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Area Forecast Discussion (AFD)

Issued by Wilmington, OH (ILN)

FXUS61 KILN 240034

National Weather Service Wilmington OH
834 PM EDT Sun Jun 23 2019

A warm front will lift north into the area this evening and
cross the area overnight. This will be followed by a cold front
on Monday. Both features will bring increased threats of showers
and thunderstorms, some which may be severe. High pressure will
build into the area on Tuesday with dry weather and comfortable
temperatures. Warmth and humidity will spread back into the area
as the week wears on with temperatures getting back above


First line of convection is in the Scioto Valley and working
east while weakening. A second line in western Indiana down into
Kentucky will move east and should affect the region overnight.
The nw counties could see some rumbles of thunder from the 
storms out by Terre Haute, while the storms in central KY could 
build north into nrn KY. In between an area of showers will 
lift up across the rest of the fa. Increased PoPs to likely to 
categorical for the first half of the night, before allow PoPs 
to decrease.

Temperatures will be steady state for much of the fa in the mid
to upper 60s as the region is rain cooled this evening. The few
areas in central OHio and the lower Scioto Valley that have 
cooled down yet, will in the next hour or two.


Expect there to be scattered showers and thunderstorms ongoing
on Monday morning as stronger height falls head east through the
Great Lakes - driving a cold front through the forecast area at
peak heating. Overall shear profiles as areas destabilize is a
little better as wind fields will be increasing aloft. 30-40kts
of effective shear with some mid level enhancement suggest storm
evolution /which may start as discrete cells/ will quickly form
to line segments with frontal forcing and unidirectional lower-
mid tropospheric flow. Given the timing of the forcing and
frontal boundary - things may get started convectively a little
earlier than the usual mid/late afternoon event. Things begin 
to get going as early as noon or so on the west side of the 
forecast and slowly build in coverage/intensity in the 
afternoon. This favors areas along/east of I-71 to intercept the
best juxtaposition of shear and instability at peak heating, so
would not be surprised to see a watch and/or collection of 
wind-focused severe reports in this area. 

Storms will shift east Tuesday evening with dry weather expected


Tuesday starts out nicely dry and comfortable in the wake of a cold 
front with generally sunny skies and highs within a degree or two of 
80. High pressure ridge south of the region will be oriented sw-ne 
and permit a sw surface flow to increase humidity, primarily during 
the day Wednesday. This modest increase in low level moisture will 
coincide with a weak surface front. Front is expected to trail a 
remnant lobe of H5 vorticity maxima, connected southwestward to an 
upper circulation progged to cross the lower TN Valley late Wed and 
overnight. Will not rule out thunder on Wednesday, but inclusion of 
pops seems prudent with scattered terminology. Expect to downplay 
thunder chances until a few hours in the late day that would have 
all of the ingredients in play to create deeper convection. This is 
still hit-or-miss and models are by no means in agreement on the 
finer details.  Expect a rapid decrease in any activity Wed evening 
in favor of clearing overnight as loss of daytime heating 
effectively removes most of the shower threat by midnight. Surface 
front will die out as it butts into the high pressure ridge 
mentioned earlier that is still located just s and se of ILN CWA. 

Surface high builds back over the region Thursday into Friday with a 
disorganized surface wind field underneath a broad upper ridge 
building over the central U.S. and a general increase in heights for 
the eastern third of the country. Shortwave energy will likely be 
transient through the lower Great Lakes and Ohio Valley next 
weekend, and could accompany yet another weak cold front/wind shift 
that is currently forecast by the GFS to occur Saturday. European 
has this wind shift/front to happen before daybreak Saturday and is 
more robust with a H5 trough versus disjointed shortwave energy 
passing on northwest flow aloft. Both models have a surface high 
build in strongly behind the front and follow it with a l/w trough, 
reinforcing colder and drier air at the very end of the forecast. 

Regardless of how the exact scenario plays out this coming weekend, 
pops with some thunder chances will remain in play until future 
forecasts get a better handle on the mass fields and permit a finer 
detail to emerge on timing/placement and potential occurrence. 

Temperatures will gradually rise through the week but likely be 
capped in the mid 80s for most of the region. A few upper 80s may be 
possible but that will occur in the south half of CWA on Thurs or 
Fri. It will also be highly dependent on generally sunny skies which 
are more likely Thursday. Friday has better indications of pop up 
showers being possible due to daytime heating, which would stop 
temps from pushing much past the 85 degree mark. Overnight lows will 
be in the mid to upper 60s through the period, topping out just shy 
of 70 Fri and Sat night.


Line of thunderstorms has moved through KILN and will affect
KCMH/KLCK for the first few hours of the forecast.

TAFs will then go back to VFR conditions with scattered to
broken mid or high clouds as we await the possibility of 
additional convection overnight. Confidence is low on whether 
the pcpn in ern IL/wrn IN will hold together. Expect the line of
thunderstorms in wrn KY to stay south of KCVG/KLUK. So brought 
some VCSH back in to the tafs after 04Z and lingered it until 
about 12Z.

After 12Z, thunderstorms are expected to redevelop as a cold 
front moves through the TAFs. Started thunder at CVG/LUK around
15Z, but waited until 17Z for CMH/LCK. Precipitation end from
west to east between 21-00Z tomorrow.

OUTLOOK...Thunderstorms are possible Wednesday.




LONG TERM...Franks