260
FXUS61 KBTV 161818
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
218 PM EDT Sun Aug 16 2026
.WHAT HAS CHANGED...
As of 217 PM EDT Sunday...
Increased thunder chances during the midday and afternoon hours on
Monday, but severe t-storm potential remains low.
&&
.KEY MESSAGES...
As of 217 PM EDT Sunday...
1. Widespread showers overnight, with separate development of
showers and some embedded thunderstorms midday/afternoon Monday.
2. Seasonable conditions persist through the second half of the
week with mainly dry weather Thursday into Saturday.
&&
.DISCUSSION...
As of 217 PM EDT Sunday...
KEY MESSAGE 1:
High clouds are in the process of increasing from west-to-east
across northern New York and Vermont this afternoon, associated with
mid-level trough extending from northern Ontario southward across
Lake Huron, Lake Erie and into Ohio. PBL winds have turned southerly
with 1022mb sfc anticyclone now east of Cape Cod. Southerly winds
should remain moderate overnight with approaching frontal system and
absence of much radiational cooling overnight. Overnight lows will
generally range from the low-mid 60s. With the increasing southerly
gradient flow, a Lake Wind Advisory has been posted (see Marine
section below for tonight. The Lake Wind Advisory may be necessary
through the morning hours on Monday as well.
Not much in the way of mid-tropospheric height falls overnight, but
some low-level WAA in advance of the approaching front should be
just enough to yield scattered rain showers overnight, especially
after 03Z or so. There is some marginal elevated CAPE for parcels
lifted from 850-775mb per HRRR and NAM3 forecast soundings. As such,
kept with the idea that there could be a few embedded convective
elements with a few overnight rumbles of thunder possible. PoPs are
highest across central/nrn VT during the pre-dawn hours (70-80%) and
generally 30-50% elsewhere.
Heading into Monday...surface boundary progresses through slowly
from west to east. If we get some breaks in the cloud cover, there
is a chance for modest PBL destabilization by late morning/early
afternoon. Consistent with this, the 12Z HRRR developed 500-800 J/kg
SBCAPE during the peak heating hours Monday, that is relatively
uncapped. Anticipating a separate broken line of showers - and
perhaps a few embedded thunderstorms - to develop during the midday
hours while drifting slowly ewd across central/ern VT by mid-late
afternoon. Weak mid-level lapse rates and modest sfc-6km shear
suggest that if thunderstorms form, they are unlikely to become
severe. However, have shown a separate period of 60-70% PoPs to
account for this expected separate period of convective showers and
storms during Monday afternoon. High temperatures on Monday will be
seasonable to slightly below average for mid-August, in the mid-
upper 70s.
KEY MESSAGE 2: Lingering showers will move out on Wednesday night and
Thursday as broad cyclonic flow slowly migrates eastward. After the
system moves off, a period of drier weather looks to return for the
latter half of the week. Daytime temperatures increase towards
climatological normals into next weekend with highs in the 70s and
lower 80s as well as overnight lows falling into the 40s and 50s.
There is the potential for another system to sweep through next
weekend bringing some sustained showers. We`ll continue to monitor
this potential as the event approaches.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Through 18Z Monday...Dry conditions through the daylight hours today
with southeasterly winds 5-15 knots, more east-northeasterly 5-10
knots at site MSS. Widespread showers with beneficial rainfall
tonight will be followed by scattered showers and localized
thunderstorms Monday. As rain showers arrive this evening and
tonight, we`ll see a general trend towards MVFR or lower ceilings,
reaching widespread MVFR cigs by 01Z-04Z Monday. Winds should
persist out of the south, with sites MSS and SLK picking up a more
southwesterly component around 05Z-08Z. Southerly flow will likely
remain channeled and gusty through the Champlain Valley, gusting
20-25 knots at site BTV throughout the night tonight and early
Monday morning. IFR ceilings are possible sometime tonight and into
Monday morning as well, though some uncertainty remains. Most likely
spots for IFR ceilings will be SLK and MSS with that southwesterly
wind, though no site is out of the question. As of this afternoon,
confidence is not high enough to include in the TAF. Most model
soundings are not as saturated as probabilistic data might suggest.
As the showers approach and we get additional observations from
areas upstream, this may increase confidence in one direction or
another. LLWS is also possible as a southwesterly low level jet
crosses the region around 02Z-12Z Monday. Most likely spots for low
level wind shear are BTV, SLK, MPV, EFK, and RUT, though brief LLWS
may occur elsewhere as well.
Outlook...
Monday Night: Mainly VFR, with local IFR possible. Slight chance
SHRA.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA,
Chance TSRA.
Wednesday Night: VFR. Chance SHRA.
Thursday: VFR. Slight chance SHRA.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
&&
.MARINE...
As of 217 PM EDT Sunday...
A Lake Wind Advisory has been posted for Lake Champlain tonight. A
sharp increase in southerly gradient flow is expected this evening,
with sustained winds 20-30kt over the broad lake through the
majority of the overnight hours. The Great Lakes Wave Model
indicates max wave heights of 3-4 ft between 06-14 UTC from near
Colchester Point to east of Valcour Island, which appears reasonable
based on expected southerly sustained wind speeds. Should see
those wind speeds lessen after noon on Monday.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
WHAT HAS CHANGED...Banacos
DISCUSSION...Banacos/Storm
AVIATION...Storm
MARINE...Banacos
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