-- Discussion containing changed information from previous version are highlighted. --
551
FXUS61 KBTV 161127
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
727 AM EDT Sun Jun 16 2024

.SYNOPSIS...
After a pleasant Father`s Day, temperatures will soar across
the North Country as high pressure builds over the region.
Worst conditions will begin Tuesday and continue through
Thursday with a combination of temperatures above 90 degrees
and higher humidity resulting in dangerous heat index values
likely above 100 degrees for some locations. Overnight
temperatures will not sufficiently cool to mitigate heat related
impacts, especially for vulnerable populations.

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
* Today will be a good day to finalize preparations for a
  period of extended hot conditions.

As of 718 AM EDT Sunday...Only minor adjustments necessary with
conditions matching closely to the forecast. The Saranac Lake
airport did manage to drop below freezing and reached a new
daily minimum temperature record of 30 degrees. Elsewhere, there
have been reports of isolated pockets of frost in the
Adirondacks and northeastern Vermont. Also, there is a little
more fog than expected that formed at sunrise; this should
dissipate over the next hour. Otherwise, today will be pleasant
and ideal for outdoor activities.

Previous Discussion...A seasonally mild day is ahead for
Father`s Day with ample sunshine and light winds. This will be
the last day for cooler conditions with high pressure ridging
northward by Monday bringing a prolonged period of hot
conditions. Tonight will be much warmer than this morning due to
increasing cloud cover ahead of a weak warm front. A few
showers will be around early Monday, but coverage will likely be
isolated with the front lifting quicKly into Canada by Monday
afternoon. Heat will build through the day under increasing
southwesterly flow and strong warm air advection. Progged
925-850mb temperatures increase into the low 20s and upper teens
respectively supporting highs in the mid/upper 80s.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 334 AM EDT Sunday...Warm, moist air will continue to
stream northeast overnight Monday. Sheltered areas of eastern
Vermont will be the last to see this humid air mass arrive, and
so 60s to near 70 is expected. Tuesday will mark the beginning
of oppressive heat. A large upper level high will set up just to
our south. 925hPa temperatures will climb to 25- 26 C, which
under full sunshine is suggestive of temperatures in the mid to
upper 90s. Despite how humid the air on the ground is, the air
aloft is actually quite dry, and this will likely result in only
localized diurnal showers and storms. Dry air aloft and
forecast subsidence in the mixed layer is supportive of very
efficient warming that pushes us well into the 90s across the
region and perhaps coming close to 100 even. There won`t be much
flow beneath high pressure, and so it will feel unpleasant.
Given the cool days that we`ve just experienced and that this is
the first major heat of the season, we have not had a chance to
acclimate to these conditions. So heat-health impacts are
expected to be high. HeatRisk is currently forecasting Moderate
to Major heat impacts, mainly due to heat being a cumulative
impact. High heat is the highest cause of weather related
fatalities. Please be prepared for this event. This could be a
life-threatening heat event. Sites such as
weather.gov/safety/heat-survivors has anecdotes highlighting the
importance of taking heat events seriously. Other helpful
resources include heat.gov, and locally
vem.vermont.gov/preparedness/heat for VT and
health.ny.gov/environmental/emergency/weather/hot for NY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 334 AM EDT Sunday...Potentially deadly heat will continue into
Wednesday. There will be no overnight relief with overnight lows in
the mid 60s across the Dacks and eastern Vermont, and low to mid 70s
in the broader valleys. As noted earlier, the impact of heat is
cumulative. So Wednesday will likely the worst day, and not just
from forecast number values. Conditions on Wednesday are almost
exactly like Tuesday`s. Temperatures are likely to soar again into
the mid to upper 90s. In fact, the forecast has 90 before noon...
With it being the second day in a streak of warm weather, HeatRisk
is forecasting Major to Extreme heat impacts across the region. Be
extra vigilant of your health, drinking plenty of water and avoiding
prolonged strenuous activity during the hottest time of day. Check
up on friends, neighbors, and those most vulnerable to heat.

A weak trough will start nosing into northern New York Wednesday
afternoon, and that could leave the St. Lawrence Valley slightly
cooler in the lower 90s. This should also result in some greater
extent of showers and thunderstorms as the weak upper trough grazes
the international border. Again, despite how humid it is on the
ground, the mid-levels are rather dry. Although this might not
result in large coverage of storms, it does mean that there will
likely be about 2000-2500 J/kg of CAPE with inverted V type
soundings at 25-30 knots of 0-6km shear. Any storm that could
develop on Wednesday may be capable of producing severe storms due
to the heat and marginal shear. The latest GFS forecast even
suggests some mid-level cooling aloft may generate some 7-8 C mid-
level lapse rates. So in addition to heat, we may be dealing with
strong storms. However, will note that this trough and its placement
will likely be influenced by convection in the Northern Plains.
Convective feedback and the small nature of this trough means it
could be more prone to error than the average forecast with larger
features not as influenced by convection.

On Thursday, flow will become a bit more westerly as the ridge
starts to flatten in advance of an incoming upper trough and
attendant cold front. Although some of the edge of the heat will be
taken off by about 2 to 4 degrees north, that`s still low to mid
90s, and still mid to upper 90s south. Additionally, this will
provide a sharper focus for showers and thunderstorms during the
evening hours while about 30-40kts of 0-6km shear is present. Plenty
of warmth suggests CAPE values approaching 1000-1500 J/kg is still
likely. The front itself looks to shift south and east sometime on
Friday.

Dry air will filter in behind this front, and it will be a welcome
relief. Overall, it`s not significantly cooler behind the front, and
so above normal temperatures in the mid to upper 80s will still be
likely running forward. The broad upper high will be weakening and
shifting south. This will put us in a stream of showers and
thunderstorms riding along the periphery of the ridge axis.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
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Through 00Z Monday...A few VLIFR cigs are out there in the
vicinity of MPV/SLK where fog formed around sunrise. This should
dissipate by 13Z with VFR for the remainder of the period. Winds
will be light out of the south today and tonight. Only other
sensible weather will be towards the end of the period along the
Canadian border where a few showers will be possible mainly for
MSS/EFK, but could dip towards SLK/PBG/BTV around 12Z.

Outlook...

Monday: VFR. Slight chance SHRA.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Slight chance SHRA, Slight chance TSRA.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Chance SHRA, Slight chance TSRA.
-- End Changed Discussion --

&&

.CLIMATE...
Hot temperatures will result in values near records by the
middle of next week. Below are some of the records under threat
of being broken.

Record High Temperatures:

June 18:
KBTV: 97/1994 Forecast 98
KMPV: 93/1994 Forecast 93
KPBG: 94/1994 Forecast 93
KMSS: 97/1994 Forecast 94
KSLK: 94/1907 Forecast 93

June 19:
KBTV: 100/1995 Forecast 98
KMPV: 95/1995 Forecast 94
KPBG: 93/2001 Forecast 94
KMSS: 94/1955 Forecast 93
KSLK: 93/1994 Forecast 92

June 20:
KBTV: 95/2012 Forecast 94
KMPV: 90/2020 Forecast 92
KPBG: 94/1964 Forecast 92
KMSS: 92/2012 Forecast 91
KSLK: 92/1995 Forecast 89

Record Low Temperatures:

June 16:
KSLK: 32/2020 Forecast 30


Record High Minimum Temperatures:

June 19:
KPBG: 70/1949 Forecast 70

June 20:
KPBG: 70/1953 Forecast 72
KSLK: 68/2012 Forecast 68

&&

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

&&

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