Smugglers' Notch

000
FXUS61 KBTV 281112
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
712 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 /12Z TUESDAY THROUGH SATURDAY/...
Through 12Z Wednesday...An area of showers with embedded
thunderstorms will slowly move into the region from west to east
today. MSS and SLK should see them by 13Z, but it will likely take
until mid-afternoon for them to reach the rest of the region.
Reductions of visibility to MVFR and IFR will occur in the heaviest
of the rain, accompanied by lightning. On and off showers and storms
will occur during the night and through tomorrow. Southerly to
southeasterly winds will increase during the day today and continue
through tonight. Gusts in the 10-20 KT range are expected at the
terminals, with potentially higher gusts at BTV and RUT. Intervals
of LLWS will occur this evening and tonight. Ceilings will lower
tonight, likely into the MVFR and IFR range for most places. The
terminals most likely to see IFR ceilings are MPV and EFK, and the
terminals least likely are BTV and RUT.

Outlook...

Wednesday: Mainly VFR, with local MVFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: MVFR/IFR conditions possible. Chance SHRA,
Slight chance TSRA.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Slight chance TSRA.
Thursday Night: VFR. Slight chance SHRA.
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...Myskowski