-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 110807
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
407 AM EDT Thu Apr 11 2024

.SYNOPSIS...
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The active weather pattern continues with additional rounds of
rain and storms through this evening. Showers persist tonight
through the daytime on Friday before drier conditions return for
the start of the weekend. Gusty winds are expected tonight and
Friday, with above normal temperatures trending below normal on
Friday before warming up once again for the upcoming weekend.
Much above normal temperatures are expected by early next week
with more rain and storms possible.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Broad sfc low pressure across the wrn TN Vly will track to the
NE along a sharpening warm front draped across wrn TN/KY and ern
IN and far SW OH through early afternoon. Although the sfc
pressure pattern will remain somewhat broad in nature, it will
be deepening through the daytime today (likely ~990mb) as it
moves into the ILN FA by the afternoon, signaling for yet
another anomalously-deep sfc low to be tracking through the OH
Vly this spring.

The expanding warm sector will envelop most of the ILN FA
(except perhaps EC IN and WC OH) by peak heating, a normally-
concerning situation considering the aforementioned deepening
sfc low tracking right through the area as well. The warm
sector, while characterized by sfc DPs in the lower 60s,
however, is likely to be muddied somewhat by repeated rounds of
SHRA and extensive cloud cover. In the absence of a more-
pronounced dry slot, which latest guidance suggests won`t be
quite as "clean" as previous data, there remains considerable
uncertainties regarding just how much sfc-based destabilization
is able to occur (owing to slightly cooler sfc temps). This
lends itself to questions about the potential for severe storms
locally. Needless to say, the difference in instability
stemming/generating from sfc temps of ~73F vs. ~68F (favored)
is quite large and undoubtedly the degree to which we are able
to warm (or not) will ultimately dictate severe potential by the
afternoon.

Diving further into the details, latest data shows a fairly
large band of SHRA moving from SW to NE across central KY into
NE KY and south-central/central OH between about 12z-17z, with
the best LL destabilization occurring on the SE/E flank of this
axis of SHRA/TSRA, with current guidance suggesting this will
ride within a corridor either on the far ern edges of Scioto to
Hocking to Licking Counties or entirely E of the ILN FA
altogether between about 17-19z. Suffice to say, the spatial and
temporal window for concern here appears to be rather small
locally, or at the very least smaller than earlier data/fcsts
suggested. And while the LL and deep-layer shear would suggest
convective organization, perhaps in several line
segments/clusters, the signal for tornadic potential appears to
be focused E of the local area. Certainly, given the SE sfc flow
and veering winds with height (albeit not abruptly), a tornado
cannot be ruled out within that Scioto to Hocking to Licking
corridor (assuming sufficient SB destabilization), but given
current trends, the focus for most concerning severe weather
appears to be just to the SE of the ILN FA (i.e. Lawrence to
Washington counties in OH).

In fact, when considering the entire expected evolution of
convection locally today, the greatest potential for a few strong
storms may end up being near/S of the center of the sfc low
itself, which should coincide with a narrow axis of LL
convergence and SB-instby near/S of the I-71 corridor from
19z-23z. This being said, even this corridor of better instby is
still somewhat meager (perhaps only on the order of 600-900
J/kg). Additionally, the LL wind fields (sfc-850mb) are
actually quite a bit weaker further to the W (within this
corridor of better instby) as you get closer to the broad LL
low, with the best LLJ positioned well to the E in ern OH by
21z. So with slightly better thermodynamics in these areas
comes much weaker LL/deep-layer speed/directional shear,
suggesting a low (but not zero) severe potential.

So all in all, it just doesn`t appear like the necessary
ingredients are going to come together in a manner that would
support more than an isolated local severe storm potential,
even in central/south-central OH within the ILN FA. Certainly
there is /some/ potential, but locally the best overlap of
kinematics and thermodynamics would probably be focused in the
17z-19z time frame within a 4-6 county area (if that). This may
be one of those situations where having a ~990mb deepening low
(albeit broad) darting to the NE through the region with a
well- established warm sector (DPs >=60F) just doesn`t lead to
much within the ILN FA as the mesoscale environment just doesn`t
respond or evolve in the necessary ways. This is not to say the
severe threat is zero within the ILN FA, because it certainly
is not. But... the latest data suggests a less concerning setup
than had been the case just 12-24 hours ago. The HWO has been
adjusted accordingly to reflect the latest thoughts.

