098
FXUS61 KBTV 171157
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
757 AM EDT Sat Aug 17 2024

.SYNOPSIS...
Mainly light rain showers, with a few heavier showers in the St.
Lawrence Valley, will be primarily across northern New York
today as a weak low pressure system ambles eastward. Rain
chances will slowly increase into Vermont tomorrow with more
widespread rainfall on Monday. By late Tuesday, drier and cooler
weather will take hold.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 757 AM EDT Saturday...Main change was to overhaul PoPs
based on radar, rain gauge, and mesoanalysis data. The corridor
of rain is rather narrow and not expected to move eastward much,
with only brief periods during the day where any showers could
be possible into Vermont. Have maintained slight chance of
thunder in this area mainly in western St. Lawrence County for
later today, as some very skinny CAPE could support an embedded
thunderstorm. Showers evident on radar in the southern
Adirondacks moving towards our area will likely result in only a
trace amount of rain, as our region from the Champlain Valley
eastward has a plethora of dry air aloft.

Previous Discussion...
A couple of features will drive our weather through the
weekend: a sprawling low pressure area currently centered over
Michigan and a high pressure area just south of the Canadian
Maritimes. These features will only slowly move eastward, which
in turn will gradually turn the balance towards the low pressure
area and increasingly frequent rain showers, mainly in northern
New York. Instability and moisture will be on the increase, but
persistent low level southeasterly flow around the high
pressure system will promote stable air. These conditions will
greatly limit potential for significant rain along and east of
the Green Mountains, and even farther west with some influence
of the marine air evident back to the eastern Adirondacks.
Daytime temperatures will be near seasonable values, while
moderately humid air and breezes will keep temperatures
overnight on the mild side.

The referenced wind will be notable after several days of light
winds. Southeast or south-southeast winds are expected to increase
this morning, especially across the Adirondacks and Champlain Valley
as the 850 millibar flow maximizes in this corridor and slowly
shifts to the east. Locations across northern portions of the
Adirondacks and near Lake Champlain should be able to tap into these
winds aloft to see some peak gusts in the range of 30 to 35 MPH this
evening into the early morning hours.

While flooding risk is low, a marginal risk for excessive
rainfall in our western areas looks reasonable. There will be a
sharp gradient between poor ingredients for much rain at all and
heavy rain potential. The St. Lawrence Valley will have much
better moisture and instability than areas to the east, and yet
the dynamics look too limited to take advantage. That being
said, the local probability matched mean HREF rainfall does
show a narrow 3" rainfall total through Sunday evening in a
very narrow swath, indicative of a reasonable worst case
scenario. The timeframe of the heavier rainfall probably would
be Sunday afternoon. Some convective allowing models show a few
footprints of hourly rainfall of an inch during this period
across southeastern St. Lawrence County. The associated
stronger convection would be tied to a an embedded shortwave
lifting northeastward through central New York, and the
predictability of such a feature is fairly low in this time
range.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
As of 349 AM EDT Saturday...Surface low and upper level trough will
be centered over Western New York on Sunday evening. These features
will continue to slowly track eastward during Sunday night. Showers
will increase in coverage overnight and spread eastward ahead of
surface trough which will cross the region during the day Monday. As
the surface front crosses our area on Monday, we could see some
heavy rain and also embedded thunderstorms. Rainfall totals across
our area from Sunday night through Monday will range from around a
half an inch in eastern Vermont, up to an inch in the Adirondacks.
Models continue to indicate that heaviest precipitation will be on
Monday afternoon, and models also continue to show a linear feature
developing as the cold front crosses the area. Will need to monitor
potential for heavy rain as PWATs will be in excess of 1.5 inches.
It has been over a week since we`ve had widespread precipitation, so
at this time think we`ll be able to handle some rain without
flooding issues developing. Will need to watch for training
thunderstorms. Have added heavy rain wording to the forecast. There
will not be a lot of surface based instability with temperatures not
making it out of the upper 70s in our warmest spots. Winds will be
gusty out of the south ahead of the cold frontal passage as well,
especially in the Champlain valley where the flow will be channeled.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 349 AM EDT Saturday...Upper level trough will linger a bit
behind the surface low, this will lead to continued chances for
showers on Monday night into early Tuesday. By Tuesday afternoon
surface ridging will build into our area and showers will come to an
end. With strong cold front east of our region, temperatures will be
cool Monday night and Tuesday. We will have some locations in the
Adirondacks in the mid 40s Monday night, then highs will likely
remain in the 60s areawide on Tuesday. Surface and upper level
ridges will build into our region Tuesday night and remain through
much of the week. We will have a gradual warming trend with
temperatures returning to seasonable levels and drier weather once
again.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Through 12Z Sunday...VFR conditions in much of the area will
continue. The exception is in eastern Vermont where a shallow
stratus deck is resulting in a mix of MVFR and IFR conditions at
EFK and MPV. Expect gradual improvement with scattering of this
low cloud deck some time through the 14Z to 18Z period at these
sites. Through much of the TAF period, a corridor of showers
will affect KMSS and possibly SLK at times, with increasing
chances of reducing visibilities to 4SM.

Winds will continue to be SSE generally 4 to 8 knots through
the period with periods of gustiness, primarily at BTV this
morning, and possibly again towards 00Z. Peak gusts will be near
20 knots.

Outlook...

Sunday: VFR. Chance SHRA, Slight chance TSRA.
Sunday Night: Mainly VFR, with local IFR possible. Likely SHRA.
Monday: Mainly MVFR, with local IFR possible. Definite SHRA,
Slight chance TSRA.
Monday Night: Mainly MVFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. NO SIG WX.

&&

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

&&

$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff
SHORT TERM...Neiles
LONG TERM...Neiles
AVIATION...Kutikoff