650
FXUS61 KBTV 191849
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
249 PM EDT Sun Jul 19 2026
.WHAT HAS CHANGED...
As of 249 PM EDT Sunday...
No significant changes at this time.
&&
.KEY MESSAGES...
As of 249 PM EDT Sunday...
1. Rounds of showers and some thunderstorms are expected later
Tuesday (especially northern New York) and Wednesday (especially
Vermont) associated with a fairly slow moving frontal system.
2. No significant impacts through the extended forecast.
&&
.DISCUSSION...
As of 249 PM EDT Sunday...
KEY MESSAGE 1:
Breezy northwest winds will diminish tonight, supporting a chilly
night, as high pressure centered to our south approaches and then
shifts east into the western Atlantic Ocean tomorrow night.
Meanwhile, near surface smoke today is lingering across the Ohio
Valley into the Mid-Atlantic region, and is being well captured by
the RRFS-Smoke model. As winds turn southerly on Tuesday, we`ll
likely see some smoke return; forecast concentrations currently are
indicated to be in the "unhealthy for sensitive groups" range. Some
haze associated with smoke aloft will also likely filter in from the
north tonight into Monday. Vertically integrated smoke may not
become thick enough to reduce air temperature substantially on
Tuesday, with progged values approaching 100 mg/m2, but it`s
something to monitor. Think the combination of increasing clouds and
smoke will lead to another day with daytime temperatures
underachieving, although unlikely as significantly so as yesterday;
this will have implications for the thunderstorm potential discussed
below.
The main weather impacts for the midweek timeframe continue to be on
track with another seasonally potent low pressure system passing to
our west bringing widespread showers and thunderstorm chances. It
continues to not look particularly impactful for our area, but there
are some things to watch for given another potent/dynamic low
pressure system coming through. A primary low should pass
through northern Quebec on Tuesday, with an additional wave of
low pressure developing along the surface boundary closer to
northern New York and Vermont Tuesday night into Wednesday.
While the area of greatest instability is favored to our
south/west over central New York and points south, thunderstorm
probabilities for Tuesday afternoon/evening have increased
slightly into the 35-40% range for most locations in west-
central Vermont and southwestern portions of the Adirondacks and
St. Lawrence Valley, dwindling eastward slightly where
potential for thunderstorms increases after sunset. Lowest
chances of thunderstorms through Tuesday night are across the
Northeast Kingdom. The general west-east gradient is consistent
with thunderstorm probabilities in machine learning data, which
also greatly favors stronger variety of thunderstorms staying
away from our forecast area given limited instability (possibly
remaining under 250 J/kg) associated with moist adiabatic lapse
rates and limited surface heating. With substantial height
falls occurring overnight, instability may actually increase
overnight shifting eastward; the best combination of ingredients
for heavy rain may be in the early morning hours, but concerns
for excessive rainfall at this time are low. Streamflow and soil
moisture are near normal currently and will trend below normal
following a couple of dry and sunny days. As such, impactful
rainfall would tend to be very isolated and reliant on deep
convection and training of thunderstorm cells, which at this
time is unlikely for any of our region. Late Tuesday perhaps
western portions of northern New York will have enough
instability for heavy rainfall rates, but convection during this
period is likely to be progressing eastward.
The somewhat more interesting forecast scenario appears on
Wednesday in Vermont. Probabilistic data is fairly bullish on
thunderstorm potential (6 hour chances increase to around 30%
after 2 PM) across northern Vermont, greatest in central to
northeastern areas. Compared to 24 hours ago, these
probabilities are fairly similar but the maximum area shifted
northward. Will note that while the upper level forcing for
precipitation will be supportive of widespread showers, the
severe weather potential is questionable and may favor areas to
our south and east; mid-level cooling and drying aloft may
inhibit thunderstorm development. However, if there is enough
low level moisture and diurnal heating, ingredients for
thunderstorms will be present in Vermont given the obvious
triggering mechanism. The current projected location of surface
fronts puts a triple point near the northern Champlain Valley
Wednesday morning. Therefore, the wind fields could be conducive
to rotating storms if other required ingredients come together
including sufficient low level moisture and instability. Some
data shows a surge of instability in the relatively modest 1000-
1500 J/kg range overlapping 30-35 knots of deep layer shear in
eastern Vermont Wednesday afternoon just ahead of the cold
front, but even less CAPE is shown in other guidance which
further reduces the risk of stronger storms. Overall, if the
timing of the frontal passage is on the later side, both the
thunder and severe risks would increase across Vermont;
generally New England will have this stormy potential on
Wednesday. Localized heavy rain is possible conditional on the
thunderstorm development, and the Excessive Rainfall Outlook
marginal risk across Vermont reasonable at this point.
KEY MESSAGE 2: Precipitation associated with a departing trough of low
pressure will come to an end by Thursday morning. High pressure will
move in during the day Thursday allowing temperatures to climb into
the mid 80s by Friday for the warmer valley locations. A weak front
could reach unto our area late Friday or Saturday bringing a
scattered chance of thunderstorms briefly. Outside of the scattered
showers, the weekend will be dry with near normal temperatures.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Through 18Z Monday...VFR expected through the period with
FEW/SCT cloud bases mainly 040-070 AGL at most terminals.
Northwest winds moderately gusty to 25 kt through 00Z, abating
thereafter. No precipitation expected.
Outlook...
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Slight chance SHRA, Slight chance TSRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Definite
SHRA, Slight chance TSRA.
Wednesday: MVFR/IFR conditions possible. Definite SHRA, Chance
TSRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
&&
.MARINE...
Gusty northwest winds 15 to 25 knots will continue into early
evening before diminishing tonight. Waves should be mainly
around 1 to 2 feet with some localized higher waves favored on
the Vermont side of the lake towards Shelburne Bay given the 310
degree wind direction. Winds will drop below 10 kts overnight
and waves will drop below 1 foot accordingly.
After a quiet period, another southerly wind event will likely
occur during the day on Tuesday.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
WHAT HAS CHANGED...Kutikoff
DISCUSSION...Langbauer/Kutikoff
AVIATION...JMG
MARINE...NWS BTV
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