492
FXUS61 KBTV 301639
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1239 PM EDT Sun Jun 30 2024

.SYNOPSIS...
Humid air ahead of a cold front will help supply enough fuel
for scattered morning thunderstorms. Some storms may be capable
of a few strong to locally severe wind gusts and flash
flooding. Chances of thunderstorms will decrease during the
afternoon as drier air begins to enter the North Country, and
precipitation chances will diminish tonight. Quieter weather is
expected for the upcoming week with seasonable warmth and mostly
rain-free conditions.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 1232 PM EDT Sunday...Biggest change with this update was
to temperatures. With ample sunshine, they`ve soared well into
the 80s across much of VT, while NY spots are in the mid/upper
70s. This is already above previously forecasted highs by 3-5
degrees, and have increased maximum temperatures for this
afternoon accordingly. Otherwise, the rest of the forecast
remains in good shape. We continue to see isolated to scattered
convection popping up along the pre-frontal trough, with the
bulk of the activity having been in the northern tier of
counties along the international border. Storms have not been
overly impressive so far, with updrafts getting sheared apart
before being able to gain much appreciable height. We will
continue to monitor closely, but so far the main threat has been
torrential rainfall; saw one rain gauge near Franklin, VT that
recorded nearly an inch in less than 30 minutes. Any
strong/severe storms would be capable of producing damaging
winds, as evidenced by strong cells that have been crossing
southern NY over the past couple of hours. Please remain weather
aware today, especially if you have outdoor plans.

Previous discussion...A strong and complex frontal system will
progress through the northeastern US today. At the moment, we
are in the warm sector with ample heat and humidity, but because
of the nocturnal timing, instability is pretty low, especially
in Vermont. In northern New York, particularly in St. Lawrence
and Franklin counties, there is notably higher instability. This
environment should support thunderstorm development in the pre-
dawn hours as outflow from a cluster of showers in Ontario
approaches, providing necessary lift to grow existing showers,
which are being hampered by mid- level dry air. Given ample
effective shear and downdraft CAPE, organized thunderstorms will
be capable of isolated, damaging wind gusts, so we will be
focused on the morning convection over the northern counties of
our region as it moves across northern New York and Vermont.

Following this, there will be one more opening for impactful
weather associated with a pre-frontal trough, between 8 AM and
about 1 PM. There will likely be at least some sunny breaks in
the sky, allowing for temperatures to warm into the low 80s
across much of Vermont to boost instability. Coverage of
thunderstorms remains questionable given the drying aloft, but
any cells will also be capable of damaging wind gusts with
similar parameters given high deep layer shear and DCAPE.
Generally the threat will shift southeastward during this time
frame.

Then this evening we will see winds back to the northwest,
supporting lowering humidity following some scattered showers
along and just behind the cold frontal passage. Low temperatures
should be about seasonable in the upper 40s to near 60. Dry
weather is expected tomorrow. With continued cold air advection
and the related northerly breezes, temperatures tomorrow will
end up actually a little below normal, mainly in the low to mid
70s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 324 AM EDT Sunday...Surface high pressure building into the
region with a cooler, drier airmass with low temperatures in the
40s/L-M50s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
As of 324 AM EDT Sunday...Really no changes from yesterday`s
perspective...High pressure still in control on Tuesday with
moderating temperatures to near or slightly above seasonable levels
with highs in the U70s-L80s. Tuesday night will feature upper ridge
axis across the NE and dampening with the approach of a northern
stream shortwave with the surface high shifting SE for the
development of a return SSW flow and temperatures back into the
M50s-L/M60s.

Northern stream shortwave shifts east across southern Canada which
will dampen further the heat ridge across the southern CONUS. A warm
front traverses the area Wed with increased heat/humidity but likely
decent amount of clouds which may limit instability. Pre-frontal
trof may try to move during or shortly after peak heating so can`t
rule out showers and t-storms late Wed then front Wed eve especially
in northern NY possibly holding off in VT until around/after any
firework celebrations but stay tuned. as there are some firework
celebrations Wed eve. Highs in the upper 70s-M80s with dewpoints
back AOA 60F.

Upper level shortwave rotates east across southern Ontario/Quebec
thus the cold front slowly moves across CWA but appears to wash out
across the area. Therefore showers overnight Wed night with a
leftover morning shower possible on the 4th. Otherwise, despite a
lingering boundary there appears to be lack of any lift or
instability and should be mainly dry or only a shower for
Independence Day festivities with temperatures in the U70s-M80s.

Another northern stream shortwave/trof moving across the upper
Mississippi Rvr Vly Friday lifts ENE across the northern Great Lakes
and weakens Friday night and takes a similar path across SE Canada
Saturday. Weak low pressure associated with it will follow suit but
the lingering boundary will attempt to lift across our area as a
warm front Friday night-Saturday for some shower activity but not a
repeat of yesterday. Also right now, I`m leaning toward mainly
dry for Friday.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Through 12Z Monday...Aside from SLK where ceilings are as low as
1200 feet, VFR conditions are present this morning with isolated
showers primarily in northern New York. Following some daytime
heating, showers and thunderstorms will become more likely ahead
of a pre-frontal trough through about 16Z. Still have
relatively higher chances across the SLK-PBG-BTV area through
this period. A direct hit would support brief heavy rain and IFR
conditions, but mainly VFR/MVFR conditions are expected to
continue. Winds mainly 5 to 10 knots have already trended
westerly; they are primarily southwesterly this morning and
expected to become westerly this afternoon, and then
northwesterly towards 00Z. The northwesterly winds will be
accompanied by additional shower chances along with lowering
ceilings, with MVFR conditions most likely at SLK and EFK
overnight.


Outlook...

Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Slight chance SHRA.
Wednesday Night: Mainly VFR, with local IFR possible. Chance
SHRA, Slight chance TSRA.
Independence Day: Mainly VFR, with local IFR possible. Slight
chance SHRA.

&&

.HYDROLOGY...
The threat for localized heavy downpours and isolated flash flooding
continues across our region through midday. We`ve generally
seen between 0.75" and 1.5" of rain over the last 24 hours.
Sharp river rises of the East Branch of the Passumpsic in East
Haven and the Lamoille River in Johnson occurred overnight,
indicative of hydrophobic soils. Therefore, scattered heavy
showers and thunderstorms this morning will be capable of flash
flooding in portions of northern Vermont today.

&&

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

&&

$$
SYNOPSIS...Kutikoff
NEAR TERM...Hastings/Kutikoff
SHORT TERM...SLW
LONG TERM...SLW
AVIATION...Kutikoff
HYDROLOGY...Clay/Kutikoff