321
FXUS61 KBTV 180538
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
138 AM EDT Sat Jul 18 2026
.WHAT HAS CHANGED...
As of 228 PM EDT Friday...
The potential for severe weather remains in place but is largely
conditional as wildfire smoke may limit daytime heating in some
locations. Should we have severe weather, gusty winds looks the
primary and likely only mode of severe weather given tall/skinny
CAPE profiles and strong deep layer shear.
&&
.KEY MESSAGES...
As of 228 PM EDT Friday...
1. Smoke, showers, and thunderstorms, some strong to severe,
expected Saturday afternoon and evening.
2. Drier weather expected Sunday and Monday.
3. Frontal passages bring chances for showers and thunderstorms
on both Tuesday and Wednesday before high pressure dominates our
weather on Thursday and Friday.
&&
.DISCUSSION...
As of 228 PM EDT Friday...
KEY MESSAGE 1: As winds shift from the north to south Saturday morning,
we will see wildfire smoke once again lift north into the North
Country. The HRRR and RAP smoke analysis continue to show 50-100
micrograms per cubic meter by Saturday afternoon which will likely
begin to degrade air quality. Should this trend continue, the
issuance of an air quality alert is possible. This smoke will
be the wild card in a potential severe weather event across
northern New York and Vermont as the thick smoke cover could
have an impact in insolation and limit diurnal heating (as with
the previous event on Tuesday/Wednesday). However, models are
handling this smoke much better than last time so we can say
with decent confidence that multiple strong to severe
thunderstorms will be possible.
The environment will be highlight by Strong deep layer shear of 40-
45 knots and CAPE values in the 500-1000 J/kg range. High PWAT
values of 1.7-1.8 inches will keep thermodynamic profiles moist-
adiabatic with modest lapse rates which is the key limitation
to instability Saturday afternoon. Still with deep moisture and
strong shear profiles, some storms could contain severe wind
gusts and have the potential to produce a wet microburst. Hail
looks rather unlikely given high freezing levels and limited
CAPE in the hail growth layer. A tornado can`t be ruled out but
the low level lapse rates and low level helicity should severely
limit that potential. These showers and thunderstorms will exit
to the east Saturday night.
KEY MESSAGE 2: We will likely see a few lingering showers across
eastern Vermont during daybreak on Sunday but drier air filtering in
through the morning hours should put an end to those quickly.
Clearing skies will accompany these drier conditions which will lead
to a beautiful Sunday. Dry conditions will persist Sunday and Monday
with seasonal temperatures, plenty of sunshine, and light winds.
KEY MESSAGE 3: Upper level low pressure will swing through Ontario on
Monday night, though models continue to show timing discrepancies,
and there remains disagreement on how close the surface low pressure
will get to the US-Canadian border. We anticipate cloud coverage
will increase Monday night, with precipitation likely beginning in
northern New York Tuesday morning and spreading eastward throughout
the day as low pressure edges into Quebec and a warm front treks
across northern New York and Vermont. Tuesday afternoon,
thunderstorms are possible as highs reach into the seasonable upper
70s to mid 80s, with highest instability in the St. Lawrence Valley
and western Adirondacks paired with widespread modest shear.
Nighttime lows in the 50s to mid 60s are anticipated for the early
week. A cold frontal boundary is expected to cross the forecast area
Tuesday night, bringing another round of showers with embedded
thunderstorms, then deterministic models diverge sharply in
their solutions. Some projections show another frontal boundary
or an area of low pressure moving through the Northeast on
Wednesday, while other suggest the upper trough becomes
negatively tilted. General consensus suggests precipitation is
likely outside of shadowed areas on Wednesday with thunderstorms
again possible, then precip chances drop Wednesday night into
Thursday under high pressure. We will be monitoring the midweek
period for potential of strong or severe storms and also for
heavy rainfall. Chances of a half an inch of rainfall within 24
hours runs around 50-80%, most likely Tuesday through Wednesday
as modeled precipitable water values max out 1.50- 2.00 inches
on Tuesday afternoon and evening. Highs for the mid and late
week are expected to be around the 70s and lower 80s with lows
in the upper 40s to lower 60s, though this may depend on how
exactly the atmospheric pattern shapes up during this period.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Through 06Z Sunday...Quiet/VFR aviation weather conditions are
expected to prevail through 12Z Saturday. Light rain showers are
spreading across our area overnight, but not expecting any
reductions below VFR as activity remains light. Light and
variable winds overnight will become southerly after sunrise
with increasing gustiness; gusts to 25 kts are expected at BTV,
especially during Saturday afternoon. A low level jet will also
cross the region from SW-NE starting around 12Z-15Z, so LLWS is
forecast at most of the TAF locations except RUT. Included some
visibility restrictions during the daylight hours Saturday in
haze and wildfire smoke. In terms of precipitation, currently
seeing a leading band of -SHRA, followed by a stronger line of
showers and possibly embedded thunderstorms during the late
afternoon into the early evening hours. A few storms could be
strong to severe late in the day, but are not currently
mentioned in the TAFs due to uncertainties related to timing and
spatial coverage of activity. Brief heavy rainfall and gusty
winds will be possible.
Outlook...
Sunday: Mainly VFR, with local MVFR possible. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: Mainly VFR, with areas MVFR possible. Likely SHRA,
Chance TSRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Definite
SHRA, Chance TSRA.
Wednesday: MVFR/IFR conditions possible. Likely SHRA, Chance
TSRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Air Quality Alert from 6 AM this morning to 11 PM EDT this
evening for VTZ001>011-016>021.
NY...Air Quality Alert until midnight EDT tonight for NYZ026>031-
034-035-087.
&&
$$
WHAT HAS CHANGED...Clay
DISCUSSION...Storm/Clay
AVIATION...Neiles
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