ILN issues Area Forecast Discussion (AFD) at Aug 12, 6:27 PM EDT
564
FXUS61 KILN 122227
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
627 PM EDT Tue Aug 12 2025
.SYNOPSIS...
Hot and humid conditions with light winds are expected to persist
through the period. The greatest chance for showers and embedded
thunderstorms will be Tuesday afternoon through Wednesday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
The upper level ridge continues to break down with southwesterly
flow developing more in earnest especially for areas along/west of
the I71 corridor. Several of the convective allowing models keep
thunderstorm activity going into the overnight, and with very weak
steering flow, increasing warm cloud depths and PWs rising above 2
inches, some concern for locally heavy rainfall. Still a fair amount
of uncertainty on coverage/locations, but will mention the potential
for some thunderstorms to contain heavy rain and a risk of localized
flooding. With some dry air aloft and DCAPES increasing to over 900
J/Kg, a few storms may become strong with an outside chance for a
severe storm.
Overnight lows near 70 to lower 70s tonight.
&&
.SHORT TERM /WEDNESDAY NIGHT/...
The weak cold front will push through the region on Wednesday,
entering the mid Ohio Valley during a relative lull in convective
activity. By the time diurnally enhanced instability ramps up, the
front should be through west central Ohio and the upper Miami Valley,
so the focus for renewed convection should primarily be along/east of
the I-71 corridor. While the steering flow is expected to not be
quite as weak as on Tuesday/Tuesday night, some potential lingers in
the east for locally heavy rain so will continue a mention in the
Hazardous Weather Outlook. Highs in the lower/mid 80s in the
Mid/upper Miami Valley and west central Ohio, with mid/upper 80s to
the south and east ahead of the front, which should clear most of the
forecast area by 00z.
Wednesday night lows will dip into the lower/mid 60s where partial
clearing occurs in west central Ohio/eastern Indiana, but most
locations will remain under a cloud deck which will keep much of the
area with lows in the upper 60s behind the front.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Northern portion of eastern U.S. mid level ridge is suppressed as a
long wave trof settles across the southeast Canada and northern New
England. An embedded shortwave and slow moving front looks to keep a
chance of showers and thunderstorms in the forecast Thursday. The
highest pops will be observed over our eastern counties.
Another weak shortwave will track east southeast across the region
on Friday, but there will be limited moisture to work with - so
expect most of the region to remain dry.
Mid level ridge to build northeast into the MS River Valley and Ohio
Valley this week end with surface high pressure becoming
reestablished along the east coast. This will result in height and
thickness rises and warmer temperatures.
After a brief break in hot and humid conditions - temperatures and
dewpoints will be rising again this weekend. NBM mean max Heat
indices rise into the upper 90s Saturday and approach 100 across the
south Sunday and Monday. Ensemble probabilities of GFS/ECMWF/Canadian
suggest that the probability of the max heat index exceeding 100 is
only 10 to 15 percent. NBM has a tendency to be too high with
surface dew points - so it is something to continue to track as the
week progresses.
Thunderstorm chances increase Monday thru the middle of next week as
the mid level ridge gets suppressed and a northwesterly flow
develops. This change in flow and increase in thunderstorm chances
will likely lower temperatures with highs generally in the mid and
upper 80s Tuesday.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Prevailing VFR conditions are expected this evening, but there
remains a chance of thunderstorms. Confidence is still too low to
include this specifically in the TAFs, so a PROB30 group will be
continued through around midnight. If and when storms develop, this
can be adjusted to prevailing or TEMPO TSRA. However, much of the
evening and overnight hours will be dry.
Still looks like some stratus will develop overnight, so MVFR
ceilings have been included at all TAF sites, and below 2kft at all
but KDAY. Expecting this to lift and/or scatter out to VFR in the
14Z-16Z time frame. Visibilities overnight are likely to remain VFR,
but a brief period of MVFR is possible.
Additional showers and storms may develop on Wednesday. Coverage
looks spotty, so only a PROB30 group will be used for this TAF
issuance.
OUTLOOK...Thunderstorms are possible again on Thursday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JDR
NEAR TERM...JDR
SHORT TERM...JDR
LONG TERM...AR
AVIATION...Hatzos
Source: ILN issues Area Forecast Discussion (AFD) at Aug 12, 6:27 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202508122227-KILN-FXUS61-AFDILN)
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