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000
FXUS63 KLMK 160732
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
332 AM EDT Tue Apr 16 2024

.KEY MESSAGES...

*   Showers and thunderstorms are likely tonight through
    Wednesday night. The severe threat Tuesday night into
    Wednesday morning looks low.

*   Severe weather potential still exists for the daylight hours
    of Wednesday, although confidence has lowered considerably.
    Currently, southern IN carries the highest risk on
    Wednesday.

*   Thursday night could carry another severe threat.

*   Significant cool-down appears increasingly likely next weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 329 AM EDT Tue Apr 16 2024

Convective activity from earlier tonight has pretty much shut down,
although will occasionally see a few blips on radar along the warm
frontal boundary. This feature is currently draped in a WNW to ESE
orientation from roughly HNB down through LEX, and is expected to
slowly move northeastward to northern IL, central IN, and southern
OH by early to mid afternoon. Will keep some low chance pops across
our north through the morning to account. By midday, we`ll be placed
more solidly in the warm sector with steady to occasionally gusty S
winds taking hold by late morning. Overall, the gustiness may be
held a bit in check by fairly prominent mid and upper sky cover
until early afternoon, however a break in that sky cover is expected
through the peak heating hours, where temps are expected to surge
into the low 80s for many. Gustiness should peak during this stretch
with 20 to 25 mph expected to be common.

Later this evening, a convective complex is expected ahead of an
approaching cold front and should move into our western CWA between
8 and 11 PM EDT. From there, elevated convection is expected to move
eastward across our CWA. Not much change in the thinking with this
overnight convection as low level stability should mitigate larger
concerns for a severe threat. In addition to soundings showing the
stable layer in place, the latest HREF probabilities for any notable
ML CAPE values stays at 0% until right around sunrise in our far NW
CWA. So, pretty high confidence in any convection staying elevated
and the severe threat staying low. As previous forecasts have noted,
the overall shear profile will be quite high, and thus there is some
hesitation to completely rule out an isolated instance, but overall
not really concerned. SPC kept a Marginal risk for part of our
region, and think the best chance for any issues would be right
before sunrise across our NW CWA as those 40-50% probabilities for
around 500 J/KG of ML CAPE work into the area.

Some notable changes to the Wednesday forecast as confidence in
severe weather potential has lowered. Morning convection should
continue to push across our eastern CWA, well ahead of the trailing
cold front that will likely hang up just to our NW. Forecast
soundings through the afternoon show a pretty strong inversion just
below 700 mb, and recent runs of data have kept much of the
convective activity to our north across central IN into OH. Some
data does support convective activity along and north of the Ohio
River closest to the strongest forcing, which is also where SPC has
trimmed the Slight Risk significantly to just cover that area. Like
the idea of leaving the Marginal risk over the rest of the CWA for
the time being because the overall shear profile would still remain
quite favorable for some supercell storm modes if convection were to
fire, so don`t want to completely let the guard down yet. However,
current data appears to make it difficult for any parcels to reach
their LFC given the inversion, at least across the southern 2/3 of
our CWA. The bottom line here is that if the inversion does end up
as strong as currently advertised, then we might dodge a bullet for
much of our CWA. That being said, can`t let our guard down yet as
the inversion is the only limiting factor to what would otherwise be
a favorable environment for severe convection and likely some
supercell storm modes. Stay up to date of the latest forecasts over
the next 24 to 36 hours.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 336 PM EDT Mon Apr 15 2024

Tuesday night, a stacked low pressure system is expected to cut east
across Iowa while dragging a cold front through the Ozarks. This
will initiate a line of convection across Missouri that will work
its way eastward across the Lower Ohio Valley. The line will have
plenty of moisture in an airmass with precipitable water values just
over 1.5", but by the time the line begins to enter our western
counties (4-6z), the line would have outrun its instability. Model
soundings show deep layer shear will still be strong, but the line
will be elevated and sub-severe at that time. This line will likely
be east of our southern Indiana counties by 12z Wednesday and east
of our Kentucky counties by the early afternoon. Around this time,
the actual cold front will be nearing the western edges of the CWA.

Wednesday afternoon and evening, the front will begin to work east
across southern Indiana and central Kentucky. This is expected to
kick off a more concerning broken line of convection. Model
soundings agree that this round of precipitation will have plenty of
instability, ranging from 1,500 to 2,000 J/kg MLCAPE. Hodographs
also agree with deep layer shear, 0-6 km, around 40-50 knots with
strong low level storm relative helicity as well, so believe SPC`s
Slight risk is well placed. All severe weather types are on the
table, including severe winds, large hail, and tornadoes. Over the
next 24 hours, the CAMs will begin to capture this period and should
add more details.

Behind the cold front, upper flow becomes more zonal, and besides a
passing low pressure system to our south on Thursday night, which
will bring a chance for more rainfall Thursday night and Friday, the
rest of the week should be fairly quiet.

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 329 AM EDT Tue Apr 16 2024

Convective activity has diminished across the region at this hour,
and looking for a quiet remainder of the overnight into the rest of
the day. Looking for generally light SE winds to take hold early
this morning once remnant outflow boundaries settle down. Ceilings
will be VFR with Sct-Bkn mid and upper clouds.

By mid to late morning, look for stronger S winds to take hold in
the 10 to 15 mph range, gusting up around 20 to 25 mph at times.
Variable mid and upper cloudiness could hurt the gust potential, but
any breaks in the clouds should allow for the gustiness to increase.

Steady to occasionally gusty winds could last into later Tuesday
night early Wednesday morning, along with the arrival of some
showers and storms expected. Ceilings should stay VFR through the
first half of the night, although any shower or storm could reduce
vis below VFR thresholds.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

SHORT TERM...BJS
LONG TERM...KDW
AVIATION...BJS