FXUS61 KBTV 180240
Area Forecast Discussion
National Weather Service Burlington VT
1040 PM EDT Thu Aug 17 2017
High pressure will shift east tonight as a warm front
approaches from the southwest. Showers and thunderstorms are
possible with the warm front after midnight tonight into Friday,
especially in northern New York. Showers will taper off Friday
night, and remain possible on Saturday mainly over the higher
terrain. Sunday will be warm, a little less humid, with no rain
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1038 PM EDT Thursday...Current forecast is in good shape
as leading edge of warm advection rainfall/showers has reached
St. Lawrence county as of 02Z. Surface ridge across central New
England will continue to shift eastward overnight, allowing a
warm front to lift northeast into the region from the eastern
Great Lakes. Leading edge of warm and noticeably more moist air
to push into mainly the New York side of the forecast area
during the overnight hrs. Surface dewpoints in the 50s to be
replaced by 60s dewpoints. Precipitable water rises with the
surge of warm moist air, 1.5" across most of the region to near
2 inches in the south of the forecast area. Sharp gradient of
Showalter Index values moves into northern New York after
midnight and this will enhance the potential for elevated
convection. The 18Z NAM indicates elevated CAPE approaching
800-1000 J/Kg for parcels lifted from 875mb in vicinity of srn
St. Lawrence County around 09Z Friday. Thus, some embedded
convective elements and thunder possible toward daybreak for the
far wrn portion of the CWA, but tstm potl mostly holds off til
daylight hrs Friday.
Overnight lows will see an early drop, then start to rise
around midnight in northern NY and early morning hours in the
Champlain Valley. Green Mountains and eastward will experience
normal diurnal trend in temps. Lows will mainly be in the mid to
upper 50s, except lower 60s expected in the Champlain and St.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
As of 349 PM EDT Thursday...For Friday the warm front lifts
through the rest of the forecast area and showers and increasing
chances for thunderstorms as atmosphere destabilizes. Shortwave
ridging at 500 mb shifts east, and by mid day Friday upper flow
becomes diffluent ahead of approaching shortwave trough moving
through the Great Lakes Region. Warm moist airmass remains in
place through the period with dewpoints remaining well into the
Forecast CAPE 500-1000 j/kg, not great but enough to support
some thunder. With high PWATS and warm cloud depth nearing
12,000 feet looking for efficient rainfall production and heavy
rainfall rates, however storms should keep moving along to
mitigate flooding risk.
Highs Friday in the 70s to near 80, and lows Friday night hold
in the 60s.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 318 PM EDT Thursday...Mainly dry weather is expected from
Saturday night through Tuesday morning. Surface ridge builds
over the region Sunday keeping things quiet through early
Tuesday. A shortwave will cross the area Saturday and Sunday. As
the ridge slides to the east Tuesday moisture and warm advection
will increase on southwest winds bringing more humid and
unstable air to the region, with precipitation chances
returning. Deepening low pressure will move from the northern
Great Lakes will move up the St. Lawrence seaway by Wednesday
bringing unsettled weather once again. Greatest precipitation
chances look to be Tuesday night and early Wednesday. Drier
weather returns to the region Thursday.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...VFR conditions this evening will
deteriorate as showers along approaching warm front lower cigs
and vis to MVFR after 06z northern NY, 10-13 UTC in Champlain
Valley and Vermont. Some embedded thunderstorms are possible at
KMSS due to elevated CAPE in the area.
Low level jet of 30-40kts around 2kft will produce LLWS at KSLK
mainly between 08z-13z. Elsewhere, expect the jet to not be as
strong. Surface winds will increase out of the south early
morning Friday and throughout the mid-day. SE component of
surface winds could lead to periods of VFR conditions at KRUT
and KBTV through at least the mid morning hours.
Showers and embedded thunderstorms continue throughout much of
Friday, becoming less numerous during the late afternoon. Cigs
may rise to VFR conditions as skinny dry slot moves across the
North Country in the afternoon hours, ahead of main frontal
Friday Night: VFR/MVFR. Chance SHRA...Slight Chance TSRA.
Saturday: VFR. Breezy. Slight Chance SHRA.
Saturday Night: VFR. Slight Chance SHRA.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Chance SHRA...Slight Chance TSRA.