Scientific Forecaster Discussion
fxus61 kbtv 210749
Area forecast discussion
National Weather Service Burlington Vermont
349 am EDT sun Jul 21 2019
unseasonably warm conditions will continue across the north country
today before a cold front brings some relief tonight. Isolated to
scattered thunderstorms are possible this afternoon ahead of the
front, while quieter and cooler conditions expected Sunday night.
The next best chance for rain across the region comes Monday and
Monday night as low pressure slides along the front positioned just
to our south. Areas of moderate to heavy rain are possible, mainly
across southern Vermont.
Near term /through Monday/...
as of 348 am EDT Sunday...very muggy conditions continue this morning
with dewpoints in the 70s across the area. Some scattered showers
are moving eastward into northern New York at this hour, meager remnants
of an mesoscale convective system that pushed through the Great Lakes yesterday. This
activity will progress eastward through the early morning hours with
perhaps a brief downpour and a rumble of thunder or two. We should
see a break in the precipitation for a few hours once this moves
through, but anticipate additional isolated to scattered convection
to develop this afternoon as a couple of weak surface
fronts/boundaries cross out of Canada. The first will move through
late this morning into the afternoon, ushering in a slightly drier
airmass. The second boundary will be more of a wind shift line, and
this should bring a bit more widespread shower activity this
evening, particularly in northern areas. Instability will be limited
by a mid-level warm layer, and Max values will be displaced from
better shear. So while thunderstorms will be possible, don't
anticipate much in the way of any severe potential. That being said,
any stronger storms will be capable of producing briefly heavy
rainfall and some gusty winds. It'll be another hot and muggy day,
especially in our southern areas which will see the aforementioned
lower dewpoint air move in later in the day. Heat index values will
once again spike into the mid 90s in these locations, so the heat
advisory remains in effect through the day today.
For tonight...any lingering shower activity will wane by late
evening as daytime heating is lost. It will be noticeably drier as
dewpoints drop through the 60s, giving way to a much more
comfortable night with lows in the mid 50s to lower 60s. Dry weather
will continue through the morning hours Monday before our next round
returns in the afternoon. Low pressure will slide along a frontal
boundary positioned just to our south, resulting in another surge of
moisture. Steady rain will move into our southern sections during
the afternoon, with the heaviest precipitation in southern Rutland
and Windsor counties in Vermont. Temperatures will be much cooler than
what we've seen recently, topping out in the mid to upper 70s.
Short term /Monday night through Tuesday/...
as of 321 am EDT Sunday...wave low expected to form along stalled
frontal boundary will bring additional chances for mainly stratiform
rainfall Monday night into early Tuesday. Model discrepancies
persist, with 00z European model (ecmwf) a bit further north with the sfc low
track across NYC area and enewd across southern New England.
Meanwhile, the 00z GFS soln has the sfc low track south of Long
Island and south of Cape Cod during Monday night, with more
minimal quantitative precipitation forecast across our County Warning Area. Took a model blend at this point,
indicating pops 60-70% Monday night across south-central VT, but
lower to the north and west. In addition to rain, may see some
patchy fog around, especially across central/ern Vermont. By 12z
Tuesday, indicated pops down to 40% for Rutland/Windsor
counties, and just a slight chance further north. Quantitative precipitation forecast will
depend on low track, but generally expecting 0.50-0.75" across
Rutland/Windsor counties, with progressively lesser totals to
the north and west. Stratiform rain during Monday night becomes
more showery and gradually more isold during the daylight hours
Tuesday. Should see increasing sun by afternoon. Low
temperatures Monday night generally expected in the upper 50s to
lower 60s, with tuesday's highs mainly in the mid 70s with
humidity in a more comfortable range by Tuesday afternoon with
2-M dewpoints falling into the 50s.
Long term /Tuesday night through Saturday/...
as of 321 am EDT Sunday...all in all, a quieter weather pattern
is anticipated during the long- term period, with temperatures
initially near to slightly below normal for late July Wednesday-
Thursday. Will see temperatures and humidity levels increasing
once again for Friday and through next weekend, but not to the
extent observed this weekend. Forecast valley highs generally
range from the low-mid 80s for Friday, followed by mid to
possibly upper 80s for Saturday-Sunday. A modest shortwave
trough in nwly flow brings the best chance for rain shower
activity and possibly a thunderstorm on Thursday afternoon.
Otherwise rain chances are 20% or less throughout the long-term
Aviation /08z Sunday through Thursday/...
through 06z Monday...generally anticipate VFR conditions to
persist through the period, with exceptions at kmpv and kslk
through 12z Sunday. Kmpv was the only site that saw rain
Saturday evening, and it has already seen IFR conditions in fog
in the past hour. Expect it will continue to jump around between
MVFR and IFR through 12z. Kslk ceilings will remain MVFR through
daybreak as well, with occasional reductions in visibility due
to fog. Otherwise, scattered showers moving in through the early
morning hours, with MVFR visibility possible in any
precipitation. Another round of showers and isolated
thunderstorms is expected mid-afternoon through this evening,
and these too may drop conditions to MVFR from time to time. Winds
will generally be from the south and southwest at speeds of 10
knots or less, but shift to the west and northwest after 18z on
Monday: VFR. Slight chance rain showers.
Monday night: mainly VFR, with local MVFR possible. Chance rain showers.
Tuesday: VFR. Slight chance rain showers.
Tuesday night: VFR. No sig weather.
Wednesday: VFR. Slight chance rain showers.
Wednesday night: VFR. No sig weather.
Thursday: VFR. Slight chance rain showers.
Vermont...heat advisory until 8 PM EDT this evening for vtz009-011-012-