Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 132328

Area Forecast Discussion
National Weather Service Wilmington OH
728 PM EDT Sun Aug 13 2017

A weak upper disturbance will pass south of the area tomorrow.
Otherwise, high pressure will continue to extend across the
region into Tuesday. The chance of showers and thunderstorms
will return for Wednesday into Thursday as moisture increases
ahead of a cold front.


Cumulus will diminish with the loss of heating. But high and mid
clouds ahead of a short wave in the lower Mississippi Valley will
spread in from the southwest later in night. Guidance seems to
have a reasonable handle on lows.


Short wave will track east northeast across the Tennessee Valley
on Monday. This will induce a weak inverted trough at the
surface that will extend across the southeast counties. Could
see a few showers in this region, although it is likely that
anything that would fall would be rather light. This will move
off in the afternoon and clouds will decrease late in the day
and into the night. Temperatures are forecast to be a few
degrees warmer than today except in the far southeast where a
thicker cloud shield may linger long enough to suppress highs
slightly. Lows Monday night will be slightly warmer than


By Tuesday morning, surface ridging will have begun to break down
across the OH Vly region, allowing for southerly return flow to
become a bit more established in the area. With this, seasonal
warmth and PWATs will make a return to the area. Although there will
likely be a surface frontal boundary positioned in the southern
Great Lakes region by Tuesday afternoon/evening, the forcing, both
aloft and at the surface, will remain marginal at best in the local
area. With this, decided to keep Tuesday dry for now, despite
increasing warmth and low level moisture.

By midweek, numerical guidance begins to diverge on exactly how the
weather pattern may evolve towards the upcoming weekend. Although
many solutions point towards several upper level disturbances moving
through the mean layer nearly-zonal flow for the second half of the
workweek, there continues to be some differences in timing and
overall amplitude of said features, both at the surface and aloft.
With these differences, timing out individual periods of increased
pcpn chances /which will be largely dependent on positioning and
timing of individual features/ continues to be a challenge. This
being said, the 12z suite of models did converge a bit regarding
timing of the main system of interest for Thursday into early Friday.

Kept chance PoPs starting on Wednesday /mainly across the west/ even
though the degree of instby and forcing remains somewhat in doubt.
Do think that Thursday may end up featuring the most widespread
shower and storm activity as more focused upper level support
arrives and the surface low tracks east across the Great Lakes
region. As such, did increase PoPs to the likely category during the
afternoon and early evening. Kept chance PoPs through early Friday
with aforementioned timing uncertainties.

Models have come into a bit better agreement regarding the fcst for
next weekend, showing surface high pressure and northwest flow in
place. With this, maintained a dry fcst for both Saturday and Sunday.

Seasonal warmth is expected through most of the workweek, although
with increased clouds and precipitation chances Thursday and early
Friday, highs will likely be several degrees cooler than on Tuesday
and Wednesday. Did bump up temps across the board for Tuesday and
Wednesday as midlevel ridging nudges further north into the region
and southerly surface flow increases. Would not be surprised to see
a few 90s either of these days, especially for the
southeastern/eastern third or so of the FA where clouds and pcpn
coverage will likely be more limited.

Near normal temperatures are expected Thursday through the end of
the period.


There are still a few lingering cu across the area but these
should continue to dissipate over the next hour or so. We will
continue to see some cirrus stream in from the west through the
overnight hours. A weak disturbance moving across the Tennessee
Valley will lead to an increase in some lower VFR cigs along
and south of th Ohio River later tonight into Monday morning.
There could also be a few showers associated with this feature
but the best chance for any pcpn should remain to the southeast
of the southern TAF sites.

OUTLOOK...Thunderstorms possible Wednesday night into Friday.




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