-- Discussion containing changed information from previous version are highlighted. --
823
FXUS61 KBTV 250821
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
421 AM EDT Tue Jun 25 2024

.SYNOPSIS...
-- Changed Discussion --
Sunny skies will promote seasonably warm temperatures today
after a cool start. A cold front approaching from the west will
spark scattered showers tonight. Following a period of dry
conditions tomorrow, a potent trough will provide forcing for
numerous showers overnight into Thursday morning. Chilly high
pressure will settle in by Thursday night, then another frontal
system will support the return of active weather on Saturday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 421 AM EDT Tuesday...To start the day, fog is the main
story. River valley fog gradually expanded overnight throughout
all of the typical spots, particularly east of the Green
Mountains, despite quite a bit of northerly flow aloft. Given
the strong subsidence in the wake of the trough that moved
through the region yesterday, this fog is not surprising, but it
has been poorly modeled with a tricky scenario featuring very
shallow surface inversions. Gradient flow between low pressure
to our east and high pressure to our southwest is generally out
of the west, but the terrain is helping it become south or
southwesterly in the St. Lawrence and Champlain valleys and
limiting fog potential in these areas. Winds just above the
surface are mainly 15 MPH or greater even where fog has
developed, which will help the fog dissipate fairly quickly
after sunrise.

Then the story becomes pleasantly warm conditions. A dry air
mass will help temperatures rise quickly with sunny skies.
Forecast soundings show afternoon mixing above 800 millibars,
and have blended in some bias-corrected model output statistics
for the highs to nudge them up a bit in many locations.
Generally looking at highs in the 80s for most spots with low
humidity, so it should be a lovely day. Precipitation chances
are nil through late afternoon.

Tonight another strong low level jet, peaking at about 50 knots,
will make its way into the region and shower chances quickly
increase from west to east, especially towards midnight. Think
most locations will stay dry as coverage will be limited by
relatively weak forcing. A kink in the upper level flow will
ride eastward as mid level flow turns southwesterly and surface
pressure falls ahead of a weak cold front. This system does not
have much moisture return with a lack of deep southerly flow,
and so between that and the non-existent surface based
instability in place ahead of the front, the only potential for
thunderstorms is if there is organized convection upstream that can
hold together as it rips eastward. If so, showers would be
capable of gusty winds, with the greatest potential in our
western areas.

The main impact of this system may instead be providing another
period of breezy conditions. Uniform westerly flow looks to set
up behind this front under a weak cold air advection pattern,
which will allow for gusts of 25 to 30 MPH across the
Adirondacks along with central and eastern Vermont. Another
period of sunny skies will follow the frontal passage, then
clouds will rapidly increase late in the day from the west as a
much more vigorous trough approaches to bring rain. The chances
of rain through Wednesday evening begin to ramp up primarily in
northern New York, although it is hard to be more specific yet
with uncertainty on the position of the boundary that showers
may focus on before showers overspread the area Wednesday night.
Temperatures on Wednesday should be a bit cooler than today,
but 850 millibar temperatures on the cool side of the front
aren`t much colder. Assuming there is abundant sunshine through
at least the first part of the day, highs should warm into the
mid 70s to mid 80s.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
As of 332 AM EDT Tuesday...A period of rain showers with embedded
heavier downpours is likely Weds night into Thurs associated with
mid/upper lvl trof and potent s/w energy. The best dynamics look to
arrive overnight, when instability is minimal, which should limit
rainfall rates and associated flash flooding threat. Best
combination of lift and moisture with pw values btwn 1.0 and 1.50"
wl be acrs central/southern VT on Weds night. Have pops in the
likely to cat range (60-80%) for now, which wl increase as
confidence increases on exact placement and timing of heaviest QPF.
Precip looks to range btwn 0.25 and 0.75 with some localized heavier
amounts possible over southern VT zones. Temps with clouds and
precip wl be in the mid 50s to lower 60s on Weds night. Initial s/w
energy departs our eastern cwa by 15z, however secondary energy in
the northern stream jet approaching our SLV region by 18z. Moisture
and instability is limited, but dynamics look good for the potential
of a few additional showers. Areal coverage wl be limited by the
lack of deep layer moisture on Thurs aftn. Highest schc/chc (15-30%)
wl be acrs northern VT. Progged 925mb temps btwn 14-16C support
highs mid 70s to near 80F on Thurs. Sfc high pres builds directly
overhead on Thurs night into Friday morning. MEXSLK has a cool 35F
(a sign the turn has occurred), but feel boundary layer moisture wl
promote fog development and limit temps from completely bottoming
out. For now have lows upper 30s to upper 40s with patchy areas of
fog likely.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
-- Changed Discussion --
As of 332 AM EDT Tuesday...Friday wl be a classic North Country
Chamber of Commerce type summer day with mostly sunny skies,
comfortable humidity values, and temps close to normal for late June
with highs mostly in the 70s. Next mid/upper lvl trof impacts our
cwa Sat into Sunday with another round of unsettled wx likely. Once
again system looks to impact us in fragments, resulting in several
rounds of showers and embedded thunderstorms over the upcoming
weekend. First feature is warm frnt on Sat morning with weak
embedded vort, could produce a few light showers over northern NY.
Next piece of energy is the pre-frontal trof and associated
elongated vorticity that arrives late Sat aftn/evening, while the
actual sfc cold frnt impacts our cwa toward 12z Sunday. This piece
meal concept to sfc and upper air features makes timing precip
chances over the weekend very challenging. Crnt guidances suggests
highest potential btwn 18z Saturday and 06z Sunday, but this entire
time period wl not be a washout. Crntly soundings show limited
instability with moist adiabatic profiles and warm cloud depths, as
pw values surge btwn 2.0 and 2.25 inches on Sat. In addition, strong
llvl wind profiles develop with progged 850mb winds of 45 to 50
knots ahead of pre-frontal trof feature, so expect localized gusts
25 to 35 mph in SLV and CPV on Sat aftn before precip arrives. As
always if more sfc heating occurs, given our strong wind profiles
and dynamics, the potential for a few stronger storms wl need to be
watched. In addition, given the recent rainfall, there wl be a non
zero threat for flash flooding, especially given the very high pw
values. As time frame becomes sampled by high res CAM output, the
confidence in timing and placement of heaviest qpf footprints wl
increase. System slowly clears our cwa by Sunday aftn with improving
conditions and drier air for early next week. Highs generally near
normal for the weekend into early next week , but overnight lows
much above normal, especially on Sat night with southerly winds and
increasing dwpts.
-- End Changed Discussion --

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Through 06z Wednesday...Fog is present at EFK and SLK, where
IFR/LIFR conditions are favored to persist through around 12Z
based on climatology before quickly improving. River valley fog
in central Vermont has developed but remains just outside of the
MPV terminal. Given satellite trends, have left out prevailing
fog there but have tempoed it in from 09Z to 12Z given 30-40%
chances of development overnight.

Otherwise, surface winds will remain light/calm at all
terminals through morning, then increasing into the 6 to 12
knot range during the day ahead of an approaching low pressure
system. These winds will largely be southwesterly across much of
northern New York, southerly in the Champlain Valley, westerly
at RUT and MPV, and northwesterly at Newport. Winds will trend
southerly across the region after 00Z as shower chances
develop, mainly in western portions of the airspace. There could
be some gusty winds late in the period with these showers with
dry low level air in place.


Outlook...

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

&&

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

&&

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