-- Discussion containing changed information from previous version are highlighted. --
911
FXUS61 KBTV 200522
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
122 AM EDT Thu Jun 20 2024

.SYNOPSIS...
Dangerous heat and humidity will continue across the region
into tomorrow for just one more day with highs in the 90s
combining with humid conditions to create heat index values up
to 100. Please continue to take appropriate precautions to avoid
heat stress as heat can have a compounding effect. Scattered to
numerous showers and thunderstorms are possible tomorrow, which
could possibly severe and heavy featuring hail, frequent
lightning, downpours, and gusty winds.

&&

.NEAR TERM /THROUGH FRIDAY/...
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As of 116 AM EDT Thursday...The forecast generally remains on
track early this morning, with few changes needed with this
update. Muggy conditions persist across the region, with
temperatures in the upper 60s to upper 70s; a few spots are
still reporting temperatures in the low 80s. Dewpoints remain
in the upper 60s to mid 70s, as well. An area of showers with
embedded thunderstorms is slowly moving eastward along/just
south of Lake Ontario. This feature isn`t being handled too well
by latest CAM guidance, but expect portions of northern NY
could see some showers and a few rumbles of thunder as we head
toward daybreak.

Previous discussion...Showers and thunderstorms that are
stretched across the forecast area this afternoon will gradually
taper off into the evening as we lose instability and sunlight
tonight. Temperatures are not expected to fall very low tonight
with forecast lows in the lower to mid 70s for most. If
temperatures at the Burlington Airport (BTV) don`t fall below 80
degrees by midnight, we will tie the all time warmest minimum
temperature. Some areas of the forecast area, particularly
valley spots that had rain today, may experience patchy fog
tonight as moisture gets trapped under an inversion.

The mild night will start us off warm again tomorrow as
temperatures climb into the upper 80s to mid 90s. Hottest
conditions are most likely to occur in the Champlain and
Connecticut River Valley, where heat indices could approach 100.
This will be not quite as warm as today was, as a frontal
boundary is likely to produce some precipitation and bring
slight cooling from north to south. With shortwave forcing,
increasing wind shear, sufficient instability, and oppressive
heat, there is a marginal to slight (5-15%) chance of a severe
thunderstorm for most places across the forecast area of
northern New York and Vermont. The primary severe threat from
any storms will be gusty, damaging winds, however, there is also
the potential for hail and frequent lightning. In addition to
severe concerns, very high precipitable water rates are
conducive to heavy downpours. If storms become stationary along
the frontal boundary and repeat downpour in one spot, there
could be the risk of flash flooding.
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&&

.SHORT TERM /FRIDAY NIGHT/...
As of 405 PM EDT Wednesday...The short term focus wl be
potential for showers and embedded thunderstorms associated with
slow moving cold frnt dropping south. The greatest potential
for showers and embedded storms look to be acrs central/southern
VT on Friday where pw values are still near 1.5" and sfc based
CAPE values are in the 500-1000 J/kg range. Much drier air with
lower humidity values wl be near the International border
associated with sfc high pres near Hudson Bay. The latest trends
however have been for less of a southerly push associated with
this 1022mb high pres, as frnt becomes stationary acrs central
NY into SNE. Progged 925mb temps btwn 18-21C support cooler
highs on Friday with values upper 70s to mid 80s. Greater
potential for cloud cover may hamper warming acrs southern
sections, but humidity values wl be higher in Rutland/Windsor
counties too. Areal coverage of showers wl decrease on Friday
night as weak subsidence develops and axis of deepest moisture
is just south of our cwa. Have continued with some token 15-25%
chance pops for now with temps in the 60s. Also, given recent
rainfall and some lighter winds areas of patchy valley fog is
possible, especially CT River Valley and parts of
central/northern VT.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 405 PM EDT Wednesday...An unsettled pattern with
occasional showers are likley for this upcoming weekend into
early next week. The exact timing and placement of heaviest
precip is still getting fine tuned, but several parameters are
coming together for localized heavy rainfall. These parameters
include a nearly stationary west to east oriented boundary, pw
values btwn 1.5 and 2.0", deep warm cloud layer up to 11kft, and
intervals of favorable 850-700mb fgen forcing. Its always
challenging for placement of heaviest qpf in narrow west to east
axis of favorable dynamics and moisture that is several days
away. Best potential attm looks to be acrs the northern Dacks
into central/northern VT. WPC has part of our cwa in marginal
for Day 3, which looks reasonable, especially given the activity
over the next 1 to 2 days. For now have continued with high
likely pops for Saturday into Sunday. As we get closer these
pops can be fine tuned with regards to timing and placement and
hopefully we can find a few hours of dry weather this upcoming
weekend. Temps wl be near normal for highs with values in the
mid 70s to lower 80s while lows hold in the 60s. Late Sunday
into Monday, potent s/w energy and associated sfc low pres wl
track north of our cwa. However, given the dynamics and boundary
associated with this system, another period of showers with
embedded storms looks likely. Still some uncertainty on timing
and amount of instability, but dynamics should be enough to
support some rumbles of thunder. Much drier and quieter weather
returns for early to middle of next week with near normal temps.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
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Through 06Z Friday...Aviation challenge is fog potential
through early Thursday morning followed by timing of convection
on Thursday. Dewpoints are in the upper 60s to lower 70s,
indicating very high low level moisture content, but KCXX VAD
shows 20 knots just off the deck. So thinking some 3-5SM HZ is
possible at SLK/PBG/MPV/EFK, but given winds just off the deck,
feel potential for fog with IFR or lower conditions is <10%
attm. For Thursday, expect areal coverage of showers/storms to
increase toward noontime with some localized strong to severe
storms possible. Any storms will have the potential to produce
strong/gusty outflow winds up to 40 mph, frequent cloud to
ground lightning and MVFR vis in heavier rain. The greatest
potential will be between 17z and 22z on Thursday, with
conditions improving toward sunset. Have used VCSH/VCTS for
now, but as confidence in timing improves prevailing groups and
tempo`s for MVFR cigs/vis will be needed on Thurs. Another round
of potential fog after 00z Friday, especially in areas that see
rain. Have left out of the TAF for now given it is right at the
forecast period.

Outlook...

Friday: VFR. Chance SHRA.
Friday Night: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.
Saturday: MVFR/IFR conditions possible. Chance SHRA.
Saturday Night: Mainly VFR, with areas MVFR possible. Likely
SHRA.
Sunday: Mainly MVFR, with local VFR possible. Likely SHRA, Chance
TSRA.
Sunday Night: MVFR/IFR conditions possible. Likely SHRA.
Monday: Mainly VFR, with local MVFR possible. Likely SHRA.
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&&

.CLIMATE...
Hot temperatures will result in values near records. Below are
some of the records under threat of being broken.

Record High Temperatures:

June 20:
KBTV: 95/2012 Forecast 92
KMPV: 90/2020 Forecast 90
KPBG: 94/1964 Forecast 88
KMSS: 92/2012 Forecast 87
KSLK: 92/1995 Forecast 86


Record High Minimum Temperatures:

June 20:
KPBG: 70/1953 Forecast 73
KSLK: 68/2012 Forecast 67

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
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VT...Heat Advisory until 8 PM EDT this evening for VTZ001>011-
     016>021.
NY...Heat Advisory until 8 PM EDT this evening for NYZ026>031-034-
     035-087.
-- End Changed Discussion --

&&

$$
SYNOPSIS...Storm
NEAR TERM...Hastings/Storm
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Hastings/Taber
CLIMATE...Team BTV