541
FXUS61 KBTV 070238
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
1038 PM EDT Sun Oct 6 2024
.SYNOPSIS...
A cold front is expected to bring widespread rainfall and gusty
winds to the region overnight tonight and early Monday morning.
Unsettled weather is expected through much of the upcoming week with
isolated to scattered rain showers possible on Tuesday and Wednesday
with the potential for a few mountain snow showers Thursday morning.
Temperatures will hover near seasonal normals before warming above
normal next weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1030 PM EDT Sunday... The line of heavy showers ahead of the
cold front has been able to hold together well due to strong
dynamics and some elevated instability. It is mostly over
northern New York but it has just begun to enter Vermont. It
will reach the rest of Vermont in next few hours. There is
still some embedded lightning but the amount has been gradually
diminishing this evening and it will continue to do so as it
moves through Vermont. However, the showers will stay together
well.
You wouldn`t know it by looking outside right now, but we`ve
got a dynamic frontal system that is slated to move through the
North Country during the overnight hours. Taking a look at
current radar and satellite imagery, a distinct line of showers
and thunderstorms continues to move north of Lake Ontario. These
showers and thunderstorms will continue to track eastward and
will move across the region, mainly from 8 PM tonight through 5
AM on Monday. Model soundings continue to show a couple hundred
J/kg of elevated instability this evening and through the
overnight hours which could support a few rumbles of thunder but
no strong thunderstorms are expected. Rainfall amounts
associated with this frontal passage will range from 0.25 to
0.5" with a few locations seeing slightly higher amounts.
Additional rain showers appear possible on Monday given
steepening mid-level lapse rates but should mainly be confined
to the higher terrain. Any showers Monday afternoon will likely
dissipate Monday evening with the loss of daytime heating.
In the meantime, however, gusty southerly winds are expected,
especially across the Champlain and St. Lawrence Valleys, as the
pressure gradient ahead of the approaching frontal boundary begins
to tighten up. Wind gusts up to 30 mph will be possible in the wider
valleys with other locations likely 20 mph or less. Winds will begin
to abate by daybreak on Monday as weak surface high pressure begins
to nose into the region.
&&
.SHORT TERM /TUESDAY NIGHT/...
As of 253 PM EDT Sunday...The center of a closed 7h/5h circulation is
progged to be centered southeast of Hudson Bay with cyclonic flow
and channeled vorticity energy acrs our fa. This cyclonic/upslope
flow, combined with steepening daytime lapse rates and some lake
moisture enhancement wl produce plenty of clouds with scattered mtn
showers on Tues. Given the thermodynamics and associated moisture
profiles from area soundings expect a diurnal trend in
clouds/precip, with greatest coverage during the 17-22z timeframe.
Have the highest pops/qpf and cloud cover over the northwest facing
slopes of the northern Dacks and central/northern Green Mtns in VT.
Also, have sharpened the valley to summit thermal gradient for highs
on Tues, with valleys in the upper 50s while summits struggle in the
mid 30s to lower 40s, supported by progged 850mb temps near 0C. Tues
night is relatively quiet as cyclonic flow aloft prevails with
clouds lingering over the trrn. Difficult to determine how clouds
and winds might influence temps, but have trended toward the 75% NBM
for lows, especially wider valleys with warmer Lake Champlain
waters.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 253 PM EDT Sunday...The Weds aftn/evening time frame continues
to look interesting as potent s/w energy and very cold air aloft of
-32C at 500mb rotates acrs our cwa. This energy, combined with a
pocket of enhanced 850 to 500mb rh>70% supports increasing areal
coverage of precip late Weds into Weds night from west to east acrs
our cwa. Have increased pops into the 70-90% range for the trrn with
30-50% valleys. Timing of best forcing associated with s/w energy
has been delayed by 2 to 4 hours this run, but given thermodynamics
and forcing would not be surprised for a few rumbles of thunder. In
addition, weak elevated instability profiles and cold air aloft
profiles, support embedded convective graupel within the stronger
updrafts. As moderately strong low level caa develops behind s/w
energy under increasing nw flow expect a period of upslope precip.
Given progged 850mb temps btwn -4C and -6C and 925mb temps dropping
close to 0C, anticipate snow levels near 2000 feet briefly on Thurs
morning. Confidence is increasing for an inch or so of snow
accumulation above 2500 feet by Thurs morning acrs the northern
Dacks and portions of the central/northern Greens based on latest
trends. Have utilized the mtn max and min temp adjust tool to
highlight cooler temps at summit and sharpen the valley to summit
thermal gradients on Weds thru Thurs. Highs mostly 30s summits to
mid 50s valleys and lows in the 20s mtns to mid 30s to lower 40s
valleys. 1027mb high pres slowly builds eastward into our cwa by
late week with slowly clearing skies and warming thermal profiles.
The cyclonic flow aloft and lingering 850 to 500mb moisture,
suggests clouds are likely in the mtns for Thurs into Friday. If
clearing can develop with lighter winds on Friday morning,
widespread frost would be possible, but given time frame just
watching the potential attm. By next weekend flow aloft becomes
zonal with embedded s/w`s and associated mid lvl moisture, which wl
eventually increase the potential for scattered showers. For now
have a token 30% but as confidence increases on timing and evolution
we wl fine tune the fcst.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Primary hazards will be thunderstorms and
LLWS as a cold front moves through the North Country 00-08Z.
Southerly winds gusts to 25kts will shift westerly over this
time frame and decrease to around 10kts. MVFR VIS associated
with rain showers along the front will also be possible
overnight. Winds turn westerly after frontal passage with flow
becoming increasingly block. The result will be an extended
period of MVFR/IFR CIGs 06-18Z mainly in the Adirondacks, along
the Greens, and east of the Greens as well. After 16Z, enough
gradient remains to support westerly SFC gusts to 20kts for
MSS/BTV with gusts generally to 15kts elsewhere.
Outlook...
Monday Night: VFR. Slight chance SHRA.
Tuesday: VFR. Chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. Chance SHRA.
Wednesday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.
Thursday: Mainly MVFR, with areas VFR possible. Slight chance
SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: VFR. NO SIG WX.
&&
.MARINE...
Southerly winds have been gusting up to 25-30 KTs on Lake
Champlain this evening. Waves are expected to build to 2 to 4
feet, except up to 3 to 5 feet across the broad lake. The
gusty winds at or above 25 knots are expected to last until
late in the night. Winds will weaken through the morning hours
tomorrow. The lake will rapidly calm with the loss of gusty
winds tomorrow morning.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Clay
NEAR TERM...Clay/Myskowski
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Boyd
MARINE...Team BTV
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