133
FXUS61 KBTV 061422
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
1022 AM EDT Tue May 6 2025
.SYNOPSIS...
Damp weather conditions will continue. By Wednesday night, a
persistent upper low will begin to depart the region. Briefly
cooler and drier conditions will give way to additional rain,
mainly over Vermont Friday afternoon into Saturday. The
development of a broad upper ridge across the eastern US signals
a likely pattern change next week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1014 AM EDT Tuesday...Timing of rain showers and
associated pops/qpf continues to be the challenge with deep
closed vertically stacked cyclonic circulation over the Ohio
Valley. As weak sfc instability develops associated with several
narrow dry slots rotating acrs our cwa, expect the areal
coverage of showers with embedded rumbles of thunder to increase
in areal coverage/intensity this aftn/evening. The highest
probability of CAPE values near 500 J/kg continues to be located
over the SLV/western Dacks and have the highest potential for
thunder is in this area. Otherwise, sounding analysis shows the
potential for some training/back building showers/storms, given
the unidirectional flow aloft and small MBE velocities <10
knots, so we wl cont to monitor hydro threat. As instability
wanes this evening, intensity/coverage of showers should
decrease by 03z. Did make some minor tweaks to pops/qpf, but
kept temps the same, even thou we are running several degrees
too cool. A bit more humidity noted this morning with sfc dwpts
climbing into the mid 50s to lower 60s per obs.
Previous discussion below:
Slow moving upper low pressure is beginning to accelerate
northeastwards. Currently, we are at the confluence of a moist,
southeasterly fetch off the Atlantic Ocean. A 40-50kt LLJ and a
pocket of mid-level dry air evident on water vapor will lift
northeast with scattering of precipitation. Near 70 to mid 70s
should be prevalent in the Champlain Valley and St. Lawrence
Valleys while the rest of the region will linger in the 60s.
Daytime heating and dewpoints in the mid 50s should allow for
about 500 J/kg of CAPE, perhaps even 1000 J/kg over the St.
Lawrence Valley. Pulse convection should initiate mid- afternoon
and lift north in increasingly southerly flow. If there`s
anywhere that could have a stronger storm, it`d be the St.
Lawrence Valley due to better instability and shear of about
30-35 knots. Low-level flow is relatively weak and low-level
lapse rates are also poor. So if any storm is to produce much,
it`ll have to be sustained and breach a stable layer around
700mb. Some small hail and locally gusty winds could develop in
the St. Lawrence River Valley, but the rest of the region will
remain firmly garden variety.
The other thing that will need monitoring will be convection in
southern Vermont. The last two days has yielded 1-2 inches
across Rutland and Windsor Counties. 3 hour flash flood
guidances are about 1.6-1.8" and 6 hour is about 1.8-2". The
latest HREF forecast does not highlight this region, instead
emphasizing western St. Lawrence County, but that region is
tough to flood. Occasional HRRR runs have a narrow swath of 1-2"
cutting into Windsor County, and this suggests a watchful eye
kept there during afternoon convection.
By tonight, decreasing surface instability and entrainment of
dry air again will cause activity to wane, except continuing in
St. Lawrence County due to close proximity with the surface
low. Another warm mid-spring night with upper 40s to upper 50s
is expected Tuesday night. Upper level low pressure will be
overhead Wednesday with a surface cold front shifting southeast
late in the day. High res guidance has backed off some on
coverage and have mostly 40-70 PoPs once instability develops
Wednesday afternoon. With little wind shear, garden variety
thunderstorms are possible. Outside showers, it will be an
otherwise pleasant day in the mid 60s to lower 70s.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
As of 304 AM EDT Tuesday...Scattered showers Wednesday night will
become increasingly isolated and confined to higher terrain going
into early Thursday, with the forecast eventually trending mainly
dry by the evening. Despite the diminishing shower threat, skies
will remain partly to mostly cloudy as an upstream shortwave
approaches from the west. Low temperatures Wednesday night will
range through the 40s, while highs Thursday will be in the 50s for
most locations. This will be noticeably cooler than the previous few
days, although the brief break in rain showers for most will make
Thursday a good day for those searching for some relief from the
persistent showers.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 304 AM EDT Tuesday...The shortwave trough moving in from the
west will close off into another upper-level low Friday, which will
mean a return to the showery pattern for parts of the Northeast.
Highest confidence is in rain developing Friday and Saturday for
parts of southern and eastern Vermont, but there is some hope for a
drier conditions further west into northwestern VT and northern NY.
This setup will be due in part to the development of a coastal low
late Friday into Saturday under the upper low, with some question
remaining as to just how close to the New England coast the low
tracks as it moves northeast. The 24 hour model trend of the
deterministic GFS has been to generally shift the precipitation
further east with each consecutive run, supported by decreasing
probabilities for measurable precipitation in our western counties
amongst the GEFS ensemble guidance. Meanwhile, the ECMWF is holding
strong to a further inland track, resulting in (another) rainy
Saturday for most of our area. The 00Z deterministic run of the
Canadian is holding on to the faster trend as a whole with the
system, bringing some rain to eastern counties on Friday but keeping
Saturday mainly dry. A look at the ensemble QPF guidance shows a few
individual ensemble members clinging to a washout on Saturday, but
by and large the ensemble guidance is favoring lighter precip
amounts for northern NY and northern VT. Thus, have stuck close
to the National Blend forecast for PoPs for the weekend, keeping
25 to 40 percent PoPs for most of Vermont and into our eastern
NY counties for Saturday. As the low exits Saturday night,
confidence increases in a dry Sunday with drier air and surface
high pressure moving in from the west. Drier weather will last
into early next week with a warming trend in temperatures.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Through 12Z Wednesday...Conditions are mainly VFR outside some
1500 ft agl ceilings at KRUT and KMPV with rain showers lifting
northwestwards. Winds are out of the south to southeast, mainly
5 to 10 knots with a few gust to 15 knots. A relative lull in
precipitation will take place for the next 6 hours. Some partial
clearing should push all sites to VFR and a slight increase in
wind speeds. South to southeasterly winds of about 40 knots at
2000 ft agl appear to subside a bit earlier based on latest
data, and have LLWS tapering off about 18z now. Beyond 18z,
additional showers and lower ceilings to 1500-4000 ft agl will
advance back north. There could be a few embedded thunderstorms,
but mainly moderate rain is likely, with a few PROB30 groups
with 4-5SM indicating this idea. Showers again ebb about 00-03z
and winds trending towards 5 knots. As this batch of showers
lifts north, there will be some lower ceilings behind it such
that KMPV could fall to 900 ft agl ceilings and perhaps KEFK.
Otherwise, ceilings likely not to adjust much between 00z and
12z Wednesday.
Outlook...
Wednesday: Mainly VFR, with local MVFR possible. Chance 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. Slight
chance SHRA.
Friday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Saturday: VFR. Chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Haynes
NEAR TERM...Haynes/Taber
SHORT TERM...Duell
LONG TERM...Duell
AVIATION...Haynes
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