511
FXUS63 KLMK 161743
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
143 PM EDT Wed Jul 16 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Warm and humid conditions with scattered thunderstorms are
  expected today.  Torrential rainfall, gusty winds, and lightning
  will be the main threats with today`s storms.

* Unsettled weather pattern likely shaping up for the remainder of
  the week and into the weekend.  Daily chances of showers and
  thunderstorms are expected with torrential rainfall, gusty winds,
  and lightning.  Localized flooding could become a problem across
  portions of southern IN and into northern Kentucky.

&&

.UPDATE...
Issued at 959 AM EDT Wed Jul 16 2025

An MCV/mid-level shortwave is noted over south central IN this
morning on visible satellite imagery and via 700 mb height trough on
SPC mesoanalysis. The convection which fired early this morning did
so within an area of PVA ahead of the trough axis. Now that this is
overhead, most of the convection and rain has moved into northeast
KY and southern OH, although isolated clusters of showers have
developed over south central KY. As this trough axis continues to
lift northeast through the day, would expect mid-level NVA and
resulting subsidence to suppress convective activity, especially
along and west of I-65. Latest runs of the HRRR tend to support
this, though it still seems like we could get isolated cells as sfc-
based instability increases to around 2500-3000 J/kg this afternoon,
though convection will likely be tempered by aforementioned mid-
level subsidence. With less in the way of shower/storm coverage
expected this afternoon, temperatures should have little difficulty
warming into the upper 80s and lower 90s. It is possible that we
could outpace the current temperature forecast, especially across
the southern half of the CWA. Farther north, the temperature
forecast is more uncertain, as low stratus lingers near the MCV over
southern IN.

Only made minor changes to temperatures, PoPs, and winds for later
today, given that a somewhat drier/warmer/breezy setup is looking
more favorable.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 325 AM EDT Wed Jul 16 2025

Early this morning, a weak upper level shortwave trough axis was
pushing through the lower Ohio Valley.  This feature is driving the
current convection moving through portions of southern IN and north-
central KY this morning.  Convection thus far has been somewhat
strong, mainly producing torrential rainfall, some gusty winds, and
quite a bit of CG lightning.  Current convection in the I-65
corridor will continue to move off to the northeast this morning.
Additional convective development will be seen across portions of
western KY and southwest IN this morning as the mid-level wave
passes through. Quick rainfall amounts of a quarter to a half inch
will be possible with this activity.  Some very isolated three
quarter inch to perhaps an inch may occur in some spots.

For today, scattered convection will likely be ongoing at the start
of the period across portions of southern IN and northwest KY as
aforementioned mid-level wave moves on through.  Additional
development may occur east of I-65 later this morning as the wave
heads into OH.  After that, we may have a bit of suppression across
the region in the wake of the upper level wave passing through due
to trailing subsidence.   However, that probably will not hold off
additional convective development in the afternoon/eve as temps warm
into the upper 80s to around 90 and dewpoints in the 70s.  Afternoon
instability will likely climb in to the 2500-3000 J/kg range with
PWATs running around 2 inches.  Wind shear through the column
continues to look rather week despite rather deep layer flow.
Clusters of pulse type storms producing torrential rainfall, some
gusty winds, and quite a bit of CG lightning will be the main
threats with this activity.  Rainfall amounts in thunderstorms will
be in the 0.25-0.75 inch range, though some very localized amounts
of 1-2 inches will be possible in some locations.

For tonight, some scattered showers/storms will likely be found
across the region this evening, though if I had to pick an area of
highest concentration, it would be across southern IN and into
northern KY.  This convection looks to diminish after sunset with
overnight temps dropping into the lower-middle 70s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 325 AM EDT Wed Jul 16 2025

By Thursday, deep layer flow across the region looks to remain
fairly zonal as faster belt of westerlies suppresses the southeast
ridge.  The latest NCEP models continue to bring a slow moving
frontal boundary further south towards the Ohio River during the
daytime hours.  South of this front, a very moist airmass is
expected to be in place with afternoon highs topping out in the
upper 80s to near 90 and dewpoints firmly in the 70s.  This will
produce adequate instability to drive convection across the region.
Convection looks to be focused along the front and will be aided by
remnant MCVs moving along the boundary.  Vertical shear is stronger
across our northern CWA with a quick drop off in shear with southern
extent.

Most concentrated area of showers and storms for Thursday will
likely be along the front.  Current projections suggest that the
area at most risk for storms will be along and perhaps just south of
the I-64 corridor.  Here afternoon instability should result in CAPE
values of 2500-3000 J/kg.  Warm cloud depths up to 13000-14000 ft
AGL are expected with PWATs running up near 2-2.1 inches.
Thunderstorms capable of damaging winds, mainly due to waterloaded
downdrafts will be the main severe threat, along with torrential
rainfall and intense cloud to ground lightning.  Rainfall amounts
could become problematic in spots Thursday afternoon/evening mainly
across southern IN and into portions of northern Kentucky if
training of convection develops and areas see repeated rainfall.
Along the I-64 corridor rainfall amounts of 1-2 inches could develop
with localized 3-4 inch amounts being possible in some areas.  If
subsequent forecasts continue to suggest heavy rainfall, a Flood
Watch for portions of the area may be required in future forecasts.

For the weekend and into next week, the upper level pattern is not
expected to change all that much.  SE ridge will remain in place
with a rather deep west to east flow across the Ohio Valley. Remnant
frontal boundary will likely remain in the vicinity of the Ohio
River, but am not sure it will make it south of that.  Episodic
bouts of convection are likely as remnant MCVs move along the
boundary.  Model soundings continue to show rather weak shear
thorugh the column through this period, so waterloaded downdrafts
capable of producing strong winds will be the main threat along with
torrential rainfall and plenty of lightning.

Upper level ridge may attempt to build a little more to the west
with a more northwesterly flow pattern developing across the Midwest
and Ohio Valley as we move into next week.  This could set the stage
for some MCS clusters to trail down along the periphery of this
ridge and into the region.  The overall synoptic pattern is one that
can produce excessive rainfall in the Ohio Valley during the warm
season and we`ll be watching the evolution of the pattern very
closely.  Daytime highs will remain in the upper 80s to around 90
with overnight lows in the low-mid 70s.

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 142 PM EDT Wed Jul 16 2025

Scattered SHRA and isolated TSRA will be possible this afternoon
east of I-65. However, subsidence in the wake of a departing mid-
level wave will play a role in suppressing vertical convective
development. Therefore, kept just a VCSH mention at LEX, RGA, and
BWG due to lower confidence in TSRA this afternoon. SW winds will
remain breezy through sunset, with gusts to around 20 kt possible.

The overnight period looks relatively quiet/dry and mainly VFR with
lighter SSW winds. Some fog looks possible early Thursday, mainly at
HNB. SCT TSRA will be possible after 18Z Thursday.

&&

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

&&

$$

UPDATE...CSG
SHORT TERM...MJ
LONG TERM...MJ
AVIATION...EBW