Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1037 PM EDT Tuesday Jul 28 2015
above normal temperatures will be the rule across the north country
right through the end of the week with 80s to around 90 degrees.
There will be the threat for a thunderstorm this evening and
Wednesday...but the greatest chances will be on Thursday when a
cold front moves into the region. Some thunderstorms will have the
potential to be strong or severe on Thursday.
Near term /until 6 am Wednesday morning/...
as of 1030 PM EDT Tuesday...high pressure both at surface and
aloft will continue to build into forecast area overnight.
Isolated strong thunderstorms which moved south from Ontario and
Quebec earlier this evening dissipated rapidly as they approached
or entered forecast area. Not expecting any further development
overnight...with mainly clear to partly cloudy skies. Still
looking at a mild and muggy night with some patchy fog later on.
Expect lows mainly in the 60s...except some 50s in the normally
cooler portions of the Adirondacks and Northeast Kingdom.
Short term /6 am Wednesday morning through Thursday night/...
as of 350 PM EDT Tuesday...northwest flow/ridging aloft continues
on Wednesday...but 850/925mb temperatures warm further...thus
should be looking at an even warmer day than Tuesday. Expecting
partly-mostly sunny skies once again with perhaps some convective
debris clouds passing up and over the ridge. Once again with
500-1200 j/kg of MLCAPE...will see redevelopment of cumulus field over
the terrain and perhaps an isolated shower or thunderstorm.
Forecast soundings indicate less capping than Tuesday...however
wind profiles show much less in the way of wind shear. Thus no
severe threat is anticipated. Will be looking at highs from the
upper 80s to low 90s area-wide.
Southerly flow increases out ahead of an approaching frontal system
Wednesday night. We'll be looking at a very mild night with lows in
the 60s and lower 70s.
Frontal system arrives Thursday...but appears messy. Could be
looking at an initial pre-frontal trough and possible area of
showers/thunderstorms that push through the first half of
Thursday...while the actual front doesn't reach the region until
later Thursday evening. Upper trough lags further behind...with
passage of that not likely until Thursday night. Potential for
strong to marginally severe thunderstorms is there Thursday
afternoon if the atmosphere can recover...although most favored
across Vermont and especially points east. Current NAM/GFS model
forecasts indicate 1000-1500 j/kg of cape and near 40 knots of 0-6km
Cooler and drier air mass takes its time filtering in Thursday
night...but showers/storms should end in the evening. Lows 55-65f.
Long term /Friday through Tuesday/...
as of 350 PM EDT Tuesday...seasonable temperatures and weather through
the extended period as large-scale polar upper low takes up
residence over hudsons Bay leaving the northeast in persistent
broad trough with the axis mainly over the Great Lakes.
Weak pieces of shortwave energy will be moving through the flow
aloft through the period and may be enhanced by daytime heating to
trigger showers or a thunderstorm just about any day in the
extended forecast. Lack of any strong forcing for precipitation
and limited moisture will keep any rainfall generally be on the
light side. Model differences with timing and amplitude of the
various short wave features make pinpointing any particular day's
A weak surface boundary may bring scattered showers and/or storms
on Saturday, but the best chances for precipitation during the period
look to be Monday into Tuesday as the upper low digs slightly
southward from James Bay to the Great Lakes. This will allow a
weak cold front to approach the area as a better focus for
850 temperatures running 10-14c with a trend toward cooler by Tuesday as the
trough sags south. Temperatures through the period will be near
normal...middle 70s to lower 80s with lows in the middle 50s to lower
60s. Should be fairly comfortable as well with dew points
generally in the 50s to low 60s.
Aviation /03z Wednesday through Sunday/...
through 00z Thursday...mainly VFR expected this evening. Isolated
showers/storms this evening appear as if they will avoid taf sites
as they dissipate. Mainly calm air tonight leading to LIFR fog at
kmpv/kslk 06-12z Wednesday. Chance MVFR in mist elsewhere. VFR
conditions again on Wednesday with just scattered clouds. Winds
becoming west to southwest 5 to 10 knots Wednesday.
Outlook 00z Thursday through Sunday...
Thu: VFR with brief MVFR/IFR in showers/storms with passage of
cold front. Isolated severe turbulence/winds/hail possible.
Fri: mainly VFR. Slight chance PM -shra.
Sat/Sun: mainly VFR. Chance PM shra/tsra.