Area Forecast Discussion
Issued by NWS Wilmington, OH

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248
FXUS61 KILN 242345
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
745 PM EDT Sat Jun 24 2017

.SYNOPSIS...
Upper level trough over the Great Lakes this weekend into early
next week will lead to cool temperatures with scattered showers
and thunderstorms mainly north of Wilmington`s area.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Highly amplified mid/upper level flow with ridge centered over
the west coast and a mean trof over the Great Lakes and eastern
US. Westerly flow across the Ohio Valley with an embedded s/w
tracking through the southern Great Lakes. A good deal of
cumulus clouds have developed today with showers/thunderstorms
north of ILN/s area. These diurnal clouds along with the
passage of the s/w will lead to the dissipation of clouds this
evening.

Expect mostly clear skies for the remainder of the night. With a
dry airmass in place temperatures will drop to cool lows in the
lower and middle 50s.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Mid level shortwave trof to drop into the mean trof position
Sunday. A surface reflection in the form of a weak front will
pass through the Ohio Valley Sunday afternoon. Moisture is
limited with this system and with weak forcing have elected to
keep the forecast dry, although an isold shower or thunderstorm
is not out of the question across the north during the
afternoon. Cool temperatures to continue with Sundays highs from
the lower 70s northwest to the upper 70s southeast.

Expect clouds to diminish after sunset Sunday, with some clouds
lingering across the north. Expect cool lows Sunday night in the
lower and middle 50s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
On Monday morning, large-scale troughing will exist over the eastern
half of the CONUS, with a relatively dry air mass in place over the
Ohio Valley. A weakening shortwave will be moving southeast into the
southern Great Lakes, which is expected to lead to greater low-level
moisture and chances for precipitation in that region. However, its
impacts over the Ohio Valley will be very limited, with little
confidence in more than an increase in cloud cover -- primarily in
the northern half of the ILN CWA. Would not be impossible to have a
few light showers develop north of I-70, but the dry air mass
precludes adding this to the forecast for now. Will only maintain a
20-PoP in the NE CWA later Monday night into Tuesday morning, as a
secondary shortwave moves through the upper Ohio Valley. Despite an
expectation for a reasonable amount of sunlight, the continued 850mb
cold advection will lead to this being the coolest day of the
extended forecast period.

Dry high pressure will move into the region Tuesday, influencing
conditions through the middle part of the week. With a turning of
winds to the south on Wednesday, a more appreciable warmup will
begin, with temperatures returning to the 80s.

As a more progressive pattern begins to set up for Thursday and
beyond, model differences become more pronounced, leading to lower
confidence -- especially in precipitation timing through the rest of
the week. There is agreement that a frontal zone will set up east-to-
west across the southern Great Lakes, with the ILN CWA in the warm
sector within solid deep-layer southwesterly flow. As convection
develops at the north end of this warm sector, and along the frontal
area, there will eventually be some propagation downstream which may
impact the ILN CWA -- perhaps on Thursday afternoon, and then again
as additional waves of precipitation occur going into Friday. How
much of the CWA remains capped is a question, as is the exact
position of the front. Because of this, PoPs will be kept on the
lower side of things for now, with a model blend suggesting higher
precipitation chances north of the ILN CWA. Differences in the
evolution of an upstream trough going into the weekend will preclude
more than very low confidence in the forecast late Friday into
Saturday.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
A broad mid level trough will remain across the Great Lakes and
Ohio Valley through the TAF period. Embedded disturbances will
rotate east through this trough across the Great Lakes with main
sensible weather expecting to remain north of the terminals. A
weak cold front will push southeast into the region late in the
period.

Otherwise, only some cirrus is expected overnight, so VFR
conditions will prevail.

On Sunday, diurnal heating will result in FEW-SCT cumulus clouds
ahead of the weak cold front. An increase in the surface pressure
gradient and fairly decent mixing will increase winds from the
west in the sustained 10 to 15 knot range with gusts in the 20
to 25 knot range beginning around 16Z. Winds will diminish with
the loss of diurnal heating around 00Z Monday.

OUTLOOK...No significant weather expected.

&&

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

&&

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



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