-- Discussion containing changed information from previous version are highlighted. --
173
FXUS61 KBTV 271124
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
724 AM EDT Thu Jun 27 2024

.SYNOPSIS...
A cold front will continue to produce scattered showers this
morning across the region, before drier weather with increasing
amounts of sunshine returns by this afternoon. Temperatures
will only warm into the mid 60s to lower 70s with northwest
winds 5 to 15 mph. A cool and clear night with some patchy
valley fog is anticipated tonight, before a beautiful Friday is
expected with plenty of sunshine and comfortable temperatures.
Unsettled weather returns on Saturday afternoon into Sunday,
along with breezy south winds.

&&

.NEAR TERM /THROUGH FRIDAY/...
-- Changed Discussion --
As of 717 AM EDT Thursday...Cold frnt is slowly moving acrs
northern NY this morning and just now entering the northern
CPV/VT area with associated band of scattered showers. These
showers wl continue to impact the northern Dacks into
central/northern VT thru this morning. Have noted the 06z
guidance is showing the potential for additional isolated/widely
scattered showers this aftn acrs northern VT associated with
secondary vort. Did tweak pops to highlight this potential,
along with keeping likely pops this morning associated with
fropa. Rest of fcst in good shape.

Previous discussion below:
Surface analysis places cold frnt along the International
Border this morning with scattered showers along this boundary.
As this front drops south this morning, expect areas of
scattered showers to prevail from northern NY into
central/northern VT, with greatest concentration and highest qpf
acrs the dacks into the northern VT mtns. A relatively strong
area of high pres for late June wl continue to build southeast
this aftn into Friday with much cooler and drier air developing
on brisk north/northwest winds this aftn. As mixing develops
this wl cause sfc dwpts to drop back into the 40s with
increasing amounts of sunshine this aftn. As 1028mb high pres
settles directly overhead by 12z Friday, expect mostly clear
skies tonight with light north winds under 5 knots. Given these
conditions and recent rainfall, anticipate some localized patchy
fog, especially where cross over values are reaches, such as
the northern Dack valleys and parts of the CT River Valley. Some
uncertainty in fog/br coverage over central/northern VT, due to
gradient. Also, a cool night is anticipated with lows mid 30s
SLK to upper 40s/lower 50s CPV. Would not be surprised to see
some patchy frost near SLK. Friday wl feature plenty of sunshine
with just some fair wx cumulus acrs the trrn with temps warming
into the upper 60s to mid 70s with very low humidity values.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 352 AM EDT Thursday...Changeable weather will continue.
The dry air mass will allow temperatures to cool quickly after
sunset Friday but lows will end up much milder than the previous
night as temperatures steady overnight. The air will be
modulated by warm air advection as high pressure moves to our
east. An unseasonably strong pressure gradient will develop as
said high pressure sits to our east and low pressure moves
northeastward near the central Great Lakes. This pattern will
promote increasingly strong southerly winds, especially in the
northern Champlain Valley due to channeling. Expect rough
conditions on Lake Champlain due to good mixing as air
temperatures aloft will be cooler than the lake water; several
hours of sustained 30 knot winds are likely on the broad lake.
Mean hourly wind gusts will tend to increase during the day and
peak in the late afternoon hours, with maximum values most
likely in the 40 to 45 MPH range in the northern slopes of the
Adirondacks, much of the Champlain Valley, and favored. There is
some uncertainty in the strength of the 850 millibar
southwesterly flow, however. The latest model blend shows 50 to
55 knots looks reasonable, higher than what global ensemble data
suggested. But there is also some more alarmingly strong winds
shown in the 00Z NAM12, which increases the jet to 65 knots and
shows the inversion height just above. At the very least, if you
are on the higher mountain summits, strong winds near 60 MPH
will be possible Saturday evening. The extent of gusty winds
will be dependent on how quickly rain showers overspread the
area. Generally chances of rain will be focused earlier in the
day in western areas, gradually expanding eastward across
Vermont by the evening hours, which will reduce the chances of
mixing down the stronger winds aloft.

The focus Saturday evening into the overnight will then turn to
heavy rainfall potential. At this time, excessive rainfall looks
unlikely but there are some things going for it such that a
marginal risk is reasonable. While lapse rates will tend to be
moist adiabatic such that thunderstorms are unlikely, the
atmosphere looks supportive of efficient, heavy rain processes.
Most parameters, save wind shear, are favorable for torrential
rain in any convection. However, elevated instability looks
limited such that thunderstorms are very unlikely through this
period. Any heavier elements also are unlikely to be training
over a single location as bulk shear vectors look west-
southwesterly, not parallel to the pre-frontal trough that will
be the focus for these showers. This trough will gradually slide
eastward, followed by another area of showers approaching ahead
of perhaps another pre-frontal trough. Given the messy pattern
and continued forcing for precipitation, have maintained chances
of showers areawide through the period. Under the continuous
southerly low level flow, temperatures will be steady and mild
Saturday night in the 60s. Rainfall amounts look to average 0.5"
to 0.75", although that will need to be refined moving forward.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 352 AM EDT Thursday...A moderately strong cold front will
pass through the region Sunday from the west. A blend of model
guidance suggests CAPE of 500 J/kg could develop ahead of this
boundary if it passes through late enough in the day; a morning
passage would put a damper on the instability. At this time,
have maintained a slight chance of thunder for all of northern
New York and Vermont for the afternoon. Following this system,
another period of refreshing air will arrive. Save an isolated
shower Monday morning associated with an upper trough swinging
through, the first half of next week looks stellar for outdoor
activities as anticyclonic flow dominates our weather. Wednesday
we will see more seasonable humidity return as southerly flow
develops, but chances for showers are low, especially east of
the Adirondacks.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Through 12z Friday...Changeable conditions are anticipated at
our taf sites this morning associated with a cold frnt. Expect a
brief of rain showers associated with the boundary btwn 12-16z
from SLK into our VT taf sites. In addition, as winds shift to
the north/northwest cigs will trend toward MVFR at MPV/EFK/RUT
and BTV for several hours this morning, before improving again
after 16z. Intervals of MVFR/IFR cigs are likely at SLK thru
14z, before conditions improve to VFR by this aftn. South winds
acrs the VT terminals shift to the north/northwest by 16z at 5
to 10 knots with gusts 15 to 20 knots thru 22z, before becoming
4 to 8 knots this evening and trrn driven overnight. Still
thinking some patchy fog is possible at SLK btwn 07-11z, so have
VCFG for now, but can use tempo group once confidence increases
in later forecast packages. Less confidence at MPV due to bl
winds and slightly less probability of temps reaching cross over
values.

Outlook...

Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.
Saturday Night: Mainly MVFR, with local IFR possible. Likely
SHRA, Slight chance TSRA.
Sunday: Mainly VFR, with local IFR possible. Chance SHRA, Slight
chance TSRA.
Sunday Night: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Monday: VFR. Slight chance SHRA.
-- End Changed Discussion --

&&

.MARINE...
Unseasonably strong winds are expected on Saturday when a Lake
Wind Advisory will be needed for Lake Champlain. South winds
may exceed 25 knots by daybreak and will likely be above 30
knots on the broad lake at times during the day. Rough waves
will develop quickly. Wave heights on the broad lake and inland
sea may build into the 3 to 5 feet range Saturday morning.

&&

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

&&

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