-- Discussion containing changed information from previous version are highlighted. --
783
FXUS61 KBTV 211721
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
121 PM EDT Tue May 21 2024

.SYNOPSIS...
A few showers and scattered storms are possible across northern
New York this morning. More widespread thunderstorms are
expected this afternoon into early evening, some of which could
be strong to locally severe. Temperatures also warm well into
the 80s today and again on Wednesday before cooler temperatures
and drier weather return on Friday into Memorial Day weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1002 AM EDT Tuesday...The KCXX and KTYX radars show morning
showers and embedded thunderstorms continuing across nrn NY at
14Z. This activity will continue ENEWD at 20-30kts resulting in
brief moderate rainfall and some embedded rumbles of thunder
through 16-17Z across the northern Champlain Valley into far nrn
VT. Better large-scale forcing arrives with the shortwave
trough centered across the Ottawa Valley. This feature combined
with peak daytime heating (valley 2m temperatures in the mid
80s) is expected to result in renewed convective initiation
across the eastern slopes of the Adirondacks, with convective
storms translating ewd across the Champlain Valley into central
VT during the 3-7pm time frame. Most of the very high-resolution
guidance highlights Essex County NY into Addison County VT with
the highest concentration of convective activity during the
mid-late afternoon hours. With PBL temps in the low-mid 80s and
dewpoints reaching the mid-60s, anticipate SBCAPE values of
1000-1500 J/kg, with minimal CINH as better forcing arrives near
18Z. Sfc-6km bulk shear values of 25-30 kts should be
supportive of multicellular storms and storm clusters resulting
from outflow interactions. Should see a few strong to severe
storms, with localized wind damage and mostly sub-severe hail
possible. SPC Day 1 Outlook continues with a Marginal Risk
across most of our forecast area, which looks on track based on
the latest observational trends. Convection should dissipate
late this evening with onset of the diurnal cooling cycle.

Another round of convection is possible on Wednesday, though there
is less synoptic scale lifting and shear. Currently, an area of
convection should develop over Ontario where there looks to just be
enough lift from another weak shortwave. As the storms reach the
region, they will outrun this forcing and encounter less favorable
conditions. There is a chance of seeing severe storms over northern
New York. The SPC put these areas in a marginal risk again. However,
the conditions looks less favorable than Tuesday. These storms will
weaken as they travel east and they should lose any severe
characteristics as they reach Vermont. Wednesday will likely be the
hottest day of the year so far, with highs generally ranging between
85-90.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
As of 300 AM EDT Tuesday...Showers and thunderstorms continue into
the evening hours on Wednesday. Models depict a pre-frontal trough
crossing the area Wednesday evening into the early overnight hours,
with a few hundred J/kg of surface-based CAPE helping to fuel the
forward motion of any storms that form earlier in the afternoon.
0-6km shear is quite marginal between 15 and 20 kt, so while a
stronger storm or two cannot be ruled out, at this time, they are
less likely to reach severe criteria. The current Day 2 SPC
convective outlook has marginal risk (level 1 of 5) across our far
western zones, which seem reasonable given the overall weak shear
and unimpressive forcing. PWATs are in the 1.2 to 1.4 inches range,
which is in the 90th percentile according to the SPC sounding
climatology for the Albany, NY upper air site. While locally heavy
downpours are possible with any storm that develop, flooding threat
is low given the overall fast moving nature. Temperatures wise,
southerly flow means overnight lows will generally be in the mid to
upper 60s, with similar dew points making for a rather muggy night.
Winds gusting 15 to 25 mph at times would help it feel more
tolerable.

Surface cold front comes through on Thursday with height falls and
temperatures aloft falling during the day from west to east. Dew
points should fall rather quickly into the 40s and 50s by the
morning hours across northern NY, but could stay near 60 across
Vermont. As such, the best chance for decent shear to overlap with
surface-based instability is across Vermont on Thursday afternoon.
And this is where the forecast indicates better chances for
thunderstorms. At this time, while a few stronger storms are
possible, they should stay mainly below severe criteria.
Temperatures wise, best probability of low to mid 80s would be
across Vermont, with cooler temperatures in the low to mid 70s
across northern NY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
As of 300 AM EDT Tuesday...Behind the cold front on Thursday, we get
a reprieve from the recent early season heat, with much more
seasonable highs in the upper 60s to mid 70s expected on Friday into
much of the weekend. While a few showers cannot be ruled out, our
region should see mainly dry weather and rather refreshing
conditions with dew points in the 40s and 50s. The next chance for
more widespread showers and thunderstorms does not arrive until
Memorial Day itself but forecast confidence is low this far out.

&&

.AVIATION /17Z TUESDAY THROUGH SUNDAY/...
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Through 12Z Wednesday...Isold to scattered thunderstorm activity
may impact TAF locations 19-23Z across VT and northern NY this
afternoon/early eve. Brief heavy rainfall and gusty winds are
possible, along with dangerous cloud-to-ground lightning.
T-storm activity dissipates later this evening with mainly scattered
midlevel (VFR) cloudiness. May see BR/FG formation east of the
Green Mtns, especially in the CT River Valley, during the pre-
dawn hours on Wednesday. During Wednesday morning, VFR
conditions expected with just FEW-SCT200-250. Winds generally
light S-SW across the region this afternoon away from any
thunderstorm activity.

Outlook...

Wednesday Night: VFR. Chance SHRA, Slight chance TSRA.
Thursday: VFR. Chance SHRA, Slight chance TSRA.
Thursday Night: VFR. Slight chance SHRA.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: Mainly VFR, with local IFR possible. Slight
chance SHRA.
Sunday: Mainly VFR, with areas MVFR possible. Slight chance SHRA.
-- End Changed Discussion --

&&

.CLIMATE...
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Record High Temperatures:

May 22:
KBTV: 93/1977
KMPV: 90/1994
KMSS: 89/1977
KSLK: 91/1911

Record High Minimum Temperatures:

May 22:
KBTV: 70/1911
KPBG: 65/1975
KSLK: 63/1921

May 23:
KPBG: 65/1964
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...Chai
NEAR TERM...Banacos/Chai/Myskowski
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Banacos/Myskowski
CLIMATE...Team BTV