FXUS61 KBTV 120524
Area Forecast Discussion
National Weather Service Burlington VT
124 AM EDT Sun Aug 12 2018
Most of the North Country should remain on the dry side tonight with
just a few passing showers across Southern Vermont. Rain chances
will increase slightly on Sunday as conditions become more favorable
for afternoon thunderstorm development. An upper level low will
become cutoff from the mean flow on Sunday which will help bring a
chance of showers to the region through the majority of the weak as
a series of disturbances move across the mid-Atlantic and New
England. Slightly above normal temperatures are expected to
continue through the upcoming week.
.NEAR TERM /UNTIL 2 PM THIS AFTERNOON/...
As of 119 AM EDT Sunday... Have increased pops across
central/southern vt, as current obs at VSF shows moderate rain
with 0.10 in the past hour. Also, given the clouds/precip across
region, have reduced areal coverage of fog tonight. Still
anticipating a few patches in the deeper valleys, especially
across the northern dacks where cross over values will be
reached. Otherwise, no significant change made to temps or winds
with this update.
It`s been a cloudy but seasonably warm day across the North
Country as weak shortwave ridging has helped to keep us on the
dry side. While a pretty potent shortwave resides to out south,
our 500 mb heights have actually been rising throughout the day
in response to this shortwave. Decent rainfall has been observed
to our south but the presence of dry air in the low to mid
levels have helped mitigate rain chances thus far. However, our
heights begin to drop this evening and the return of
southwesterly flow aloft will advect moisture across the region;
especially southern Vermont. This will lead to increasing rain
chances across southern Vermont through the overnight period but
generally less than a tenth of an inch is expected as it will
take some time to saturate the lowest level of the atmosphere.
It also looks like fog is possible tonight, especially over
eastern Vermont and northern New York as increasing moisture
gets trapped underneath an increasingly strong surface based
inversion. Any fog that does develop will quickly mix out
shortly after sunrise on Sunday.
Rain showers, with the possibility of a thunderstorm or two, will be
more widespread on Sunday as instability increases through the late
morning and afternoon hours. While overall shower activity will
still be widely scattered, some locally decent rainfall is possible
with weak steering flow aloft. Also, the lack of any synoptic scale
forcing, shower and thunderstorm activity could be limited to the
higher terrain of the Adirondack and Green Mountains. Overall,
tomorrow should be pretty nice with seasonable temperatures with a
few passing afternoon showers and thunderstorms.
It should be noted that we currently sit at 24 straight days of high
temperature at or above 80 degrees at the Burlington Airport. The
record stands at 25 consecutive days and it looks like we should hit
80 degrees once again tomorrow afternoon, which would tie the
.SHORT TERM /2 PM THIS AFTERNOON THROUGH MONDAY NIGHT/...
As of 308 PM EDT Saturday...A closed mid/upper low centered near the
Ohio/Pennsylvania border will drive the weather over the North
Country for the first part of the work week. The forecast area
will be situated northeast of the low, in a zone of diffluent
flow aloft which will promote synoptic-scale ascent and lead to
unsettled weather. Cyclonic flow around low pressure in the
low-levels centered slightly further east will advect Atlantic
moisture northeastward into Vermont/northern New York. Some
isolated to scattered showers/thunderstorms will develop during
the afternoon hours Monday as peak heating maximizes
instability. Lack of low-level forcing will result in best
chances for showers in areas of higher elevations. Temperatures
Monday will be near to slightly above normal, but dewpoints in
the upper 60s will bring a return of the muggy weather that has
characterized much of this summer.
Monday night, the upper low will start to gradually lift
northeastward, providing better dynamics and increasing coverage in
showers towards the morning hours. Forecast soundings indicate PWATs
will reach their peak Monday night/early Tuesday morning, with
values peaking between 1.8" and 2" overnight. Flow throughout the
column will be very weak (MBE vectors < 5kts), warm cloud depths
will approach 12.5 kft, indicating potential for very efficient
precipitation processes, and moisture will be plentiful. Taking all
these factors into account, any convective showers/thunderstorms
that do develop will have the potential for localized heavy
rainfall. Low temperatures and dewpoints Monday night morning will
be in the mid to upper 60s in the valleys, and upper 50s to mid 60s
in higher elevations.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 308 PM EDT Saturday...As the center of the upper-low continues
to lift north and eastward Tuesday, showers will increase in
coverage through the day. Some embedded thunderstorms are
possible during the afternoon hours as diurnal instability is
maximized. Given the amount of moisture in the atmosphere, near
moist-adiabatic lapse rates are expected, which will limit the
severe threat. Main concern will continue to be the potential
for locally heavy rainfall. Not expecting any widespread
hydrology concerns, but will be watching closely for any stalled
or training cells that could pose a very localized flash flood
threat. As the core of the upper-low lifts over New England
Tuesday night, we will see a little bit of elevated instability,
and a rumble of thunder overnight can`t be ruled out. Wednesday
was originally looking a little drier as shortwave ridging
tries to build in, but the 12Z model suite has continued the
trend of flattening the ridge. This opens up the forecast area
to the influence of upper waves moving through the increasingly
zonal flow, so have kept PoPs in the 35%-55% range for
More progressive flow looks to become established towards the second
half of the week, so expect showery, unsettled weather to continue.
High temperatures will continue to run a few degrees above normal
for the long term, though the good news is we aren`t seeing any
indications of any heat waves coming up in the foreseeable future.
Low temperatures will generally be in the 60s, about 5-10 degrees
above climatological normals for this time of year.
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
Through 06Z Monday...Aviation challenge tonight will be
potential for fog/br and low clouds at mpv/rut. Overall,
thinking areal coverage of fog/br will be limited due to clouds
and lack of obs reaching cross over temps. Thinking best chance
will be at slk btwn 09-11z this morning, which i have included a
tempo for brief ifr conditions. Otherwise...rap soundings show
low level moisture increasing at rutland with potential for IFR
cigs toward sunrise and mvfr cigs prevailing at mpv in low
stratus clouds, associated with developing southeast moisture
advection. Rest of our taf sites will experience vfr conditions
with light and variable winds this morning, becoming
east/northeast today at 4 to 8 knots.
Monday: VFR. Chance SHRA, Slight chance TSRA.
Monday Night: Mainly VFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday: Mainly VFR, with local IFR possible. Definite SHRA,
Tuesday Night: Mainly VFR, with local IFR possible. Chance SHRA,
Wednesday: Mainly VFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Wednesday Night: MVFR/IFR conditions possible. Slight chance
Thursday: Mainly VFR, with local IFR possible. Chance SHRA,