Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 171907
AFDBTV

AREA FORECAST DISCUSSION
National Weather Service Burlington VT
307 PM EDT Wed Jul 17 2019

.SYNOPSIS...
An active period of weather is expected across the North Country
through Saturday. Showers are expected this morning with heavy
downpours possible over southern areas. A cold front drops south
from Canada and heavy downpours from showers or storms will be
possible this afternoon over northern areas. The cold front
pushes south tonight and drier weather is expected for Thursday
and Thursday night. Hot and humid conditions are expected on
Friday and Saturday. There could be some late afternoon and
evening thunderstorms on Friday. The best chance for
thunderstorms...some of which could be strong or severe...looks
to be Saturday afternoon and night.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 142 PM EDT Wednesday...Some showers are starting to pop
along our northern zones this afternoon, so far no lightning
present. Previous discussions follow.


Overall forecast in good shape with only minor tweaks to
timing/areal coverage of showers and current temperatures this
morning. Remainder of forecast on track with plenty of clouds
and showers around...a better potential for thunderstorms this
afternoon especially across the north...and localized flooding
also possible.

Previous Discussion...
First surge of moisture associated with tropical system Barry
is now moving into our area...mainly across the southern
sections. Flow aloft will be west to southwest this morning and
thus expect additional showers...some with heavy downpours...to
move across most of the area. Precipitation shield is not
continuous upstream but would expect additional showers or
isolated storms to move in across the same areas getting the
precipitation this morning. This could enhance the potential for
localized flooding given the high moisture content...but not
expecting widespread flooding. One interesting trend is this
afternoon the flow aloft becomes more west and northwest which
helps to bring down a cold front from Canada. Thus northern
areas that are not receiving much in the way of precipitation
this morning could see bursts of heavy downpours from showers
and storms ahead of the southward moving front this afternoon.
With precipitable water values around 2 inches the potential for
localized flooding will exist later this afternoon and into the
early evening hours. With plenty of clouds and precipitation
over the area today high temperatures will generally be in the
70s to around 80.

The front moves south of the area by about midnight and this
will help to bring precipitation to an end from north to south
during the first half of the night. Lows will generally be in
the mid 50s to lower 60s. Thursday looks to be a day of
transition with weak high pressure over the area and limited
forcing to inhibit convection. Thus most of the area should stay
dry with a return to south-southwest flow later in the day which
could develop a shower or two over parts of northern New York.
Highs on Thursday will be in the upper 70s to lower 80s.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 254 PM EDT Wednesday...Friday is looking to be an incredibly
hot and humid day with temperatures especially in the valley
locations pushing 90 with dew points in the low to mid 70s across
the board. Heat Index values will be pushing mid to upper 90s,
building throughout the day with such high dewpoints. Heat
advisory will be likely for the valleys. During the morning
hours a warm front pushing north along with elevated instability
may result in showers with a rumble of thunder across northern
NY into the CPV. Significant diurnal heating throughout the day
will lead to an increased risk of spot thunderstorms working
their way in during the late afternoon into early evening hours.
Lack of forcing and limited deep layer moisture will result in
isolated to widely scattered coverage. Northern NY into northern
VT would have the best chance for these storms to develop,
which should quickly dissipating with their movement eastward.
Southerly winds will be increasing throughout the day as mixing
improves and gradient sharpens with approaching boundary, with
highest speeds over the trrn. Friday night, warm and muggy
temperatures will remain in the low 70s in valley locations with
upper 60s elsewhere, while still keeping the dewpoint in the
upper 60s to low 70s. The overnight looks to be relatively calm
weather wise before what`s expected to be the warmest day of the
season on Saturday with similar atmospheric conditions to
follow.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 254 PM EDT Wednesday...Active period of weather
anticipated for Saturday into Sunday with very warm/humid
conditions and the chances for strong to severe thunderstorms.
The highest combination of heat/humidity values will be Saturday
aftn where heat index values will be in the lower 100s in the
warmer valleys. Many parameters coming together for scattered
strong to severe storms Saturday aftn/evening.

Saturday is looking to be yet again another hot and humid day
with air temperatures pushing into the upper 80s to mid 90s.
Heat index values will be climbing into the upper 90s with the
low 100s not out of the question, with the oppressive dew points
in the upper 60s to mid 70s. These temperatures are supported
by 925mb level temperatures ranging from 26-28 celsius, with
dry/super adiabatic conditions only impacted by increased cloud
cover or precipitation. Associated daytime heating and upper
level wind shear of 35-45kts will lead to the development of
strong to severe thunderstorms working their way through our
area. Still some uncertainty on timing of sfc boundary and upper
level support for providing synoptic scale lift. However, with
CAPE values in the 2500 to 3500 j/kg and deep layer shear of 35
to 45 knots, will produce an environment favorable for organized
convection with scattered strong to severe thunderstorms
possible. South winds 10-20kts surface and mid level winds of
40-50kts will enhance deep layer shear to support organized
convection Saturday afternoon. Looking at Saturday night,
temperatures will follow the same pattern as the night before
with temperatures looking like they will break the 70 degree
mark, with lows in the mid to upper 60s. The dewpoint during the
overnight hours still remains at the mid to upper 60s, with the
NEK seeing the most comfortable overnight conditions. Lingering
instability could produce the occasional thunderstorm moving
through the area as that should not be ruled out of the
question.

Sunday through Tuesday...Large scale pattern change will slowly
evolve by early next week. Still some uncertainty how quickly
the sfc boundary and associated dynamics will drop south of our
cwa. Latest 12z ECMWF continues to show lingering
instability/moisture across our central/southern CWA on Sunday
with pws near 2.0. Have continued to mention chc pops with some
thunderstorms possible, given instability. Temps will range from
the mid 80s to lower 90s across our cwa, with lowering dwpt
values as north winds develop. Sfc high pres and deeper drying
will result in comfortable temps/humidity levels for early next
week, with decreasing chcs for precip. Highs mainly in the mid
70s to lower 80s.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Through 18Z Thursday...Area of showers currently moving into
Vermont and Northern New York, as well as some showers popping
up across our northern zones. For now have included VCSH at all
of our TAF sites, and tempos for TSRA. By about 00z all of the
showers and convection should be moving south of the region.
Winds during this time frame will be generally out of the south
between 5-10 knots. As cold front sags south from Canada
overnight, it will be bringing with it improved conditions on
northwesterly/northerly winds between 5-8 kts.

Outlook...

Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: Mainly VFR, with local MVFR possible. Slight chance SHRA,
Slight chance TSRA.
Friday Night: VFR. Chance SHRA, Chance TSRA.
Saturday: VFR. Chance SHRA, Chance TSRA.
Saturday Night: VFR. Chance SHRA, Slight chance TSRA.
Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA,
Slight chance TSRA.
Sunday Night: VFR. Chance SHRA.
Monday: VFR. Chance SHRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Evenson
NEAR TERM...Evenson/Neiles
SHORT TERM...CAM/Taber
LONG TERM...CAM/Taber
AVIATION...Neiles


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