FXUS61 KBTV 140005
Area Forecast Discussion
National Weather Service Burlington VT
805 PM EDT Fri Sep 13 2019
High pressure over the North Country today will give way to an
occluded low pressure system tracking out of the Great Lakes tonight
with gusty southerly winds developing this afternoon and continuing
tonight. Light rainfall spreads into the region late tonight into
early Saturday morning, then shifts eastward throughout the day.
Seasonable temperatures and drier weather will follow on Sunday but
another round of showers will be possible Sunday night. High
pressure will then settle into the region through the first half of
the upcoming week bringing warmer and drier conditions to the region.
.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 800 PM EDT Friday...No major changes needed with this
update other than to tweak sky grids to match latest
satellite/observations trends, mainly across far western St.
Lawrence county. Otherwise, going forecast remains on track.
Previous Discussion...Gusty winds will continue through the
remainder of the afternoon with near superadiabatic lapse rates
at the surface aiding in the mixing of a pocket of stronger
winds aloft. With this loss of heating around sunset, we should
see a brief lull in the gusty winds; although winds will still
remain around 10 mph or so. The high pressure that helped bring
a beautiful and sunny day to the North Country will be quick to
exit this evening as a cold front moves eastward across the
Great Lakes region. As this happens, the pressure gradient
across the North Country is going to increase rapidly which will
yield increasingly stronger and gusty winds through the
overnight period. This stronger gradient is going to be coupled
by a 50 knot LLJ which is going to be strongest over the
Champlain Valley and northern New York. All of this should yield
winds of 10-25 mph at most locations but in the areas in the
vicinity of Lake Champlain, wind gusts will likely be sustained
between 20 and 25 mph with gusts upwards to 40 mph.
These gusty winds overnight should really hinder how much we cool
off tonight. Based on trends from this afternoon and the 12Z
guidance, we went ahead and raised overnight lows anywhere from 2-5
degrees with the biggest change in the Champlain Valley where the
winds will be the strongest. Cloud cover will also be on the
increase ahead of the approaching cold front which will also help to
moderate temperatures a bit. Overall, there will be a big difference
in lows between northern New York and eastern Vermont with lows in
the mid to upper 50s across New York and in the mid 40s across
Rainfall associated with the cold front will begin to move into the
St. Lawrence Valley around 5 AM and slowly spread eastward through
the morning hours. With the strong southwesterly low level jet in
place, it seems like the Adirondacks will eat up a lot of the
moisture which will keep the Champlain Valley significantly drier
than northern New York due to downsloping. As the front slides
through, the main moisture axis will slip to our south which will
really hinder our precipitation processes leading to storm total
amounts less than a quarter of an inch except on some upslope
locations where up to a half of an inch will be possible.
Thunderstorm potential looks less impressive than before with the
best forcing passing well to our north, less than optimal
thermodynamic profiles and diminishing moisture. Thus, have removed
any mention from the current forecast. Rainfall associated with the
front will taper off from west to east Saturday evening.
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 253 PM EDT Friday...Trends in the data suggest a rather nice
day on Sunday with highs in the mid 60s to lower 70s. Flow aloft
will be from the west-northwest and much of the day should remain
dry. As pointed out by the midnight shift flow aloft becomes more
northwest by Sunday evening so as upstream moisture tries to move
in...much of it should be shunted to our southwest. Can see just a
slight chance of showers getting into portions of northern New York
and far northern Vermont very late in the day and then becoming more
confined to portions of northern New York and southern Vermont as
Sunday night progresses. Rainfall amounts should generally be less
than a tenth of an inch. With lows ranging from the mid 40s to mid
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 253 PM EDT Friday...Northwest flow aloft prevails over the area
on Monday and this will again help keep the bulk of precipitation
south of our area...but southern tier of our forecast area should
have a chance of showers through at least the morning hours before
exiting to the southeast during the afternoon hours. Starting Monday
night and continuing right through Wednesday high pressure will
build into the region and bring quiet weather to the region with no
precipitation expected. We will see temperatures a few degrees below
normal in this pattern...but by the end of the week an upper level
ridge will start to build toward the Northeast. This should start a
warming trend in the Wednesday through Friday time period with above
normal temperatures expected on Thursday and Friday. The dry weather
continues on Thursday and into most of Friday before a trough of low
pressure moves toward the region.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Through 00Z Sunday...Main aviation hazard will be winds
associated with a strong south/southwesterly 50kt 925mb jet.
Winds will begin to increase out of the south towards 04z
between 15-20 knots, with gusts up to 30 knots possible,
especially for KBTV, KPBG and KMSS. The threat for low level
wind shear exists across much of the area between 04-08z. After
08z, core of jet will begin to exit north and east diminishing
LLWS threat. Expect turbulence in the vicinity of terrain and
the Champlain Valley. Winds will remain gusty out of the south
on Saturday between 20-25 kts gradually weakening after 20z.
Mix of MVFR/VFR ceilings through the period as a low pressure
system moves across the region. High clouds will overspread the
area from west to east through the overnight hours with mainly
VFR ceilings. Ceilings will begin to lower to MVFR conditions
towards 11z for KSLK & KMPV. Valley locations such as KMSS,
KPBG & KBTV will remain VFR through the period. Chances for
precipitation increase between 09-11z for KMSS, KSLK & KMPV with
generally light showers and no visibilities reductions...VCSH
expected elsewhere. Chances for showers diminish towards 16z,
with only lingering MVFR/VFR clouds through remainder of period.
Saturday Night: VFR. Slight chance SHRA.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. Slight chance SHRA.
Monday: VFR. Chance SHRA.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Southerly winds will continue to increase through this afternoon
into this evening as high pressure departs the region. A strong
pressure gradient will begin to develop this evening as a cold
front begins to approach the region which will create gusty
southerly winds ranging from 25 to 35 knots with stronger gusts
to 40 knots possible after midnight. Seas this afternoon will
build from 2-4 feet to 4-6 feet after midnight as the persistent
strong winds help to build the seas. The strongest winds and
highest seas will be observed from Kingsland Bay to St. Albans
Bay. These gusty winds and high seas will continue through
Saturday morning before beginning to slowly diminish and subside
as the gradient begins to relax during the afternoon hours.
Winds will likely not drop below 25 knots until Saturday
evening. Those with outdoor interests along Lake Champlain
tomorrow should take caution if planning to do any boating on