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418
FXUS61 KILN 071456
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1056 AM EDT Tue May 7 2024

.SYNOPSIS...
Several rounds of showers and storms are expected through
Thursday amidst a continued warm and humid pattern. Slightly
cooler air will filter into the region late in the week, with
slightly drier conditions also expected. However, periodic
chances for showers will likely linger into the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Morning update trended the forecast towards HRRR/RAP blended
into current forecast. This seemed on track for T/Td and
accounted for line of storms crossing the CWA this morning, with
a break behind it. While placement and occurrence of storms in
the airmass this afternoon/evening remains in question, the
model blend noted above looked to capture probability of
rain/storms if not relatively well then well within reason.

Weak showers running nw-se that tail off over Warren County have
a warm frontal appearance. The airmass difference here is an
uptick in dewpoints behind it.

Parameters of significant shear and instability remain in place
this afternoon for severe weather. This is an all-mode severe
weather threat with damaging winds, large hail, isolated
flooding, and tornados. Tornado parameters per SPC and some AI
forecasts have the entire CWA with a potential of significant
tornados >EF2. The AI enhances a more narrow corridor running
sw-ne through Cincy metro area, curving northward into Dayton
metro area.

Previous Discussion:
Vigorous low pressure over the northern Plains will lead to a
moist southwest flow of air across the Ohio Valley today. A
decaying band of showers with isolated thunder is expected to
slide east through the region late this morning through early
this afternoon. Severe storms are not expected with this band.

As a shortwave is ejected northeast from the southern Plains
into the Ohio Valley, an increase in mid- level flow and backing
low- level winds will be seen in the vertical profile by later
in the afternoon. A surge in warm, humid air will likely occur
just ahead of the shortwave`s arrival. Forecast soundings from
the HRRR are concerning, with surface CAPE late this afternoon
into the early evening approaching 2,500 J/kg and effective
shear reaching around 60 knots. Curved hodographs lead to
effective SRH exceeding 200 m^2/s^2.

The latest guidance suggests a less forced environment late
this afternoon, so scattered, discrete supercells are expected.
All hazards appear likely with these storms. High temperatures
will reach into the upper 70s to lower 80s.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
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A cold front associated with the shortwave will shift east
across the local forecast area late this evening through
midnight. While hodographs are a bit less curved for this
period, an increase in forcing leads to higher coverage of
thunderstorms, and likely a more organized linear mode. Can`t
rule out some embedded supercells as well based on persistent
bulk shear ahead of the front.

The shortwave will exit to the east late tonight, leading to a
quieter conditions extending into Wednesday. Bright May sunshine
allows high temperatures to exceed 80 degrees across the middle
Ohio Valley. We may see some increase in cloud cover late in
the period as another shortwave begins to eject northeast into
the middle Mississippi Valley.
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&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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A warm frontal boundary will be draped along the Ohio River
early Wednesday evening, extending east from a surface low over
the mid Mississippi Valley. As the low tracks east Wednesday
night, the boundary will begin to lift slowly north across
southern portions of our fa. There remains some uncertainty with
just how far the front will make it, along with the better
instability, but the 00Z models appear to have trended
everything a bit farther to the south. Still, expect to see
showers and thunderstorms overspread the region Wednesday
evening and continue into the night as the surface low moves
through our area.

With very favorable shear and an instability gradient along the
boundary, some severe storms will be possible, with the best
chances mainly along and south of the Ohio River, closer to the
better instability. Damaging wind and large hail will be the
main severe threat, although an isolated tornado will also be
possible. Also, with the potential for training storms along the
boundary and PWs in the 1.5 to 2.0 inch range, there will be a
heavy rain/flood threat, especially across southern portions of
our area Wednesday night. Pcpn will taper off later Wednesday
night into Thursday morning as the low moves off to the east.

An upper level trough will settle in across the Great Lakes and
Ohio Valley heading into the weekend and into early next week.
A series of embedded mid level short waves rotating through the
trough will bring additional chances for showers and a few
thunderstorms each the day, especially Saturday afternoon and
evening. Temperatures will be seasonably cool through the
weekend with highs mostly in the 60s. More seasonable
temperatures will return on Monday with highs in the low to mid
70s.
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&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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Lingering MVFR vsbys at CVG are expected to break up in the
next 2 hours with low clouds scattering out underneath an
overcast mid deck aoa 8kft. Line of showers west of the region
will hit CVG/LUK/DAY around 17Z, ILN 18Z, and CMH/LCK 19Z. A
lull in the thunderstorms is expected, then daytime heating and
increasing instability with backing winds and a bump in low
level moisture will promote a second round of storms, some
severe this late day and early evening. Storms in this later
environment will be more discrete and scattered versus coming in
as a line, so VCTS seemed to be the better forecast for
everyone attm. Storms exit to the south-southeast, first at DAY
around 03Z, then by 05Z at the remaining TAF sites.

Outside of thunderstorm activity and this morning`s low clouds,
ceilings should remain VFR, but will amend if this is appears to
not be the case as necessary.

Clouds will begin to decrease after 06Z as the weather system
exits to the east. Will need to watch for stratus/fog
development in the pre-dawn hours if the clouds clear early.

OUTLOOK...Thunderstorms will be possible late Wednesday into
Wednesday night. MVFR/IFR CIGs are possible Wednesday night into
early Thursday and again on Friday.
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&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...
NEAR TERM...Franks
SHORT TERM...
LONG TERM...JGL
AVIATION...Franks