987
FXUS63 KLMK 161052
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
652 AM EDT Sat Aug 16 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Hot and humid through early next week, with highs in the 90s. Heat
  index values of 105+ are possible Sunday through Tuesday.

* Isolated to scattered showers and thunderstorms will be possible
  late this evening into Sunday. This activity may bring brief heavy
  rainfall and relief from the heat.

* A cold front will likely bring relief from the heat, along with
  increasing thunderstorm chances, by the middle of next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 350 AM EDT Sat Aug 16 2025

Winds are calm, and skies are clear early this morning. Patchy
valley fog is noted on satellite imagery, and river valley fog is
expected to gradually expand through sunrise. More widespread dense
fog looks unlikely. Temperatures have dropped into the low to mid
70s and should at least drop another degree or two this morning.

Upper level ridging will continue to build eastward from the Plains
into the Midwest/MS Valley today. A strong mid-level ridge is
centered over Missouri and will remain in that vicinity through the
short term. A couple mid-level shortwave perturbations are rounding
the top of the ridge over the Upper Midwest and western Great Lakes.
These waves have helped initiate a couple rounds of convection
already, with the initial wave weakening over central IL early this
morning. However, we will stay warm and dry this morning with
upstream convection likely only making it as far southeast as
central IN. But we will need to keep a closer eye on upstream
convection as we move into tonight.

For today, southern IN and central KY will mainly be hot and dry.
Ridging at the surface and aloft will work to inhibit any vertical
growth. A rogue, isolated shower/storm or two could fire during the
heart of the afternoon, but coverage will be less than yesterday.

Temperatures will warm into the low to mid 90s under partly to
mostly sunny skies. We should start to see increasing high clouds
from upstream convection drift in from the north this afternoon and
evening. We`ll also have another round of SCT afternoon cumulus.
Afternoon heat index values will likely top out in the upper 90s to
low 100s. A handful of KY mesonet stations may briefly approach 105.

Additional convective development looks possible this afternoon and
evening across portions of central IN as subtle shortwave ripples
stream southeast over the mid-level ridge. By late this evening,
some of this activity may approach southeastern IN and northern KY
in a weakening state. Any convective clusters or lines will struggle
to make into the region due to increased inhibition, waning
instability, and weak deep-layer shear. However, the latest suite of
00Z CAMs does boost confidence a bit in scattered, weakening showers
and storms surviving into portions of southern IN and north-central
KY. Bumped rain/storm chances into the 20-30% range in the northern
forecast area, mainly after 00Z Sun. Otherwise, the majority of
tonight will be relatively dry and warm with lows in the low to mid
70s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 350 AM EDT Sat Aug 16 2025

Weakening convection from tonight will likely send one or more
outflow boundaries south through southern IN and portions of central
KY Sunday morning. This outflow may initiate new isolated to
scattered showers and storms across the area on Sunday, particularly
during the afternoon and evening hours. Think the NBM is
underselling the rain/storm chances a bit, so have bumped up PoPs
accordingly. The precip and associated cloud cover would certainly
slow down sfc warming, so the temperature forecast is a bit more
uncertain on Sunday. It`ll still be hot, but exactly how hot is
tricky. Sticking with highs mostly in the low to mid 90s. Heat index
values should still top out in the 95-105 range.

The heat will persist into early next week with strong mid-level
ridging lingering over the Mid-MS and Lower OH valleys. This period
looks relatively dry, with highs in the mid/upper 90s. Heat index
values of 100-105+ are likely, and a Heat Advisory may eventually be
needed for this time frame.

From Tuesday into Wednesday, mid and upper level ridging weakens
over our area and re-centers itself over the Four Corners. As the
ridge retreats, an upper level trough dropping southeast over the
Great Lakes will push a sfc cold front through the Ohio Valley. This
will bring some relief from the heat, as well as increasing
thunderstorm chances, around the midweek time frame (perhaps as
early as late Tuesday). Heading into late next week, highs in the
mid/upper 80s are more likely. Rain chances could linger into
Thursday, though the end of the week may end up dry if the cold
front makes a clean pass through the region.

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 651 AM EDT Sat Aug 16 2025

Other than some brief fog at HNB to start the period, VFR conditions
are expected. SCT thin cirrus will stream overhead from the
northwest today. A SCT afternoon cu field is expected after 16Z.
There is a very low chance for a few isolated shra/tsra this evening
into the overnight.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Air Quality Alert until midnight EDT tonight for KYZ029>031.
IN...Air Quality Alert until midnight EDT tonight for INZ077>079-
     090>092.

&&

$$

SHORT TERM...EBW
LONG TERM...EBW
AVIATION...EBW