700
FXUS61 KBTV 170627
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
227 AM EDT Wed Jun 17 2026
.WHAT HAS CHANGED...
As of 226 AM EDT Wednesday...
Confidence has increased for strong to severe thunderstorms on
Thursday afternoon.
&&
.KEY MESSAGES...
As of 226 AM EDT Wednesday...
1. A pair of systems expected to track through today and
tomorrow. The second on Thursday will bring more potential impacts
of winds and thunderstorms with embedded heavy rain and damaging
winds.
2. Showery, breezy conditions are expected for the early
portion of the weekend.
3. A low pressure system will likely bring widespread rain to
the region on Monday, followed by seasonably warm temperatures next
week.
&&
.DISCUSSION...
As of 226 AM EDT Wednesday...
KEY MESSAGE 1: Today will open up with increasing clouds and some
showers and thunderstorms as an upper trough lifts northeast.
Although it`s not the strongest trough, it`s managed nighttime
convection in the Great Lakes region. South flow today should allow
for moderation into the 70s to near 80 today. Despite somewhat dry
dewpoints, good lapse rates in tandem with the upper trough should
produce scattered to numerous shower activity. Winds aloft are not
strong, but with dry air entrainment, there should be some
acceleration of winds in any thunderstorms. Looking upstream at
Buffalo, NY, showers and storms have produced gusts around 30-35
knots. So that could be in the cards for us too.
Thursday`s activity will be more significant. A sub-990mb low will
pass near to north of Ottawa. The level of synoptic support is quite
strong with a near 130mb upper level jet nosing in. Isentropic
ascent, some elevated instability, and large scale lift will result
in a swath of moderate to heavy rain as the warm front races
northeast. After the warm front lifts out of the region, the
question continues to be how much wind will be able to mix to the
surface after any rainfall. Winds of 45-50 knots descends to about
1500-2000 ft above ground levels. So it will not take much to mix
winds to the surface; however, the warm sector has trended towards
continued convection embedded within the warm sector as occlusion
quickly takes place late Thursday morning into the afternoon. For
now, max wind gusts are depicted reaching 30-40 mph, and locally up
to 45 mph near Malone, New York. With all the leaves on the trees,
this could pose a greater likelihood for downed branches. Isolated
to scattered power outages will be possible on Thursday.
Next on Thursday will be the convection: The Storm Prediction Center
has upgraded the Severe Weather Outlook to a Slight Risk (Level 2 of
5) for isolated strong to severe thunderstorms. The situation
involves high shear in the 0-6km layer of 45-55 knots while
instability of 500-750 J/kg and somewhat low equilibrium levels make
it likely that activity remains short and tilted. CAMs are split on
timing as well, and that will affect how much instability convection
has to develop. With the fast flow, the main concern will be whether
any storms can mix down the strong winds to the surface, and that
will be the primary severe weather hazard. Given such a strong
surface low, excellent inflow from southeast flow, and the quick
westerlies aloft, rotating updrafts are possible. The HREF/REFS
indicates some helicity tracks through the region as well. However,
the strong shear mentioned before may tilt updrafts too much to
sustain organized convection. The system will track east Thursday
evening with storms clearing the region.
KEY MESSAGE 2: Thursday`s strong low pressure gets stuck near Quebec
City for a few days with an upper low nearby. This will impart
breezy west-northwest winds with occasional showers. The greatest
chances will be along the international border given proximity to
the surface low. Both days feature some tall, skinny CAPE profiles.
Given that fast flow will continue with some good low-level lapse
rates, a few showers could produce gusty winds, but none are
anticipated to be particularly strong. Temperatures will trend
cooler heading into the weekend with a seasonable day Friday before
the core of the coldest air arrives Saturday placing temperatures in
the lower 60s to lower 70s.
KEY MESSAGE 3: A deep trough over the Canadian maritimes will linger
through the weekend bringing showers and the occasional thunderstorm
to the Northeast before finally shifting out into the Atlantic Ocean
early next week. There remains the potential for a potent low
pressure system to pass to our south which would produce widespread
rain and embedded thunderstorms across the region on Monday and
Monday night. Determinstic models continue to disagree on exact
track and timing of this system, with 40-65% chance of measurable
precipitation Monday afternoon and 25-50% chance of a half an inch
within 24 hours during this period. With so much disagreement in the
determinsitic global models, temperatures early next week may depend
on precipitation, but the majority of models at this point seem to
be suggesting temperatures could increase to and even reach slightly
above seasonal normals by midweek with highs in the upper 60s to
lower 80s and lows in the upper 40s to lower 60s.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Through 06Z Thursday...Isolated to scattered showers with a few
thunderstorms likely Wednesday afternoon. VFR conditions are
expected to be the main flight category over the next 24 hours.
There is the low chance of some fog development in the typical
valley locations (SLK most likely spot) early this (Wednesday)
morning, but overall thinking light winds and clouds should keep all
sites in northern New York and Vermont clear of vis and cig
restrictions through the morning hours. Current light and variable
winds are anticipated to increase out of the south around 09Z-15Z
Wednesday to 5-15 knots. Showers and thunderstorms are likely to
develop at 15Z-21Z Wednesday, though coverage will be spotty and
scattered, so have utilized PROB30s farther out in time than usual.
Most likely sites to see thunderstorms will be SLK, PBG, and MSS
from 16Z through 23Z Wednesday. SLK is most likely site to see
occasional southerly wind gusts 15-20 knots, but any site that gets
a thunderstorm could have a quick, strong gust. However, severe
weather is not forecast over the next 24 hours.
Outlook...
Thursday: Mainly VFR, with areas MVFR possible. Windy with gusts
to 30 kt. Definite SHRA, Slight chance TSRA.
Thursday Night: VFR. Windy with gusts to 30 kt. Chance SHRA.
Friday: VFR. Chance SHRA, Slight chance TSRA.
Friday Night: VFR. Chance SHRA, Slight chance TSRA.
Saturday: Mainly MVFR, with local IFR possible. Likely SHRA,
Chance TSRA.
Saturday Night: MVFR/IFR conditions possible. Chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight
chance TSRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
WHAT HAS CHANGED...Haynes
DISCUSSION...Storm/Haynes
AVIATION...Storm
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