852
FXUS61 KBTV 280710
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
310 AM EDT Tue Jul 28 2026

.WHAT HAS CHANGED...
As of 217 AM EDT Tuesday...

The forecast remains on track. Rainfall amounts have been
refined with the latest guidance, but no significant changes to
the overall forecast messaging. Highest rainfall totals still
expected over northern NY and southern VT today through
Wednesday night. Some isolated flash flooding remains possible,
mainly tonight into Wednesday, but widespread hydro issues are
not anticipated at this point.

&&

.KEY MESSAGES...
As of 217 AM EDT Tuesday...

1. Numerous showers and thunderstorms today with localized heavy
rain.

2. Periods of rain continue tonight through Wednesday night.
Isolated flash flooding is possible if storms repeatedly track
over the same area.

3. Unsettled weather continues into the weekend with the
approach of another developing mid to upper level trough.

&&

.DISCUSSION...
As of 217 AM EDT Tuesday...

KEY MESSAGE 1: Strengthening deep southerly flow ahead of a
developing low will support scattered to numerous showers and
thunderstorms today, with locally heavy rainfall being the main
threat. Dewpoints in the 60s today will locally reach near 70
over the Saint Lawrence Valley and portions of the Champlain
Valley. This will translate to a slightly more humid air mass
today, though temperatures will not be quite as warm as
yesterday. Throughout the day today, a shortwave aloft will dig
into the base of broader longwave troughing over eastern Canada,
eventually closing off into a closed low over the northeastern
US later today. The approaching system has triggered the
development of scattered showers and thunderstorms upstream,
which will increase in coverage as they move eastward into our
forecast area today. Minimal deep-layer shear will limit
overall severe potential, and the greatest threat for today`s
thunderstorms will remain heavy downpours. It continues to
appear that the most likely area to receive locally heavy
rainfall today will be northern NY and southern Vermont, where
today`s rainfall amounts will range from 0.5 to 1.0+ inches.
Higher resolution models indicate some isolated swaths of 1-2
inches are possible today in these areas, especially if multiple
storms or heavy showers track over the same area. Central and
northern Vermont will generally see rainfall amounts today under
0.5 inch, though some areas could see locally higher amounts if
a heavier storm moves over. These ranges are the general
expected QPF amounts for today, but expect high variability in
QPF swaths based on where individual storms track today.
Overall, these amounts could result in ponding in poor drainage
areas, but the overall flood risk for today is relatively low
due to antecedent dry conditions. The exception would be if any
showers or thunderstorms continually train over the same area
and locally exceed flash flood guidance. For reference, current
one hour flash flood guidance from the NERFC is around 1.5-2.5
inch/hour, and current three hour flash flood guidance is 2-3
inch/hour. We will be watching hydro closely today, but
widespread issues are not anticipated.

KEY MESSAGE 2:  Overnight tonight, showers and thunderstorms will
continue as the low shifts closer. With warm cloud depths
supporting efficient rainfall production and precipitable water
values 1.5 to 1.75 inch, locally heavy rainfall remains a threat
overnight, though waning instability will temper overnight
rainfall rates somewhat. The flow will increase from the
southeast overnight, which will allow for some increased
topographic influences in the overnight QPF forecast. This
pattern favors higher overnight rainfall amounts over the
eastern slopes of the southern Greens along with the eastern
slopes of the Adirondacks. With the prolonged precipitation
event, the relative flood risk does increase slightly going into
Tuesday night, especially as noted before if multiple heavy
showers train over the same area. Widespread issues are not
anticipated, but isolated flash flooding can`t be ruled out.

