623
FXUS61 KBTV 050725
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
325 AM EDT Mon May 5 2025
.SYNOPSIS...
Cool and unsettled weather continues for the first half of the week
with additional showers likely and temperatures slightly below
normal. The highest probability of precipitation and heaviest
rainfall amounts today will be across Rutland and Windsor counties.
Localized amounts greater than 1 inch are possible. Very little
rainfall is expected near the international border. Temperatures
will be in the mid 50s to mid 60s today.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 324 AM EDT Monday...Showers continue to saturate the southern
half of Vermont this morning as a stationary front and axis of rich
moisture sit across southern New England. The moisture axis is
projected to shift northward throughout the day today as flow picks
up out of the southeast, advecting in air from over the Atlantic
Ocean. In fact, we`re expecting a southeasterly low level jet to
develop overhead with winds at the 850mb potentially reaching around
45 knots. While much of the atmosphere below 700mb will be
saturated, high resolution models are indicating there will be some
near-surface mixing to allow for some gusts to reach the surface,
notably downsloping areas where slopes face the west or northwest.
This downsloping could also produce shadowing in terms of
precipitation, resulting in less wet weather in these areas
throughout the day. Additional rain shower precipitation will be
focused on southwestern forecast areas with up to a quarter inch
possible. Temperatures will be warmest in northern areas that don`t
receive as much precipitation with highs in the mid to upper 60s.
Otherwise, rainier spots will have highs in the upper 50s to mid
60s.
Moisture will continue to flow into the forecast area tonight with
the potential for showers expanding to the northern reaches of the
forecast area. Most likely spot for rain will continue to be
southern Vermont, Essex County, New York, and southeasterly upslope
slopes, though some precipitation is also likely elsewhere,
including along the international border. Additional rainfall
amounts will be about 0.01-0.30" with highest amounts in southern
zones and lowest in the Northeast Kingdom. The low level jet will
continue to strengthen, potentially kicking up 850mb level winds up
to 55 knots. Due to this, we continue to forecast downsloping winds
and shadowing on western and northwestern slopes tonight. However, a
low level inversion should prevent gusts from mixing down much at
lower elevations. Areas that become warmer today will hold onto some
of that warmth tonight in the lower to mid 50s, otherwise we could
have temps dropping into the upper 40s to lower 50s.
Low pressure will begin to shift towards the forecast area from the
Ohio Valley tomorrow, bringing additional frontal forcing and
triggering more showers and potentially a few rumbles of thunder.
Highest chance of thunderstorms will be in northern New York,
particularly the St. Lawrence Valley, where an arm of instability
could reach up to and where temperatures could soar as high as the
lower 70s. Elsewhere, temperatures will only reach the upper 50s to
upper 60s, staying coolest east of the Greens. The axis of moisture
powering showers will likely shift to our east, mainly impacting New
Hampshire while a more thundery line of precipitation approaches
from New York. The central and northern portions of the forecast
area will actually fall into a drier period, though passing showers
are still expected. An additional 0.05-0.40" is anticipated, with
highest amounts falling across the Connecticut River Valley into
southern and central Vermont, as well as St. Lawrence County. The
low level jet will also begin to pull away from the forecast area,
though surface southeasterly flow should remain breezy for much of
the day.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 324 AM EDT Monday...The persistent upper low will get
reintegrated into the large scale flow. As it lifts northeastwards,
cooling aloft will help produce marginal destabilization. Some
scattered activity will propagate north as the surface low reaches
the St. Lawrence Valley in tandem with a lead vort max while morning
temperatures range from the mid 40s to mid 50s. The bulk of
precipitation will develop once the upper low is overhead and a
surface cold front behind the weak low then near Quebec City will
send southeastwards. Strong surface convergence along the front and
temperatures to about 70 yielding roughly 500 J/kg of CAPE Wednesday
afternoon. Thunderstorms are anticipated to be garden variety due to
light flow with shear generally less than 20 knots. With PWATs near
to just over an inch, a few could produce locally heavy rainfall.
Despite the loss of diurnally driven instability, showers should
continue overnight as a sharp trough digs southeast while moisture
wraps around the departing upper low. Increasingly northwest flow
should favor our northern mountains with orographic enhancement. A
cooler night in the upper 30s to upper 40s is forecast.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 324 AM EDT Monday...Well, forecast trends have continued
steadily adjusting the replacement upper low to the west with
ensemble mean 500mb heights now onshore as opposed to the Gulf of
Maine. The main implication is that there will be increased cloud
cover. From the perspective of frost, this decreases the likelihood
of its occurrence. However, the proximity of the upper low brings
rain into the forecast for another Friday/Saturday. Recall we`ve
been pointing out the NBM`s 10-20% chance of precipitation was
comfortably below climo probability of precipitation averages. The
NBM has now bumped up to 25-40% and long range ensemble guidance has
crept up to 40-60%. Rain will come from surface low pressure
developing to the east of the upper low and curling up the East
Coast. Analysis of ensemble clusters indicates the 500mb low could
be located in a wide number of locations. So how much and how
widespread the precipitation will be depends on the track of this
upper level feature.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Through 06Z Tuesday...Persistent showers continue across
southern Vermont, resulting in visibilities fluctuating around
1-5 miles for RUT. Potential for precipitation will decrease
over the next few hours there as moisture gets shunted
southward, however, there is still the chance for IFR
visibilities to continue, off and on for the rest of the early
morning. Other Vermont sites could have some patchy fog and/or
low stratus, such as MPV and EFK, though this may be off and on
as well. Showers are projected to increase in areal coverage
throughout the day today, spreading north and bringing
widespread ceilings 3000 feet and less above ground level by
about 15Z-21Z.
RUT will again be an exception, likely keeping MVFR or lower
ceilings for much if not all of the next 24 hours. Elsewhere,
VFR conditions are likely to return by around 22Z-02Z, though
there remains some uncertainty on the exact height of ceilings
tonight as much will depend on the location of weather features
and strength of moisture advection off the Atlantic Ocean.
Visibilities over the next 24 hours look to be 4+ miles outside
of MPV and RUT. Around 23Z-04Z, we anticipate some potential for
LLWS to develop as a weak low level jet brushes by. Surface
winds, currently calm, are expected to increase out of the
southeast, gusting 20-30 knots at RUT around 16Z onward due to
downsloping. MSS will follow its own path again with
northeasterly winds instead.
Outlook...
Monday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHRA.
Wednesday: Mainly MVFR, with local IFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with areas IFR possible. Chance
SHRA.
Thursday: Mainly MVFR, with local IFR possible. Chance SHRA.
Thursday Night: Mainly MVFR, with local IFR possible. Slight
chance SHRA.
Friday: Mainly MVFR, with areas VFR possible. Slight chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Storm
NEAR TERM...Storm
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Storm
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