203
FXUS61 KBTV 121741
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
141 PM EDT Sun May 12 2024

.SYNOPSIS...
Unsettled weather continues today with scattered showers and
cool temperatures. Once again hit and miss type showers are
anticipated with mostly light rainfall as temperatures climb
into the mid 50s to lower 60s. A warm front will produce more
showers on Monday followed by a cold front with showers and
embedded thunderstorms on Tuesday. Highs warm back into the mid
60s to lower 70s on Tuesday, before a slight cooling trend
occurs for midweek.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 127 PM EDT Sunday...Light rain showers continue across the
region this afternoon, with an increase in coverage compared to
this morning. Temperatures remain cool for this time of year,
currently ranging from the upper 40s in central Vermont to the
60s in the St. Lawrence Valley. Minimal changes were made to the
forecast with this update, just small adjustments to
temperatures to reflect the latest trends.

Previous discussion below:
Water vapor shows the center of a closed and vertically stack
cyclonic circulation is located near Buffalo, NY this morning.
Meanwhile, radar and sfc obs are indicating some scattered light
rain showers prevail over northern NY into parts of the CPV,
while most of central/eastern VT remains dry. The theme for
today wl be a slightly more robust areal coverage of showers,
especially spine of Green Mtns into northern NY, including the
CPV, but a complete washout is not anticipated. Timing of areal
expansion of precip is challenging, but thinking highest pops wl
be btwn 15z-22z today, with activity waning toward evening.
Have noted a small pocket of sfc based CAPE of 100-200 J/kg with
rather steep sfc to 3 km lapse rates, so similar to yesterday a
rumble or two of thunder is possible, but feel coverage wl be
<10% so have not included in grids attm. In addition, freezing
levels are near 4500 feet or 850mb and given cooling temp
profiles aloft, cannot completely rule out some very localized
pea size hail in the stronger updrafts this aftn, similar to
yesterday. Areal coverage and forecaster confidence is too low
to mention in grids attm. Progged 850mb temps hover near 0C
today with 925mb temps of 7 to 8C, supporting highs only in the
mid 50s to lower 60s, with mostly 40s in the mtns above 2000
feet. Based on deepest 850 to 500mb rh progs, weak differential
heating boundary, and rotation of s/w energy around cyclonic
circulation I have likely pops over northern NY with chc pops
extending into VT.

As sfc heating wanes and moisture profiles decrease with
building heights tonight, showers wl dissipate with skies
becoming at least partly cloudy, with some mostly clear skies
likely in NY. Based on upstream obs some patchy valley fog is
possible btwn 04z-10z where clearing develops and rain occurs
today, something to watch moving forward, especially as winds
become light overnight. On Monday, clouds quickly overspread the
region from west to east as a warm frnt approaches. Additional
light showers are likely especially btwn 15-21z from northern
NY into portions of VT. Highs on Monday warm back into the 60s
with southerly flow and modest 925mb to 850mb waa.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 403 AM EDT Sunday...Warmer, wetter conditions continue to unfold
during this period. Monday night a warm front type of feature
featuring strong mid-level warm air advection will further push
through the region, with focus of showers generally in northern
areas where rainfall, PoPs, and thunder chances look greatest.
Some elevated instability could lead to rumbles of thunder with
the showers that push through. While not particularly high, PWAT
will surge based on progged 3 hourly change upwards of 0.4"
associated with a modest southerly low level jet. This regime
should keep temperatures steady or even warm overnight.

For Tuesday, particularly during the afternoon/early evening, the
chance of thunderstorms generally has increased a bit. Likewise,
high temperatures have jumped a few to several degrees from the
previous forecast, especially in much of Vermont, associated with
more likely sunny breaks in the cloud cover before showers return.
There is a faint signal for severe weather, mostly driven off of the
GEPS, with a scenario that shows upwards of 30% of members with CAPE
exceeding 500 J/kg overlapping bulk wind shear greater than 30 knots
Tuesday afternoon. Most scenarios keep us too cloudy and cool to get
too much instability, and the large scale forcing for strong storms
looks fairly poor with a weak frontal system and height falls during
this period. Overall, the signal for some heavy rain is relatively
high compared to strong thunderstorms, especially late Tuesday when
the weak frontal boundary slides into the region and may be slow to
progress to our southeast.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
As of 403 AM EDT Sunday...Tuesday night will likely be wet with
a low chance of embedded thunder, with strong model agreement
on precipitation at this time. Chances of rain generally shift
southeastward over time through such that Wednesday may wind up
being dry for many. That being said, with continuity and blend
of ensemble data that shows showers lingering, we keep rain
chances through Wednesday night while tapering them off to near
zero by Thursday morning. Before the frontal boundary shifts to
our southeast, 0.5" to 0.75" is the most likely rainfall total
in Vermont and northern New York based on the NBM Quantile
Mapping and Dressing technique, with high end potential based on
the 90th percentile, primarily in Vermont, of up to 1.75". Note
that near zero rainfall is just as likely a possibility,
associated with a much faster frontal passage on Tuesday
afternoon.

Following the potential rainy conditions midweek, as a coastal
storm looks to pass well to our south, we will sit in a zone of
weak high pressure that may provide a lull in unsettled weather
for Thursday into Friday morning. The upper level pattern is
pretty divergent for late in the week, so while precipitation
chances increase again Friday into Saturday, the nature of the
showers and any convective chances is rather uncertain.
Temperatures generally look to be seasonably warm with highs
mainly in the upper 60s to mid 70s through this period. There is
relatively large uncertainty for Saturday, especially in
southern portions of Vermont, based on NBM standard deviation
values, so expect changes moving forward on that day`s
forecast.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Through 12Z Monday...Scattered to numerous showers continue
across the region this afternoon, with unsettled conditions
expected to continue for the next several hours. Primarily VFR
flight conditions can be found at all terminals, although
occasional MVFR ceilings can be found within showers. Showers
will gradually diminish towards 00Z Monday, with VFR conditions
prevailing overnight. With the recent rainfall, there is the
possibility of some patchy fog overnight if skies clear out,
particularly at KSLK, although confidence is not high enough to
include in the forecast. Winds this afternoon have been
southerly between 4 to 8 knots, and will trend light and
variable overnight.

Outlook...

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

&&

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

&&

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