904
FXUS63 KLMK 221715
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
115 PM EDT Sat Jun 22 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Above normal temperatures expected again today in the mid-upper
    90s.

*   Scattered showers and storms possible Sunday, and again by the
    middle of next week. Gusty winds the primary threat in any
    stronger storms that develop.

*   Heat Index may rise above 100 degrees on Tuesday, especially
    west of the I-65 corridor.

&&

.UPDATE...
Issued at 1115 AM EDT Sat Jun 22 2024

The going forecast remains on track. Temperatures per the Kentucky
Mesonet were in the mid/upper 80s with heat index values in the
low/mid 90s. Unlike the past few days, skies remained mainly clear
over the region. If the situation were the same as the previous days
I would have been more inclined to increase afternoon temperatures
but given high clouds increasing from the northwest and increased
winds out of the southwest ahead of the approaching system, will
maintain the current forecast. No changes are expected at this time.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 306 AM EDT Sat Jun 22 2024

High pressure at the surface and ridging aloft remains over the
region this morning. Skies are clear and winds are calm.
Temperatures have fallen into the mid-upper 70s and will continue to
fall through dawn. Expecting to see eastern river valleys touch the
upper 60s, rural areas in the low 70s, and urban areas in the mid
70s. Brief, patchy fog is possible in the eastern river valleys in
the pre-dawn hours.

Through today, ridging and high pressure will weaken some and shift
southeastward as flow aloft becomes more zonal. Skies will remain
mostly clear through the mid-morning, before diurnal Cu begins to
develop in the afternoon. With scattered skies and southwesterly
winds, the region will warm efficiently. 1000-850mb thickness are
around 1430-1440m, suggesting low-mid 90s. Expecting to see high
temperatures about a degree or two warmer than Friday, with rural
areas in the low-mid 90s and urban areas in the mid 90s. Heat
indices will be in the mid-upper 90s.

Towards the end of the day, troughing will strengthen over the upper
Midwest and allow the associated low pressure system to deepen. This
system will increase pressure gradients over the Ohio Valley
bringing light to breezy winds in the late afternoon. This low
pressure system will propagate eastward over the Great Lakes region
through the overnight hours. Showers and storms initially along the
cold front will begin to outpace the best forcing along the front
and dissipate as they reach the region early Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 306 AM EDT Sat Jun 22 2024

A decaying line of showers and storms will likely be pushing into
the region Sunday morning ahead of a frontal boundary. The
shower/storm activity should dissipate by the time it slides into
central Kentucky, but residual mesoscale boundaries from the morning
activity as well as the eventual arrival of the frontal boundary
itself will serve as additional focus areas for convective
development in the afternoon. Deep layer shear is fairly marginal
(<30kts), but depending on how low/mid level lapse rates recover in
the wake of the morning activity, we could see enough instability to
help fuel some isolated stronger storms. Gusty winds would be the
most likely threat with any strong or severe storm as DCAPEs could
exceed 1,000 J/KG should mid-level clouds clear out in time.

While drier air (and lower Td`s) will filter in behind the front
Sunday night, post-frontal conditions early next week don`t look to
give us much, if any, relief from the heat as the bulk of the
`cooler` air resides well off to our north. High temps by Tuesday
could be back into the mid/upper 90s for many locations, and peak
heat indices west of the I-65 corridor could exceed 100 degrees.

Another frontal boundary will take aim at the region late Tuesday
into Wednesday and bring another round of much needed showers/storms
with it. In the wake of the front, temperatures will `fall` closer
to (but still slightly above) climo normals for this time of year.

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 114 PM EDT Sat Jun 22 2024

All TAF sites should continue to expect VFR flight categories
through the forecast periods. Current visible satellite shows
scattered mid-level Cu developing over the region with just some
isolated showers forming around RGA along the I-75 corridor this
afternoon. This activity has been extremely isolated and ends as
quickly as it forms. Other than that, the Cu field will start to
clear out after sunset due to the loss of daytime heating. Should
remain fairly quiet overnight but an approaching system working into
the Great Lakes tonight and its associated cold front will increase
the chance of a few showers and isolated storms towards tomorrow
morning into the afternoon. This will also bring increased clouds
with lowering CIG to around 5K ft. Most of the showers/storms will be
out ahead of the approaching cold front and any storms that form to
our northwest tonight will weaken and breakup as it approaches the
Ohio River by daybreak tomorrow with a flair up of activity possible
near the end of the forecast as the boundary works across the area
during the day. Winds will remain out of the southwest today into
tonight and start to increase to around 10kt tomorrow morning.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Air Quality Alert until midnight EDT tonight for KYZ029>031.
IN...Air Quality Alert until midnight EDT tonight for INZ091-092.

&&

$$

UPDATE...BTN
SHORT TERM...SRM
LONG TERM...DM
AVIATION...BTN