769 
FXUS61 KBTV 071007
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
607 AM EDT Fri Oct 7 2022

.SYNOPSIS...
A strong surface cold front will sweep across the region today
with a band of showers and falling temperatures by this
afternoon with brisk westerly winds developing. A rumble of
thunder is possible over central and eastern Vermont today with
the heavier showers. A cool and mainly dry day is on tap for
Saturday, before more showers arrive on Sunday.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 605 AM EDT Friday...Quick update to increase pops to 100%
and bump qpf up from CPV into parts of central/northern VT thru
14z this morning. Otherwise, actual cold frnt is just entering
the SLV attm and will be associated with additional showers and
wind shift as it moves from west to east acrs the fa, along with
falling temperatures.

Previous discussion below:
Crnt radar shows initial band of showers associated with pre- 
frontal vort and mid lvl moisture is moving acrs the CPV this 
morning. This wl continue to lift ne acrs our cwa this morning 
into central/eastern VT. Meanwhile, well defined sfc convergence
line associated with strong cold frnt is approaching the SLV 
attm with mostly post frontal light rain showers. This frnt 
combined with upper lvl support and some deeper moisture wl 
continue to move from west to east acrs our cwa today. Expecting
the boundary to be in the SLV by 12z, northern NY around 15z 
and into the CPV by 18z. Latest CAMS continue to support minimal
axis of sfc based CAPE values of 250 to 500 J/kg developing 
acrs central/eastern VT this aftn. Have continued to mention 
schc for thunder acrs this region with line of showers. Pops wl 
be near 100% as the boundary interacts with some limited 
instability from sfc heating. Temps wl be on the roller coaster 
today, based on progged 925mb values. Still expecting temps to 
fall sharply acrs the higher trrn of the dacks and into parts of
the CPV this aftn, supported by 925mb to 850mb thermal profiles
and sounding data. For BTV thinking a late morning/early aftn 
high temp near 70F, but by 5 PM temps wl be near 50F and 
continuing to fall overnight.A similar type scenario acrs 
northern NY with mid morning highs in the upper 50s to mid 60s, 
but falling back into the mid/upper 40s to lower 50s by sunset, 
looks reasonable, with 30s acrs the higher trrn. Temps fall 
quickly behind showers acrs central/eastern VT late this aftn, 
with brisk westerly winds of 15 to 25 mph developing, helping to
advect the cooler temps. 

For tonight, not impressed with depth of moisture profiles and 
potential for snow or even freeze drizzle/drizzle. Best 850 to 
700mb rh fields wl lift north of our cwa and stay closer to the 
mid/upper lvl trof, while well defined dry slot acrs the central
Great Lakes angles into our fa. NAM/NAM 3KM seems a bit too 
aggressive with llvl moisture trapped below inversion, so have 
trimmed back pops and areal coverage of drizzle/freezing 
drizzle, mainly confined to trrn. Temps are tricky with an 
advection type night anticipated, with lows ranging from the 
mid/upper 20s northern NY mtns to near 40F CPV/lower CT River 
Valley. If winds decouple associated with developing inversion 
patchy frost is possible acrs the SLV and potentially central VT
valleys, where the growing season continues until Oct 11th. On 
Saturday, soundings show plenty of dry air overhead as pws drop 
to 0.25 acrs our cwa. A spot sprinkle or flurry may be possible 
in the mtns and east side of Lake Champlain from for lingering 
stratus cumulus clouds from upslope flow, caa and lake enhanced 
moisture but qpf wl be light and very minor. Temps wl struggle 
in the mid/upper 40s to lower/mid 50s most areas.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
As of 328 AM EDT Friday...Saturday night into Sunday, surface high
pressure is expected to remain well south with a ridge axis
extending northeast from it shifting east. Increasing southwest to
west-southwesterly flow in advance of a reinforcing shot of cold air
will allow for intermittent lake effect showers to stream off Lake
Ontario. Dry air appears to erode the streamer, such that we may not
see too much in the way of rainfall amounts, but have gone ahead and
started to focus the PoPs in far southern St. Lawrence County and
Franklin County accordingly (30-50%) with generally less than 0.10".
Should any of these showers make it to a mountain summit, there
could be some very light snow, as the freezing level appears to be
about 2500 ft elevation Saturday night. A reinforcing cold front
will shift southeastwards on Sunday, and speed convergence along its
axis and the addition of moisture off Lake Ontario should produce
scattered precipitation and abundant cloud cover, even if the
thermal gradient and synoptic forcing are not overly strong with
this system. Additional rainfall amounts will likely be just a few
hundredths. The overall effect will be a somewhat dreary Sunday, as
high temperatures reach the upper 40s to mid 50s with increasing
west- southwest winds during the day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 328 AM EDT Friday...Heading into Sunday night, it appears the
front stalls and ultimately washes out, which makes it difficult to
transition PoPs out, especially with an additional shortwave
rounding the larger scale trough during the day on Monday. Some
slight chance (15-20 PoPs) exist near the thickness gradient and
where the vort tracks, but any activity will not be anything to
really write home about. It will be fairly cold, though, and outside
of Lake Champlain, the North Country should fall into the 30s. Post-
frontal winds will continue, and this may keep frost from
developing, except in sheltered regions of eastern Vermont. For now,
no explicit mention of any frost has been made, and we'll reevaluate
the position of the front and its impact on this aspect of the
forecast.

Cool on Monday, with below normal temperatures near 50 into the mid
50s for most. As high pressure settles overhead, winds should
decrease and skies should begin to clear out, and this should set
the stage for some frost Monday night into Tuesday. Thereafter,
conditions will gradually moderate, with high temperatures likely
back into the 60s by Wednesday and Thursday with mostly dry weather
underneath the 1026mb high. The large scale pattern over the US will
then begin to amplify, with a fairly strong trough beginning to
carve out over the Great Lakes. It looks like the warm frontal
precipitation during the day Thursday, and the cold front shifts
east Thursday night into Friday. Depending on the amplitude of the
trough, this could be soaker with probabilities of greater than
0.50" already about 30 percent or so for the area.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
Through 06Z Saturday...Changeable flying conditions expected the
next 12 to 24 hours as a cold front moves across our airspace.
First batch of showers impact most of our northern sites btwn
06-10z this morning with brief mvfr vis possible. Next batch of
showers approaches the SLV around 12z...SLK by 15z...PBG/BTV
around 18z, and thru most of VT by 21z, with another period of
MVFR VIS/CIGS likely. South/southwest winds 5 to 10 knots wl
shift to the west/northwest behind sfc cold frnt and increase 10
to 15 knots with gusts 15 to 20 knots expected. A period of IFR
cigs are possible across northern NY taf sites this aftn with
developing northwest upslope flow, before drier air at the sfc
lifts cigs back into the MVFR by evening. 

Outlook...

Friday Night: VFR. Slight chance DZ, Slight chance FZDZ.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA.
Sunday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Columbus Day: Mainly VFR, with areas MVFR possible. NO SIG WX.
Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Tuesday: VFR. NO SIG WX.

&&

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

&&

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