Area Forecast Discussion
Issued by NWS Wilmington, OH

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649
FXUS61 KILN 181822
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
222 PM EDT Thu Jul 18 2019

.SYNOPSIS...
While a few downpours will be possible today, most areas will
remain dry and very warm and humid as a dome of heat builds over
the Ohio Valley that will last well into the weekend. Dangerous
heat and humidity will be present during the afternoons through
Saturday, with very warm and muggy overnights. A weak cold
front may temper the heat and humidity and bring an increasing
chance of storms by Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
There is currently an MCS moving across northern Indiana. A
majority of this feature is expected to stay north of the
region. Even though this features may just clip northern
portions of the area, there is some better instability just
south of this feature. There is a weak disturbance that moves
through during the day as well. With that in mind expect some
isolated to scattered thunderstorm activity to develop across
the region today. Given decent DCAPE values the main threat from
these storms would be damaging winds. In addition, given the
moisture profiles, heavy downpours will be possible with storms
that develop. Expect precipitation to taper off early this
evening as the disturbance pushes east and also with the loss
of daytime heating.

The other story for today will be the heat. Already seeing some
heat index values in the upper 80s and lower 90s as temperatures
are in the 80s and dewpoints lower to upper 70s. Heat index
values will be around 100 this afternoon. While this is more in
advisory criteria, kept excessive heat warning in place due to
cumulative effects of heat expected over the next several days
and given previous collaboration with surrounding offices.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Little relief - at all - from the heat and humidity overnight as
temperatures remain in the middle 70s. Stuffy and oppressive.

On Friday - this will be one of two /with Saturday/ of the
pinnacle days of the heat event with widespread heat indices
around 105 /locally higher in urban areas/. 594dm 500 mb ridge
centered over Kentucky with weak west-northwesterly mid level
flow over the Ohio Valley and favorable low level flow out of
the west will push 925mb temps toward 28C which means daytime
highs into the mid 90s while mid 70s dewpoints are maintained.
This will be one of the higher-end heat days for the ILN CWA in
the past few years - and warrants the issuance of the Excessive
Heat Warning. Presence of the ridge and weak subsidence should
keep ridge-riding MCSs to the north of the area with hot
sunshine dominating.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
With a broad upper ridge in place, heat and humidity requiring
Excessive Heat Warning continue Saturday. Under weak forcing but
ample instability, a few thunderstorms could develop across the
north half of the FA Saturday afternoon. Otherwise weather should be
mainly sunny and dry.

The upper ridge will begin to break down on Sunday when falling
geopotential heights will be noted, allowing temperatures and heat
indices to be reduced slightly while possibly remaining in heat
advisory range. There will be a good chance for thunderstorms by
Sunday evening as an east-west oriented cold front pushes south from
the Great Lakes, providing convergence and lift to the unstable
airmass in place.

Thunderstorm chances continue mainly across southern locations
Monday with the cold front positioned near the Ohio River. Dry
weather conditions are likely Tuesday and Wednesday when a large
surface high is forecast to build under a northwest upper flow.

After Saturday when highs are forecast to reach the mid 90s, expect
temperatures to show a downward trend due to cold advection.
Readings should slip to the low 90s Sunday, the mid 80s Monday, and
mainly low 80s Tuesday and Wednesday.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Isolated to scattered thunderstorms will be across the region
today. Have VCTS in at KDAY, KILN, KCVG, and KLUK. Limited
precipitation to VCSH at KCMH and KLCK where there is expected
to be less coverage and instability, however cannot rule out an
isolated thunderstorm as well.

Precipitation is expected to diminish this evening and be dry
for the overnight hours into the day on Friday. Some patchy
reduced vsbys will be possible overnight with fog, however
expect winds to stay up some and therefore do not expect it to
be as widespread as last night.

Cu will develop during the day on Friday, however with lack of
forcing any precipitation should be limited and have dry
conditions.

OUTLOOK...Thunderstorms possible Sunday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Excessive Heat Warning until 8 PM EDT Saturday for OHZ026-034-
     035-042>046-051>056-060>065-070>074-077>082-088.
KY...Excessive Heat Warning until 8 PM EDT Saturday for KYZ089>100.
IN...Excessive Heat Warning until 8 PM EDT Saturday for INZ050-058-
     059-066-073>075-080.

&&

$$
SYNOPSIS...Binau
NEAR TERM...Novak
SHORT TERM...Binau
LONG TERM...Coniglio
AVIATION...Novak



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