847
FXUS61 KBTV 060547
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
147 AM EDT Tue May 6 2025
.SYNOPSIS...
Cool and unsettled weather continues for the first half of the
week with additional showers tonight through tomorrow. As our
upper-level low translates into the region tomorrow,
thunderstorms are possible in the St. Lawrence with continued
rainfall in southern Vermont. Localized rainfall amounts greater
than an inch are possible in southern Vermont with a tenth to
half an inch likely from the international border to central
Vermont and northern New York by Wednesday. Temperatures will
continue to be seasonably cool through mid-week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 138 AM EDT Tuesday...One batch of rain is departing.
Another will arrive soon with ongoing confluence between upper
level low over the Ohio River Valley and an area of high
pressure across the Canadian Maritimes. Made tweaks to PoPs to
capture hourly radar data with no major changes needed.
Previous Discussion...Showers will continue to overspread the
area this evening as a stationary boundary and axis of sub-
tropical moisture sits across southern New England. Moisture
will shift northwards tonight out of the Atlantic with the most
likely locations to see continued rain in southern Vermont and
Essex County in New York. These locations could see between
0.25-0.5 inches of rain overnight, with locally higher amounts
possible along the eastern slopes of the Greens. Near the
international border and in the northern Champlain Valley,
showers will be more isolated with lower precipitation amounts
expected near 0.1-0.2 inches overnight. Associated with
moisture, an 850mb jet will continue to build over the region as
the upper-level low in the Ohio Valley finally begins to move
to the northeast. 850mb winds near 50mb could be realized at
mountain summit level, though a low- level inversion within
shower activity should keep a lid on the higher gusts in the
valleys. Mountain summits could see gusts up to 40 mph with
westerly 20 to 30 mph gap winds possible in the western facing
downslope regions of the Greens tonight. These gusts could help
to limit shower activity in the western downsloped regions
through possible shadowing effects overnight. On the flip side,
in southern Vermont, this jet will help aid in localized
frontogenesis which could lead to localized heavier downpours
across Rutland and Windsor Counties. Temperatures tonight will
be warmer in the St. Lawrence Valley and northern Champlain
Valley where shower activity will be less widespread. Generally
temperatures tonight will be 50 to 55 areawide. As temperatures
cool, some patchy fog is possible in the lower Connecticut River
and Champlain Valleys overnight, though widespread fog is not
anticipated.
Tomorrow, the upper-level low arrives in New York with added frontal
forcing and additional showers. The main axis of moisture looks to
move to the east into NH late Tuesday morning, although showers will
still be possible in southern Vermont, and along the Connecticut
River Valley. Frontogenesis and some clearing in the St. Lawrence
Valley underneath the upper low will lead to the development of
instability Tuesday afternoon. Probabilities of greater than 500
J/kg of SBCAPE near Ogdensburg are 100%. Given cool air aloft, LCLs
will be low with lapse rates around 6-7 C. Severe weather chances
are low however, given the likely development of widespread cumulus
limiting daytime heating and subsidence cooling tomorrow. Main
threats tomorrow would be locally gusty winds with small non-severe
hail and/or graupel given low freezing levels aloft. Shear should be
near 20-30 mph which should limit any flash flooding potential, but
we will continue to monitor conditions as they become more apparent
tomorrow. Outside of the St. Lawrence Valley, light to moderate
scattered showers are possible throughout the day. It does not look
like a full washout of a day, with shower activity not as widespread
as today. Temperatures tomorrow will be fairly similar to today with
slightly warmer temperatures from southerly waa.
Showers will taper off and become more drizzly and isolated Tuesday
night as the upper low moves directly overhead. Subsidence should
clear out any prevailing precipitation though low-level moisture
could keep some lingering drizzle overnight. Lows Tuesday night will
be a few degrees warmer than tonight with values in the low to mid
50s.
&&
.SHORT TERM /WEDNESDAY NIGHT/...
