861 
FXUS63 KLMK 012324
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
724 PM EDT Thu Aug 1 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Thunderstorm chances continue Friday into Saturday. Torrential 
    rainfall could result in localized flash flooding, especially 
    where the ground is already saturated. Gusty winds also possible 
    in the stronger storms. 

*   Dry weather Sunday into early next week, but hot temperatures 
    will return, pushing the heat index near 100 at times.

&&

.UPDATE...
Issued at 529 PM EDT Thu Aug 1 2024

Dropped the Heat Advisory for a handful of counties where 
thunderstorms have dropped temperatures 20 degrees. Thanks to PAH 
for coord.

Would like to hold on to the SVA a little longer and monitor trends 
before dropping counties. Yesterday afternoon widespread storms 
moved through the region, but SPS-level storms still managed to 
redevelop behind the storms mid-evening. Today we still have a few 
hours of sunshine left, and there has been some redevelopment, 
albeit relatively weak, between EVV and PAH. While we will still 
probably drop western counties from the SVA early, don't want to 
jump the gun.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 319 PM EDT Thu Aug 1 2024

The same overall pattern remains with upper ridging over the western 
US. Northwest flow continues to bring round after round of 
convection through southern Indiana and central Kentucky. 

We began the afternoon by issuing a Heat Advisory from a line from 
Perry County, Indiana to Monroe County, Kentucky and to the 
southwest for heat indices near 105 degrees. Based on observations, 
we could have added Dubois County as well, but approaching showers 
will cool them within the next hour. 

For the rest of the day, eyes will be on convection that has just 
entered southwest Indiana. While the storm developed over southern 
Illinois, it exploded, producing lots of lightning and severe winds 
over 50 knots, but now the overall strength of the storm has 
weakened as outflow has jumped ahead of all but the southern part of 
the line. As the system moves eastward along a MLCAPE gradient of 2-
3,000 J/kg, the system is expected to increase in size, and with 
DCAPE values around 1,000 to 1,100 J/kg gusty winds will be the 
primary concern along with lightning. Deep layer shear remains weak, 
but with storm to storm and outflow interaction, localized areas of 
enhancement will be possible. 

Flash flooding is also of concern as we head through the afternoon 
and evening hours. Precipitable water values are currently around 2" 
around current convection with 1.8-1.9" values over the CWA. These 
are close to the same values that have been over the CWA for the 
last few days, and with warm temperatures in place, most areas have 
been able to handle most of the rainfall as long as there are some 
breaks in the heavy rainfall. There could be so isolated issues if 
any heavy rainers sit stationary, but believe the expected 
progressive nature of the convection will limit widespread flooding 
issues. 

Tonight and tomorrow, as a closed upper low rides in on the 
northwest flow from the Midwest towards the Lower Ohio Valley, 
isolated to scattered showers remain possible. During the overnight, 
the added low level moisture could lead to patchy fogging and/or low 
stratus while other areas see more clearing. Low temperatures 
tonight are expected to drop into the low to mid 70s before mid to 
upper 80s return tomorrow.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 319 PM EDT Thu Aug 1 2024

Showers and storms should start winding down in coverage Friday 
night with the loss of daytime heating and no appreciable 
lifting/forcing mechanism in place. Isolated to scattered activity 
could linger into the morning hours, and then increase in coverage 
some during the afternoon Saturday, but drier, more stable air 
working in behind an upper level trough should steadily end the rain 
threat from west to east. 

Dry weather should continue Sunday into early next week as warmer 
850-700mb temps cap convective development. Temps will be on the 
warmer side of climo due to the lack of more widespread clouds and 
convective development (likely climbing into the low 90s), and 
dewpoints in the upper 60s to low 70s will certainly make it feel 
muggy. At this point, though, it appears we'll stay short of heat 
advisory criteria, with most spots hitting 95-100 degree peak heat 
indices through next week. 

Rain chances may begin to creep up by midweek depending on how the 
upper level flow evolves. Most models keep us on the southern 
fringes of the more active flow aloft, which in theory would result 
in most convective waves/MCSs passing just to our north. Current 
forecast carries small PoP chances to account for these waves as 
well as any potential diurnal pulse-convection that may develop on 
mesoscale boundaries.

&&

.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 723 PM EDT Thu Aug 1 2024

Earlier storms will have moved off to the east by the start of the 
TAF period other than a few lingering rumbles of thunder at RGA and 
possibly LEX/BWG. For the remainder of the night, skies should be 
partly cloudy with light winds. Can't rule out widely scattered 
thunderstorms overnight once again in the humid air mass, though low 
confidence restricted TAF mention to PROB30. Could see some light BR 
at HNB/RGA around dawn.

Another day of scattered storms is expected tomorrow, so went with 
PROB30 for the afternoon hours.

&&

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

&&

$$

UPDATE...13
SHORT TERM...KDW
LONG TERM...DM
AVIATION...13