Highs today range from the lower 60s in EC IN and WC OH to the
upper 60s in the lower Scioto Valley and NE KY.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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As we progress past sunset and the sfc low begins to pull NE of
the local area, a sharp wind shift is expected with the FROPA,
which should progress W to E from EC IN (around 22z) to central
OH (around 01z). Gusty WNW winds to 30-35kts are expected late
this evening into early overnight before subsiding just a bit
past about 08z or so.

The SHRA should taper off progressively from W to E between
about 23z-03z, respectively, with dry conditions for several
hours before wraparound pcpn moves back in during the predawn
hours. The digging S/W on the wrn periphery of the deepening
midlevel low should provide enough persistent forcing amidst an
amply- saturated profile to keep SHRA going through most, if not
all, of the daytime Friday as well (especially in central OH).
Frankly, it`s not going to be a nice day to be outside on
Friday as WNW winds of 20-25 MPH will gust to 35-40 MPH as
steady light rain falls for most locales (especially for OH)
through at least mid afternoon. There may be some subtle
attempts for the pcpn to taper off late afternoon, but trailing
S/W energy may make this difficult to achieve. Highs will top
out in the lower 50s (central OH) to the mid 50s (SE IN and N
KY).
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&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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Westerly winds will keep up around 10-15 mph overnight Friday as
temperatures drop to the lower 40s under clearing skies. Saturday
will be sunny with a good increase in upper heights as the l/w
trough exits east. Highs will range from the lower 60s in west
central Ohio to the upper 60s in Kentucky south of the interstate
loop. Winds will not be as strong as previous days but still see 10-
15 mph with higher gusts area wide.

Zonal upper flow keeps a generally neutral height pattern over the
region through Sunday night, as warm southwest flow precedes a weak
surface low circulation cutting east through the lower Great Lakes.
Sunday will see highs in the low to mid 70s, some upper 70s in the
lower Scioto Valley and parts of northern Kentucky. The low will
also bring a chance of rain to the region that will be more
pronounced in central Ohio, peaking in the late day/early evening.

As the low trails a weak and dissipating cold front south of the
Ohio Monday, high pressure will build briefly in the northern Ohio
Valley. Increasing heights should permit highs to reach the mid 70s
in west central Ohio, upper 70s to near 80 elsewhere. Dropped the
chances of rain from late Monday night through Tuesday given the
warm sector signal of light precip but had to run with guidance
beginning Tuesday evening. This is when rain chances ramp up through
the overnight but still remain in the chance category.

From Wednesday onward, rain chances will continue but will not
certainly be the noted prevailing weather. Overnight lows max out
Tuesday night in the lower 60s, with daytime highs Wednesday similar
to Tuesday - mid 70s in the north and northwest, near 80 south and
east. The increased cloud cover associated with the rain chances
Thursday will bring about a 2-3 degree drop in highs, remaining in
the 70s which remains a solid 10 degrees above normal.
-- End Changed Discussion --

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Pockets of SHRA, albeit in a somewhat widespread fashion,
continue to work their way to the NNE through the region and
this will remain the case through most of the TAF period. On-
and-off SHRA are expected through the daytime, with some
embedded ISO/SCT TSRA possible during the mid/late afternoon,
especially for srn sites (KCVG/KLUK/KILN) and ern sites
(KCMH/KLCK). The presence of heavier SHRA is reducing VSBYs,
mainly to MVFR. However, some brief IFR VSBYs certainly may be
possible periodically as well.

CIGs should generally be a mix of MVFR/IFR for wrn sites through
daybreak before eventually trending to more solidly MVFR past
18z. Ern sites of KCMH/KLCK will stay with VFR CIGs through the
first several hours of the TAF period before trending MVFR past
12z until late afternoon where CIGs may go back to VFR again
before returning to MVFR/IFR for the final several hours of the
TAF period.

The other item of note will be the winds, which should generally
be out of the ESE around 8-10kts through daybreak before
trending more out of the SSE past 15z, still generally around
12kts or so with ISO gusts to 18-20kts through 22z-23z. After
22z-23z, a sharp wind shift to out of the WNW will progress
through the area, with WNW winds of 15-20kts and gusts to around
30kts by 00z for most spots. Westerly winds may gust close to
35kts between about 02z-06z for KDAY/KILN/KCMH/KLCK as the SHRA
tapers off. However, SHRA should move back in once again for the
end of the KCVG 30-hr TAF.

OUTLOOK...MVFR ceilings will continue at times through Friday.
Some IFR ceilings are possible. Wind gusts of 30 knots or
greater are possible Friday.

&&

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

&&

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