FXUS61 KBTV 200826
Area Forecast Discussion
National Weather Service Burlington VT
426 AM EDT Sun Aug 20 2017
We will see clouds and some lingering showers over the area
early this morning...but drier air will begin to move in and
increasing amounts are expected as the day wears on. High
temperatures will be in the mid 70s to lower 80s. Dry weather
continues tonight and Monday as high pressure moves across the
area. A warming trend will take place with highs in the 80s and
a good deal of sunshine. Above normal temperatures continue on
Tuesday with highs in the 80s...but an approaching trough of low
pressure will enhance the potential for showers and
thunderstorms Tuesday afternoon and night.
.NEAR TERM /THROUGH MONDAY/...
As of 426 AM EDT Sunday...Water vapor imagery shows well
defined trough over Quebec Province early this morning which is
enhancing rain showers over northeast New York and northwest
Vermont. These showers will continue through about 12z...which
is when trough axis finally shift east of the area. Noticeable
drying is taking place upstream across southeast Ontario and
thus we should be able to see increasing amounts of sunshine as
the day wears on. Highs will be in the mid 70s to lower 80s.
For tonight and Monday...high pressure builds in tonight and
gradually exits the area on Monday. Dry weather is expected
during this time period with little in the way of cloud cover as
well. Flow in the low and mid levels becomes west and
southwest...which will allow for warm air advection to take
place. Based on increasing 850 mb temperatures all areas should
easily get into 80s with a few spots in the Champlain Valley
getting into the upper 80s. Solar eclipse viewing on Monday
still looks good with little in the way of cloud cover.
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 424 AM EDT Sunday...Brief 500 mb shortwave ridging
Sunday night, otherwise upper flow is predominately zonal
westerly. A surface high centered over PA on Sunday will move to
off the Delmarva coast by Monday, with surface ridging nosing
north into New England. Quiet weather will result, although
building heights and more sunshine will warm temperatures a few
degrees each day. Highs Sunday 75 to 85, while Monday will be
solidly in the 80s. 850 mb and 925 mb temps support 87 at KBTV
on Monday. Increase in humidity Monday as the surface ridge
shifts east and return flow brings surface dewpoints well into
the 60s especially in the St. Lawrence valley.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 424 AM EDT Sunday...pretty decent agreement with the
12z suite of models for the week. Generally letting the model
blend ride, especially for Wednesday onward. No big changes to
the overall scenario expected, though some of the details -
especially for Tuesday -- appear to becoming a bit more clear.
The models have shifting back a little faster such that we have
better timing with the combo of strong dynamics and instability
with peak afternoon heating, suggesting an increased chance of
organized strong convection and locally heavy rains late
Tuesday. Still rather far out in time to lock down any specific
details, but some of the model guidance did catch my attention.
For the daily details, keep on reading.
Monday night: For most of the region, it will be quiet --
however can`t rule out an isolated shower out across the St
Lawrence Valley and close to the Canadian border. This is from
the initial surge of moisture that will be moving across the
region in a deepening southwest flow. Dewpoints will also start
to increase overnight, so a little muggy feeling.
Tuesday/Tuesday Night: This is the time period the latest model
runs are now focusing in. Potentially a very active 12-18
hours. Upper trough will be moving into the Great Lakes, and
promote the development of a fairly deep surface low for this
time of the year (sub 1000mb). Potent system will also have a
pretty strong low/mid level jet, with 850mb winds 40-50 knots,
which will be spreading into northern NY by afternoon. All the
models show pretty solid amount of instability, with the NAM the
most unstable (probably too high with dewpoints). There is some
question as to how much sun we`ll see, which will also have an
impact on high temperatures and instability, but bottom line
we`ll have instability and strong dynamics in place. Noted that
SPC had shown a day 4 slight risk just southwest of our region,
but that was based on the 00z models, which were a little slower
in timing. Also noted a good slug of moisture with this system,
with precipitable water values nearing 2.0". That suggests
locally heavy rainfall is a good bet as well, and based on some
model signals, rainfall totals over 1 inch will probably occur.
Bottom line, we`ll have to keep watch for how later model runs
trend. Could be a busy weather day/evening with strong/severe
t-storms and locally heavy rain. As they say on TV, "Stay Tuned
for later updates".
Wednesday: Based on the 12z guidance timing, looks like residual
showers will be around in the morning and diminishing by
afternoon as the surface front moves through. Given some
uncertainty in model trends, have kept in a fairly wide
timeframe for the chance of showers, though in reality we might
be sunny and dry for the afternoon.
Thursday/Friday/Saturday: large scale broad upper trough will be
settling in across the eastern half of the US. For sensible
weather in our region, it looks like an extended period of
slightly below normal temperatures but relatively dry/comfy
weather. Have a very small chance for a brief light shower
across the higher terrain of northern VT and northern NY for
Thursday, but otherwise chances for rain are less than 10%
Friday and Saturday. Highs will range from the upper 60s in
higher elevations to lower 70s in the valleys.
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
Through 06Z Monday...An upper level trough is moving across the
area early this morning and will be east of our area by 12z.
Expect VFR to MVFR ceilings through 12z before VFR conditions
are expected for the remainder of the period as little in the
way of cloud cover is expected. Winds will pick up from the west
and northwest this morning at speeds in the 5 to 15 knot range
before tapering off after 00z tonight.
Monday: VFR. Breezy. NO SIG WX.
Monday Night: VFR. Slight Chance SHRA.
Tuesday: VFR. Breezy. Chance SHRA...Slight Chance TSRA.
Tuesday Night: VFR/MVFR. Occasional SHRA...Slight Chance TSRA.
Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Slight Chance SHRA.
Thursday: VFR. Slight Chance SHRA.