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079
FXUS61 KBTV 202006
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
406 PM EDT Thu Jun 20 2024

.SYNOPSIS...
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Showers and strong to severe thunderstorms will continue this
evening, potentially featuring hail, frequent lightning, downpours,
and gusty to damaging winds. Our hot streak will come to an end with
temperatures returning to seasonable levels to end out the week.
Additional thunderstorm chances are expected over the weekend with
the best chances occurring Sunday.
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&&

.NEAR TERM /THROUGH SATURDAY/...
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As of 405 PM EDT Thursday...
**Severe Thunderstorm Watch in Effect Through 8 PM**

High pressure located in the Atlantic Ocean continues to draw warm,
moist air into the forecast area from the west/southwest this
afternoon and evening, and mid level westerly winds will be
strongest across the international border where deep layer shear is
most significant. A cold frontal boundary will be dropping through
this evening from north to south, continuing to trigger showers and
thunderstorms as well as putting an end to our three day heat wave.
As the front clashes with our warm, humid air mass in place, this
will be the focus of convection this evening. Deep layer shear as a
whole is meager, but precipitable water values are impressive, up to
around 2 inches in some spots. Modeled MLCAPE values are 2000-3000
J/kg. The main concern with these storms will be damaging wind gusts
and hail, which has already been reported across portions of the
forecast area this afternoon. In addition to severe concerns, we are
also monitoring the thunderstorms for heavy rain over the same area,
as this could result in isolated flash flooding. The storms are
expected to be slow moving along the stalling front, which would
allow a heavy storm to drop an impressive amount of rain in one spot
before moving on under high pwat conditions. Expected rainfall
amounts will vary depending on where thunderstorms occur, but
generally thinking 0.20-1.00". Thunderstorm threat should end around
8 PM this evening as we lose daytime heating and instability.

Low temperatures will fall into the 60s for most tonight, which will
be much cooler than it has been the last few nights, but still a
good 5-10 degrees above average. Thick moisture at the surface will
result in patchy fog in the classic valley locations and those that
received plenty of rain from the showers and storms today. Tomorrow
will be cooler than today, returning our highs back to around
seasonable levels in the upper 70s to mid 80s. Showers and
thunderstorms are expected to return tomorrow, mainly for the
southern half of the forecast area along the frontal boundary.
Severe weather is not anticipated tomorrow. Rainfall amounts should
be up to a half an inch. Tomorrow night, this frontal boundary will
be stalled out just to our south, which again will be where most
showers set up. Lows will fall even farther tomorrow night into the
mid 50s to mid 60s, still about 5 degrees above climatological
normals. Once again, there is the potential for some fog with the
stationary boundary and low level moisture.
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&&

.SHORT TERM /SATURDAY NIGHT THROUGH SATURDAY/...
As of 318 AM EDT Thursday...The cold front will stall just to the
south of the region Friday night. There could be a few showers
across southern Vermont but overall most places will stay dry.
Despite being north of the front, the Canadian high pressure
struggles to gain much influence over the region so while being a
little cooler and drier, it will not be overly refreshing. Lows only
fall back into the 60s. The front will gradually work its way back
north through the region on Saturday, bringing some showers and
possible embedded thunderstorms with it. The instability should
mostly be elevated so there is not much of a severe threat. PWATs
will rise back between 1.5 to 2 inches and some areas of heavy
rainfall are possible. With the slow moving nature of the front,
entraining storms could lead to isolated flash flooding. However,
there will not be much instability and the forcing from the front
looks on the weaker side, so this should keep the threat of flash
flooding more localized. Therefore, the marginal risk ERO from the
WPC seems reasonable.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
As of 318 AM EDT Thursday...The front looks to stall during the day
on Sunday and its exact placement will be key for any flooding or
severe threat. Ensemble guidance has shifted to favoring the front
to stall a little farther north over Quebec. This would allow the
region to get into the warm sector and modest CAPE would be able to
develop. Right now, the GFS/Euro ensembles bring between a 30-60
percent chance of higher than 500 J/Kg across the area, with the
highest values to the south and the lowest values to the north. With
adequate deep layer shear in place, this could lead to the
possibility of a couple severe storms. However, if the front were to
stall over the region, there would likely be a higher flooding
threat and less of a severe threat. Showers and storms look to train
along the front, and with a low approaching from the west, the
synoptic lift looks to increase as the day goes on. Also, PWATs will
continue to be between 1.5 to 2 inches so there will be favorable
conditions for heavy rainfall. The scenario could cause some flash
flooding to occur, particularly since there will have been a decent
amount of previous rainfall. Right now, the WPC has a moderate to
slight ERO for the region due to the threat of the heavy rainfall
and this makes sense. However, if the front continues to trend to
the north, this might need to be downgraded. The low moves through
the region Sunday night into Monday and brings widespread rainfall.
Behind it next week, drier and cooler air gradually filters down
from Canada, but it will take some time for the air to feel
refreshing.   .AVIATION /... Through 18Z Monday...There is a line
of showers and thunderstorms slowly moving eastward across northern
New York. It will likely hold together and pass over MSS and SLK
this morning. Whether it sticks together into PBG and Vermont is
questionable but there will at least be scattered showers and
thunderstorms around during the afternoon. Scattered storms will
develop across northern New York as well in the afternoon, but due
to their hit or miss nature it cannot be definitively determined if
they will hit any of the airports or not. Besides being able to
produce frequent lightning, the showers and storms will briefly
lower visibilities at any terminal they reach to MVFR and possibly
IFR. The storms should dissipate overnight before developing again
tomorrow morning. Patchy fog will likely develop across the region
tonight and there is a decent chance it develops at SLK and MSS.
Winds are generally light and southerly during this period. LLWS is
not a concern.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Through 18Z Friday...Showers and thunderstorms are popping up
around the region currently and will continue through at least
00Z. Any storms will have the potential to produce strong/gusty
outflow winds up to 60 mph, small hail, frequent cloud to
ground lightning and MVFR vis in heavier rain. Another round of
potential fog after 06z Friday, especially in areas that see
rain. Have gone with IFR conditions at at KMPV/KSLK, with some
MVFR mentions at other stations. All stations should return to
VFR after 13Z on Friday.


Outlook...

Friday Night: VFR. Slight chance SHRA, Slight chance TSRA.
Saturday: Mainly MVFR, with areas VFR possible. Chance SHRA,
Slight chance TSRA.
Saturday Night: MVFR. Chance SHRA, Slight chance TSRA.
Sunday: Mainly VFR, with areas MVFR possible. Definite SHRA,
Chance TSRA.
Sunday Night: Mainly MVFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Monday: Mainly VFR, with areas MVFR possible. Likely SHRA, Slight
chance TSRA.
Monday Night: VFR. Chance SHRA.
Tuesday: VFR. NO SIG WX.

&&

.EQUIPMENT...
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Our radar KCXX is currently down. Time of return is unknown at
the moment.
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&&

.BTV WATCHES/WARNINGS/ADVISORIES...
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.

&&

$$
SYNOPSIS...Storm
NEAR TERM...Storm
SHORT TERM...Myskowski
LONG TERM...Myskowski
AVIATION...Hastings/Verasamy
EQUIPMENT...Team BTV