Periods of rain, locally heavy at times, will continue through the
day Wednesday and into Wednesday night.  By Wednesday morning, the
surface low will be centered near northern New Jersey.  The system
will send waves of rain northward through our forecast area,
interspersed with some drier periods especially further north.
Instability Wednesday will be lower than the previous few days,
which will keep coverage of thunderstorms more limited.  This in
turn will somewhat limit rainfall rates without the convective
aspect, though the moist atmosphere and additional lift in
orographically favored areas (mainly eastern slopes of the southern
and central Greens along with eastern slopes of the Adirondacks)
will maintain the localized heavy rain and isolated flash flood threat.
Rainfall totals for Wednesday and Wednesday night will be
highest in these orographically favored areas, where 0.75-1.5
inches are forecast. Elsewhere , rainfall amounts will range
from 0.25 to 0.5 inch...lowest in rain shadowed areas of the
Northeast Kingdom.

The heavy rain threat and isolated flood threat comes to an end
Thursday as the low weakens and departs. Scattered showers will
weaken through the day and additional rainfall amounts will be
limited to just a few additional tenths of an inch.

KEY MESSAGE 3: An unsettled weather pattern will continue into the
weekend as our approaching system slowly departs Friday with an
additional system possibly arriving sometime late into the weekend.
There is still a large spread in timing of the departure of our
approaching system and the weekend system, but trends have moved
towards lingering showers and embedded thunderstorms Friday, with a
more delayed trend in the weekend activity, perhaps closer towards
Monday next week. Models denote cyclonic circulation lingering to
our south and east Friday with continued wrap around moisture in
portions of eastern Vermont. With easterly flow blocked against the
Greens, a differential heating boundary between the cooler eastern
Vermont and warmer Champlain Valley and northern New York may set
up. This will lead to areas of shower development along the
convergence boundary Friday afternoon potentially.

Weak ridging tries to build into our cwa for Saturday, before
another shortwave, associated with a 700-500mb trof approaches from
the Great Lakes. Model ensembles in the GEFS and GEPS denote a more
delayed system evolution closer to Sunday or Monday, with more
isolated to scattered terrain showers Saturday afternoon. This is
line with abundance of subsidence that may be across the area as our
current system occludes and subsides over southern New England late
this week. Latest guidances shows Saturday highest potential over
northern NY, while Sunday activity wl be more widespread impacting
both VT and NY. Limited run to run continuity and large spread in
potential solutions results in low forecaster confidence and
associated predictability on probability and timing of precip,
especially Sunday into early next week. Temps will be driven by
clouds/precip, but mostly above normal values anticipated,
especially at night with lows in the upper 50s to upper 60s, while
highs range from the mid 70s to mid 80s. Some levels of humidity are
expected, but the probability of much above normal temps or
significant heat is low given the anticipated pattern.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Through 06Z Wednesday...The main aviation challenge for the
remainder of the night will be localized valley fog
development. Valley fog is expected at terminals that recently
picked up rain, including KMPV and KEFK. Further west,
confidence in fog development over KSLK and KMSS is slightly
lower due to flow just off the surface, which may promote enough
mixing to prevent dense fog development. Nonetheless, given
recent rainfall, have still included mention of BR development
at these sites given recent trends and rainfall. Can`t
completely rule out fog at the other terminals, but have left
mention out of the TAFs given lower confidence.

Isolated morning showers with a few embedded thunderstorms will
become increasingly widespread from west to east through the
day today. After 18Z, periods of moderate to locally rain and a
few embedded thunderstorms may produce localized MVFR to IFR
visibility restrictions, with a trend towards lower MVFR ceilings
expected towards and after 00Z.

South/southeasterly winds will increase to 5-10 knots during
the day today. Some afternoon gusts 10-20 knots are expected at
Vermont TAF sites between 15Z and 00Z today.

Outlook...

Wednesday: Mainly VFR, with local MVFR possible. Windy with gusts
to 30 kt. Likely SHRA, Slight chance TSRA.
Wednesday Night: MVFR/IFR conditions possible. Likely SHRA.
Thursday: Mainly MVFR, with local IFR possible. Likely SHRA,
Slight chance TSRA.
Thursday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, Slight chance TSRA.
Friday: VFR. Chance SHRA, Chance TSRA.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Slight chance SHRA, Slight chance TSRA.

&&

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

&&

$$

WHAT HAS CHANGED...Duell
DISCUSSION...Danzig/Duell
AVIATION...Duell