870
FXUS61 KBTV 131123
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
723 AM EDT Mon May 13 2024

.SYNOPSIS...
An unsettled weather pattern will continue over the next couple
of days with several rounds of showers with embedded
thunderstorms expected. First area of showers arrives today with
a warm front, more showers anticipated tonight, followed by
numerous showers with embedded rumbles on Tuesday. The threat
for severe weather is low, along with flooding, but localized
heavy down pours are possible. Highs warm into the 60s today and
well into the 70s on Tuesday.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 717 AM EDT Monday...Minor changes to sky grids and timing
of light rain showers associated with first warm frnt. Radar is
showing some light precip approaching the SLV, with some
lightning upstream over the central Great Lakes. Have chc pops
northern NY expanding into VT toward late aftn into the evening
hours. Best potential for a rumble or two will be toward 00z
over northern NY.

Previous discussion below:
An active near term is anticipated, but threat for hazardous or
severe weather is low attm. Crntly mid/upper lvl clouds prevail
with some areas of patchy fog/low clouds beneath, which should
dissipate around sunrise. Our next feature is ahead on GOES-16
water vapor acrs the central/northern Great Lakes with some
lightning activity. This s/w energy and ribbon of enhanced mid
lvl moisture associated with first warm frnt wl move from west
to east acrs our cwa btwn 15-21z today. A band of light rain
showers is anticipated as energy weakens and instability is
limited acrs our cwa. Meanwhile, additional stronger s/w energy
and slightly better elevated instability impacts our cwa btwn
03z-12z with more showers. Best potential for an embedded rumble
or two of thunder wl be over northern NY associated with a
pocket of MUCAPE of 200-400 J/kg. Given increasing instability
parameters and pws values btwn 0.75 and 1.25 by 12z Tues,
localized heavy down pours are possible in the heavier
convective elements. Temps today are mainly in the 60s with
clouds and only cool back into the 50s to near 60F tonight.

For Tuesday, a nearly stationary boundary wl be located near the
International Border, as it becomes parallel with the mid/upper
lvl flow btwn trof to the north and ridge to the south. Pw
values wl be in the 1.0 to 1.25" ahead of this boundary, with
some sfc based instability developing in the late morning into
the mid aftn hours on Tues. The degree of instability wl be
highly influenced on amount of sunshine/clearing that can occur
and sfc heating. Latest CAM guidance shows pockets of CAPE
btwn 800-1200 J/kg acrs central/southern VT, as sfc temps warm
well into the 70s, while very little instability is progged over
northern SLV/VT. NBM CAPE probs have increased by 200-300 J/kg
from previous couple of runs, highlighting the potential for
some clearing and greater instability to develop. Progged 925mb
temps are very warm south of the boundary with values btwn
18-19C, supporting highs well into the 70s to near 80F, while
readings are only in the mid 60s near the border. This
differential/instability gradient should help to enhance
showers/thunderstorm activity btwn noon and 5 pm acrs our region
on Tues. The probability of svr or flash flooding is <10% attm,
but feel some stronger cells are possible with frequent
lighting, brief heavy down pours, and localized gusty winds to
40 to 45 mph. Shear is rather marginal for svr on Tues with
strongest core of 850 to 700mb winds displaced over southern
Canada associated with trof. Given small storm vectors the
potential for training of convection wl need to be watched, but
feel just enough southeast drift should occur to prevent issues.
Should be plenty of activity to monitor on radar Tues aftn acrs
our cwa.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 354 AM EDT Monday...Potential for additional moderate rainfall
continues and shifts south and east with time as a weak cold front
passes through, possibly by Wednesday morning. Deep moisture,
which will be present areawide aside from perhaps far
northwestern portions of northern New York, will slowly shift
southeastward supporting some embedded convection on the warm
side of the front. Have indicated slight chances of thunder
taper off by midnight with instability waning. While flash
flooding ingredients are lacking with regards to instability,
moisture flux convergence with position of the surface front and
850 millibar winds supports a broad area of fairly efficient
rain with slow system movement to the southeast overnight.
Generally the odds of the heavier rainfall amounts Tuesday night
are across central and south central Vermont. Through the day
on Wednesday, additional showers could roll through, adding to
24 hour rainfall totals which probably will average between
0.5" and 1" for most of this area, trending a bit less farther
north and west. The northern extent of the moderate rainfall is
somewhat uncertain as the ECMWF continues to bring a wave along
the front farther north such that widespread shower activity is
reinvigorated in a large swath of our region and we continue to
see warmer, southerly low level flow. The official forecast for
sky cover reflects a blend of these ideas with northern/western
areas trending partly sunny with lower chances of rain, and
southern/eastern areas mostly cloudy and with likely showers
during the day.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 354 AM EDT Monday...The weather pattern doesn`t look to
change much with a split jet pattern supporting unsettled
weather but no significant storminess. This pattern does make
precipitation chances tricky, and you`ll see a lot of "chance"
PoPs. Periodically there will be some forcing for ascent with
at least some modest low level moisture around. Best chances for
completely dry weather looks like the Wednesday night to
Thursday morning period and again Thursday night through early
Friday. Then late Friday into Saturday another relatively minor
frontal system may force more widespread shower activity.
However, exact timing is rather questionable. One of the more
likely outcomes at this time, driven mainly by the GEFS, shows
faster arrival of rain Friday afternoon, with other outcomes
suggesting low chances of precipitation until later. By
Saturday, while there is a lot of support for some shower
activity, the position of the upper level trough/ridge axes vary
greatly amongst the ensemble clusters, which suggests we still
don`t have a particularly certain forecast for the weekend.
Despite the variations, generally seasonable temperatures are
expected to continue. With small variation from day to day,
these temperatures will be quite pleasant for outdoor activities
as shower chances don`t seem to have much thunder potential
with meager instability.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...VFR conditions will prevail at all taf
sites through 18z today, with trends toward MVFR cigs over
northern NY taf sites by 00z. These lower CIGS will continue to
expand east into the CPV and VT taf sites overnight into early
Tuesday morning. Some localized IFR cigs are possible at SLK
after 06z tonight. Several waves of showers are anticipated
with first late this morning into early aftn with no
restrictions. Next round late this aftn into the overnight hours
with some MVFR vis restrictions likely in the heavier down
pours, along with a few rumbles of thunder over northern NY.
South winds 5 to 10 knots develop this morning with some
localized gusts 15 to 20 knots possible between 15-21z today.

Outlook...

Tuesday: VFR. Likely SHRA, Slight chance TSRA.
Tuesday Night: Mainly VFR, with local IFR possible. Likely SHRA.
Wednesday: MVFR/IFR conditions possible. Chance SHRA.
Wednesday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.
Thursday: VFR. Slight chance SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: VFR. Slight chance SHRA.

&&

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

&&

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