ILN issues Area Forecast Discussion (AFD) at May 1, 3:17 AM EDT
817
FXUS61 KILN 010717
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
317 AM EDT Thu May 1 2025
.SYNOPSIS...
Periods of scattered showers and storms are expected each day through
Saturday, with showers lingering into Sunday and Monday as well.
Above normal temps through Friday will trend below normal by Sunday
through early next week as a very unsettled pattern develops across
the region. Daily chances for showers are expected Sunday through
Tuesday, with much below normal temperatures expected during this
stretch.
&&
.NEAR TERM /THROUGH TODAY/...
A few patches of SHRA/TSRA continue to sprout about from time-to-time
amidst broad/large-scale moist ascent ongoing as the weak warm front
continues to pivot N. This activity will continue in an ISO fashion
through daybreak before coverage increases once again by early
afternoon with the development of some diurnally-enhanced ML/SB
instby.
Although convective coverage should be fairly widespread by early to
mid afternoon across the area, the severity, or at the very least the
extent of the severity, of such activity is a bit more in question.
This is owing to the influences of a band of decaying convection that
will be coming into the wrn ILN FA toward mid-morning, bringing with
it some overturned air and extensive cloud cover. This will
overspread the wrn third or so of the local area by noontime, with
the most robust CI expected between 16z-18z on the ern periphery of
this instby gradient (which should be near or just east of the I-75
corridor by this time). This suggests that the severe threat should
be focused more across the central/eastern parts of the local area by
mid/late afternoon as the destabilization efforts in the W may be
hampered quite a bit. Even so, guidance still varies on the degree of
destabilization E of the I-75 corridor, with some data suggesting
MLCAPE may struggle to reach 1000J/kg. This is likely owing to a lack
of better daytime heating as well as relatively meager midlevel
lapse rates. This being said, if better destabilization can evolve
(favored E of I-75), the presence of sufficient effective bulk shear
on the order of about 30kts may allow for one or more linear clusters
of storms to develop and drift to the ENE through mid/late
afternoon. This puts the best chance for a pronounced severe threat,
albeit still /somewhat/ isolated, by midday in central OH to south-
central OH and NE KY, with lower chances further to the W. At this
juncture, strong to damaging winds appears to be the primary threat,
with large hail being a distant second owing to the questionable
midlevel lapse rates. Do think this is a setup that will render
perhaps a handful of severe storms, with many more storms remaining
sub-severe in nature.
Highs will range from the mid 70s near/W of I-75 to the lower 80s in
the lower Scioto Valley. The pressure gradient increases and
forecast soundings show momentum transfer around 25-30 kts. Have
bumped up NBM winds with southwest winds gusting up to 30kts during
the afternoon.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/...
ISO convective activity will continue into the evening hours as the
front, or any semblance of a LL boundary, will remain well to the NW
of the local area amidst broad-scale troughing digging into the mid
MS Rvr Vly. Temps tonight will still be somewhat mild by seasonal
standards, generally dipping into the upper 50s and lower 60s with
thickening/expanding cloud cover.
A weak sfc trof/front will begin to develop into the local area by
midday Friday as the attendant weak sfc low continues to pull far to
the NE of the OH Vly. Nevertheless, this front will provide a focus
for additional diurnally-enhanced SHRA/TSRA, with the expectation
for the greatest coverage to focus near/E of the I-71 corridor
through midday before drier conditions briefly evolve mid to late
afternoon as the boundary stalls and eventually washes out near/S of
the OH Rvr by early Friday night. Highs on Friday will range from
the lower 70s in EC IN and WC OH to the upper 70s in south- central
OH into NE KY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Shortwave energy will dig southeast from the upper Midwest into the
middle Mississippi Valley Friday night into Saturday. This will
provide impetus for weak low pressure to form and lift slowly
northeast from near Memphis, TN Friday night into the lower Ohio
Valley on Saturday. Rain will spread along and ahead of the low,
with areas southeast of Interstate 71 getting the highest coverage.
The weak surface wave will continue off to the northeast on Sunday
as the shortwave closes off and wobbles near the Ohio Valley and
Great Lakes states. This upper feature will keep a good chance for
showers and maybe even a few shallow storms each day from Sunday
through Tuesday before finally weakening and lifting northeast out
of the area on Wednesday.
The overall trend during this time will be well below normal
temperatures and mostly cloudy skies... perhaps becoming partly
cloudy heading into next week (as uncertainty increases). The
national blend of models has come in noticeably cooler with the
latest run, and may have further to go before we settle on high
temperatures perhaps 10 to 20 degrees below normal Saturday through
Monday.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
The clustering of SHRA/TSRA earlier in the evening near KCVG/KLUK has
since dissipated, leaving FEW/SCT mid clouds for the remainder of
the overnight. Cannot completely rule out a stray SHRA/TSRA from
time-to-time, but most, if not all, of the sites will remain dry
through sunrise.
The clearing skies and remnant abundant LL moisture has allowed for
some BR/FG to form at KLUK, which will persist until the gradient
tightens enough that the SE sfc flow picks up a bit toward daybreak.
The BR/FG at KLUK will lead to IFR or lower VSBYs at times for the
site.
Elsewhere, light SE flow will slowly increase toward 12z and beyond
with SCT/numerous SHRA/TSRA likely to develop and move NE through
the area between about 17z-22z. There are some indications for a
weakening trend of storms with eastward extent, so have included TS
only at wrn sites for now. That being said, brief TS will be
possible just about anywhere during the afternoon. The coverage of
activity should become more ISO in nature past about 22z, although it
won't trend completely dry through the remainder of the period. As
such, have a PROB30 SHRA area-wide by/after 00z to account for the
expectation for at least ISO SHRA to continue in the region. Any
heavier SHRA/TSRA will bring the potential for sudden VSBY
reductions.
CIGs should remain predominantly VFR through the period, but some
MVFR CIGs may try to develop/move into the area by 06z Friday and
beyond. Some brief SW LLWS on the order of about 40kts is
expected at KCVG/KLUK between about 10z-13z. Light SE flow through
12z should go more out of the SW and increase by 15z. By/past 15z, SW
winds of 15-20kts, with gusts around 25kts, are expected area-wide.
However, the gustiness will be hampered following any sustained pcpn
and cooling of the BL.
OUTLOOK...MVFR conditions possible Friday and again Saturday into
Sunday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...
AVIATION...KC
Source: ILN issues Area Forecast Discussion (AFD) at May 1, 3:17 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202505010717-KILN-FXUS61-AFDILN)
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