LMK issues Area Forecast Discussion (AFD) at Aug 19, 1:41 AM EDT ...Updated Aviation Discussion...947
FXUS63 KLMK 190541
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
141 AM EDT Tue Aug 19 2025
...Updated Aviation Discussion...
.KEY MESSAGES...
* Tomorrow, Heat index values of 100-105 are likely, mainly west of
the I-65.
* A cold front will likely bring a little relief from the heat and
increased thunderstorm chances Tuesday and Wednesday.
* Below normal temperatures expected for the second half of the
weekend into next week.
&&
.UPDATE...
Issued at 916 PM EDT Mon Aug 18 2025
Temperatures continue to fall across the area after sunset, ranging
from the upper 70s to the mid 80s as of 01Z. There is a notable
dewpoint gradient from northeast to southwest thanks to drier air
filtering in from high pressure over Quebec today. With lower
dewpoints, mostly clear skies, and light winds, temperatures should
be able to cool fairly efficiently overnight, with lows expected to
range from the mid 60s to the low 70s. Patchy fog still looks
possible in sheltered valleys and near bodies of water, particularly
across southern and western portions of the CWA.
We'll have to watch ongoing convection over northern IL and
northwest IN. Some hi-res guidance tries to bring decaying
convection associated with this activity into our southern IN
counties around daybreak Tuesday. Have nudged PoPs up slightly
tomorrow morning, but still keeping a silent (<15%) value in there
for now.
Otherwise, the forecast is on track at this time. Updated products
will be sent shortly.
&&
.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 431 PM EDT Mon Aug 18 2025
Tonight, upper ridging remains centered over much of the CONUS.
At the surface, high pressure extending southwest out of Quebec will
continue pushing through the Lower Ohio Valley, keeping weather
quiet. Any remaining diurnal cumulus will dissipate early in the
night, leaving clear skies. Already light and variable winds ease
and become nearly calm. Radiative cooling will help temperatures
fall into the mid 60s to low 70s. This could result in some light
fog as temperatures near the dew point, mainly along the eastern CWA
border in the Bluegrass and Lake Cumberland regions.
Tomorrow, the day begins under mostly clear skies, but a cold front
approaching from the northwest will increase rain chances over
southern Indiana during the afternoon hours. Even if showers and
thunderstorms hold off until later in the afternoon, increased cloud
cover is expected along the boundary.
With highs expected to climb back into the low to mid 90s and dew
points in the upper 60s to mid 70s east of Interstate 65 and into
the low 70s to upper 70s west of 65, heat index values once again
cross 100 degrees, mainly west of Interstate 65. Currently, have the
highest isolated values of 105 in the forecast across southern
Indiana from Dubois to Clark Counties. This doesn't paint a pretty
picture with what neighboring offices have out in current Heat
Advisories, plus any cloud cover or rain could limit warming in this
area. This is mainly being driven by the higher dew points from the
pooling of moisture with the incoming front. Farther south in
Kentucky, dew points are to be a little lower, reducing the heat
index values. Either way, it's going to be another warm day.
&&
.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 431 PM EDT Mon Aug 18 2025
Tuesday night, as the cold front continues to approach from the
northwest, several CAMs show better chances for scattered convection
to develop over southern Indiana before slowly working southeast
across central Kentucky. Early in the night, remaining instability
could help to get additional gusts to the surface, but the lack of
deep layer shear will help limit storm organization. As diurnal
warming is lost, gusts will become less likely as lapse rates become
more stable.
Wednesday, shower and thunderstorms chances remain as the front
slowly drops southeast through Kentucky. Guidance keeps better
chances over the southeastern CWA along a main axis of
precipitation, most areas are expected to see a mostly dry day with
afternoon and evening heating driving additional chances. The front
will bring slightly cooler temperatures with highs only making it to
near 90 for most through Saturday. Nightly lows will also see cooler
temperatures where 60s become more common than 70s across southern
Indiana and central Kentucky.
By Thursday, as a surface high gets pushed south towards the CWA,
the chances for precipitation decrease through Saturday before a
second cold front drops south through the CWA Saturday night. This
currently looks mostly dry, but noticeable cooling is expected. Highs
on Sunday and Monday are expected to only reach into the 80s with
dew points in the 50s.
&&
.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 140 AM EDT Tue Aug 19 2025
VFR expected through this most of this forecast cycle, however a few
showers and storms could develop by late afternoon, and especially
later this evening. Until then, expect mostly clear skies and light
and variable winds. Any notable wind should be out of the ESE to SE
early this morning, gradually veering to S-SW by late morning, and
then W by mid afternoon. A few high-based cumulus (6-7 thousand
feet) will likely develop through mid to late afternoon, along with
a few isolated to widely scattered showers and storms across the
northern TAF sites through the evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...CSG
SHORT TERM...KDW
LONG TERM...KDW
AVIATION...BJS
Source:
LMK issues Area Forecast Discussion (AFD) at Aug 19, 1:41 AM EDT ...Updated Aviation Discussion...---------------
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