FXUS61 KBTV 200538
Area Forecast Discussion
National Weather Service Burlington VT
138 AM EDT Mon Aug 20 2018
High pressure will provide fair and seasonably warm late summer
weather through Tuesday morning. A cold front will cross the
area Tuesday night into the first half of Wednesday with the
next chance for showers and a few thunderstorms. Behind this
front, slightly cooler and drier weather return to round out the
end of the work week.
.NEAR TERM /THROUGH TONIGHT/...
As of 138 AM EDT Monday...Going forecast in good shape with
only minor tweak being the delay of some fog development with
mid and high level clouds moving across the area early this
morning. This seems to be inhibiting the fog development a
bit...but should start to take place in the next few hours.
Quiet weather is expected over the next 36-42 hours as surface
high pressure remains bridged atop southern ON/QE into northern
New England. A ripple in the mid-level flow will remain across
southeastern New England, weakening over time as it lifts
northeast toward the Canadian Maritimes by Monday. As such any
deeper moisture and threat of showers with this feature will
remain far south and east of the forecast area. Outside some
patchy late night/early morning fog in favored locales, skies
should be mainly clear overnight with just a few/scattered fair
wx cumulus developing Monday afternoon as the boundary layer
deepens. Lows tonight to be similar to last night - mainly 50s
with locally milder readings to near 60 in the Champlain Valley
and cooler in favored hollows of the Adirondacks and northern
Greens. Corresponding highs on Monday to generally range from
the upper 70s to lower 80s.
By Monday night the aforementioned surface high begins to edge east
of the area as light southerly return flow becomes established from
the Champlain Valley westward after midnight, especially aloft.
Mainly clear skies should continue with perhaps some patchy mid to
high level cloudiness encroaching into our western counties toward
sunrise ahead of our next weather maker. Low temperatures to be
quite similar to tonight`s values across eastern VT, though slightly
milder by 1-3 degrees further west.
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 251 PM EDT Sunday...Tuesday will start off as a nice summer
day as temperatures warm into the mid 70s to lower 80s under
mostly sunny skies. However, during the day, a warm front will
steadily lift northward toward the North Country. As this
happens, a developing low over the Great Lakes Region will
quickly push into the Ottawa Valley. This will begin to increase
cloud cover through the afternoon hours while dewpoints start
to rise back into the low to mid 60s as precipitable water
values begin to increase. Throughout the day precipitable water
values will increase from less than one inch to nearly two
inches as southerly flow aloft allows a nice plume of Atlantic
moisture to advect into the region. Rainfall will be slow to
enter the region on Tuesday with rainfall not expected until mid
evening for the Saint Lawrence Valley and around midnight for
Vermont. A negatively tilted trough will set up across across
the northern United States and put the North Country in an area
of upper level diffluence which will help increase rainfall
rates and increase thunder probabilities. Latest guidance now
suggests the possibility of a few rumbles of thunder as the
upper level forcing looks more favorable than previous runs,
although lapse rates still trend near moist adiabatic given how
the moist the air mass will be.
Rainfall will taper off from west to east on Wednesday with most of
the rainfall east of the area by Wednesday evening. Temperatures on
Wednesday will be more moderated as rainfall prevents too much
heating and colder air aloft begins to filter into the region behind
a cold front. Rainfall amounts will generally be between a quarter
of inch and three quarters of an inch but some locally higher
amounts are possible through Wednesday given the deep warm layer and
high PWAT values. Once interesting feature to watch, especially for
the Champlain Valley, will be a strong southerly jet that will set
up over the region. This could have a huge influence on
precipitation values as the Champlain Valley could see significantly
less rainfall once again while upslope locations of the Green and
Adirondack Mountains could see quite a bit more rainfall. In
addition, this strong southerly jet will make for windy weather
Tuesday and Wednesday along Lake Champlain and higher elevation.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 251 PM EDT Sunday...Skies will be quick to clear on Thursday
as drier air quickly filters in behind the cold front. Temperatures
will be right around normal to slightly below normal on
Thursday as we remain under the influence of the upper level
trough and cold air advection from the north. This upper level
trough will begin to be displaced on Friday by a developing
upper level ridge which will build across the North Country
through the weekend. This will bring continued clear skies and
near normal temperatures as temperatures climb a degree or two
each subsequent day. There really isn`t a chance for rainfall
until Monday morning as the upper level ridge begins to flatten
and a disturbance could move in from the west. This is very low
confidence at this time so enjoy the sunny weather while you can
late next week and weekend.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Through 06z Tuesday...Some mid and high level clouds exist over
the area early this morning and this is helping to limit the
development of fog early this morning. Eventually low clouds and
fog will develop at KSLK and KMPV between 08z and 12z and
produce IFR to VLIFR conditions. The low clouds and fog burn off
at these site between 12z and 14z with VFR conditions expected
for the remainder of the period. At all other TAF sites VFR
conditions are expected through the entire period with no fog
expected and just some mid and high level clouds. Winds will
generally be under 10 knots through the period.
Tuesday: VFR. Slight chance SHRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Definite
Wednesday: Mainly MVFR, with local IFR possible. Likely SHRA,
Slight chance TSRA.
Wednesday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.