Area Forecast Discussion
Issued by NWS Burlington, VT-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 221917
Area Forecast Discussion
National Weather Service Burlington VT
317 PM EDT SUN MAY 22 2016
-- Changed Discussion --High pressure will move into the region tonight into Monday with
fair skies and above normal temperatures. Tuesday will see a chance
for showers for Vermont and northeast New York when an area of low
pressure lifts northeast along the New England coast. High pressure
will build into the region later in the week bringing summer-like
weather with warm temperatures and a chance for afternoon
showers and thunderstorms.
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.NEAR TERM /through Monday/...
-- Changed Discussion --As of 315 PM EDT Sunday...An odd pattern right now with a 500 mb
trough oriented ne to sw, and an upper low closing off in the base
of the trough and sagging southeast toward the VA/NC coast by 12z
Monday. Upper level flow is from the from the northeast, and the
few showers and thunderstorms that have developed are tracking to
the southwest. Lightning has mostly skipped Vermont, occurring in
NH and NY outside of the forecast area in areas that have received
more sunshine and instability while Vermont had the morning clouds
and sprinkles. Convection will continue for a few more hours then
taper off this evening. As the upper low drops south away from the
forecast area a narrow ridge will topple over into the region from
the west, and the pattern will resemble a rex block through
Monday. On Monday an elongated narrow ridge of high pressure from
the lower Mississippi valley extends up across the Great Lakes
into southern Quebec, separating our southeast US closed low from
the next trough of low pressure moving across southern Canada.
Subsidence and some drying late tonight into Monday will allow for
wide temperature swings. With good radiation tonight temps to fall
into the 40s most areas to near 50 in the Champlain & St. Lawrence
Valleys. Some patchy light fog possible in the areas that saw some
rain during the day. Plenty of sunshine on Monday and 925 and 850
support high temps in the mid to upper 70s with full mixing of the
boundary layer. Light north winds during the day with surface ridge
axis positioned to the north of the area.
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.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 237 AM EDT Sunday...Vertically stacked low pressure system
drifts east of the Delmarva peninsula during the day Monday, with
newd extending trough along the New England coast remaining in
place. It appears that overall movement/shift of this system to
the east will allow for drier air to advect into the North Country
on northerly low-level flow. As such, only included a slight
chance of showers across Rutland/Windsor counties for Monday
afternoon. Partly to mostly sunny skies (more sun north) along
with 850mb temps around +10C will yield pleasant afternoon temps
with highs 74-78F in most areas...and dewpoints dropping into the
mid-upr 40s for much of the northern 2/3rds of the region.
The vertically stacked low pressure system begins a slow northward
turn later Monday night, reaching an area east of NJ by daybreak
Tuesday. This should result in increasing mid-upr level cloud
cover across central and s-central VT during the overnight period
Monday night. Maintained just a slight chance of showers across
Orange/Windsor/Rutland Counties on nrn periphery of this system.
Increasing clouds across VT will keep lows on the mild side,
generally in the lower 50s. May see some mid-upr 40s across nrn NY
where thinner and less extensive cloud cover is forecast.
The closed 500mb low tracks nnewd across sern MA on Tuesday.
System is equivalent barotropic in nature, and likely will be
associated with bands of showers around the w/nw periphery rather
than broader zone of stratiform precipitation. Have included PoPs
40-60 percent attm, with precipitation amts 0.1-0.2" for most
sections of VT, with lighter amts across nrn NY further removed
from the low center. May see some locally heavier amts given PW
values reaching 1.2" per 00z GFS, and potential instability around
500 J/kg leading to a few embedded tstms. Some of the tstm
potential for depend on overall extent of clouds and whether or
not PBL heating/destabization can occur across the region. We will
continue to monitor. Deep layer NE flow would result in slow w-sw
storm motions if embedded convection were to develop. Highs on
Tuesday generally expected in the low to mid 70s.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
As of 237 AM EDT Sunday...Upper low departs east of New England on
Wednesday, resulting in drier conditions and a transition toward a
warmer and more humid overall weather pattern for the bulk of the
extended forecast period. There has been an increase in run-to-run
variability in the GFS and ECMWF...making daily details a bit
uncertain. Anticipate highs Wednesday in the mid-upr 70s with just
a slight chance of a late aftn/eve shower. Building heights and
strengthening SW low-level flow should yield highs into the lower
80s for some valley locations Thursday/Friday/Saturday. Will
likely also see a gradual increase in humidity with dewpoints
getting into the lower 60s by Friday into Saturday. With air mass
becoming more moist/unstable, PoPs continue generally 30-40% each
.AVIATION /19Z Sunday THROUGH Friday/...
Through 18Z Monday...VFR with scattered showers and possibly a
thunderstorm mainly central and southern Vermont this afternoon,
then patchy IFR visibility in fog in mountainous TAF sites during
early morning hours. rain showers forming in instability in
northeast Vermont where sunshine has broken out, and are tracking
southeast ahead of a slow moving surface front. Potential for MVFR vis
and VFR cigs in the showers, however kept all VFR in actual TAFs.
Showers to dissipate with loss of surface heating, then clearing
skies. KMPV and to a lesser extent KSLK will have some residual
moisture from afternoon showers combined with radiational cooling
to produce some IFR fog in the 07-12z timeframe. Conditions
improve to VFR clear after 12z.
Outlook 18Z Monday through Friday...
18z Mon - 12z Tue: VFR/high pressure
12z Tue - 12z Thu: VFR with chance of afternoon showers Tuesday
and Wednesday with brief MVFR visibility restrictions.
12z Thursday - Friday: VFR/high pressure.