Winooski, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

020
FXUS61 KBTV 211133
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
733 AM EDT Sat Jun 21 2025

.SYNOPSIS...
Very pleasant weather is expected today. Overnight, showers and
thunderstorms will shift southeast, with the potential for
scattered strong to severe thunderstorms capable of frequent
lightning, heavy rain, and damaging winds. The early part of
next week will feature increasing heat and humidity, especially
Monday. A cold front will slide south late Tuesday and
Wednesday, which will return us to more seasonable weather.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 725 AM EDT Saturday...
**Heat Advisory in effect from 11 AM Sunday through 8 PM Sunday
 for high heat and humidity across the St. Lawrence Valley,
 southern Champlain Valley, and lower Connecticut River Valley.
 Heat will continue to build, and a Extreme Heat Watch is also
 in effect Monday through Tuesday evening across the Champlain
 Valley and lower Connecticut River Valley

**Slight Risk Outlook (Level 2 of 5) tonight for scattered
 severe thunderstorms in St. Lawrence and Franklin Counties with
 the primary hazards being strong damaging winds, frequent
 lightning, and heavy rain.

Today`s forecast features fantastic weather. Mid-level ridging
will promote dry conditions with fair weather cumulus and a
steady breeze in the afternoon as we mix in some of that dry air
to the ground. Expect temperatures to climb in the upper 70s to
mid 80s with comfortable dewpoints.

This evening, the ridge will slide east, allowing increasing
southwesterly return flow. Warm, moist air will advect as a broad
warm front moves northeastwards. An MCS is present over the Northern
Plains and will race east parallel to that warm front and pass just
north of Montreal towards midnight. Sustaining this complex of
thunderstorms will be increasing 55-65 kt 850hPa flow driving
instability quickly northeast across the Great Lakes region. There
will also be a deep elevated mixed layer present, resulting in a
tongue of high instability. The main forecast question is how much
thunderstorm activity occurs south of the MCS, which will depend on
the instability advecting into the region. Typically, it is best to
have the high instability already in place, leading to some
uncertainty in the coverage and intensity of activity. Ensemble
clusters continue to depict modest spread in the speed of 850mb
flow and available instability. A notable shift northward in
several model scenarios could also result in the highest
instability and moisture to be north of the international border
given how high instability tapers off in its eastward extent.
The potential remains conditional and somewhat uncertain, with
one scenario being some decaying nighttime thunderstorms and
moderate rain, or strong to severe thunderstorms with the
potential for damaging winds and a real lightning show. The
Storm Prediction Center has maintained a Slight Risk outlook for
northern New York with the primary hazard being damaging winds.
HREF max gusts depict a few ensembles that highlight the
potential for strong to severe thunderstorm wind gusts within
the Slight Risk.

Some of this activity could bleed into Sunday morning depending on
how quickly the MCS translates east-southeast. If the MCS lifts far
enough north and convection south of it drives a cold pool
southwards, then we may also have precipitation develop as
southwesterly flow brings back that warmth and moisture back across
Vermont and northern New York. Some high res guidance is sparking
convection associated with that Sunday afternoon and evening.
Fortunately, the speed of deep-layer flow will have decreased
substantially, but this potential for convective development in the
midst of the elevated mixed layer and a forcing mechanism in
isentropic lift could result in thunderstorms getting to tap into
2000-2500 J/kg of CAPE. Dry air should limit coverage, but the
presence of a boundary could focus clusters if enough activity
can get going. SPC has placed the forecast area in a Marginal
Risk outlook (Level 1 of 5) across the region, and given this
potential scenario, this seems reasonable. Temperatures climbing
on Sunday, especially south given the mesoscale frontal
boundary over the northern extent of our forecast area.
Temperatures will range from the mid 80s to lower 90s, and heat
indices will creep up towards 87-97 across the region.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 321 AM EDT Saturday...
**Extreme Heat Watch in effect 11 AM Monday through 8 PM
 Tuesday

**Dangerously hot conditions with heat index values up to 105
 possible for the Champlain and Connecticut River valleys Monday
 morning through Tuesday evening. Heat related illnesses
 increase significantly during extreme heat and high humidity
 events.

High pressure in the southeastern United States will advect mild and
humid air into the forecast area on Sunday night with lows failing
to fall below the mid 60s to mid 70s. Dew points will remain
steadily in the mid 60s to lower 70s, resulting in uncomfortable
sleeping weather. This will also act as a warm starting off point
for temperatures to rise quickly Monday.

