816
FXUS61 KBTV 070754
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
354 AM EDT Tue May 7 2024

.SYNOPSIS...
A beautiful day is on tap for today as high pressure settles over
the region. Temperatures will warm into the mid 60s to mid 70s again
under clear, blue skies. Rain and possibly a few thunderstorms are
expected on Wednesday. Wet weather continues thereafter, and we`ll
trend cooler heading into the latter half of the week with
temperatures struggling to rise above 60 by the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 354 AM EDT Tuesday...With plentiful sunshine and temperatures
warming well above normal, we`re expecting a picture perfect day
today. Once any patchy fog dissipates, there won`t be much beyond a
few passing clouds and highs will once again reach into the mid 60s
to mid 70s. Low levels will become quite dry as lapse rates steepen
under daytime mixing, and minimum relative humidity values will drop
down into the 25 to 35 percent range. However, relatively light
winds (though gusts to 20 mph are possible) and our recent rainfall
will help to limit fire weather concerns. High pressure starts to
move eastward tonight, making way for low pressure approaching from
the midwest. Clouds will increase ahead of this system, but the bulk
of any rain will hold off until early Wednesday. Winds will turn to
the south/southeast, helping to keep temperatures a few degrees
warmer than last night/this morning. Lows will be in the 40s
areawide.

Things become more interesting on Wednesday as ridging breaks down,
putting us in the interplay between an upper low centered near the
Canadian Maritimes and another over the Upper Midwest. A shortwave
trough will break off the latter feature and looks to wrap around
the eastern trough, swinging directly across our region. Lift will
be aided by an upper jet also moving overhead. PWATs surge toward an
inch, and with favorable dynamics, expect a swath of showers will
spread from west to east early Wednesday morning into the early
afternoon hours. Some of the rain could be briefly heavy at times,
and while better chances will remain to our south, can`t rule out a
rumble of thunder or two over our southern sections. Once this
initial rain exits by mid afternoon or so, things become a little
more questionable. Mid levels dry out while lapse rates steepen,
allowing for elevated CAPE values of 300-600 J/kg. Shear will be
ample, on the order of 50-60 kt. The question will be how much the
atmosphere can recover after morning`s precipitation, and whether
the cap could be broken and storms become surface based. Note that
most CAMs are indicating convection breaking out behind the main
precipitation shield, keeping most of the stronger activity to our
south. Still, there are some indications that there could be some
discrete cells or multi-cell clusters that cross central/southern
sections of our forecast area, some of which could be strong.
Main threats would be small hail and gusty winds. Note that the
latest Day 2 Convective Outlook from the SPC does have the
Marginal Risk area just barely intruding into our far southern
CWA, namely far southern St Lawrence and Essex Counties in NY
and southern Rutland and Windsor Counties in VT. Stay tuned to
later forecasts, especially if you have outdoor plans.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
As of 354 AM EDT Tuesday...Challenging forecast for Wednesday night
with changeable conditions as weak low pressure and a surface cold
front passes by with trailing upper level boundaries following
behind. The primary cold front poised to pass through at the start
of this period looks to have shallow sharpness, as depicted by
modeled 2 meter temperature gradients versus those higher up. Ahead
of the boundary, forecast soundings in south central Vermont
generally show low levels stabilizing quickly. However, with dew
points in the 50s and moderately steep 700-800 mb lapse rates,
meager elevated instability of about 150-350 J/kg per HREF
interquartile range supports keeping a slight chance of thunder
going through early evening. Farther north, there are greater odds
of low level winds having switched from southwesterly to
northwesterly by this time indicative of loss of any remaining
instability.

There may be enough shallow mixing behind the front that reduces the
coverage of fog, but overall the combination of expected rainfall on
Wednesday combined with additional forcing for ascent and loss of
deep moisture suggests drizzle and patchy fog overnight. For now,
have a mix of shower chances and fog/drizzle in locations favored to
see low clouds, such as in the vicinity of the mountains. After
sunrise, its unclear if low clouds will linger or if some partial
sunshine may greet us as the upper level pattern looks rather
unsettled and with only the weakest ridging building in behind
Wednesday`s system.

Overall, precipitation chances on Thursday have decreased a bit from
the previous forecast and remain a bit higher as one goes southward.
However, the forcing for additional rainfall on Thursday looks
bifurcated - it will be either non-existent in scenarios that keep
our area under the influence of a northern jet stream, or
substantial in a scenario with a quickly approaching shortwave from
the southwest. In the coming days, the actual solution should become
clear. Regardless, Thursday looks mostly cloudy and seasonably cool,
and potentially chilly while low clouds in the morning hang around.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 354 AM EDT Tuesday...This period continues to look rather
unsettled and potentially moderately wet. The beginning of the
timeframe still looks most certain to be rainy (near 70% chance for
most locations both Thursday night through Friday daybreak and
during the day Friday). There is a consistent synoptic signal
amongst model guidance for a slow moving low pressure system to
approach from the southwest and produce isentropic lift in our
region. Variations in the storm track provide uncertainty in both
timing and intensity of precipitation, with odds of a heavier
rainfall as you go into southern portions of our Adirondack region.
Several members of the GEFS are particularly wet such that the Otter
Creek basin-average rainfall during this period could be around an
inch; on top of the rainfall from Wednesday, the potential for minor
flooding of this river remains low but non-zero. Otherwise, a wider
flood threat is not foreseen with lack of tropical moisture or
convective, intense precipitation with this system.

Beyond Friday, we will continue to see the influence of a longwave
trough supporting occasional chances of showers. As a closed upper
low to our west slowly crosses our region, precipitation should
become more isolated in nature with increasing breaks in the clouds
after an overcast start to the weekend. Probabilistic data shows no
statistically significant change to our cool temperatures across the
weekend even if each day trends warmer. By Monday, highs look to
return to near seasonal norms in the middle 60s.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Through 06Z Wednesday...Mainly VFR conditions expected through
the TAF period. Exception will be potential IFR in patchy fog
08z-12z this morning. Clouds will continue to decrease through
the early morning hours, with FEW-SKC to prevail the remainder
of the period. KMPV and KSLK have the best chances for any fog,
though still uncertain as to how prevalent and dense it will be
given most recent moisture profiles. Have kept with 2SM and a
SCT IFR deck for now, but will need to watch trends closely for
any IFR/LIFR potential. Regardless, fog threat would be over by
13z and VFR prevails thereafter. Light and mainly terrain-driven
winds through 14z will trend north/northwest 5-10 kt during the
daylight hours Tuesday, then light and variable again after 00z
Wed.

Outlook...

Wednesday: Mainly MVFR, with areas VFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Chance
SHRA.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Thursday Night: Mainly VFR, with areas MVFR possible. Likely
SHRA.
Friday: Mainly MVFR, with local IFR possible. Likely SHRA.
Friday Night: Mainly MVFR, with areas IFR possible. Chance SHRA.
Saturday: MVFR/IFR conditions possible. Chance SHRA.

&&

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

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Hastings
SHORT TERM...Kutikoff
LONG TERM...Kutikoff
AVIATION...Hastings