604
FXUS61 KBTV 100609
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
209 AM EDT Mon Jun 10 2024

.SYNOPSIS...
An upper level low pressure system centered over southern Quebec
this morning will gradually weaken as it pulls away toward the
Gulf of St. Lawrence. A continued moist northwesterly flow will
bring abundant clouds today, along with scattered light rain
showers, especially during the morning hours today. The
influence of the upper low will gradually diminish with a trend
toward warmer and increasingly sunny conditions for the Tuesday
through Thursday time frame. Valley high temperatures should be
well into the 80s by Thursday. The next frontal system is
expected to arrive on Friday, with a chance for scattered
showers and thunderstorms to end the work week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Showers remain isolated to scattered across the forecast area
tonight, so kept with probability of precipitation around
20-40% over the next few hours. Some mist appears to be
obscuring visibility in the Newport, Vermont, area as clear sky
spots move overhead, so have added patchy fog to the valleys of
eastern Vermont with this update. With winds remaining elevated
overnight, fog is not expected to be dense or widespread, but at
higher elevations low clouds could have a similar effect.
Otherwise, forecast is on track with temperatures falling into
the upper 40s to mid 50s overnight and more showers continuing
tomorrow. Previous discussion below:

Previous discussion...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 1026 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.

&&

.SHORT TERM /TUESDAY NIGHT/...
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.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...A continued moist W-NW flow will bring
occasional light rain shower activity, especially to the
northern TAF locations through the remainder of this morning.
Expecting ceilings to generally lower through 15Z this morning,
with IFR ceilings expected at KSLK between 7-12Z, and periods of
MVFR cloud cover elsewhere. HIR TRRN OBSCD through the
remainder of this morning. A few additional showers are possible
this afternoon, but mainly across s-central VT and possibly at
KRUT. With partial clearing Monday night, patchy fog is expected
to develop and may result in periods of LIFR conditions during
the pre-dawn hours on Tuesday. This would be most likely to
occur at the KMPV and KSLK taf locations. Winds are generally
expected to be 10 kts or less throughout the TAF period.

Outlook...

Tuesday: VFR. 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 local IFR possible. Chance SHRA,
Slight chance TSRA.

&&

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

&&

$$
SYNOPSIS...Banacos
NEAR TERM...Clay/Storm
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Banacos