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081
FXUS61 KBTV 211934
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
334 PM EDT Fri Jun 21 2024

.SYNOPSIS...
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Unsettled weather will continue through the weekend as a frontal
boundary wavering over the region will result in repeated rounds of
showers and thunderstorms. Ponding on low lying roads may be
possible Sunday with heavier showers and storms. Temperatures will
be much more seasonable through the weekend, as well, with highs
generally in the 70s and 80s.
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&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
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As of 328 PM EDT Friday...A cold front sinking southward across
southern Vermont into southern New England this evening will be the
focus of showers and thunderstorms. Showers and thunderstorms along
the southern zones of our forecast area could be locally heavy with
precipitable water values up to 1.75 inches. Thunderstorms are not
anticipated to be severe within the bounds of our forecast area,
however, some may be gusty in those southern zones, closest to the
core of high CAPE values.

Showers and thunderstorms will dwindle into the overnight hours as
daytime heating wanes, however, many high resolution models are
showing a resurgence of showers as the frontal boundary lifts
northward back into our forecast area early tomorrow morning. We`re
expecting up to a couple tenths of an inch of rain throughout the
night. In addition to the return of showers, patchy fog is expected
to return overnight tonight. Lows tonight will fall into the upper
50s to mid 60s, remaining 5-10 degrees above seasonal averages.

Chances of showers and thunderstorms resurge tomorrow along the
frontal boundary in our forecast area, and the primary threat with
these will be heavy rainfall with deep warm cloud layers about 12000
feet. We are within the marginal area of WPC`s Excessive Rainfall
Outlook, indicating at least 5% risk of rainfall exceeding flash
flood guidance within 25 miles of a point as precipitable water
values approach 2 inches in spots. Overall expected rain amounts
from the daytime hours tomorrow will be 0.15-0.35", but locally
higher in heavy storms. Some of these storms could be a bit gusty
with modest instability and shear present, but overall we are not
anticipating widespread severe weather. Highs tomorrow will rise
into the 70s for most, near seasonable.

Tomorrow night, a low pressure will ride the stalled frontal
boundary through our forecast area as a larger scale system
approaches from the west. Precipitable water and warm cloud depths
continue to look favorable for heavy rain throughout the night.
We`re forecasting 0.10-0.90" of rain throughout the night, but
locally more in heavy showers or thunderstorms. Lows tomorrow night
will be similar to tonight, with temperatures falling into the 60s
for most.
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&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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As of 328 PM EDT Friday...Sunday will be another active weather day.
A surface low, potentially even sub-1000mb, will track east over the
Great Lakes region and drive Saturday`s warm front to the north.
Depending on how far north it goes, we may land solidly within the
warm sector with some partial clearing. What will be challenging for
vigorous convective development will be the timing of a prefrontal
trough. Without a capped environment, any daytime heating will
initiate showers and thunderstorms. Although 750-1500 J/kg is most
likely, there`s conditional chances for reaching 2000 J/kg while
35-40 knots of shear is present. Being positioned so near the warm
front still, there may be good to excellent low-level convergence
and increased helicity as the low tracks closer. However, if there`s
too much convective debris, the potential for strong to severe
thunderstorms would become more limited. Additionally, precipitable
waters remain above 1.5". Given the favorable low-level forcing,
there could certainly be locally heavy downpours. Hydro concerns may
be non-zero depending on how Saturday evolves. If we deal with a
situation where the warm front fails to make appreciable northward
progress, then multiple rounds of rain could also take place.

Temperaturewise, conditions will be coolest along the international
border near the front, with low to mid 70s. In the typically cooler
Adirondacks and Northeast Kingdom, mid 70s will also be most likely.
In the broader Champlain and lower Connecticut River Valleys, expect
upper 70s to lower 80s. The actual cold front does not arrive until
Monday morning. Conditions will remain in the upper 50s to upper
60s, about 5 degrees above normal.
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&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
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As of 328 PM EDT Friday...Once low pressure moves east, deep low
pressure reaches peak intensity. Decreasing thicknesses, cool
northwest flow amidst wrap around showers will result in upper 60s
to mid 70s for most (though still near 80 in the southern half of
the Connecticut River Valley). The upper low will be slow to shift
east initially. Chances for showers will linger into next Tuesday
morning. Dry weather only hangs around for 24-36 hours before
another cold front sweeps through sometime next Wednesday night or
Thursday afternoon. It`ll be after this front where it looks like we
could see more appreciable drying.
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&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Through 18Z Saturday...Scattered showers are developing across
the forecast area this afternoon, so VCSH is plentiful within
the TAFs. Watching RUT closely at this time as thunderstorms may
approach. Outside of showers and thunderstorms occasionally
lowering cigs and restricting vis, VFR is expected for all sites
through about 04Z-12Z Saturday, which is when fog/mist is
expected to develop, with highest confidence at SLK, MPV, and
RUT. Fog will likely last about 06-12Z, then low ceilings will
prevail at most if not all sites early tomorrow. We are
anticipating more widespread showers and thunderstorms for
tomorrow as a frontal boundary lifts north, which could keep
conditions soupy with low ceilings and visibilities. Winds
throughout the next 24 hours will be largely light and variable
to calm outside of thunderstorms.

Outlook...

Saturday Night: Mainly VFR, with local IFR possible. Likely SHRA.
Sunday: Mainly MVFR, with local IFR possible. Definite SHRA,
Chance TSRA.
Sunday Night: Mainly MVFR, with areas VFR possible. Likely SHRA,
Slight chance TSRA.
Monday: Mainly VFR, with areas MVFR possible. Likely SHRA, Slight
chance TSRA.
Monday Night: Mainly MVFR, with areas VFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday: VFR. Slight chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA,
Slight chance TSRA.

&&

.HYDROLOGY...
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A stalled boundary with rounds of showers and thunderstorms,
heavy at times, could produce flash flooding this weekend.
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&&

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

&&

$$
SYNOPSIS...Storm
NEAR TERM...Storm
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Storm
HYDROLOGY...Team BTV