Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1052 am EDT Thu Jul 28 2016
a frontal boundary just north of the international border early
this morning will settle slowly southward across the north country
today. Meanwhile, an upper level disturbance across the central
Great Lakes will move eastward, and result in scattered showers
and thunderstorm activity near the frontal zone this afternoon and
evening. High temperatures will generally reach the mid to upper
80s across the region today. A few showers are possible again on
Friday, mainly across south- central Vermont as the low-level
frontal zone continues to shift southward into southern New
England. Cooler and drier air will filter in across northern
sections, with highs in the lower 80s for Friday and upper 70s to
lower 80s for Saturday, with lower humidity levels.
Near term /until midnight tonight/...
as of 1047 am EDT Thursday...have an area of showers currently
tracking across the northern Adirondacks. Otherwise just cloudy
conditions and temperatures continue to slowly rise. Did not make
any significant changes for 1030 am update this morning. Previous
Mild conditions prevail across the north country early this
morning with dewpoints in the low-mid 60s and temperatures rising
through the upper 60s and lower 70s at 1130z. Surface analysis
shows a weak frontal boundary across southern Quebec into
southeastern Ontario. Winds are nearly calm south of the
boundary...and light northwest-north poleward of the trough line with
dewpoints mainly in the mid- upper 50s north of the front (an air
mass that will be in place across the north country for friday).
Some mid- upper level clouds are streaming ewd across the region
this morning, mainly a function of convective debris from
thunderstorms yesterday across the upper MS River Valley and
Great Lakes region. These mid-level clouds will be in place much
of the day resulting in filtered sunshine.
Remnant 500mb vort across the central Great Lakes will shear out
ewd in west-east belt of strengthening 300-200mb flow approaching
90-100kt across Lake Ontario ewd into nrn New York/Vermont by 18z this
afternoon. Forcing aloft is not great...with limited height falls
and only brief period in lfq of upper jet during early afternoon.
Low-mid tropospheric flow will remain rather light in vicinity of
sfc trough/frontal zone, as it sags southward into nrn New York/Vermont by
early to mid afternoon. Insolational heating with filtered
sunshine will yield 2-M temps in the low-mid 80s, and with mid 60s
dewpoints in place, will contribute to SBCAPE values around 1000
j/kg and precipitable water values of 1.5 to 1.6" this aftn. Bulk of the day will
be dry in most locations, but will see some scattered convective
cells around during peak heating hrs per ncar/10member WRF
ensemble and the 06z btv-4km WRF. While we can't rule out a
stronger thunderstorm or two, combination of mid-level lapse rates
only around 6 c/km and very weak low- level flow should limit
overall robustness and organization of scattered showers and
thunderstorms this afternoon. Isolated stronger cores could have
some small hail or gusty winds, but anticipate below severe limits.
Pops peak around 60-70 percent 18-20z across central/nrn VT, and
generally 40-50 percent across S-central sections.
Into the early to late evening hours, will see convective
coverage and intensity gradually diminish and generally focus
across S-central Vermont as frontal zone settles southward.
Precipitation should be generally ending by 06z, with patchy fog
possible in favored valleys 06-12z, especially in areas seeing
daytime/evening thunderstorm activity and residual wet ground
conditions. Low temperatures tonight generally in the low- mid
Short term /midnight tonight through Saturday/...
as of 341 am EDT Thursday...cluster of convection looks to affect
more of southern New England on Friday than northern areas. Would
expect a fairly sharp gradient of precipitation given the west to
southwest flow aloft. Areas near the Canadian border should remain
dry with a chance of showers across central and south central
Vermont. High temperatures on Friday will generally be in the
upper 70s to lower 80s. Any lingering precipitation comes to an
end Friday evening with high pressure starting to build down from
Canada late Friday night into Saturday. No precipitation is
expected during this period with highs on Saturday in the mid 70s
to lower 80s.
Long term /Saturday night through Wednesday/...
as of 341 am EDT Thursday...trends in the data now suggest a
shortwave trough moves into the region on Sunday for a chance of
showers right through Sunday night. The pattern looks to change
for the first half of next week with an upper level ridge of high
pressure gradually building in for relatively dry weather and a
gradual warming trend with highs in the 80s all areas Tuesday and
Aviation /15z Thursday through Monday/...
through 12z Friday...generally VFR with scattered-bkn070-100 much of
the day. Scattered shower and thunderstorm activity 16-20z, and
then gradually diminish in coverage during the evening hours,
while generally shifting southward into southern Vermont. Brief
periods of MVFR/IFR possible in shower and thunderstorm activity
with brief heavy downpours. Mainly carried vcsh in tafs at this time.
Winds generally light S-SW, becoming light north-northwest with weak frontal
passage this afternoon...and remaining light north tonight. Patchy
fog possible during the 06-12z Friday period, especially at
locations seeing shower/thunderstorm activity during the
aftn/evening period with residual wet ground conditions.
Outlook 12z Friday through Monday...mainly VFR. Isolated -shra
possible S-central Vermont/krut during Friday afternoon. Chance for
additional showers on Sunday, with isolated -tsra possible mainly
across southern sections.