734
FXUS61 KBTV 051746
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
146 PM EDT Fri Jul 5 2024

.SYNOPSIS...
Warm and humid conditions will continue across the North Country and
Vermont for the next several days with daily highs in the mid 80s to
near 90 resulting in moderate heat risk levels. There is a low
chance for isolated showers and thunderstorms today, with more
numerous and stronger storms possible Saturday afternoon and
evening. Drier days are forecast for Sunday and Monday, with another
round of showers and thunderstorms likely late Tuesday into Tuesday
night along a cold front passage. Slightly cooler and less humid air
returns midweek.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 134 PM EDT Friday...It`s a warm and humid day. A small
tongue of dry air is slipping into part of the region, and we`re
seeing some of that mix down to the surface now. Before BTV was
at an unpleasant 71 dewpoint, but is now better off at 63. It`s
a mix across the region due to how small the pocket of dry air
is, and it`s plenty warm with 80s regionwide now. With this,
showers are starting to fire. No lightning yet, but wouldn`t be
surprised if we see some soon. As per usual, the first to fire
are long the interface of the northeastern Adirondack foothills
and Lake Champlain breeze. Only minor adjustments needed.
Previous discussion below.

Persistence is the general forecast for today as the region
will see little to no airmass change from yesterday with the
exception being increased humidity as dewpoints rise into the
mid 60s to low 70s in response to a 1.5-2" PWAT plume lifting
northward through central/southern New England. Morning clouds
should trend more scattered through the afternoon, with mean
925mb temps of +22-24C almost identical to yesterday so highs
should follow suit within a degree or two of yesterdays values
in the mid 80s to around 90. Model guidance additionally
continues to show some decaying shortwave energy ejecting
northeastward from Great Lakes and Ohio Valley, but water vapor
doesn`t support much mid- level moisture this afternoon so
despite some good instability, the likelihood of convective
development is rather low. Still, CAMS still support the
potential for something to form along the lake breeze or higher
terrain so we`ll maintain some slight to low chance pops for
showers and thunderstorms.

A lack of any strong forcing continues tonight, but we`ll remain in
this warm and humid airmass so much like this morning, we can`t rule
out some isolated showers and rumbles of thunder though most of the
region should remain dry with lows mainly upper 60s to lower 70s.
The forecast for Saturday continues to be challenging with guidance
waffling back and forth with the potential for convection. In
contrast to yesterdays 12Z runs, today`s 00Z guidance shows a
sharper shortwave lifting from the Ohio Valley into the Northeast in
the afternoon providing the needed dynamics to support strong
thunderstorm development. While the NAMnest is a little bonkers in
regard to the instability owing to overdone dewpoints, the FV3 is
quite reasonable and soundings indicate the potential for MUCAPE`s
up to 2000 J/kg and DCAPE`s over 1000 J/kg along with 50kts of 0-6km
bulk shear. SPC currently highlights only general thunder over the
region, but if trends continue we could see the day shift upgrade to
a marginal risk for severe storms with the main threat being
damaging winds from a wet microburst.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 337 AM EDT Friday...Showers and isolated thunderstorms continue
into Saturday evening, but become more widely scattered as the night
goes on. High pressure builds in from the Ohio Valley along with the
advection of a drier and cooler air mass. A weak shortwave trough
crossing the region on Sunday could spark some scattered showers,
but guidance has trended drier for Sunday. So there is increasing
confidence that Sunday could well be a nice day for outdoor
activities by early July standards in the North Country. Sunday
night looks to be cooler than of late, with lows in the mid 50s to
low 60s, except mid 60s across the Champlain valley.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 337 AM EDT Friday...Surface high moves overhead on Monday,
which should be the a pleasant day for outdoor activities with
comfortable humidity. Ensemble guidance shows increased
probabilities for a shortwave trough to approach the area in the mid
week time frame, so once again rainfall and thunderstorm chances
will be on the increase. NAEFS ensemble situational awareness table
shows PWATs and IVT rising to over 90th percentile for our region
later Tuesday into Wednesday, so multiple rounds of heavy rainfall
is certainly possible with a slow-moving cold front nearby providing
the focus for scattered to numerous thunderstorms. Looking upstream,
the anomalous PWAT plume appears to have its origins in the Gulf of
Mexico. Accordingly, WPC has also highlighted a marginal risk for
excessive rainfall for Day 5 (Tuesday into Tuesday night) for
northern NY. While it is still too premature to get into specifics,
those with outdoor plans middle of next week should stay up to date
with the forecast. Cold front should finally clear the region on
Thursday, leading to a drier end to the work week along with
comfortable humidity.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Through 18Z Saturday...Mainly VFR conditions are expected, but
short intervals of MVFR or IFR possible depending on isolated
shower development. The chance for a thunderstorm impacting a
TAF terminal appears low and have only mentioned VCSH for now.
The precipitation forecast is tricky, with several atmospheric
impulses maintaining the potential after sunset. Tried to
depict VCSH mainly where there is at least moderate confidence
in activity near a terminal. Winds are currently variable across
the region, and will become north to northeast at KPBG, KMSS,
and KBTV, while remaining light and variable elsewhere. Some fog
may develop overnight, which will depend on rainfall. For now,
have highlighted 4 or 5 SM at KEFK, KSLK, and KMPV. With clouds,
it will not be radiation fog, but mainly a function of surface
relative humidity and possible rain. A broader swath of rain
will lift northeast between about 08z and 15z. This will have
embedded heavy rain and thunder, but impacts to visibility are
generally not shown in TAFs for now. Ceilings will lower with
this batch of rain down to 1500-3000 ft agl. Some improvement
will take place as rain shifts east about 15 or 16z and 5 knot
winds become south to southeast, except likely east or northeast
winds at KPBG and KMSS.

Outlook...

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

&&

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

&&

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