-- Discussion containing changed information from previous version are highlighted. --
191
FXUS61 KBTV 121947
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
347 PM EDT Mon May 12 2025

.SYNOPSIS...
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Mostly dry conditions will persist through mid week before chances
of showers increase late week and especially over the weekend. A
warming trend will send temperatures above average for much of the
week, and the humidity will increase for late in the week.
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&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
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As of 346 PM EDT Monday...A weak shortwave is passing through this
afternoon and it has brought an area of light showers to the
Northeast Kingdom. Despite a very dry layer in the lower levels of
the atmosphere and surface dew point depressions ranging in the
35-45 degree range at the onset, the rates were heavy enough for the
precipitation to reach the ground. With the dry air, there has been
significant evaporational cooling and temperatures have fallen
several degrees since its onset. These showers will exit to the east
within the next couple hours. A cold front will move through this
evening but it will have little impact on temperatures. The lower
clouds should clear out later in the evening and winds will go
mostly calm, so decent radiational cooling conditions will develop.
However, with a warmer airmass than this morning, there is not a
frost concern. Return southerly flow will quickly develop tomorrow
and temperatures will rise back into the 70s for most places. A
marine modified airmass will help keep areas east of the greens
slightly cooler, while more sunshine and a larger distance from the
Atlantic will cause parts of the St. Lawrence Valley to make a run
at 80. Isolated showers and thunderstorms are possible over northern
New York tomorrow afternoon, but there is not a severe threat with
these. Flow becoming more southeasterly tomorrow night will help
advect more of the modified marine airmass into areas east of the
Greens, and temperatures there should fall into the 40s, but
elsewhere, they will likely stay in the 50s.
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&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
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As of 346 PM EDT Monday...A slow pattern change will take place on
Wednesday as ridging shifts to the east and a conveyor belt of
clouds and shower chances arrives from the south and west. There is
some model disagreement on how quickly the mostly cloudy skies move
in, but overall the trend is perhaps a little quicker leading to a
slight cooling trend in the forecast high temperatures. Amidst the
cloud cover, there will be lower 850 millibar temperatures which
will limit surface temperatures even as mixing deepens diurnally.
Highs should range from 72 to 77 in most locations. Noted that these
temperatures are largely on the cool side of the blended guidance,
which I think is reasonable given the expected mostly cloudy skies
throughout peak heating. Hard to dismiss at least a chance of light
showers throughout the day with somewhat greater chances as you go
south and west, but with those cooling low level temperatures and
warm mid- level air, heavy showers and/or thunderstorms are not
expected. Overnight, moderately moist and increasingly warm air
aloft will result in a mild night areawide, with lows largely in the
mid and upper 50s. There is weak model consensus on an cluster of
heavier showers, expected to move inland off of the southern New
England coast, moving northward into southern portions of Vermont
overnight. Accordingly, PoPs increase closer to 40% in areas near
the southern Green Mountains, tapering off towards the north and
west.
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&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
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As of 346 PM EDT Monday...Thursday remains the first day of three to
end the week in which there are some thunderstorm chances, but they
are least likely with only marginal CAPE per ensemble and
deterministic model guidance even in the more bullish scenarios. If
thunderstorms develop, they should be non-severe with weak wind
fields aloft, and probabilities are higher in northern New York than
in Vermont. Temperatures look very similar to Wednesday, ranging
from the mid 70s to upper 70s in most places.

Friday continues to look more active with better dynamics, and
especially thermodynamics, to play with. Progged instability across
all model clusters is moderate and spread is relatively low, so
confidence is fairly high in CAPE roughly 500-1000 J/kg. Bulk wind
shear is more questionable, with most scenarios showing limited
shear with the upper level low and associated stronger flow lagging
too far to the northwest. As such, we`re not looking at a high
impact day; however, with much more likely precipitation and
thunderstorm chances, outdoor activities at some point will be
affected areawide. Broad consensus on timing is in the 2 PM to 8 PM
window, but showers could linger into the nighttime hours.

Chances of stronger variety thunderstorms remain for Saturday, but
it remains rather uncertain with a large range in possible outcomes.
Best overlap of shear and CAPE continues to more likely be to our
south, with perhaps portions of south central or even eastern
Vermont favored for strong thunderstorms if ingredients come
together. Small differences in the evolution of the upper level low
to our west will control the timing and strength of both the surface
cold front and the flow aloft that will transport moisture and
generate wind shear. In the coming days the predictability of this
system should increase and confidence in impactful weather will
increase. Broadly speaking, most model guidance shows rain showers
areawide moving through the area Saturday afternoon and evening, but
much of that timeframe could be dry.

Regardless of timing of the cold front, Sunday remains on target to
be noticeably cooler than the previous several days, especially if
the upper level trough to our west comes far enough south. The
latest trends do indeed support scattered showers on Sunday; model
clusters with over 60% of members signal likely rain during the day.
There is a slight lean towards higher chances in northeastern
Vermont, but it is hard to rule out more rain on Sunday areawide.

For Monday, the upper level low may depart enough to bring us a dry
day. That being said, the strong model consensus right now,
especially amongst the ECMWF and its ensembles, is for lingering
shower chances as we sit in the northwestern flank of this system.
Temperatures would be similar to Sunday, ranging through the 60s, or
a few degrees below normal for most spots.
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&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday... VFR conditions are expected for the next 24
hours. Winds will generally be westerly this afternoon, before
becoming more northwesterly this evening after the passage of a weak
cold front. BTV and PBG will be exceptions as they should switch
from southerly to northerly due to funneling up and down the
Champlain Valley. MSS will instead switch from southwesterly to
northeasterly after the frontal passage. Wind go mostly calm late in
the evening. Winds will increase during the day tomorrow and quickly
become southerly in most places. Winds will generally gust in the 10-
20 KT range this afternoon and then in the 5-15 KT range tomorrow.

Outlook...

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

&&

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

&&

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