922
FXUS61 KBTV 021043
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
643 AM EDT Sun Aug 2 2026

.WHAT HAS CHANGED...
As of 215 AM EDT Sunday...

Isolated flash flood threat remains for late today into early
Monday with the upcoming low pressure system due to potential
for slow- moving showers and thunderstorms. Best potential for
any localized flash flooding is across the northern Adirondacks
and St. Lawrence Valley of New York.

&&

.KEY MESSAGES...
As of 215 AM EDT Sunday...

1. Moderate to locally heavy rainfall through Monday with an
isolated risk of flash flooding.

2. Seasonably warm and wet for the second half of next week and
next weekend.

&&

.DISCUSSION...
As of 215 AM EDT Sunday...

KEY MESSAGE 1: Interesting synoptic setup with vertically-stacked low
pressure system centered across Indiana early this morning. A
positive tilt mid-level trough extends newd from the closed low
across sern Michigan into sern Ontario. This positive tilt trough
should serve as a slow-moving focus for convergence and deformation,
with ongoing showers and embedded convective activity likely to
spread northeastward during the daylight hours today (Sunday). While
best precipitation focus should be across the International Border
into Ontario, may see some bands of moderate to locally heavy
rainfall lifting across the St. Lawrence Valley later this morning
into the afternoon hours. Combination of rich moisture (PW values
1.9 to 2.0) and some training thunderstorm potential with SBCAPE
values 500-1000 J/kg does bring potential for widespread 1-2"
rainfall with locally higher amounts across St. Lawrence and
Franklin Counties today. The 00Z HREF Probability Matched Mean QPF
guidance suggest a few locations could see rainfall amts exceeding
2" thru 12Z Monday. Topographically, it is relatively difficult to
get flash flooding in the St. Lawrence Valley given flat terrain,
and QPF values suggest only an isolated threat. Will continue to
message this isolated threat via the Hazardous Weather Outlook.
Narrow CAPE profiles with modest mid-level lapse rates suggest there
isn`t a severe threat with this activity. Have included heavy
rainfall wording only into the forecast grids.

Abundant clouds across the St. Lawrence Valley and the Adirondacks
will keep high temperatures generally in the 74-78F range this
afternoon. Rain generally holds off across Vermont thru early
evening, and partial sunshine allows temperatures to reach the lower
80s in most locations from the Champlain Valley ewd.

For tonight and Monday, wave low moving newd across the Eastern
Great Lakes and across the St. Lawrence Valley will eventually allow
the baroclinic zone to shift ewd as as cold front tonight into
Monday. It appears the bulk of the widespread shower and embedded
thunderstorm activity will be 06-18Z Monday from the Champlain
Valley ewd associated with strengthening low-level frontal
convergence and right entrance region of impressive 90-100kt 250mb
jet for this time of the year. Have indicated 80-100% PoPs overnight
into Monday morning, gradually diminishing thereafter as best
dynamic support and PWATs shift east of our forecast area. Overall
rainfall amounts from the Champlain Valley ewd are expected to range
from 0.5" to 1", with some locally heavier amounts possible due to
thunderstorms. Flash flooding is not currently expected in VT. Highs
on Monday will generally range from the upper 70s to lower 80s.

KEY MESSAGE 2: A typical mid to late summer set-up is in store for the
second half of the upcoming week and next weekend. A strong Bermuda
high pressure system (nearly 600 dm) is forecasted to situate across
the western Atlantic with an elongated but not highly amplified
trough across the northern US. This will keep the longwave pattern
Thursday through Sunday relatively the same with several rounds of
shortwave energy aiding the longwave trough from falling apart. The
North Country will be in a peculiar spot between the ridge and main
upper level trough which should help bring warmth, moisture, and the
occasional shortwave trough overhead. Basically, this means that we
should see periods of showers and possibly a few thunderstorms daily
with temperatures hovering within a few degrees of normal (generally
low to mid 80s). No significant storm systems appear likely on the
horizon given we have no distinguishable surface features to produce
convergence/lift and modest flow aloft. High PWAT values in the 90+
percent range will allow any showers or thunderstorms that develop
to be heavy rainers but they will be scattered at best and short-
lived, meaning flooding isn`t a concern at this time.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Through 12Z Monday...We`ve already begun to see a few showers
move through KMSS this morning but the latest radar trends show
a noticeable break for much of the morning. Widespread rainfall
is on track to move into northern New York this afternoon with
rain slowly pushing eastward through the evening. It will likely
take until 06Z before rain moves into the Vermont terminals
while northern New York should see rainfall between 18Z and 00Z.
MVFR to brief IFR conditions are possible within this rain given
a very moist environment and visibility reductions will likely
be tied to convective elements embedded within the showers.
Winds will be from the south at 10 to 20 knots ahead of the
rainfall with winds diminishing below 10 knots at the onset of
the rain showers. Wind shear is likely to develop as winds
weaken with winds at 2000 ft around 40 knots.

Outlook...

Monday: Mainly VFR, with areas MVFR possible. Likely SHRA.
Monday Night: VFR. Slight chance SHRA.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Chance SHRA, Slight chance TSRA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, Slight chance TSRA.
Thursday: Mainly VFR, with local IFR possible. Chance SHRA,
Chance TSRA.

&&

.CLIMATE...
Possible heavy rainfall tomorrow into Monday could approach
daily rainfall record levels. Below are the current daily
precipitation total records that may be broken at our area
climate sites.

Record Precipitation:

August 2:
KMSS: 1.31/2020

&&

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

&&

$$

WHAT HAS CHANGED...Banacos
DISCUSSION...Banacos/Clay
AVIATION...Clay
CLIMATE...NWS BTV