textproduct: Louisville

KEY MESSAGES

* A cold front pushing into the area from the north tonight will bring numerous showers and thunderstorms. A few strong to severe storms will be possible, especially west of I-65. Damaging winds and localized flash flooding are the main threats with storms.

* Low chances for showers and storms (<20%) linger for Friday- Saturday with warm temperatures in the low to mid 80s.

* After a brief cooldown this weekend, low chances for showers stick around through midweek next week.

SHORT TERM /THROUGH FRIDAY/

Issued at 301 AM EDT Thu Aug 20 2026

Through Daybreak Thursday...

Looking across the region this morning, there are multiple clusters of showers and thunderstorms approaching southern Indiana and south central Kentucky. Two clusters of storms are currently in western Kentucky, with the northern cluster moving eastward and currently moving over Ohio County. This cluster has been sub- severe so far, producing a 36 mph gust in Crittenden County earlier in the night. The southern cluster has produced > 80 mph winds, as well as a radar-confirmed tornado. This cluster is moving more in an ESE direction along the KY/TN border, currently moving over Logan County. A third cluster/line of severe-warned storms has also developed in west-central Indiana, moving southeastward towards southern Indiana and entering the far northern CWA in the next 1-2 hours.

Per the latest SPC mesoanalysis, surface-based instability is rather meager over southern Indiana and central Kentucky (<300 J/kg), with drier low-level moisture and a stable surface layer in place. The main features that are driving these storms is increased elevated instability (500-1000 J/kg MUCAPE), as well as a 30-40 kt low-level jet over SW Kentucky, SE Missouri, and W Tennessee, and a mid-level jet maxima (40-50 kt). The placement of these jet features has resulted in 35-45 kt of effective bulk shear over western Kentucky and southwestern Indiana, along with 200-300 m2/s2 of ESRH over western Kentucky. With that said, the most recent guidance continues to suggest that the environment will become less favorable as it moves over central Kentucky and southern Indiana through the remainder of the overnight. The main thing to look out for will be the backbuilding of showers and storms over south central Kentucky as a result of the enhanced LLJ. This could pose a localized flooding concern for places south of I-64, where a Flood Watch is currently out until 8 AM EDT. From the latest HREF 6 hour LPMM, swaths of 2-3+" rainfall totals are still outlined for areas west of I-65 and south of I-64, with 1-2" swaths to the east as the system slowly weakens. Overall, the concern for strong to severe storms (damaging winds is primary threat) remains in our far western CWA, where a Severe Thunderstorm Watch is out for Logan, Simpson, Warren, Butler, and Allen counties until 7 AM EDT. The line of storms in Indiana could produce some gusty winds, but with weaker winds shear and instability, the severe potential is on the lower end.

Daybreak Thursday through Thursday Night...

The clusters of showers and thunderstorms will be in our far eastern CWA in east central Kentucky by daybreak as a weak surface cold front moves in from the northwest. This features will slowly drift over the region on Thursday, departing to the south and east by Thursday evening. Chances for showers and thunderstorms will also decrease throughout the day, with only 35% or less POPs by midday. Elevated SBCAPE (1000-1500 J/kg) during the afternoon hours, especially along and south of the Ohio River, could help spark some isolated showers and storms across the area. Thankfully, wind shear will be reduced and will keep the potential for strong to severe storms to near zero. Afternoon highs across the region will be in the low to mid 80s, with overnight lows in the mid to upper 60s forecast. Once the cold front pushes through, surface high pressure and low-level dry air fills in over southern Indiana and central Kentucky, setting up a period of mostly dry conditions to end the workweek.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 301 AM EDT Thu Aug 20 2026

=====Friday - Midweek=====

The weak cold frontal boundary moving through the area should slowly clear our SE communities though remain close enough for increased cloud cover Friday morning in the SE. Further towards the NW in southern IN and along the Ohio River, clearing skies may allow for fog formation as dew points will remain elevated in the upper 60s at least. Further towards the south, there may be enough remnant moisture for some morning-daytime showers and perhaps a rumble of thunder. PoPs remain low for these areas as there still remains uncertainty on if an impulse of activity along the Appalachians can form to create more shower coverage for KY. Otherwise, temperatures remain warm low to mid 80s with light southerly winds.

For the weekend, the synoptic scale flow features a deep digging trough over the eastern CONUS, further supported by strong ridging upstream over the mountain west of CONUS. With a high at the surface, conditions should at least initially be dry Saturday. Depending on a shortwave expected to move into the eastern US, spotty to scattered convection may return in the afternoon. However, there is a growing trend to keep the trough axis too far east to feature any really impactful storms in our CWA. For now, low afternoon PoPs will remain Saturday night into Sunday.

Once the shortwave passes, slightly and much drier air should filter into the lower Ohio Valley for Sunday, making conditions feel much less muggy. Sunday should mostly be dry as well. Highs reach the mid to upper 80s Saturday to the low 80s Sunday. As for early next week, troughing over the eastern seaboard of the US seems to persist and we'll be in between that and a ridge to our west. Being on the periphery of continuous NW flow, any little disturbance traveling along this flow will continue to keep low PoPs in place. Highs are cooler to start, gradually warming as the week progress from the low 80s to upper 80s by Wednesday.

AVIATION /12Z TAFS THROUGH 18Z FRIDAY/

Issued at 736 AM EDT Thu Aug 20 2026

Over the next 1-2 hours, showers and thunderstorms will clear out of the area, with occasional VIS/CIG drops expected with any heavier showers. For the remainder of the morning and into the early afternoon, the main impact to flight categories should come from low stratus, with low MVFR ceilings gradually scattering out later today. As a cold front sinks from north to south, winds will veer from southwesterly this morning to the north by this evening before going light and variable tonight.

VFR conditions are expected for the afternoon and evening, with a low (10-20%) chance for a shower or storm. Tonight, lingering low- level moisture will lead to favorable conditions for fog, though confidence in the magnitude and coverage of fog is low at this time.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch until 7 AM CDT this morning for KYZ026-027-061>064- 070>078-081-082. IN...None.