366 
FXUS63 KLMK 241503
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1103 AM EDT Tue Aug 24 2021

.Forecast Update...
Issued at 1055 AM EDT Tue Aug 24 2021

Rinse and repeat forecast today with persistent sfc and upper 
ridging. Currently looking at oppressive dewpoints in the lower/mid 
70s with the late morning spike, but continued boundary-layer growth 
will mix those down to around 70 this afternoon. Max temps in the 
lower/mid 90s for most, while upper 90s in the Louisville heat 
island will likely result in a better mixdown with dewpoints into 
the upper 60s. The end result will be heat indices just either side 
of 100 for most, but approaching 105 under the strongest influences 
of the heat island, or in southern Indiana, strong 
evapotranspiration in cornfields. 

Will continue to highlight the heat via Special Weather Statements 
as almost the entire area will stay out of Heat Advisory territory.

&&

.Short Term...(Today and tonight)
Issued at 300 AM EDT Tue Aug 24 2021

Surface high pressure continues to keep winds light over our portion 
of the Ohio Valley. Ridge aloft also will reinforce dry conditions 
as well as heat. We are starting the early morning with some upper 
clouds as a weak wave moves within that ridge aloft. Those clouds 
are showing signs of thinning out though, and by this afternoon 
expect similar lower-level scattered cloud development to what 
Monday brought. Will be watching through daybreak for patches of fog 
to form. Eastern KY valleys already have good coverage, per latest 
satellite data, but the clouds here have slowed development down.

Expect highs today to be equal to if not a little warmer than 
Monday. NBM 10-90th percentile range for SDF today is from 93 to 98, 
with the median at 96. Given Monday's 97, will lean towards the 
upper end of that spread. Heat indices likely will top out around 
100 for most locations east of a line from Shelbyville to 
Tompkinsville in KY, whereas points west will see 100-105. Tonight 
under more clear skies, will watch again for patches of fog, but the 
persistence of drying soils slowly should erode the chances for fog 
development until we reach our next cool down.

On this date in weather history, back in 1992, category 5 Hurricane 
Andrew made landfall just south of Miami, FL.

.Long Term...(Wednesday night through Monday)
Issued at 314 AM EDT Tue Aug 24 2021

On Wednesday, the long term begins with more of the same. Upper high 
pressure remains centered over Oklahoma and extends towards the 
northeast over the Lower Ohio Valley. The main flow of the jet 
stream will continue to cut from northern California northeast 
towards eastern Canada, remaining well north of our area. At the 
surface, high pressure is expected to be centered over Ohio. This 
should keep skies over the CWA mostly clear, winds light, and 
temperatures high. Highs are expected to climb into the 90s in the 
CWA. Those west of Interstate 65 will likely see the mid 90s, 
farther east the low 90s, and Louisville, the area sauna, will 
likely be knocking on the door to 100. Dew points in the low 70s 
will push heat indices over 100, possibly in the 102-104 range along 
and west of Interstate-65. 

On Thursday, a surging upper trough will help to push the high, over 
Oklahoma, east towards an Atlantic high parked off the coast of 
North Carolina. At the same time, a surface high will strengthen 
over South Carolina as it drifts to the northwest. This will begin 
to act as a east to west moving warm front pulling in deeper 
moisture over the CWA increasing precipitation chances. No shear and 
modest summer CAPE values are expected to keep things garden 
variety. Precipitable water values are just under 2", so heavy 
rainfall and lightning will likely be the greatest hazards. 

To start the weekend with high pressure and upper riding overhead, 
mostly dry conditions are expected. Temperatures will remain hot in 
the upper 80s to mid 90s through Sunday.

&&

.Aviation...(12Z TAF Issuance)
Issued at 615 AM EDT Tue Aug 24 2021

High pressure at the surface and aloft will continue to keep our 
weather dry with fairly light winds this TAF period. High clouds 
earlier this morning have thinned out, and so far HNB and BWG have 
gone to MVFR. As we get into the late morning and early afternoon, 
expect a cloud field to develop in the 5-6 kft range and then skies 
should clear out again this evening. Best potential for early 
Wednesday morning reduced vsby looks to be at BWG.


&&

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

$$

Update...RAS
Short Term...RJS
Long Term...KDW
Aviation...RJS