470
FXUS63 KLMK 300511
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
111 AM EDT Sun Jun 30 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Very warm and muggy this afternoon with heat index readings
    peaking around 100 to 105.  Scattered storms possible through
    the evening with torrential rainfall, gusty winds, and lightning
    being the main threats.

*   Another period of unsettled weather returns to the region by
    late Wednesday and Thursday.

&&

.UPDATE...
Issued at 846 PM EDT Sat Jun 29 2024

Widely isolated showers and storms continue this evening across the
region. We may continue to see isolated activity pop up tonight into
early tomorrow morning as a weak front approaches from the north.
The convection thus far within our CWA has been relatively mild
likely due to marginal mid-level lapse rates and weak capping in the
850-700mb layer. Still can`t rule out an isolated stronger storm
overnight, but conditions will become less favorable for robust
convection the deeper we go into the night. Forecast remains on
track.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 344 PM EDT Sat Jun 29 2024

Afternoon satellite imagery and observations reveal partly sunny
skies across the forecast area.  Temperatures were in the upper 80s
to the lower 90s.  Dewpoints continued to hold in the lower-mid 70s
resulting in heat indices in the upper 90s to the lower 100s
(generally 98-104).  The area remains generally devoid of convection
with the exception of a line of shallow showers over across Garrard
and into Madison county.  Other storms were located up to our north
along the I-70 corridor.

With temperatures in the upper 80s to the lower 90s and dewpoints in
the low-mid 70s, instability has ticked up across the region with
MLCAPE values surging into the 1500-2500 J/kg range, with slightly
larger values of SBCAPE locally.  While instability is decent, low-
mid level lapse rates and deep layer shear remain rather marginal
and the best synoptic scale forcing is off to our northeast.  For
the remainder of the afternoon, isolated-scattered storms could
develop over the region.  Current thinking is that our northeastern
sections would have the highest chance of seeing convection.  Temps
will top out in the upper 80s/lower 90s before cooling into the 80s
by evening.  An MCV evident WV imagery coming into central IN may
spark a round of shower/storms this evening across the region.  HRRR
has been trying to drum up some convection mainly over the
Bluegrass, but approaching MCV/wind shift over IL/MO may be enough
to kick up some storms this evening. For now will continue to keep
30/40% PoPs going.  Main threats with any storm will be torrential
rainfall, gusty winds, and frequent lightning.

Surface cold front will continue to push southward overnight and
some additional convection may fire along that boundary.  However,
most CAMs keep the most significant convection to our
west/southwest.  Another warm night of temperatures is expected with
readings only dropping into the mid-upper 70s.

For Sunday, surface frontal boundary is forecast to drop through the
region.  This will bring cooler and less humid conditions to the
area.  We may see some scattered showers along the front in the
morning across the north and then a few showers/storms could
continue through the afternoon across the south as the boundary
continues toward the TN valley.  Highs will only warm into the upper
70s/lower 80s across southern IN with lower 80s (80-85) across
Kentucky.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 344 PM EDT Sat Jun 29 2024

By Sunday night, the cold front will be south of the region. Surface
high pressure, centered over the Midwest, along with upper ridging
will quickly clear skies over the Lower Ohio Valley. Cold air
advection from northerly winds on the eastern side of the high will
help drop low temperatures into the low 50s (southern Indiana) to
the low 60s (southern Kentucky) which is 15-20 degrees cooler than
Saturday night`s lows. The continued CAA will help to limit highs on
Monday to the upper 70s to low 80s. The cold front followed by
northern winds will also help knock dew points down into the 50s
which will help make things feel much more comfortable throughout
southern Indiana and central Kentucky, but as the center of the
surface high gets pushed across the Great Lakes, return flow will
begin lifting temperatures back into the 90s by Tuesday. This will
also begin lifting dew points across the region as Gulf of Mexico
moisture begins to get funneled up the Mississippi and Ohio River
Valleys. Dew points in the 60s will return on Tuesday before the 70s
on Wednesday. Upper 80s to low 90s are expected to remain into the
weekend, and with the pressure gradient between the surface high on
the East Coast and the approaching cold front to our northwest
increasing, warm air advection and moisture transport will increase.
This will push highs into the mid 90s and dew points into the mid
70s which will result in heat indices in the 100-104 range over the
western half of the CWA. Currently, this looks to be be the hottest
day of the week.

By Wednesday night, an approaching cold front being pushed by an
upper trough will push the upper ridge out of the Great Lakes region
and through New England, leaving more zonal upper flow north of the
upper high over the South. This will likely cause the cold front to
flatten from west to east north of the high to the south. This will
likely place the front just north of the CWA. In an environment with
precipitable water values climbing over 2", shower and thunderstorm
chances will begin increasing before the front gets pushed south of
the region by Friday or Saturday.

&&

.AVIATION /06Z TAFS THROUGH 12Z MONDAY/...
Issued at 110 AM EDT Sun Jun 30 2024

High level clouds will continue to stream over the region in the
coming hours ahead of an approaching cold front. VFR conditions are
expected at the terminals, but LEX may have some ceilings near MVFR
threshold by sunrise tomorrow. Will also keep an eye on any
thunderstorm activity this morning along the front, which guidance
has been agreeing fairly well on a 1-2 hour window for BWG around
12z this morning. Otherwise, as the front passes through, expect a
hard shift in wind directions. Post-frontal northwest winds could
get gusty at times during the afternoon and near 20kts.

&&

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

&&

$$

UPDATE...DM
SHORT TERM...MJ
LONG TERM...KDW
AVIATION...CJP