FXUS61 KBTV 171407
Area Forecast Discussion
National Weather Service Burlington VT
1007 AM EDT Sun Jun 17 2018
Scattered clouds will prevail across much of the area today
with very warm temperatures rising well into the 80s, possibly
approaching 90 in some locations. Dewpoints will increase this
evening and overnight, making for a very muggy night. The hot
and humid conditions will continue right into Monday, which may
be even a few degrees hotter than today. Scattered showers and
thunderstorms will impact the North Country from late tonight
through Monday evening as a cold front crosses the region. Any
showers that develop will have the potential to produce heavy
rainfall with some isolated gusty winds. Cooler and drier air
will follow behind the cold front and persist through the middle
of the week.
.NEAR TERM /THROUGH MONDAY/...
As of 958 AM EDT Sunday...Forecast is doing extreme well this
morning with no significant changes made with update. Water
vapor and upper air analysis shows mid/upper lvl ridge overhead
with dry air/subsidence aloft. This will provide cwa with mostly
sunny skies and warm temps. Some mid/upper level debris clouds
from upstream convection may spill over ridge and impact our cwa
this aftn/evening, which could make for a beautiful sunset.
Otherwise...upstream 925mb temps off the Buffalo and Maniwaki
soundings were 20c and adding 10c for good mixing supports
mid/upper 80s valleys and l/m 80s mountains, which is exactly
what we have in the grids. Maybe a spot 90f or so in the warmer
Tonight...watching upstream convection over the northern Great
Lakes which will track along the northern Periphery of
mid/upper level ridge in the western flow aloft. Latest 12z RAP
shows ribbon of mid level moisture/omega along with embedded 5h
vort impacting our northern cwa btwn 06-12z Monday. The general
idea of increasing showers with embedded convection aft midnight
in girds looks really good based on latest trends. Interesting
RAP has axis of 400 to 800 j/kg developing across the
slv/international border, helping in the convective potential.
This decaying mcs should quickly move east and north of our cwa
by 12z Monday, but will help in advecting much deeper moisture
and higher sfc dwpts into our cwa on Monday. We will have more
information on a potential active Monday after reviewing the 12z
Previous discussion...Main concern for Father`s Day will be
very warm temperatures, followed by heat, humidity and strong
convection on Monday.
The heat ridge to our west will continue to make slow eastward
progress today. Some high debris clouds from upstream convection is
spilling over the top of the ridge down into northern New England
this morning, and this will be the norm for today, with partly to
mostly sunny skies. Temperatures will warm quickly as the ridge axis
draws near this afternoon; 925mb temps of 22-24C indicate we`ll see
highs in the mid to upper 80s areawide, with some locations nearing
90. Thankfully, the worst of the humidity will remain poised to our
west today, so heat indices will remain below 95 today. Still, it
is going to be very warm, so please take the necessary precautions
if you have any outdoor activities planned today.
Things become more interesting tonight and especially Monday as the
ridge builds across our area. Dewpoints will surge overnight,
reaching into the mid and upper 60s by daybreak Monday. This will
make for a muggy night, especially as some locations may not even
get out of the 70s for lows. MCS currently ongoing across MN/WI/MI
will traverse up around the ridge through the day Sunday. The
remnants of this system look to traverse along or just north of the
international border of VT/NY/ON/QC late tonight into early Monday
morning. This may produce some briefly heavy rainfall and a few
rumbles of thunder as it moves through the region. The focus really
turns later Monday, especially the afternoon and evening hours, as
moisture surges ahead of an approaching cold front. Convection will
fire along/out ahead of the front. Although some scattered activity
is possible during the morning hours, frontal timing has slowed
somewhat as per the latest guidance, with the bulk of any convection
holding off until mid to late afternoon. There is some question on
how any morning showers and/or debris clouds will affect instability
for the afternoon; note that SB CAPE values are quite different from
model to model, though generally 1000+ J/kg for at least portions of
the forecast area during the afternoon. Shear values around 40kt are
expected, along with equilibrium levels of 40+ kft. PWATs will be
impressive, ranging from 1.75 to 2.25 inches across the region. Mean
integrated water vapor transport off the NAEFS will be approaching
record values during this time frame, and with warm cloud depths of
of 10-14 kft, expect any convection will be very efficient rain
makes and capable of high rainfall rates. The front will be
progressive, so anticipate that storms will be moving at a good
clip. However, the aforementioned westerly moisture transport may
support training or back-building storms. While widespread flooding
is not anticipated, radar trends will have to be watched closely. In
addition, a few wet microbursts will be possible due to
precipitation loading; have kept the mention of heavy rainfall and
gusty winds in the forecast accordingly. Note that SPC continues to
include the entire North Country in a Marginal Risk in their Day 2
outlook, while WPC`s most recent Day 3 Excessive Rainfall Outlook
has much of the area highlighted in a Slight Risk.
The other concern for Monday is the very warm and humid conditions.
We are still anticipating afternoon temperatures to approach or even
exceed 90 in many locations, while dewpoints will be around 70. This
will result in heat indices of 90+, with some locations in the
southern Champlain and Connecticut Valleys exceeding 95. However,
there is still some uncertainty in exactly where the warmest and
most humid air will lie, due to aforementioned possible convective
debris cloud cover. Also note that the 17/00z progs have backed off
a bit on 925mb temps or have shifted the warmest axis just south of
our area. Therefore, have opted to not issue any heat-related
headlines at this time.
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 342 AM EDT Sunday...Widespread showers and storms will be
ongoing early Monday evening as the surface cold front sinks
into the forecast area. Will continue mention of locally heavy
rainfall and gusty winds with stronger convective cores through
the 9-11 pm hour or so before tempering things downward on both
scale and coverage as the front pushes activity further
southward. Scattered additional rainfall totals in excess of 1
inch certainly possible in this early period. By later at night
drier air on developing northerly flow behind the front will
allow skies to trend clear to partly cloudy with lows by sunrise
Tuesday from the upper 50s/lower 60s north to the lower and mid
A more pleasant day is then on tap for Tuesday as surface high
pressure bridges east from the Great Lakes and southern Canada and
the front clears well south of the region. Plenty of sunshine is
expected under more tolerable humidity levels (dewpoints in the 50s)
as high temperatures top out in the 70s.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 342 AM EDT Sunday...Mainly fair and seasonably mild to
warm weather is then expected for most of the mid to late week
time frame. Another weak surface trough will likely swing
through the area later Wednesday afternoon or Wednesday night
with a push of slightly cooler/drier air and perhaps a brief
window for a scattered shower across northern counties. However,
most areas should remain dry with the passage of this feature.
Highs in the Wednesday to Saturday time frame will generally
range from the mid 70s to lower 80s, though slightly cooler
(70s) behind the trough passage on Thursday. Lows to range
within a few degrees of climo late June norms from the upper 40s
into the 50s.
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Through 12Z Monday...VFR conditions will prevail through Sunday
night. Some high clouds will remain across the region through
the period, but no precipitation is expected through 06z Mon.
Showers will approach the international border thereafter,
perhaps affecting KPBG and KMSS late. MVFR conditions possible
in any precipitation. Nearly calm winds early this morning will
turn to the south at 5-10 kt this afternoon. Mountain sites will
see light winds overnight while wider valleys remain south
around 10 kt.
Monday: VFR. Chance SHRA, Slight chance TSRA.
Monday Night: Mainly VFR, with areas MVFR possible. Occasional
TSRA, Chance SHRA.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. Slight chance SHRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. NO SIG WX.