Area Forecast Discussion
Issued by NWS Burlington, VT

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059
FXUS61 KBTV 111415
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1015 AM EDT Tue Aug 11 2020

.SYNOPSIS...
Hot and humid weather for today with valley locations expected
to see heat indices in the mid 90s. Some showers and
thunderstorms will develop this afternoon over northern NY and
progress eastward into Vermont through tonight as a front moves
through. Some storms the afternoon may contain locally gusty
winds and locally heavy rainfall. The remainder of the week will
be drier with temperatures cooling a few degrees each day as
expansive high pressure pushes down from Canada.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1015 AM EDT Tuesday...The forecast remains on track as of
1000 am so no changes needed. Have a great day and stay cool!

Prior discussion...
Everything still on track for today to be the hottest day of
the week, and heat advisories are in effect for valley locations
starting at noon today.

Increasing southwesterly flow over the forecast area today will
advect in warmer and higher PWat air mass...with 850 mb temps
progged to climb to around 18 to 19 deg C by this afternoon.  This
will translate to surface temperatures in the upper 80s to low 90s,
although just how high temperatures climb will be dictated by cloud
cover.  Starting off the day with a bit of valley fog that will
quickly burn off, giving way to partly sunny skies for the remainder
of the morning.  Complicating the temperatures forecast is some mid
and upper-level clouds to our west associated with an approaching
frontal boundary.  These clouds will spread over northern NY/VT
through the afternoon, which will limit solar heating to some
degree.  Nonetheless, very warm air mass will allow temps to quickly
heat up today even with some clouds around.  Dewpoints will start
off fairly high, in the upper 60s to low 70s, which will make for a
muggy start to the morning.  Should see dewpoints lower some during
the afternoon however with increased mixing progged to nearly 800
mb...which will bring some drier air down to the surface and limit
to some degree our heat indices.  Overall temperature forecast
remains relatively consistent, with heat indices forecast to climb
into mid 90s in the Champlain Valley, the Saint Lawrence Valley,
parts of the Connecticut Valley.  Heat advisories remain in effect
for these valley locations valid from noon today through 7 PM.

Chances for precipitation this afternoon are trending upward, and
models starting to come to a better consensus that we will see
some thunderstorms develop later this afternoon as a front moves
into the western portion of our CWA. HiRes models are showing a
line of showers/tstorms developing over St. Lawrence County
around 3 or 4 PM, then increasing in coverage as it tracks
eastward to the Champlain Valley by early evening. The line will
likely weaken with waning diurnal instability east of the Green
Mountains as it moves into VT late evening. Noting relatively
weak shear (around 20 kts), so still not looking like a
favorable environment for highly organized convection...however
the environment will be favorable for some locally heavy
rainfall and locally gusty winds due to a few wet microbursts.
Noting in particular high PW values, mid-level dry layer,and
steep low-level lapse rates...all supportive of wet microbursts.

By the overnight hours tonight, northern NY will be dry, and
could see some fog overnight depending if they`re able to clear
out. Further east, the front will slowly progress through
eastern VT during the overnight hours, with the progress slowed
as it runs into strong ridging over the western Atlantic. Thus,
showers may linger into the mid to late morning hours Thursday
for eastern VT. Overnight lows will be in the 60s for much of
northern NY, and in the upper 60s to low 70s for VT where cloud
cover will be greater.

Wednesday will be dry save for an isolated shower or two over
eastern Vermont as the front stalls to our southeast. Humidity levels
will be noticeably lower behind the front, and highs Wednesday
will be in the low to upper 80s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
As of 417 AM EDT Tuesday...Wednesday night and Thursday will feature
quiet weather with a ridge of surface high pressure building into
our area from the North. Skies will be mostly clear/sunny and
temperatures will be about five degrees warmer than seasonal normals
for mid August.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 417 AM EDT Tuesday...The long term portion of the forecast from
Thursday night onwards remains quiet until the next possible frontal
passage around Monday night into Tuesday. High pressure ridge sinks
down over our forecast area out of Canada. A surface low pressure
system lifts northeastward through the St Lawrence river valley on
Monday and cold front crosses the area Monday night. This looks to
be our next chance at some showers and thunderstorms. Otherwise,
temperatures will run a few degrees above seasonal normals through
the period. Overall, a pretty quiet forecast for the Thu night
through Tue timeframe.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Through 12Z Wednesday...Will see increasing high and mid- level
clouds this morning ahead of some a cold front and some
associated diminishing showers to our west. After 18Z, will see
some scattered showers/tstorms develop that could bring some
locally heavy rainfall (resulting in temporary IFR visibility)
along with some locally gusty winds. The cold front will move
through after 00Z, accompanied by line of more numerous
showers/storms with the potential for some MVFR ceilings and
temporarily IFR visibilities within heavier showers. Behind the
front, will see some lingering low clouds and mist through the
end of the 24 hour TAF period.

Winds will generally be 5-10 kts, with some gusts 15 to 25 kts
possible over the Champlain Valley between 18Z and 03Z.

Outlook...

Wednesday: VFR. Slight chance SHRA.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Heat Advisory until 7 PM EDT this evening for VTZ001-002-005-
     009>012.
NY...Heat Advisory until 7 PM EDT this evening for NYZ026>028-035-
     087.

&&

$$
SYNOPSIS...Duell
NEAR TERM...JMG/Duell
SHORT TERM...Neiles
LONG TERM...Neiles
AVIATION...Duell



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