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000
FXUS61 KILN 160531
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
131 AM EDT Tue Apr 16 2024

.SYNOPSIS...
A weak cold front will stall over northern Kentucky into early
morning Tuesday. It will then return north and northeastward as
a warm front during the day Tuesday, bringing the chances of
showers and storms back across the Ohio River into Indiana and
Ohio. A low pressure and cold front will approach the region on
Wednesday and continue the chances for showers and
thunderstorms, with this system bringing the highest chances of
most widespread rain of the week. Temperatures will begin to
cool in the wake of this system heading into the end of the work
week.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
A weak frontal boundary will stall over northern Kentucky and
begin to nudge back to the north and northeast towards daybreak.
Some weak WAA moist ascent will need for us to keep a low
chance of showers and thunderstorms going across our southwest
CWA.

High cloud cover will be generally thin to the north and east,
thicker to the southwest. Additionally, some mid level clouds
will increase in the southwest overnight with the increased
moisture coming in behind the then northeastward moving front.

Increased lows in the southern half of CWA with a modest
increase over KY south of metro Cincy from the upper 50s to
lower 60s.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
As the returning boundary begins to drift northward on Tuesday
owing to large scale warm advection, weak moisture transport
into and over the boundary will continue to maintain a threat
for showers and storms along and to the cool side of the
boundary as it lifts northeast through the morning. In the wake
of the boundary passage, a non-zero severe weather setup
develops with east-southeasterly winds turning southeasterly,
and dewpoints rising to around 60F. Large scale forcing is not
overly evident, so it appears low level thermodynamics
around/near or perhaps just in the wake of the retreating
frontal zone will need to be the initiating mechanism to realize
any severe threat on Tuesday afternoon. Right now, this signal
is of very low confidence, with the parameter space supporting
hazardous weather perhaps focused a little more southeast of the
ILN CWA (where convergence is a little better) and to the west
of the ILN CWA (where dynamics with the inbound upper trough are
a little better). A supportive environment though does exist
marginally, mostly due to some nature of southeast low level
flow maintaining itself through much of the day which enlarges
hodograph curvature considerably amidst a weak instability
profile. Primary missing component is more forcing, so we will
need to watch clearing/convergent areas in the afternoon into
evening if we are to realize any hazardous weather potential.
The amalgam of CAM simulated reflectivity solutions for 18Z-00Z
largely match this idea, with some models not having much
activity after a morning shower band crosses the area, and some
generating isolated cells/clusters at peak heating.

A higher chance of rain/storms arrives later Tuesday night as a
primary arc of forcing /decaying MCS/ with the dynamic upper
trough/closed low in the central US moving east into the Ohio
Valley during the overnight. Have maintained high rain chances
here, likely not posing a severe threat as activity races out
ahead of the more slowly moving instability band well to the
west, although low level wind fields will be strong, so a
nonzero severe weather threat again during the overnight.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
On Wednesday morning, a closed upper low and associated surface
low will be moving ENE through the upper Midwest. Height falls
will be occurring over the Ohio Valley region as ridging moves
off to the east. The surface cyclone will be occluding, with a
cold front initially over Illinois at 12Z Wednesday, then moving
east into Ohio by 21Z. Ahead of this feature, the ILN CWA will
be in the warm sector, but with flow and forcing aloft that will
already be bringing precipitation into the area. This may be
leftover precipitation or convection from development on Tuesday
and Tuesday night, with some clusters of storms or a decaying
MCS moving through the area during the early morning hours. This
activity will only have a low chance of severe weather, owing
to unfavorable boundary layer conditions.

The main concern for the extended forecast period is the
potential for severe weather on Wednesday afternoon. This is a
setup where the overall synoptic features and arrangement are
favorable for severe weather -- perhaps easily favorable -- but
mesoscale details, particularly with respect to thermodynamics,
will likely have a larger contribution to the eventual outcome.
Although the surface low will be upstream of the area, and in a
gradually weakening state, the arrangement of wind through the
troposphere looks favorable from both forcing and shear
perspectives. The overall shear values support organized
convection (with wind speeds of 60kts WSW at 500mb and 40kts SW
at 850mb) with the lowest 1km of the hodographs also suggesting
enough turning / SRH to support a tornado risk. However,
forecast soundings from various models suggest the morning
activity will leave an unfavorable warm layer somewhere near
750mb-850mb, significantly limiting lapse rates in the wake of
the first round of showers and storms. It would take a decent
bit of destabilization to overcome this and produce robust /
widespread convection during the afternoon hours. It is also not
out of the question that if model timing is off, some residual
showers and storms could continue into the morning on Wednesday,
further limiting destabilization. So, this is yet another
conditional severe threat, where mesoscale details will make the
difference.

By Wednesday night, the low pressure area will find itself
absorbed into the flow to the north, as the flow across the Ohio
Valley turns more progressive. The surface boundary associated
with the Wednesday system may not make it totally clear of the
region, and another shortwave moving into the region by Thursday
night will start to activate another round of showers and
storms. This will continue into Friday, before the system moves
further south on Saturday, as cooler and drier air begins to
filter into the region.

Wednesday may be the warmest day of the week, though that will
be dependent on how the morning convective situation plays out.
Highs are currently forecast to be in the 70s, though this is
not a high confidence forecast. Slightly cooler conditions are
expected Thursday and Friday, with a cooling trend expected.
Even cooler conditions are expected over the weekend, with highs
generally in the mid 50s to around 60.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
A weak frontal boundary will begin to drift north-northeast late
tonight and towards daybreak. Some weak WAA/moist convergence
necessitates keeping some chance (low) for showers and storms
south and west of metro Cincy. VFR conditions will prevail
outside of any precipitation. 5-10kt winds will veer east-
southeast.

The frontal boundary will move northeast as a warm front during
the day. Forcing remains generally weak and most models are
sparing in their precip footprint today, so will keep just a
chance of showers/storms. 10kt winds will veer southeast-south.

An area of showers and thunderstorms will be on the doorstep of
the IN/OH border at the end of the forecast period. Will have to
put prevailing showers/thunder in the extended CVG TAF given it
running to 12z. This puts it in the crosshairs of the moist
tongue being driven in on a fairly deep layer of lower level
winds around 40kt.

OUTLOOK...LLWS possible overnight into Wednesday morning.
Showers with a chance of thunderstorms overnight into Wednesday
night. Wind gusts around 30 knots Wednesday afternoon and
evening. MVFR ceilings possible Thursday. MVFR conditions
possible Friday.

&&

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

&&

$$
SYNOPSIS...Binau
NEAR TERM...Franks
SHORT TERM...Binau
LONG TERM...Hatzos
AVIATION...Franks