-- Discussion containing changed information from previous version are highlighted. --
823
FXUS61 KBTV 131739
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
139 PM EDT Thu Jun 13 2024

.SYNOPSIS...
A warm and increasingly breezy day is expected ahead of a cold
front that will slide southeast Friday. Showers and possibly
thunderstorms will occur along this feature late tonight into
Friday. Localized stronger storms will be possible in far
southern Vermont early Friday afternoon. Cool and dry air
filters in for the weekend. Then by Monday, warm and moist air
will shift back into the region. Temperatures warming into the
upper 80s to mid 90s is expected by the middle of next week. In
conjunction with high dewpoints and warm overnight conditions,
heat impacts are likely next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
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As of 139 PM EDT Thursday...Current radar continues to show
showers along a pre-frontal trough are remaining northwest of
the region with just a 10% chance of something popping up in the
St. Lawrence Valley this afternoon. Clouds associated with this
though are moving in and sky cover should become scattered to
broken this afternoon which will limit heating across portions
of northern New York. Even so, highs will still be int he upper
70s to low 80s across the region this afternoon, with
south/southwest winds gusty up to 25 mph from the Champlain
Valley westward.

The better chances for rain will be from convection that
develops across Ontario Province that then slides eastwards late
this evening into the overnight hours. Showers and storms
should be in a broken line approaching the St. Lawrence Valley,
but loss of daytime heating and better dynamics lifting north of
the forecast area should see this convection on the decline.
Late Friday morning, increasing instability should allow
showers and storms to reintensify in conjunction with a vort max
ejecting northeastwards. Frontogenesis is expected to take
place and a cold front will strengthen as it moves across
southern Vermont Friday afternoon. This will be the window when
southern and central Vermont has the best chance for showers
and storms early Friday afternoon. With about 500-1000 J/kg of
CAPE and about 40-45 knots of 0-6km shear, there may be a small
window for strong to locally severe storms. However, better
dynamics are going to be tied to the intensifying front that
reaches peak intensity south of the region in Massachusetts and
far southern New Hampshire. The intensity of storms will be
conditional on clearing with the potential for lingering clouds
and rain from the prefrontal trough. And so SPC`s depiction of a
slight risk outlook outside our forecast area and a marginal
risk outlook at the southern fringe of Rutland and Windsor
Counties of Vermont appear reasonable. WPC has a marginal risk
for excessive rainfall covering almost the same region. Cooler
and drier northwest flow will lie behind the front, with most
topping out in the 70s to near 80, though possibly up to mid-80s
perhaps in the Connecticut River Valley.
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&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 316 AM EDT Thursday...Any lingering showers and thunderstorms
exit to the east in the evening, with north winds picking up through
the night as much colder and drier air mass advects into the region.
925mb temperatures fall from +13C to +7C by daybreak, leading to a
spectacular Saturday with abundant sunshine and dew points in the
30s and 40s. The only fly in the ointment would be the steady north
winds. Forecast soundings suggest mixing up to 850mb, which would
help mix down 20 to 25 mph gusts. With 850mb temperatures around
+5C, highs will only top out in the 60s to near 70. The cooler
apparent temperatures should be balanced out by the full sunshine on
tap and the high sun angle, given that we are only several days away
from summer solstice. Winds should diminish quickly after sunset.
With clear skies and light winds and a 1020mb surface high building
into the region, it should be a good radiational cooling night with
widespread lows in the 40s, except upper 30s for the sheltered
colder hollows and low 50s for the immediate Champlain Valley.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 316 AM EDT Thursday...Father`s Day looks to be quite similar to
Saturday, with lighter winds and daytime highs in the 70s. Dew
points look to be a tad higher, but still generally in the 40s. Once
again, with abundant sunshine and comfortable humidity, get outside
and enjoy the gorgeous conditions. And if you haven`t already done
so, you might want to set aside some time to put in the window AC as
summer heat and humidity will be making a return during the work
week. Ensemble guidance shows good agreement that a 590+ Dm upper
ridge will build across the southeast U.S., allowing for summer heat
and humidity to be advected into our region. Daytime highs could
approach or exceed 90 degrees each day from Monday into Wednesday
with little nighttime relief. Some locations, including Burlington,
could see the first heatwave of the season, defined as three
consecutive days of 90+ degree high temperatures. With dew points in
the 60s, heat index values could be in the mid to upper 90 range,
especially on Tuesday and Wednesday. Once again, at this time frame
in the forecast cycle, the fly in the ointment would be the
development of thunderstorms. Given plenty of daytime instability
and the potential for somewhere in the Northeast to be on the
periphery of a building heat dome, there is the potential for strong
to severe thunderstorms to develop and ride up and over a crest of
high pressure. Whether or not your location can muster three
straight days of 90+ highs, or is being issued with Heat Advisories,
the new experimental WPC heat risk is now highlighting the growing
potential for moderate to major (level 2 to 3 out of 4) risks of
heat-related impacts on Tuesday and Wednesday next week. It is not
out of the question that if thunderstorms do hold off, heat index
values could even push 100 degrees for part of the Champlain Valley
and the St Lawrence Valley from a combination of air temperatures in
the low to mid 90s and dew points in the mid 60s to around 70. This
would result in a low but non-zero chance of extreme risk (level 4
of 4) of heat related impacts. Given that the major heat risk
category affects anyone without effective cooling and/or adequate
hydration, the public is encouraged to take preventative measures
such as having access to AC or minimizing vigorous outdoor
activities during the peak of the heat.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Through 18Z Friday...VFR conditions will prevail across the
region through 06Z before showers and embedded thunder roll
through with ceilings lowering to MVFR from around 09-15Z at
KMSS/KSLK/KEFK/KRUT. Visibility within the showers should
generally remain VFR with brief periods of MVFR possible. Gusty
winds will likely be the main concern through the period, with
SSW gusts up to 25kts at KMSS/KSLK/KBTV this afternoon through
much of the night, and the potential for a brief period of
25-35kts at KMSS around 06Z, and potentially KSLK around 08Z
along a frontal passage. LLWS is likely aloft at all terminals
through the overnight hours as a strong low level jet of 40-50kt
traverses the region.

Outlook...

Friday Night: VFR. Slight chance SHRA.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. Slight chance SHRA.
Monday: Mainly VFR, with local MVFR possible. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Slight chance SHRA.
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&&

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

&&

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