454
FXUS61 KBTV 150604
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
204 AM EDT Thu Aug 15 2024

.SYNOPSIS...
Typical summer conditions are lining up for the next few days with
generally dry mornings followed by chances for afternoon showers and
thunderstorms. Most storms will remain below severe thresholds,
though some gusty winds and small hail is possible. Temperatures
will be a little above normal with a gradual warming trend
going into Friday. Conditions turn slightly cooler and unsettled
this weekend, with multiple chances for showers and
temperatures near seasonable normal values.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 204 AM EDT Thursday...Isolated thunderstorms continue
early this morning, which are now clustered in southwestern St.
Lawrence County with the western Vermont/Champlain Valley
activity greatly diminished. The northern New York activity was
where PoPs were quite low, so aside from capturing radar trends
in updated forecast, no substantial changes were made at this
time. Still expect patchy dense fog to develop in the river
valleys, but with a little more low level westerly wind, its
extent and duration look a bit more limited than recent nights.

Previous Discussion...Longwave pattern remains relatively
consistent over the next 24-48 hours. To our west, an
anomalously strong ridge extends from the Mississippi River
Valley north and eastward into central/northern Quebec. Further
south and east, an upper level low will continue to meander over
the Canadian Maritimes, with our forecast area remaining in
northerly flow between the two features. While the overall setup
features a drier northerly flow, there are several chances for
showers/thunderstorms to develop in associated with shortwaves
rotating around the western periphery of the upper low. Diurnal
showers with some embedded thunderstorms are expected this
afternoon into overnight tonight in association with several of
these shortwaves. Deep moisture will initially be limited this
afternoon, with water vapor satellite showing a dry layer
pressing southward through our CWA. Observed dewpoints are in
the 50s for much of the area, with a few localized readings into
the 60s. However, better moisture can be seen to our north,
poised to drop southward into our area this evening into
overnight. The nocturnal timing of the shortwaves will keep
storms going past sunset with overnight MUCAPE values ranging
from 500 to 1000 J/kg. However, will have a surface inversion
develop overnight which will tamper any threat for overnight
severe, so any nocturnal storms should remain below severe
thresholds. Will also see some fog develop in climatologically
favoured valleys, though any nocturnal showers/storms would
impact fog development.

For Thursday, little change in the overall pattern.  Expecting
another round of afternoon showers and thunderstorms to develop,
with slightly greater coverage than today`s due to better depth of
available moisture to work with.  Updraft helicity ensemble
neighborhood probabilities highlighting eastern Vermont as the area
of focus for tomorrow, which lines up with the best overlap in our
CWA of deeper moisture, decent instability (1000 to 1500 J/Kg
SBCAPE), and marginal shear (around 15-20 knots 0-6 km bulk shear).
While thunderstorms will be possible throughout our CWA, eastern
Vermont looks to have the better chance for severe storms containing
some gusty winds and small hail.  The marginal shear will generally
temper any widespread severe threat, and thus we are included in the
SPC General Thunder outline which still looks reasonable.
Otherwise, look for another warm day Thursday with highs in the
80s for much of the area.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 306 PM EDT Wednesday...Ridging will briefly cross the region on
Friday, so generally expect dry conditions to end out the work week.
That being said, it will be warm and humid (highs in the 80s and
dewpoints in the low/mid 60s) so can`t rule out a few showers
developing over the higher terrain during the heat of the afternoon.
Any activity that is able to form will wane during the evening as we
lose daytime heating. However, expect shower chances to start
increasing from the west Friday night ahead of our next system,
approaching from the Great Lakes. Lows will be somewhat
uncomfortable as moisture increases late; most spots will remain in
the 60s overnight.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 306 PM EDT Wednesday...Unsettled weather is expected through
the weekend and into early next week as a slow-moving upper low
trundles eastward from the Great Lakes and eventually across our
region. While not particularly note-worthy compared to what we`ve
experienced at times this summer, it will be fairly humid with PWATs
generally 1.50-1.75 inches through much of the period. As noted by
the previous forecaster, the question will be how much deep
convection we can get. At this point, it does appear that there will
be periods that will favor heavier rainfall rates, with deep warm
cloud depths and little forward movement/back building. Not overly
concerned at this point, but given recent heavy rainfall and wet
soil conditions, trends will need to be monitored. Note that our
entire forecast area continues to be included in the Marginal Risk
in both the Day 4 and Day 5 Enhanced Rainfall Outlooks, which seems
reasonable. Overall rain threat looks highest in NY Saturday and
Sunday as the upper trough draws near, but then expands into VT
Monday/Monday night as the trough moves eastward, with a cold front
eventually moving through sometime in the early to mid week. Daytime
temperatures aren`t expected to be especially warm during this time
frame with highs only in the mid 70s to around 80, but as mentioned
above, it will be muggy, and lows will remain in the 60s for most
spots until a frontal passage Monday or Tuesday.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...Conditions will remain VFR through much of
the period. The main aviation hazard will be locally dense
valley fog in the climatologically favored valleys, although
10 to 20 knots of westerly wind at the top of the nocturnal
inversion is present. While these winds are expected to relax
somewhat, this scenario will limit duration of fog. Greatest
chances of fog are between 09Z and 12Z at MPV, SLK, and EFK.
Showers and thunderstorms will develop during the afternoon,
with coverage at TAF sites expected to be isolated leading to
use of VCSH at this time. Greatest chances are between 18Z and
22Z. Winds will be mainly calm at the surface through the
overnight, then becoming northwesterly at most sites between 15Z
and 18Z at 4 to 8 knots, and diminishing again towards 00Z.


Outlook...

Friday: VFR. NO SIG WX.
Friday Night: VFR. Chance SHRA.
Saturday: VFR. Chance SHRA.
Saturday Night: VFR. Likely SHRA.
Sunday: Mainly MVFR, with areas VFR possible. Likely SHRA, Slight
chance TSRA.
Sunday Night: Mainly MVFR, with areas IFR possible. Chance SHRA.
Monday: Mainly IFR, with local MVFR possible. Likely SHRA, Slight
chance TSRA.

&&

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

&&

$$
SYNOPSIS...Duell
NEAR TERM...Duell/Kutikoff
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Chai/Kutikoff