Forecast Discussion - Wilmington, OH
056
FXUS61 KILN 020533
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
133 AM EDT Wed Apr 2 2025
.SYNOPSIS...
Strong low pressure brings the chance of severe storms and heavy
rain late Wednesday into Wednesday night. Additional waves of low
pressure will cause more rounds of storms with heavy rain Thursday
night into Saturday.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Quiet conditions continue for most of the overnight ahead of an
approaching warm front. By the late overnight/early morning, the
chance for showers and thunderstorms develops from west to east when
the warm front arrives. A minimal severe risk will accompany these
morning storms since all instability should be elevated. This should
limit the any small severe risk to hail. Despite heavy rain rates in
these storms, storm motion should be fast so flooding issues are not
expected late overnight. Temperatures start to rise late in the
overnight when warm air advection kicks in.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Morning showers and thunderstorms: Upon arrival of a strengthening
LLJ and deeper moisture, elevated showers and thunderstorms quickly
move across the area after sunrise into the early afternoon. The
primary threat for this activity remains isolated hail within the
stronger thunderstorms. Greatest confidence and coverage is across
the northern half of the area, but some showers and thunderstorms are
possible as far south as the Ohio River, just with lesser coverage
and lower hail threat.
Wind advisory: Behind the elevated showers and thunderstorms,
boundary layer heating occurs, increasing mixing depths. This allows
for the stronger winds above the surface to mix downward. Forecast
soundings indicate wind gusts up to 50 mph are likely with the more
efficient mixing. There is some uncertainty with cloud cover
potentially limiting high temperatures, decreasing the mixing depth.
Nevertheless, there was enough confidence for an advisory from
eastern/southern Indiana, much of western/southwest Ohio and also a
portion of northern Kentucky. The wind advisory ends midnight
Thursday, but there is likely to be ongoing severe convection.
Severe threat: With the deepening low pressure continuing its
northeast track into the upper Midwest, confidence is very high that
the local area will see a lull in convective activity from the early
afternoon and into the early evening. Can`t rule out sporadic
discrete activity ahead of the main severe threat, but the overall
atmosphere is modestly capped. This should prevent updrafts from
successfully growing into the area of greater instability higher in
the atmosphere. Height- falls are greatest west of the local area
(central and southwest Indiana), so the main development zone is
expected there between 5-7 pm. As this activity reaches the local
area (eastern Indiana, greater Cincinnati), there is uncertainty as
to the specific storm mode, which will be critical for determining
the severe hazard, especially significant tornado potential.
Early evening -- As thunderstorms move into the aforementioned area,
the cap will either be overcome by cold-pool propagation or will
have eroded with cooling 700 mb temperatures. With the cap eroded and
long- curved hodographs still in place, the parameter space for
significant tornadoes remain in tact for a few hours as thunderstorms
move into the area. This is one of the main reasons why significant
tornadoes remains possible over the western half of the local area,
despite the uncertainty of storm mode. QLCS mesovortices and embedded
supercells present the best chance for tornadoes and significant
straight-line wind gusts along with large hail.
After 1am-2am -- The activity continues eastward, moving into
locations with lower overall instability. All threats remain likely,
especially QLCS mesovortex tornado with any convection that is
occurring, however, the coverage of these threats will be decreasing
with time even if the thunderstorm coverage is in tact area wide. The
convective line continues working through the remaining instability,
exiting the area to the east and south. Rainfall is likely to
continue into Thursday morning, but the severe threat will have
added.
Flash flood threat: Flood flooding is likely to be isolated to
locations that see multiple rounds of thunderstorms. The expectation
right now is that the line will move fast enough to the east and
south, especially across the I-70 corridor. Where southwest to
northeast aligned segments occur, a quick 2 to 4" would be possible
leading to the potential for flash flooding. There is currently a
Slight Risk - Day 2 Excessive Rainfall Outlook for the whole area,
but the best chance for the above thinking is probably over portions
of southern Ohio and/or northern Kentucky as the movement of the
thunderstorms begins to slow during the afternoon hours. If the
cold-pool remains strong enough, this would decrease the potential
for multiple rounds of thunderstorms.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Upper level high pressure ridge off the Southeast Coast will keep
the Ohio Valley in persistent, moist southwest flow into the weekend.
Meanwhile, a stationary boundary will remain stalled across the
Tennessee/Ohio Valley region with several waves of low pressure
riding east along it. This will result in widespread showers and
thunderstorms through Sunday, with more focused periods of pcpn
likely with each wave, especially Thursday night, Friday night into
Saturday morning and finally possible into Saturday night.
There remains some uncertainty as to exactly where the boundary will
set up as well as the tracks/timing of each surface low, but the
GFS/CMC and ECMWF ensemble means have all been fairly consistent with
the axis of heaviest rain setting up along and just south or the
Ohio River to our southwest and then nosing up into the Tri-State
area. Both the CMC and ECMWF ensemble mean are bringing 5 to 7 inches
of rain totals into our southwest through the weekend, with the GFS
ensemble mean a little higher. Thus, confidence is fairly high that
we will see several rounds of potential flooding/flash flooding and
eventually river flooding as we progress through later this week and
into the weekend.
The pattern will finally change through the first part of next week
as the ridge to our southeast weakens and a broad upper level trough
settles in over the Great Lakes. This will lead to drier but cooler
conditions toward the end of the long term period.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions on tap for the overnight as a warm front develops and
begins to move toward the region. This front will produce showers and
storms in the 12-17Z time frame along with low level wind shear as
winds just above the surface increase dramatically.
Warm frontal convection will exit to the northeast by midday as the
main aviation weather impact becomes gusty surface winds. These
southerly gusts may approach or exceed 40 knots at times this
afternoon into the early evening. Another round of storms, a few of
which may be severe, will approach after 00Z. The most likely time of
arrival will be around midnight. Main concern here is with damaging
winds... however have opted to hold on placing these storm- related
gusts in the TAFs until we draw nearer the event and timing is more
certain.
OUTLOOK...Showers and thunderstorms will be possible at times
Wednesday through Saturday. MVFR/IFR conditions will be possible at
times during this period.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Wind Advisory from 10 AM this morning to midnight EDT tonight for
OHZ026-034-035-042>044-051>053-060>062-070>072-077>079.
Flood Watch from this evening through Sunday morning for OHZ026-034-
035-042>046-051>056-060>065-070>074-077>082-088.
KY...Wind Advisory from 10 AM this morning to midnight EDT tonight for
KYZ089>099.
Flood Watch from this evening through Sunday morning for KYZ089>100.
IN...Wind Advisory from 10 AM this morning to midnight EDT tonight for
INZ050-058-059-066-073>075-080.
Flood Watch from this evening through Sunday morning for INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...McGinnis
NEAR TERM...Campbell
SHORT TERM...McGinnis
LONG TERM...JGL
AVIATION...
NWS ILN Office Area Forecast Discussion
