FXUS61 KBTV 122014
Area Forecast Discussion
National Weather Service Burlington VT
414 PM EDT Sat Aug 12 2017
Thunderstorms through this evening will have the potential to
produce gusty winds and small hail. Storms will taper off after
nightfall, followed by cooler and drier weather early next week.
The next chance for rain will be later next week when a low
pressure system moves through Thursday into Friday.
.NEAR TERM /THROUGH SUNDAY/...
As of 408 PM EDT Saturday...Showers and thunderstorms having a
tough time getting organized over our forecast. Most unstable
CAPE over 2,000 j/kg, but convection is having difficulty
overcoming weak CIN around 900-850mb shown on BUFKIT RAP and
HRRR model data with surface temps only 75 to 80 degrees. Weak
convergence along prefrontal trough from northern Champlain
valley southwest into the central Adirondacks proving to have
limited low level convergence and lift as well. Shear is modest
at best, with 0-6km bulk shear less than 40 knots. Biggest
threat will be wind gusts 30-40 mph and pea to dime size hail in
the strongest storms. Best instability is in the Champlain
Valley, and any storms that form/move through there and head up
the western slopes of the Green Mountains bear watching.
Convection to wind down this evening with loss of surface
500 mb trough and surface cold front to move into area
overnight into Sunday morning. The surface front moves into the
St. Lawrence Valley after midnight, to the Champlain Valley by
sunrise, and east of Vermont by mid morning. Frontal lift,
morning sun, and orographic lift in northern Vermont will
continue low chance for showers in that area until the moisture
Despite the front on our doorstep there will be little airmass
change tonight, and lows will be similar to previous night in
the upper 50s to lower 60s. Sunday about 5 degrees cooler with
highs 70- 75 and some partial clearing.
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 408 PM EDT Saturday...500 mb shortwave energy exits to
our east with broad cyclonic upper level flow around a low over
James Bay. Fast westerly flow at 500 mb across the forecast area
and surface high pressure building in from the west. A weakly
sheared trough moves through in the upper flow with some models
breaking out light showers on Monday. For now I kept POPs below
slight chance level and only reflected it with a few more clouds
on Monday. Seasonable temperatures a few degrees below normal,
with highs in the 70s Monday and overnight lows in the 50s.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 1212 PM EDT Saturday...Long term period picks up where the
short term left off with high pressure continuing to dominate
at the surface while upper level low pressure east of James Bay
slowly shifts southeastward to the Gulf of St. Lawrence by
Wednesday evening. For the most part the region remains dry,
though some isolated to scattered showers will be possible
Tuesday afternoon generally in the higher terrain due to the
orographic lift as weak shortwave energy traverses the region.
An upper level ridge follows for Wednesday night through
Thursday night continuing the dry stretch, before our next
potential system moves in for Friday and Saturday. While it`s 7
days out, there`s good consensus amongst the GFS and ECMWF for
widespread precipitation these 2 days, with PWATS possibly near
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Through 18Z Sunday...scattered tsra lowering vis to mvfr with
vfr cigs moving west to east in the 19-24 UTC timeframe,
otherwise vfr cigs/vis through the evening. Cold front with wind
shift to west to occur mainly after midnight and some lowering
of ceilings to mvfr with the frontal passage. Drier air moves in
behind front and ceilings improve to vfr.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Slight Chance SHRA.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Chance SHRA.
Lake Wind Advisory the rest of this afternoon into the evening.
Wind in the 20-25 knot range just touching the advisory level
and will continue to do so through the evening. Wind in the
lower atmosphere will continue to mix down to the surface with
the daytime heating, then die down as the sun sets and mixing
subsides. Lake Thunderstorm Advisory is also in effect through
the evening. Thunderstorms forming over the Adirondacks will
move east off the mountains across Lake Champlain and create a
hazard to boaters and recreationists.