237
FXUS63 KLMK 031929
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
329 PM EDT Wed Jul 3 2024

.KEY MESSAGES...

*   Heat index values this afternoon will range from near 100 in the
    Bluegrass region to 105 or higher west of Interstate 65.

*   Scattered thunderstorms this evening will be capable of strong
    gusty winds and torrential downpours. Overnight the severe
    threat will diminish but heavy downpours remain possible, which
    could result in localized flash flooding.

*   Unsettled weather will continue through Friday with daily
    chances of showers/storms. Isolated damaging wind gusts,
    torrential rainfall, and lightning will be the primary hazards.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 328 PM EDT Wed Jul 3 2024

Low-confidence forecast in a very warm, muggy, and boundary-rich
environment.  Plenty of low-level instability, but very weak mid-
level lapse rates will limit convection to that which can find
forcing.

We do have a cold front draped across central Illinois, with
lingering outflow boundaries from earlier activity in southern
Illinois and central Indiana. Hi-res models light up these features
starting around 22-23Z, with the best chances over southern Indiana.
Will also be closely watching the differential heating along the
southern edge of the cirrus shield, which is draped close to the
Cumberland Parkway in south-central Kentucky.

Given the steep low-level lapse rates and PWAT values over 2 inches,
we could still see a few strong to marginally severe pulse storms,
with locally gusty winds and torrential downpours. Best coverage is
likely to be in southern Indiana and north-central Kentucky.

If storms organize over southern Illinois, that could yield another
wave of storms late tonight into Thursday morning. Main threat will
be heavy rainfall, given PWATs still over 2 inches and tall/skinny
CAPE profiles, and localized flash flooding is possible anywhere
that heavy rain can regenerate. WPC has a Slight Risk for excessive
rainfall just on either side of the Ohio River.

Depending on how long precip continues into Thursday morning, it
will likely limit afternoon temperatures and storm intensity. Look
for mainly hit-and-miss convection on Thursday afternoon, as the
environment is still very moist and lingering boundaries could focus
storm development.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 328 PM EDT Wed Jul 3 2024

Thursday Night - Friday Night...

Low pressure will move through the Midwest bringing a cold front
through the Ohio Valley by Saturday morning. With deep troughing
associated with the system, CVA, and a weak, but well-positioned
upper-level jet dynamics, showers and storms will be move through
along and ahead of this front on Friday. Strong storms and storm
coverage is dependent on preceding convective activity today and
Thursday. If the environment recovers from preceding convection,
present shear and ample moisture will allow for a marginal risk of
severe storms due to potential for gusty to damaging winds and heavy
downpours. Flash flooding will be possible as the atmosphere is near
max climatology for PWATs in the 2.1-2.3 inch range and dew points
in the mid 70s. As the cold front moves through Friday night, drier
and cooler weather will build into the region.

Additionally, Thursday Night (Independence Day) should be mostly
dry. A nocturnal inversion will quickly settle into the region around
sunset. Firework smoke from 4th of July celebrations will be easily
trapped under the inversion and skies will become smokey through
Thursday night.

Weekend...

Drier and near normal conditions will stick around through the
weekend. High in the mid-upper 80s, dew points in the low-mid 60s,
and a light breeze will bring pleasant summer conditions. High
pressure over the region will keep mostly sunny skies with scattered
diurnal Cu formation in the afternoon.

Early Next Week...

Deep troughing will build over the central CONUS and high pressure
will move off to the east. Southwesterly flow and moisture will
return to the region. Shower and storm chances increased Tuesday as
a the trough swings through the upper Midwest. Temperatures will
remain near normal with dew points in the low 70s.

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 133 PM EDT Wed Jul 3 2024

Main challenge in this TAF set is timing and impacts of convection.
Very juicy and boundary-rich environment does not lend much
confidence to that. However. would expect the best opportunity for
scattered thunderstorms this evening would impact HNB after roughly
22Z and SDF after 00-01Z. Differential heating could also get BWG in
on the act, but not confident enough to mention storms in the TAF
there.

Overnight we`ll see light S-SW winds and mostly mid-level debris
clouds. Could see a weakening MCS come in Thu morning, with MVFR
cig/vis possible. Will include this in the TAFs but confidence is
medium at best.  Winds will be light from nearly due west.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     KYZ023>034-038-045-053-061>063-070>074.
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     INZ076>079-083-084-089>092.

&&

$$

SHORT TERM...RAS
LONG TERM...SRM
AVIATION...RAS