Area Forecast Discussion
Issued by NWS Wilmington, OH

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867
FXUS61 KILN 261947
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
347 PM EDT Mon Jun 26 2017

.SYNOPSIS...
An upper level trough swinging through the Great Lakes will
bring a chance of showers and thunderstorms this evening and
tonight. High pressure will provide dry weather at midweek with
increasing precipitation chances toward the end of the week as
temperatures warm to near normal.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Shortwave to drop se into the mean trof position over southern
lower MI this evening. Marginal instby develops late this
afternoon into early evening over west central Ohio. Will
continue to allow very low pop chances into the west late in
the day. highs again in the lower to mid 70s.

Expect this pcpn axis to drop southeast through ILN/s FA
tonight and then diminish from the northwest. As marginal
cape diminishes with the loss of heating thunder chances
diminish so will transition to just showers.

Clouds will diminish from the northwest late tonight as surface
high pressure begins to nose into the region. Expect cold lows
to range from near 50 north to the mid 50s south.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Precipitation could be lingering in the southeast very early
Tuesday, but will move off to the southeast. In northwest flow
pattern, surface high pressure to build into the region Tuesday.
With cold 8H pool over the region expect some shallow high based
cumulus clouds to develop. Tuesday will be dry with rather cool
highs from the lower 70s northeast to the mid 70s southwest.

Surface high pressure to slide east of the region Tuesday night.
Diurnally driven cumulus clouds will give way to clear skies
early Tuesday evening. Expect cool lows from near 50 northeast
to the mid 50s southwest.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
On Wednesday morning, surface high pressure will be centered over
West Virginia, with a relatively dry air mass remaining in place
across the Ohio Valley region. With heights rising, and southerly
flow firmly in place in the low levels, warm advection should be
notable -- with a temperature rise to near 80 degrees.

As a more progressive pattern begins to set up for Thursday and
beyond, mesoscale details will play a significant role in exact
timing and placement of precipitation. A frontal zone is expected to
set up east-to-west across the southern Great Lakes beginning early
Thursday, but despite this, theta-e and wind plots suggest the ILN
CWA will remain in the warm sector (a regime of solid deep-layer
southwesterly flow) through Saturday afternoon. This will tend to
favor convective initiation upstream (north and northwest) of the
ILN CWA on Thursday and Friday, with eventual some propagation
downstream which should impact the ILN CWA. PoPs have been focused
on the northern sections of the CWA, with greater expectations
during diurnal or post-diurnal time frames (afternoon through
evening / early overnight). A shortwave moving east across Lake
Michigan will provide extra support for convection Friday evening,
but this too seems likely to not land a direct hit on the ILN CWA.
It may take until cold frontal progression on Saturday / Saturday
night before chances increase CWA-wide, and PoPs were increased on
Saturday to reflect this. Through this period, how much of the CWA
remains capped is a question, and mesoscale foci / localized forcing
will help decide if storms can develop within the warm sector. With
ample instability and at least somewhat favorable deep-layer shear,
some heavy rainfall / strong to severe storms could be possible from
Thursday through Saturday. Confidence in any specifics will keep
this out of the HWO for now.

With a clearing push behind the cold front late Saturday, models
have trended drier for Sunday, before warm advection begins to bring
a chance of precipitation into the area again on Monday.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Mid level shortwave to drop se into the mean trof position over
southern lower MI this evening. A good deal of VFR cumulus
clouds around 5000 feet have developed across the TAF sites
this afternoon. Marginal instby develops late this afternoon
into early evening over west central Ohio. A threat of showers
and perhaps an embedded thunderstorm to move across the TAF
sites this evening. Due to low expected coverage, and with
marginal instability which diminishes, have limited any mention
in the TAF forecasts to VCSH.

Clouds will diminish with skies clearing out late tonight in
as subsidence behind the upper shortwave combines with a
building surface high pressure system to the west. Expect
continued VFR conditions on Tuesday with only afternoon cumulus
clouds developing.

WNW winds at 10 to 15 kts with gusts up to 25 kts this afternoon
will diminish to less than 10 kts tonight.

OUTLOOK...Showers and thunderstorms are possible Thursday and
Friday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...AR
NEAR TERM...AR
SHORT TERM...AR
LONG TERM...Hatzos
AVIATION...AR



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