As of 400 PM EDT Monday...The synoptic scale pattern shows
mid/upper lvl circulation finally lifting northeast acrs our fa,
while weakening. The combination of cool air aloft and embedded
s/w energy under the closed circulation wl result in additional
showers with embedded thunder on Weds. Given the timing of s/w
energy, feel the best axis of sfc based instability wl be acrs
central/eastern VT on Weds, where localized sfc based CAPE
values range btwn 500-800 J/kg. Also, directly under the
circulation wl result in very slow storm motions and weak deep
layer shear parameters, so the threat for severe is minimal.
Sounding analysis indicate relatively tall CAPE profiles up to
28kft, while pw values range btwn 0.70 and 0.90", but warm cloud
depths <8000 kft, due to cool air aloft. So thinking rainfall
rates should prevent any hydro concerns, but given the upper lvl
circulation directly overhead, we wl continue to watch closely.
Also, thinking as weak sfc heating occurs and convective temps
are reached, plenty of cumulus clouds wl develop, which is
occurring today under the circulation over the Ohio Valley and
this scenario wl limit the amount of instability available for
deep convection. Have likely pops from mid morning to mid aftn
Weds with temps in the mid 60s to lower 70s. As mid/upper lvl
circulation lifts to our northeast, precip wl become trrn
focused overnight and slowly dissipate by Thurs. Have confined
highest chc/likely pops acrs the northern Dacks and upslope
areas of the central/northern Greens on Weds night. Additional
qpf wl be <0.25" on Weds night. Have trended lows on the warmer
side of guidance, given clouds and lingering mtn precip.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 400 PM EDT Monday...One mid/upper lvl trof wl be replaced
by another closing and deepening cyclonic circulation for
Friday into Saturday acrs the NE CONUS/Mid Atlantic region.
Similar to a winter like pattern the timing of s/w phasing and
eventual track of sfc low pres wl determine the placement of
highest pops and heaviest qpf. Some 12z guidance is slightly
more progressive and less amplified with mid/upper lvl trof per
the CMC/UKMET solutions, while the ECMWF/GFS show the potential
for a widespread wetting rainfall late Friday into Saturday. NBM
indicates 40 to 60% probability of qpf >0.25" late Fri into Sat
over eastern and southern VT, and <30% over the SLV. In
addition, cool northerly flow and progged 925mb temps only in
the 5-7C range would support highs struggling to reach 50F
eastern cwa, including the NEK, while the SLV would be the
warmest with values in the l/m 60s with less rain/higher cigs.
For now have increased pops into the high chc (35 to 50%)
category late Friday into Saturday with highest values acrs our
eastern sections. However, if trends cont to support a ECMWF/GFS
solution, these wl need to be increased, especially CPV and
points eastward. Sunday crntly is looking to be a drier day with
building high pres, but lingering mid/upper lvl trof, caa, and
final s/w energy could produce some mtn focused precip,
especially Sunday morning. Did note a pocket of cooler temps
aloft acrs our cwa at 12z Sunday with progged 850mb temps <0C,
supporting below normal temps. Finally high pres builds into our
region with drier conditions and seasonable temps late Sunday
into next Monday. Highs warm back into the mid 60s to lower 70s
with lows mid 30s to mid 40s.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Through 06Z Wednesday...Conditions are mainly VFR outside some
1500 ft agl ceilings at KRUT and KMPV with rain showers lifting
northwestwards. A stagnant weather pattern will result in
little change over the next 24 hours. Batches of light rain
continue to lift north, but upstream observations do not show
much in the way of visibility restrictions and intervals of MVFR
ceilings. A relative minimum in precipitation coverage is
expected from about 12z to 18z before additional shower activity
will lift up from the south. There could be a few embedded
thunderstorms, but mainly moderate rain is likely, with a few
PROB30 groups with 4SM indicating this idea. Showers again ebb
about 00z. Intermittent LLWS will also continue through the next
24 hours with winds around 2000 ft agl out of the southeast to
south at 35 to 45 knots.
Outlook...
Wednesday: Mainly VFR, with local MVFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Chance
SHRA.
Thursday: Mainly MVFR, with local VFR possible. Slight chance
SHRA.
Thursday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Friday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Friday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Saturday: Mainly VFR, with local MVFR possible. Chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Danzig
NEAR TERM...Boyd/Danzig/Haynes
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Haynes
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