784
FXUS61 KBTV 272356
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
756 PM EDT Mon May 27 2024

.SYNOPSIS...
A storm system will continue to bring showers and a few
thunderstorms tonight. Chances of locally damaging winds will
diminish through this evening as the main weather impacts will
become associated with heavy rainfall, capable of producing
ponding on roadways. Additional, less heavy or widespread,
showers with a low chance of thunder are expected on Tuesday.
Somewhat cooler conditions will follow for Wednesday with some
shower chances, and then a gradual warming trend with mainly dry
weather is favored through early next week.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 716 PM EDT Monday...After coordination with SPC and latest
LAPS showing sfc based CAPE values <500 J/kg have dropped the
Svr Thunderstorm Watch for St Lawrence County as of 7 PM. Still
anticipating a broken line of showers with a few rumbles of
thunder possible as better upper lvl dynamics arrive associated
with mid/upper lvl trof acrs the central Great Lakes. In
addition, the rain has stabilized the boundary layer conditions
over most of the cwa this evening, which has resulted in lighter
wind gusts in the 25 to 35 mph range, even thou KCXX VAD is
showing 45 to 55 knots between 4500 and 5000 ft agl. Mixing with
rain wl be limited so wind advisory has been cancelled with this
update. Still watching some heavier pockets of rainfall but
given shower motions of 25 to 35 knots and limited vertical
development the threat for flash flooding is very very low attm.
We will continue to monitor radar for wind and locally heavy
rainfall, but activity is trending favorable for no significant
impacts.

Previous discussion below:
Active weather this evening is unfolding, as radar operators
monitor fast moving convection near and just west of the
northern Adirondacks. Main concern remains a damaging wind gust
or two in St. Lawrence County associated with a relatively high
amount of storm relative helicity near the ground overlapping
modest instability. As of this writing, one severe thunderstorm
warning has been issued. Rotating cells just to the south of our
area have resulted in a single local storm report of a downed
tree so far. Generally the greatest threat of hazardous weather
is through about 5 PM, then best effective shear shifts eastward
while MLCAPE likely diminishes. We are watching the possible
intensification of a line of showers over eastern Lake Ontario
that could be a focus of damaging wind gusts. Meanwhile, we have
maintained a Wind Advisory for the northern Adirondacks and
western slopes of the northern Green Mountains through 8 PM. We
have seen sub- advisory level sustained south/southeast winds
produce downed trees in portions of northern New York. The
persistent and unseasonably strong winds are coinciding with
greater leaf area of trees, likely making them more vulnerable
to these winds than expected. The uptick in southeasterly winds
towards sunset, with near summit level winds boosting to near 55
knots, causes some concern for more utility impacts.

Aside from the winds, heavy rainfall still is expected, although
excessive rain remains a low risk with relatively short duration
of efficient rain. Favorable ingredients for heavy rain include
850 millibar dew points above 50 degrees, excellent moisture
convergence along the deep layer flow (south-southwest to
north-northeast), and high relative humidity through that deep
layer. The surface cold front that these showers will be
oriented along tonight will slowly slide through northern New
York through early this morning and across Vermont by daybreak.
Winds behind the front will be relatively light and more
southwesterly. With continued southerly flow, the air mass will
remain on the warm side in the 55 to 65 range along with
moderately high humidity overnight. Tomorrow a secondary cold
front will approach from the west, and aided by another vigorous
upper level trough we should see more showers develop by
afternoon. Coverage looks more scattered than today, but as
temperatures rebound back into the mid to upper 70s with dew
points in the mid 50s, enough surface based instability will
develop to add at least a slight chance of thunder across the
region. Behind this cold front, winds will turn out of the
northwest allowing for some notable cooling and drying, with
fresh air bringing temperatures back into the upper 40s to mid
50s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 308 PM EDT Monday...A shortwave trough embedded within a larger
scale upper trough will slide southeast Wednesday. So with daytime
heating, convective showers should develop, but are unlikely to
produce lightning with just 100 J/kg of CAPE around due to below
normal temperatures. Cool, northwest flow keep highs in the 60s for
most, with some lower 70s in southeastern Vermont. A dry airmass
shimmies south overnight, and rain chances end. A pleasant evening
in the mid 40s to lower 50s is expected.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 308 PM EDT Monday...Although model discrepancies exist, most
guidance suggests we`ll be in for dry weather. Given general
troughiness, if there`s enough moisture, then a stray pop up shower
could take place, but the vast majority of the area will stay dry
through the weekend, especially as an amplified upper ridge slides
east about next Saturday. So a gradually warming trend from 60s on
Thursday reaching back to mid 70s to near 80 by next Monday will
take place. Once the upper ridge breaks down or shifts east, then we
will observe our next chance for widespread rain sometime next week.
So it looks like an overall pleasant weekend.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...Rounds of rain will move through the
region this evening, lowering visibility at times. Terminals
should have VFR visibilities for most of the time but the
heavier embedded showers will cause some temporary reductions to
MVFR. The rain will likely be heavy enough to lower
visibilities to IFR at MPV and SLK briefly. The rain and its
associated visibility reductions should exit the region by
around midnight. Ceilings will gradually lower tonight and all
the terminals should either be MVFR or a low VFR by tomorrow
morning. Ceilings at MPV may lower to IFR for a couple hours.
Ceilings will gradually rise during the day tomorrow. Winds are
currently strong and southeasterly but they will lighten quickly
this evening. After midnight, gusts should remain under 20KTs
at all terminals and remain under 10KTs at most. Winds will
gradually shift to westerly then northwesterly overnight and
into the day tomorrow. LLWS is present at all terminals except
MSS but the wind shear should weaken below LLWS criteria by
around midnight as the low- level jet exits the region.

Outlook...

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

&&

.MARINE...
A Lake Wind Advisory continues through at least this evening as
strong low level south to southeasterly winds continue ahead of
an unseasonably strong low pressure system passing to our
northwest. Sustained winds of 20 to 30 knots with some gusts to
35 knots will be possible through about 10 PM before
diminishing, remaining out of the south overnight. Waves will
continue to build into the 2 to 3 foot range on the broad lake,
with seiche action evident.

&&

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

&&

$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff/Taber
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Myskowski
MARINE...Kutikoff