844
FXUS61 KBTV 140229
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1029 PM EDT Mon May 13 2024

.SYNOPSIS...
An unsettled weather pattern will continue over the next couple of
days with several rounds of showers, with numerous showers and some
embedded thunderstorms expected tomorrow. Seasonable high
temperatures and mild overnight lows are expected for much of the
upcoming week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1030 PM EDT Monday...Forecast remains in good shape so
only made minor tweaks to bring it up to date with current obs.
Warm front is lifting northward across NY state this evening,
helping to fuel a few showers with a few cloud flashes and even
a solitary lightning strike across far western St Lawrence
county. But lightning activity is not expected to make too much
eastward progression, as the embedded shortwave energy will be
steered northeastward roughly parallel to the St Lawrence River
valley. RAP mesoanalysis shows height rises associated with a
H5 ridge east of the Adirondacks into Vermont. One favorable
parameter is the 2-6 km AGL lapse rates, which are in the 6.5 to
7C/km range. But the expectation is that outside of northern NY
which has the best chance of hearing a few rumbles of thunder,
our Vermont zones should primarily see rain showers with the
isolated brief downpour. Temperatures will be slow to fall
overnight thanks to strong warm advection and southerly flow.

PREVIOUS DISCUSSION...Light showers across the region have
brought little to no measurable precipitation this afternoon,
with only a few hundreths at most so far. As we head into the
evening, a frontal boundary will become stalled near the
International Border, with increased chances for showers and
some possible rumbles of thunder across northern New York
overnight due to increased elevated instability and stronger
forcing. Overnight lows will be on the mild side tonight, in the
50s, although spots east of the Greens will drop into the upper
40s.

Model soundings for tomorrow show tall and skinny CAPE profiles,
supporting the idea of some heavy downpours and embedded
thunderstorms tomorrow afternoon, with PWAT values in excess of an
inch. Current QPF amounts range from a few tenths to near an inch,
with localized higher amounts expected in any thunderstorms. The
latest CAM guidance suggests CAPE values between 500 to 1200 J/kg
across southern portions of the forecast area tomorrow, with
temperatures warming into the 70s. Meanwhile closer to the
International Border, temperatures will only warm into the upper
60s. There is still a little uncertainty regarding the instability
across the region tomorrow afternoon as lingering cloud cover will
limit surface heating. There is the potential for training storm
motions with any developing convection, which will need to be
monitored given the potential for heavier downpours. While
widespread severe is not currently anticipated, NCAR is showing a
non-zero threat for some severe weather and there will likely be
plenty of activity to monitor tomorrow afternoon. Shower activity
will dwindle heading into the evening with the lack of diurnal
heating, with overnight lows expected to be quite mild for this time
of year.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
As of 402 PM EDT Monday...ANother round of showers is expected for
much of Wednesday as a cut off low becomes stuck over the Mid-
Atlantic region. This slow moving low pressure system is expected to
drape a warm frontal boundary across our forecast area which should
allow for shower activity to increase throughout the day on
Wednesday given modest heating under cloudy skies. Thermal profiles
have varied from run to run but it seems we will be looking at
closer to moist adiabatic lapse rates which in this case likely
won`t favor thunderstorms. Could a rumble of thunder occur?
Possibly, but most likely we should just see scattered to numerous
showers on Wednesday. The main focus on rainfall accumulations will
be across southern Vermont where we could see a quarter to maybe a
third of an inch of rain but lesser amounts as you get closer to the
International Border. Shower activity is expected to wane as we head
into Wednesday evening with the loss of daytime heating but a few
showers will likely continue through the overnight period.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 402 PM EDT Monday...Thursday had been looking drier for a while
but the latest guidance suggests it may not be as dry as we had been
thinking. The stall frontal boundary mentioned in the above section
will remain over the area on Thursday. We better heating due to
slightly less cloud cover, a resurgence of shower activity is
expected during the afternoon hours. It won`t be as widespread as
Wednesday but isolated to scattered showers could drop some light
rain throughout the day with thunderstorm potential again looking
rather meager. Friday, on the other hand, has trended a little drier
as the 12Z guidance is showing building 500 mb heights in response
to a deepening trough over the central US. Increasing subsidence is
expected to keep shower activity largely at bay although a few
diurnal showers cannot be ruled out.

Rain chances will increase throughout the day on Saturday as the
aforementioned trough slides eastward and we see a series of frontal
boundaries move through the region. With good fetch of Gulf of
Mexico moisture, we could see some heavy rain showers this weekend
but the details will be ironed out over the next several days. Those
with outdoor weekend plans are encourages to keep a close eye on the
forecast. This period of unsettled weather is likely to continue
well into next week with a series of disturbances likely to pass
near the northeastern US. The good news is that we aren`t expecting
any significant rainfall so flooding doesn`t look to be a concern
moving forward.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...Mainly VFR conditions are expected for
the next few hours. Winds throughout the period will range
between southeast to southwest between 5 and 10 knots through
the period, with a few gusts 15 to 18 knots at KBTV. Some
showers are already present over northern New York and did
produce some lightning, but have been decaying. The stronger
convection is north of Lake Ontario, and that will shift into
the region alongside the warm front about 02z to 03z. Showers
will be likely across the region between 03z and 10z as it lifts
north and then stalls near the international border. In heavier
elements, 3-6SM visibility and ceilings 2000-3000 ft agl will
be possible. Thunderstorm activity should decay moving east, and
so KSLK is the only to have a TEMPO for TSRA between about 03z
and 05z, but could be possible further east if it holds
together. Patches of low level wind shear will develop behind
the warm front from about 04z to 10z for 35 to 40 knot southwest
winds at 2000 ft agl.

Some partial clearing and lifting ceilings follow the warm front
10z-12z, but where warm front stalls is not entirely certain.
So outside of KMPV and KRUT, the forecast maintains VCSH for
several terminals. Additional showers and thunderstorms will
develop about 18z. A weak trough will shift south, with
convection near the trough and lifting north-northeast towards
the trough axis until is passes south sometime near or after 00z
Wednesday. It`s too far out now, but some thunderstorms could
be strong, and there will be potential for ceiling and
visibility reductions between 18z beyond 00z Wednesday.

Outlook...

Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Wednesday: Mainly MVFR, with local VFR possible. Likely SHRA.
Wednesday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA.
Thursday: Mainly VFR, with local MVFR possible. Chance SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: VFR. Chance SHRA.
Friday Night: VFR. Chance SHRA.
Saturday: Mainly MVFR, with local IFR possible. Chance SHRA.

&&

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

&&

$$
SYNOPSIS...Kremer
NEAR TERM...Chai/Kremer
SHORT TERM...Clay
LONG TERM...Clay
AVIATION...Haynes