-- Discussion containing changed information from previous version are highlighted. --
157
FXUS61 KBTV 091927
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
327 PM EDT Sun Jun 9 2024

.SYNOPSIS...
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Showers and thunderstorms will continue this afternoon and evening
before tapering off this evening. Additional showers will be
possible on Monday but we are trending back toward drier conditions
with surface high pressure expected to build into the region on
Tuesday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
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Widespread showers with isolated thunderstorms have developed across
the region this afternoon in response to modest low level heating
coupled with a weak shortwave rotating around an upper low north of
the International Border. Our 850 mb and 500 mb heights are close to
four standard deviations below normal with respective temperatures
around 2 standard deviations below normal. Even with just modest
heating, the lower heights/cooler temperatures aloft have allowed
for multiple reports of pea sized hail across the region. The
thermodynamics will remain modest, at best, with SBCAPE values
generally less than 1000 J/kg with mixed layer shear of only 20
knots. These should be limiting factors in updraft strength which
should preclude any longer lived cells capable of producing larger
hail. We will see these showers and thunderstorms continue into the
evening hours but will begin to dwindle in coverage as we lose our
heating and see the atmosphere begin to stabilize. Rainfall amounts
this afternoon should generally be a quarter of an inch or less but
could exceed a half inch in thunderstorms.

High res guidance suggests we could see a few showers linger in the
mountains overnight but we should be between shortwave energy which
should really limit the areal coverage. We will be in store for a
cloudy night with a strong nocturnal inversion trapping in a lot of
the low level moisture as a result of the showers and storms this
afternoon. As of 326 PM EDT Sunday. This inversion will mix out
after sunrise on Monday. Additional showers appear possible on
Monday but less shortwave energy should limit the coverage and
intensity of showers.
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&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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As of 326 PM EDT Sunday...Mid/upper lvl trof wl cont to linger acrs
the region during the short term, with general drying trend toward
mid week. Still cool 500mb temps btwn -16C and -18C associated with
trof and some weak s/w energy may produce a few isolated to widely
scattered showers (15-25%) on Tues. These showers wl have a diurnal
cycle with areal coverage with highs pops when instability is the
greatest during the mid aftn hours. Soundings indicate limited
instability with sfc based CAPE values in the 200-400 J/kg range and
very weak flow with trof axis nearby, so have just kept showers for
now. Did note a little difference btwn the latest synoptic scale
models with regards to thermal profiles with 12z GFS about 2 to 3C
warmer than the NAM progged 925mb temps associated with subsidence
type profile. Have used compromise of NAM/GFS and NBM and have temps
upper 60s to mid 70s. Areal coverage of precip quickly wanes on Tues
night with some clearing possible. Temps wl be highly dependent upon
clearing, so have stayed close to guidance with values in the lower
40s SLK/NEK to upper 50s CPV.
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&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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As of 326 PM EDT Sunday...The long term wl feature warming thermal
profiles and generally drier conditions as mid/upper lvl trof is
replaced by westerly flow aloft. GFS is now showing some lingering
qpf acrs NEK of VT on Weds, for now have not included in the fcst,
but something to monitor as we head toward the new week. Next
challenge wl be warming temps on Weds thru Friday with some valley
locations approaching 90F possible by Friday. Progged 925mb temps
are 16-18C on Weds, 18-20C on Thurs and 20-22C by Friday, supporting
highs upper 70s to mid 80s Weds, lower to mid 80s Thurs, and mid 80s
to near 90F for Friday. As southerly flow develops and dwpts slowly
climb, so wl the overnight lows from the 40s to mid 50s into the mid
50s to mid 60s by Friday. Similar to yesterday timing of s/w energy
and associated cold frnt along with chances for shower/storms
becomes the challenge for late week. Have kept pops in the 20 to 35%
range for now with highest probs on Friday. Did note the GFS/ECMWF
are more aggressive with potent s/w energy and showing sfc
convergence with boundary, but run to run consistency in these
scenarios has been limited, resulting in minimal confidence with
regards to pop timing and convective potential. As temps warm well
into the 80s and dwpts climb back into the 60s, would anticipate
some instability wl be kicking around to support convection on
Friday aftn/evening. For next weekend sfc high pres rebuilds back
into our region with less humidity and temps cooling back closer to
normal. As with any fcst out 7 days, timing of building high pres
and clearing wl continue to be adjusted and fine tuned this week.
-- End Changed Discussion --

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
Through 18Z Monday...Widespread showers have developed with
several lightning strikes detected near Massena. We will
continue to see shower and thunderstorm increase in coverage
over the next few hours with activity beginning to dwindle
around sunset. Overall, VFR conditions are expected through
this evening but we could see brief MVFR/IFR visibilities should
a thunderstorm move over a terminal. A mix of MVFR and IFR
stratus is expected overnight with a slow improvement back to
VFR Monday morning.

Outlook...

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

&&

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

&&

$$
SYNOPSIS...Clay
NEAR TERM...Clay
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Clay