Area Forecast Discussion
Issued by NWS Burlington, VT

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337
FXUS61 KBTV 191107
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
707 AM EDT Mon Aug 19 2019

.SYNOPSIS...
A broken line of showers and embedded thunderstorms will move
across the North Country this morning with brief heavy rainfall
and localized wind gusts to 30 mph. Additional afternoon showers
and storms are possible, mainly over eastern Vermont.
Temperatures will warm well into the 80s with a few readings
approaching 90 degrees in the Champlain and lower Connecticut
Valley. A dry and warm day is expected on Tuesday, followed by
more chances for showers and storms on Wednesday into Thursday.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 643 AM EDT Monday...A decaying line of showers continues
to move across the dacks and into parts of the cpv this morning.
Have adjusted pops to account for this precip, with some
redevelopment/increase in areal coverage possible over
central/eastern VT, including the NEK early this aftn. Guidance
continues to show an axis of instability with some deep layer
shear present across our eastern CWA ahead of this weak
boundary, so a few stronger convective cores are possible this
aftn. Otherwise, still expected a warm and humid day with highs
lower 80s mountains to near 90f warmer valleys, with pockets of
heat index values in the 92 to 94 degree range.

Forecast challenge continues to be convective chances and
associated pops today. Water vapor shows modest height falls
across the eastern Great Lakes associated with channeled 700 to
500mb vort, along with a ribbon of enhanced mid level moisture.
Regional mosaic radar indicates a broken line of showers with
embedded storms approaching the SLV early this morning. Based on
high res convective allowing models, expect precip acrs dacks
btwn 09z-11z, cpv 11z-13z, central VT 13z-14z, and thru
NEK/eastern VT by 16z. Laps shows limited instability ahead of
this line with CAPE values generally <500 j/kg, but some
elevated instability is present. Thinking brief heavy rainfall
and localized gust to 30 mph possible within the heavier
convective elements this morning.

Meanwhile, water vapor shows large area of subsidence/dry air
aloft building behind short wave energy, which should result in
clearing skies this aftn. This clearing will help warm temps
quickly into the 80s with a few locations near 90f in the
CPV/lower CT River Valley. The sfc heating will help create sfc
based cape values in the 1000 to 2000 j/kg across CPV and
portions of VT, while 0 to 6km shear is in the 35 to 40 knot
range. These parameters would support some organized convection,
however developing warm nose/cap around 800mb, along with deep
dry layer btwn 850 and 300mb with limited upper level forcing
will result in minimal activity this aftn/evening. Have mention
only schc/low chc (15% to 30%) pops from eastern Dacks into Vt
thru this aftn/evening.

Tonight into Tuesday...relatively quiet period of weather
anticipated with building heights and modest cap in place,
combined with dry air will limit threat for showers/storms.
Cannot completely rule out a stray shower/storm on Tues aftn
during peak heating/instability across the eastern Dacks or
higher trrn of Green Mtns. The best convergence will be
associated with lee side trof/lake breeze boundary interaction
on the west side of the CPV. 925mb to 850m thermal profiles are
slightly cooler on Tues with highs generally in the upper 70s
to mid 80s anticipated, with some drier dwpts/lower humidity
values as better mixing occurs during the aftn hours. Some areas
of patchy fog is likely tonight, with clearing skies and light
winds, especially as cross over values are reached in many
locations. Lows a little cooler than recent nights with readings
from the mid 40s slk to lower 60s CPV.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 351 AM EDT Monday...Still a tricky forecast for Wednesday with
variability among the models regarding precipitation/convection
and timing of the system. This is largely due in part to how
each model is handling upstream convection over Ohio River
Valley Tuesday night into Wednesday. Current run of NAM now
depicts convection lifting northward across the area with GFS
maintaining the more southern track of convection and boundary
and ECMWF somewhere in between (however the actual frontal
passage on Euro is now not until 18z Thursday)...have maintained
relative consistency with previous forecasts until there is
better consensus. Regardless of forcing mechanism, I do think
there will be precipitation around during the daytime on
Wednesday. Additionally, with such differences among the models
it is difficult to determine the potential for severe weather.
Given trends in moisture profiles and available CAPE/shear
thinking can`t rule out some stronger storms with primary threat
being wet microbursts.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 351 AM EDT Monday...Lingering moisture and upper level
troughing will keep chances for precipitation around on Thursday,
especially across the northern tier. Better cold air advection
arrives Thursday night so temperatures will be near normal in the
mid to upper 70s. Friday will bring "fall-like" weather with breezy
NW winds and variably cloudy skies. GFS-MOS guidance is coldest
among suite with highs in the mid to upper 60s valleys and 40s
mountains, however have ran with a blend of EURO/MOS for highs in
the upper 60s to low 70s across the area. Certainly feels like we`re
beginning to make the turn. After this, quiet weather is expected
for the remainder of the long term with Canadian high pressure in
control of the weather. Temperatures warm each day of the weekend
with near seasonable highs in the mid to upper 70s. Overnight lows
will be once again pleasant in the upper 40s to low/mid 50s.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...Radar shows a broken line of showers
across the dacks approaching the cpv terminals in the next 1 to
2 hours. Have utilized tempo group to indicate potential mvfr
cigs/vis in heavier showers for slk/pbg and btv. Breezy
south/southwest winds will develop btwn 12-15z at slk/mpv/mss
and btv with localized gusts in the 20 to 25 knot range. These
winds will decrease around sunset this evening and with clearing
skies, expect some patchy fog to develop at slk/mpv and probably
pbg given trends the previous couple of nights. IFR with periods
of lifr/vlifr conditions expected after 06z.

Outlook...

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

&&

.MARINE...
Lake wind advisory has been issued as CRF is sustain at 25
knots this morning. Expecting a 2 to 4 hour of lake wind
advisory winds this morning, before a gradual shift to the west
and values becoming 10 to 20 knots by midday. Waves generally 1
to 3 feet, except 3 to 4 feet in the open waters.

&&

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

&&

$$
SYNOPSIS...Taber
NEAR TERM...Taber
SHORT TERM...LaRocca
LONG TERM...LaRocca
AVIATION...Taber
MARINE...



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