221
FXUS61 KBTV 270513
AFDBTV

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

.SYNOPSIS...
A wave of rain showers will move through tonight. Although steady
rain will come to an end Thursday morning, some scattered light
showers will persist into Thursday afternoon. High pressure will
move in Thursday night, cresting overhead Friday with a dry but
seasonably cool day.  The next system moves in Saturday with another
round of rain showers and some embedded thunderstorms.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 106 AM EDT Thursday...The combination of moderately strong
low level moisture advection and associated mid/upper lvl trof
with embedded vorticity has produced a widespread light rainfall
acrs our region tonight. The first sfc cold frnt is moving acrs
the CPV attm, with secondary boundary and energy aloft over the
SLV. These two features wl continue to produce lift favorable
for additional showers for the next 1 to 3 hours, before drier
air filters into the region toward sunrise. Have made some minor
tweaks to pops/qpf and sky cover based on this thinking.
Otherwise fcst in good shape.

Previous Discussion...Water vapor satellite imagery showing
two upstream shortwaves that will both move into our forecast
area over the next few hours. The northern stream shortwave,
currently over southeastern Ontario, and the southern stream
shortwave, currently over the upper Ohio River Valley, will
bring us the next round of rain this evening into overnight
tonight. Rain showers will move from west to east this evening,
starting in northern NY between 4PM and 8PM, and move into
Vermont between 7 PM and 11 PM. Steadiest precipitation rates
will be in the late evening/early overnight hours, when rates of
around .1 to .25 inch/hour are expected. Lapse rates in the low
and mid levels are generally moist-adiabatic, precluded from
steeping in the low-levels by the nocturnal timing of the wave.
Thus, have left mention of thunderstorms out of the forecast for
the overnight hours. Storm total QPF for this evening into
tonight will range from 0.2-0.5 inches, with Vermont on the
higher end of the range and New York generally towards the lower
end of that range.

Steady rain will come to an end around sunrise Thursday morning,
although the remainder of the day will see some lingering spotty
showers continue as the area remains under broad cyclonic flow.
Additional shortwave energy moving in from the west will provide
some focus for lift, although instability will be limited to the
lowers levels under a 500 to 800 mb warm layer.  Thursday certainly
won`t be a washout, especially with drier air moving in from the
northwest through the day, but can`t rule out some light showers
amid the generally unsettled pattern. High temperatures Thursday
will be in the mid 60s to mid 70s, which will be seasonably
cool.

Thursday night, sprawling high pressure will build in and
conditions will trend completely dry with mostly clear skies.
While we remain on the western periphery of the anticyclone,
enough gradient flow will persist to prevent formation of
widespread fog, though some sheltered valleys could see some
patchy fog especially after the recent rainfall. Overnight lows
will be in the 40s to low 50s for most areas, but will locally
drop into the upper 30s in some of the colder hollows of the
northern Adirondacks.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 342 PM EDT Wednesday...Dry conditions with seasonably mild
temperatures are expected Friday; it will be a fantastic day to
enjoy the outdoors with highs in the low/mid 70s and only some
building cirrus clouds late in the day. Overnight, clouds increase
and lower ahead of the next system with shower chances increasing
over the St Lawrence Valley. With clouds and southerly flow
increasing, temperatures will be warmer than Thursday night with
lows in the mid/upper 50s to around 60 degrees.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 342 PM EDT Wednesday...A moderately strong area of low pressure
is expected to move through eastern Canada Saturday through early
Sunday bringing a fairly robust cold front with it. Winds will
noticeably increase Saturday with gusts 20-30 mph, especially in the
northern Champlain Valley, due to projected gradients. Expected
evolution of this system is for a pre frontal wave to form bringing
periods of showers Saturday with a stronger more consistent period
likely Saturday evening into the overnight hours. With ample
moisture transport, PWATs above 1.5", periods of moderate to heavy
rain and embedded thunderstorms are probable. However, flow pattern
aloft will promote faster system speed limiting the overall period
of rainfall. As such, maintained less than a 10% for flash flooding
concurring with WPC`s outlook of a marginal risk of flash flooding.

Behind the front, shower chances linger mainly over terrain and
upslope areas. These chances will diminish through Sunday with a dry
period and return of high pressure heavily favored for early next
week with a marked warming trend and highs running 5-8 degrees above
seasonal averages generally in the mid 80s. Models depict the next
period of precipitation beginning around midweek with the next
system approaching from the west.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
Through 06z Friday...Crntly VFR conditions at all sites except
MVFR cigs at SLK with periods of light rain showers. These
showers will slowly exit our terminal sites by 12z Thursday, but
as winds shift to the northwest expect some lowering cigs toward
MVFR at many sites. A period of blocked flow near sunrise could
produce localized IFR conditions at BTV for an hour or two, but
probability and confidence is too low attm to mention in TAF at
BTV. Otherwise, higher confidence of IFR CIGS associated with
upslope flow is expected at SLK, so have utilized tempo`s to
indicate this potential. Otherwise, CIGS become VFR with
clearing skies by 16z today with northwest winds 5 to 15 knots.
Tonight winds become light north/northwest under 5 knots with
some patchy fog possible toward 06z at SLK.

Outlook...

Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. Likely SHRA,
Slight chance TSRA.
Saturday Night: Mainly MVFR, with local IFR possible. Definite
SHRA, Slight chance TSRA.
Sunday: MVFR/IFR conditions possible. Chance SHRA, Chance TSRA.
Sunday Night: VFR/MVFR conditions possible. Slight chance SHRA,
Slight chance TSRA.
Monday: VFR. Slight chance SHRA.

&&

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

&&

$$
SYNOPSIS...Duell
NEAR TERM...Duell/Taber
SHORT TERM...Boyd
LONG TERM...Boyd
AVIATION...Taber