506
FXUS61 KBTV 301750
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
150 PM EDT Tue Jun 30 2026
.WHAT HAS CHANGED...
As of 117 PM EDT Tuesday...
Updated to include severe thunderstorm watch for St Lawrence
County and upgraded Excessive Heat Watch to Excessive Heat
Warning and Heat Advisory for the rest of the area. A complete
discussion will be issued by 4 PM with all the details.
&&
.KEY MESSAGES...
As of 223 AM EDT Tuesday...
1. Major to localized extreme heat risk expected Wednesday thru
Friday with heat index values near 105 degrees possible in the
Champlain Valley/Eastern Windsor and 95 to 100 elsewhere.
2. Daily chances for showers and thunderstorms increase today
and continue through Friday, with some localized strong to
severe storms possible.
3. Dangerously hot and humid conditions will linger into the
holiday weekend along with daily chances of showers and
thunderstorms.
&&
.DISCUSSION...
As of 223 AM EDT Tuesday...
KEY MESSAGE 1: Ridging builds into the region from the west for
middle and late week, with surface high pressure centering over
the mid- south. This will cause multiple days of southwest flow
and allow an area of significant heat to become established in
the region. This will be aided by an unseasonably strong area of
low pressure across the Great Plains. The ridge looks to remain
in place at least through Friday, before it finally looks to
get shunted to the south on Saturday. The peak of the highest
heat indices looks to be on Wednesday and Thursday, with the
former having the highest dew points and the latter likely
having the highest temperatures. There will be a couple factors
that could potentially mitigate the worst of the heat, but
despite those, there is high confidence of impactful heat from
Wednesday through Friday. The first factor is the potential for
showers and thunderstorms each day, which would drop
temperatures and provide clouds to minimize solar heating. Daily
ridge runners look to pass around the periphery of the high,
and even if they remain to the north over Quebec or to the west
over western New York, there will still be convective debris
carried into the region by the upper level westerly flow. The
other is the exact placement of the high, mostly affecting
Friday. Guidance is still split on the exact end of this heat
event, and there is still a low possibility that the high
retreats to the southwest enough during the day that the worst
of the heat remains to the south, though well above average
conditions would prevail. Overall, heat indices in the 95-100
range are forecast for most places, with heat indices to around
105 in the Champlain and Lower Connecticut River valleys.
Overnight lows around and above 70 will provide minimal relief
and the duration will cause cumulative effects.
KEY MESSAGE 2: The region will be on the northeastern extent of
a large ridge of high pressure, with the surface high centered
well to the south over the middle south. This puts us in the
prime area for ridge runners as they round the top of the high
over the Great Lakes and begin to dive southeast. An elevated
mixed layer will become established on Wednesday and continue
into Thursday, but as is typical, despite a few thousand joules
of CAPE, capping will try to prevent any convection from
forming. However, the shortwaves should provide enough forcing
to overcome this and set off some thunderstorms. The first MCS
is currently over Lake Huron and will move southeast today,
though guidance has thankfully been trending toward sending the
strongest convection south too quickly and keeping it to the
west. The main area to watch for strong to severe storms looks
to be St. Lawrence County. There is no model consistency for
Wednesday through Friday, but there are also no signals of
continuous convection. Even after the current MCS formed, most
model guidance was not even initializing it for a couple runs.
Additional synoptic forcing from a cold front on Saturday could
lead to the most widespread showers and storms. Overall,
adequate 0-6 KM shear and CAPE will be present all week, but the
cap and placement of the ridge will be acting against the
severe potential. Isolated to scattered strong to severe storms
will be possible any day due to the environment, but they will
be very conditional. The biggest hazard with any of these storms
would be damaging winds.
KEY MESSAGE 3: Heading into the weekend, warm weather looks to
linger although temperatures and heat indices will not be as
warm as the week above. Current forecast shows temperatures
generally in the 80s areawide, with temperatures gradually
trending cooler heading into the start of next week. Overnight
lows look to remain on the w armer side, generally in the 60s,
which may lead to accumulating heat impacts. Although it looks
like it won`t be quite as hot as earlier in the week, it is
important to remember to drink water and take frequent breaks if
working outside, especially with such an extended period of
warmer weather. There looks to be chances for showers and
thunderstorms throughout the weekend with the proximity of the
frontal boundary moving through the area, which may also help
keep temperatures cooler. There continues to be a lot of
uncertainty in this time range in regards to precipitation
chances heading into next week, with a wide range of model
solutions at this time.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Through 18Z Wednesday...VFR conditions continue to prevail at
all terminals. Winds continue to remain light and mainly out of
the south but also being influenced by upstream convection. An
area of convection is tracking into northern New York from
Ontario. Showers and thunderstorms may affect MSS and SLK
associated with this area. Brief periods of MVFR and possibly
IFR would be possible if overhead, but VFR will generally
prevail. An additional area of convection is expected to pass
through the region overnight, but timing and location is still a
bit uncertain at this time.
Outlook...
Wednesday Night: VFR. Chance SHRA, Slight chance TSRA.
Thursday: VFR. Chance SHRA, Chance TSRA. Thursday Night: VFR.
Slight chance SHRA, Slight chance TSRA. Friday: VFR. Slight
chance SHRA, Slight chance TSRA. Friday Night: VFR. Slight
chance SHRA, Slight chance TSRA. Independence Day: VFR. Chance
SHRA, Chance TSRA. Saturday Night: VFR. Slight chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
&&
.CLIMATE...
Extreme heat and humidity is possible later this week,
especially on Wednesday and Thursday, which could lead to some
daily records. Below are the current daily high and low
temperature records in jeopardy at our area climate sites.
Record High Temperatures:
June 30:
KBTV: 93/2018
July 1:
KBTV: 96/2018
KMPV: 92/2018
KPBG: 94/1968
KMSS: 94/2018
July 2:
KBTV: 97/2018
KMPV: 90/2018
KMSS: 94/2018
July 3:
KMPV: 91/2002
Record High Minimum Temperatures:
July 1:
KBTV: 76/2018
KPBG: 73/1971
KSLK: 69/2018
July 2:
KPBG: 77/2002
KSLK: 68/2002
July 3:
KBTV: 76/1911
KPBG: 73/2002
July 4:
KPBG: 71/1973
KSLK: 67/1952
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory from noon Wednesday to 7 PM EDT Friday for
VTZ003-004-006>008-010-016>020.
Extreme Heat Warning from noon Wednesday to 7 PM EDT Friday
for VTZ001-002-005-009-011-021.
NY...Heat Advisory from noon Wednesday to 7 PM EDT Friday for
NYZ026-027-029>031-034-087.
Extreme Heat Warning from noon Wednesday to 7 PM EDT Friday
for NYZ028-035.
&&
$$
WHAT HAS CHANGED...Taber
DISCUSSION...Kremer/Myskowski
AVIATION...Neiles
CLIMATE...NWS BTV
|
