to produce strong wind gusts,
hail, heavy downpours, and frequent lightning.

&&

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

&&

$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/Taber
SHORT TERM...Neiles
LONG TERM...Neiles
AVIATION...Taber
MARINE...Evenson