761
FXUS61 KBTV 020559
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
159 AM EDT Thu May 2 2024

.SYNOPSIS...
A potent upper level disturbance and weak surface low pressure
system will bring a period of scattered to numerous showers to much
of the forecast area late tonight through Thursday before high
pressure and drier conditions return for Thursday night and Friday.
Saturday will be mainly dry with a low chance for showers across
northern New York, with periods of showers likely for the latter
half of the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 153 AM EDT Thursday...
A shortwave trough continues to advance eastward across
northern New York and into Vermont. These storms should be to
the east of the region by about 10Z. The instability is all
elevated and there is no severe weather threat. There will be
some scattered showers continuing for the much of the day,
particularly over northern areas, but they will likley not have
any lightning. Previous discussion follows...

Previous discussion...Quiet weather over the forecast area
this afternoon will once again turn unsettled tonight as a potent
shortwave trough currently moving east from Lake Superior will
continue eastward through southern Ontario and Quebec tonight before
diving southeastward across the North Country and Vermont on
Thursday. A warm front currently draped across southern New York
will be the focus for showers to develop on as it lifts northward
into northern New York around midnight or shortly thereafter, with
precipitation spreading eastward through central/northern Vermont
through sunrise. Thereafter for Thursday, a cold pool aloft and
steepening low level lapse rates will support scattered showers to
continue across the region with perhaps some small hail or graupel
as well until an upper level ridge begins to build in Thursday
evening. Overall basin-averaged QPF will be light across southern
zones with only a few hundreths to a tenth of an inch expected, but
northward a light wetting rain of a quarter to third of an inch is
likely. Clouds and low level moisture will keep temps mild overnight
with lows mainly mid 40s to around 50, and highs will generally
range through the 60s on Thursday. Cooler temperatures and dry
conditions follow for Thursday night with lows in the lows and areas
of fog possible.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 345 PM EDT Wednesday...An anomalously strong, but narrow, upper
level ridge will slide eastward into the region during this period.
In the low levels, there will be less impressive low level warmth
due to the position of high pressure to our northeast rather than
east or southeast. As a result, while this pattern supports dry
weather, we don`t see anything unusually warm at the surface. Expect
warmer spots such as the central/southern Champlain Valleys
currently have about 50-60% chance of seeing 70 degree highs. As
normal highs are now in the low to mid 60s, these temperatures could
be considered seasonably warm. While southern St. Lawrence County
sees the most favorable conditions under the ridge - with gentle
downsloping easterly low level winds to warm well into the 70s, they
also will likely see thickening high clouds arrive. Similar to the
day of the solar eclipse last month, there may be a sharp north-
south oriented line between thicker and thinner cloud cover.
Generally have mostly cloudy skies for much of the day in northern
New York and partly cloudy in Vermont, but certainly not clear cut
on the degree of cloud cover with some minor impact on high
temperatures possible. Expect there will be enough mixing to
overcome any lingering morning low clouds/fog, but that is another
possible way to underachieve on temperatures. Lowering clouds will
continue to be the gradual trend ahead of a shortwave trough that
looks to slide northeastward across the Great Lakes Friday night,
and have a slight chance of showers after midnight in the far
western areas of northern New York. Precipitation chances and
amounts will be limited by continued mid- level ridging and related
lack of instability and forcing for ascent. It will be a mild night
even where winds remain light. Overnight temperatures will be
moderated by cloud cover and increasing, modest southeasterly
gradient flow, as a ridge of high pressure in eastern New England
strengthens while weak low pressure approaches from Ohio.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 345 PM EDT Wednesday...Aside from a bit more southerly wind,
the pattern on Saturday is not too different from Friday. Ridging
will slowly break down, setting up increasing shower chances through
the day with greater chances west and lower chances as you go
eastward. Especially across Vermont, even the wettest model
solutions suggest if it does rain it will be very light and brief. A
more significant shortwave will probably move through Saturday
night, leading to much greater chances of showers. Have continued to
leave out mention of thunder as elevated instability associated with
this system looks meager and better southwest of our region.

Sunday looks like the coolest/cloudiest day of the long term period
despite southerly winds and continued mild air aloft. Why? Thick
cloud cover will likely be present as mid-level southwesterly flow
increases with advection of moisture from upstream showers. A window
of clearing ahead of a cold front seems to hold off until after
sunset with the front passing through with nothing more than some
scattered showers Sunday night. Weak high pressure will then build
in for Monday, with seasonably warm and frankly beautiful weather in
store for the beginning of the week. Model agreement in quiet
weather is fairly high for the Monday-Tuesday period. The low level
temperatures have modest spread, so how warm we get on Tuesday is a
question. Widespread highs in the 70s look reasonable at this time.

Looking at the 12Z global model ensemble data, the joint probability
of surface-based CAPE exceeding 500 J/kg and deep layer shear
exceeding 30 knots suggests our next chance for notable convective
weather returns on Wednesday. Although the signal for strong
thunderstorms is greater to our southwest, one of the four global
model clusters provides a plausible scenario with deep southwesterly
flow bringing modest heat and humidity into our region, especially
northern New York. In general, more active weather looks favored
Wednesday and beyond.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...An area of scattered showers and thunderstorms
is moving west to east across the region. It should generally take
between 1-2 hours for the area to pass through a specific terminal.
They are currently over northern New York and should reach BTV and
PBG before 7Z and MPV and EFK around 7Z-8Z. These storms should be
out of the region by around 10Z and the thunderstorm threat should
be over for the rest of the day. However, there will be some
scattered showers continuing for much of the day over the northern
terminals. Ceilings will drop pretty quickly tonight and everywhere
should reach MVFR before daybreak. IFR ceilings are expected at MSS
and MPV later tonight and they cannot be ruled out at SLK either.
Ceilings will rise slowly during the day today and they should be
above IFR levels at all terminals by mid-morning. Winds will be
relatively light during this period, generally shifting from
southeasterly to southwesterly. LLWS will be a concern at every
terminal tonight before becoming weaker during the day today as a
low-level jet exits the region.

Outlook...

Friday: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.
Saturday Night: VFR. Chance SHRA.
Sunday: Mainly MVFR, with local VFR possible. Chance SHRA.
Sunday Night: Mainly IFR, with areas MVFR possible. Chance SHRA.
Monday: VFR/MVFR conditions possible. Slight chance SHRA.

&&

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

&&

$$
SYNOPSIS...Lahiff
NEAR TERM...Lahiff/Myskowski
SHORT TERM...Kutikoff
LONG TERM...Kutikoff
AVIATION...Myskowski