FXUS61 KBTV 212025
Area Forecast Discussion
National Weather Service Burlington VT
425 PM EDT Mon Aug 21 2017
Quiet weather tonight under a mild humid southwest flow with
high pressure off the mid-Atlantic coast. Very warm temperatures
continue on Tuesday, but an approaching cold front will bring
showers and thunderstorms mainly in the afternoon and evening
tapering off Tuesday night. Cooler weather is e with showers
lingering into Wednesday. The remainder of the week is shaping
up to be cooler and drier with below normal temperatures.
.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 425 PM EDT Monday...High pressure at the surface and
upper-level ridge off the mid-Atlantic coast combine to bring
fair weather and a warm humid west southwest flow over the north
country tonight. There may be a few hours of patchy fog in the
usual fog-prone valleys in the Adirondacks and eastern VT, but
there should be enough boundary layer flow to prevent widespread
fog. Low tonight mainly in the 60s except around 70 near Lake
More active weather is expected beginning Tuesday afternoon. A
low pressure system will deepens as it moves northward across
the western Great Lakes into Canada as strong 500 mb trof
approaches from the west. A strengthening southwest flow will
advect deep moisture with precipitable water to near 2" and
instability of 1000-2000 J/k CAPE. Increasing shear profiles are
expected ahead of a surface cold front with 500 mb jet of 50
kts resulting in 0-6km bulk shear of 40-50 kts with 0-1km shear
of 20-30 kt resulting in strong to severe organized storms as
mentioned in SPC slight risk outlook for the area. Highest
threat of severe storms will be 18-00z centered over VT around
21z or time of max heating. Heavy rainfall and strong gusty
winds are possible with these storms, but storm motions should
be fast enough to avoid flash flooding. Temperatures will warm
to almost 85 to near 90 across the area as 850 temps near 17C.
The cold front will move across the region Tuesday night and be
east of Vermont by 12z Wednesday morning. Still some chance of
showers and perhaps a thunderstorm as the front passes. Lows
mid 50s to mid 60s.
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 425 PM EDT Monday...On Wed a broad cyclonic west
southwest flow aloft with the upper trof axis over the Great
Lakes will bring partly sunny skies along with with cold
advection will bring a possibility of isolated shower or
sprinkle, mainly across the far north right through Wednesday
night. 850 temps fall to 8-10C and will bring high temps mainly
in the 70s with lows Wed night in the upper 40s to mid 50s.
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 425 PM EDT Monday...The upper level trough will be
swinging across the region early in the time period. Dry high
surface pressure will have already moved into the area behind a
cold front so any lingering showers will be light. An extension
of the upper level low will continue to rotate over the canadian
maritimes through the weekend swinging periodic vort maxes
across the region. This will lead to mainly slight chances for
showers over the Northeast Kingdom where orographic affects will
aid in development. Temperatures will be slightly lower than
normal throughout the period.
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through 12Z Tuesday...Mainly VFR in westerly flow under high
pressure except lcl IFR in intermittent patchy fog SLK/MPV
07-11Z as boundary layer winds will decouple but enough to
preclude prolonged fog. Winds S-SW around 10kts, with gusts
around 20kts at KMSS and KSLK. Winds will subside this evening,
decreasing to around 5 kts or less. On Tuesday, continued VFR
through 18z but shower and thunderstorm threat increases ahead
of a cold front at the end of the TAF period.
Tuesday Night: VFR. Likely SHRA...Occasional TSRA.
Wednesday: VFR. Slight Chance SHRA.
Wednesday Night: VFR. Slight Chance SHRA.
Thursday: VFR. Slight Chance SHRA.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
A storm system will approach the region tonight into tomorrow.
Ahead of the system, south winds will increase to 20 to 25 kts
over the lake by tomorrow afternoon with waves building to 2 to
4 feet. Showers and thunderstorms are also likely. Gusty winds
and heavy rain will be possible with thunderstorms. Winds will
begin to diminish by late evening.