High pressure will shift north and east for the start of the work
week, resulting in potentially the hottest day of the week as highs
soar into the 90s by noon with the highest temperatures occurring in
wider valleys, particularly the Champlain and Connecticut River
valleys. Record high maximum and minimum temperatures for several
climate sites are likely to be broken, with more details in the
Climate section below. One possible limiting factor to heat risk
concerns will be the ability for the atmosphere to mix drier air
aloft down to the surface, especially east and northeast of the
Greens where the mountains may act as a barrier between areas of
high humidity and relatively lower humidity.

Still, heat indices in the 90s and 100+ are likely, especially for
the Champlain and Connecticut River valleys, putting our HeatRisk
into the major category across the entire region. This is expected
to be the hottest weather of year so far, and Monday night`s lows in
the upper 60s to mid 70s will provide little relief overnight. The
heat will be enough to affect anyone without effective cooling
and/or adequate hydration. Be sure to stay hydrated and check on
those more vulnerable to heat impacts.

Tuesday will be our second hot day with highs in the upper 80s to
mid 90s and similar atmospheric mixing conditions to Monday. Because
of the slightly lower temperatures and dew points in the mid 60s to
lower 70s, heat indices are anticipated to reach the upper 80s and
90s in the afternoon, though 100+ indices are still possible in the
broad valleys. A cold front is forecast to move through on Tuesday
evening, bringing and end to the extreme heat with increasing cloud
cover and some precipitation (20-50% chance of measurable precip).

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 321 AM EDT Saturday...The cold front mentioned in the Short
Term discussion above is expected to stall over southern New York
and southern New England mid week with waves moving across it
bringing chances of isolated to scattered showers or thunderstorms
and generally unsettled weather for the second half of the week.
Temperatures moderate into the late week, dropping to the mid and
upper 70s during the day and the mid 50s to lower 60s at night.
Deterministic models indicate the best next chance of appreciable
precipitation occurs Friday as surface low pressure crosses the
Great Lakes west to east.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Through 12Z Sunday...Winds are currently light or terrain
driven at 5 knots or less. Fog has dissipated, leaving clear
skies. Limited fair weather cumulus is expected, with mainly
FEW070 and some high clouds at or above 15000 ft agl. After
20z, winds will trend south to southwesterly with increasing
clouds from the northwest. Showers and thunderstorms are likely
to slide southeast between 04-10z. The highest chances will be
along the international border with activity decaying as it
slides south. Fast 45-55 knot winds at 2000 ft agl will develop
along and ahead of thunderstorms, as well as increasing surface
wind speeds to 9 to 15 knots with gusts 18 to 25 knots. Although
showers and storms will move south and east beyond 10z, LLWS
will remain for a little longer and ceilings will drop towards
MVFR behind the front. Conditions will generally improve beyond
12z.

Outlook...

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

&&

.CLIMATE...
Record high maximum and minimum temperatures are likely during an
upcoming hot spell. Below are the current daily records that could
be broken:

Max Temp Records for 06-23
Site  Forecast   - Current Record
KBTV  98 (Break) - 96|2020
KMPV  93 (Break) - 90|1975
KMSS  94 (Break) - 92|2020
KPBG  96 (Break) - 95|1983
KSLK  92 (Break) - 89|1964


Max Temp Records for 06-24
Site  Forecast   - Current Record
KBTV  96 (Tie)   - 96|2003
KMPV  93 (Break) - 89|2003
KMSS  92 (Break) - 91|1957
KPBG  94 (Break) - 93|1975
KSLK  90 (Tie)   - 90|2003


High Min Temp Records
Date   KBTV      KMPV     KMSS     KPBG     KSLK
06-22  71|1976   67|1953  66|1976  68|1976  63|1976
06-23  75|1894   65|1985  71|1975  70|1975  64|1921

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory from 11 AM to 8 PM EDT Sunday for VTZ009-011-021.
     Extreme Heat Watch from Monday morning through Tuesday evening
     for VTZ001-002-005-009-021.
NY...Heat Advisory from 11 AM to 8 PM EDT Sunday for NYZ026-035-087.
     Extreme Heat Watch from Monday morning through Tuesday evening
     for NYZ028-035.

&&

$$
SYNOPSIS...Haynes
NEAR TERM...Haynes
SHORT TERM...Storm
LONG TERM...Storm
AVIATION...Haynes
CLIMATE...Team BTV