textproduct: Louisville

KEY MESSAGES

* Patchy fog is likely this morning, with some pockets of dense fog possible.

* Isolated to scattered slow moving showers and storms (20-40% coverage) are possible east of I-65 on Wednesday, and across most of the area Thursday. Most locations will remain dry.

* Better shower and storm chances, along with summer warmth and humidity, will return later this week, peaking at 40-60% Friday into Saturday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 305 AM EDT Wed Aug 5 2026

This Morning through Tonight...

Across the area this morning, greater low-level moisture is starting to creep to the north and west as a cut-off low lifts slowly out of the southern Appalachians. This moisture return has allowed higher sfc dewpoints and more cloud cover to move back into the area, with scattered 5k ft stratus showing up on nighttime microphysics satellite imagery. A few showers have even developed over eastern KY; however, most hi-res guidance suggests this should dissipate over the next few hours. Between now and sunrise, patchy fog will try to develop if we can get enough breaks in the stratus deck. There is a roughly 20% chance of sub 1 mile visibilities along and east of a Glasgow-Winchester line per the 00Z HREF, with the greatest chances for fog in the sheltered river valleys.

Today, our area will be sandwiched between approaching broad troughing from the NW and the aforementioned cutoff low to the SE. In between these features, mid-level ridging is expected to extend from western KY into southwest IN. The combination of higher sfc dewpoints and cooler mid-level temperatures along and east of I-65 should support a gradient in instability across the area, with around 1500-2000 J/kg MLCAPE expected to extend from Lake Cumberland up into the Bluegrass this afternoon. It is in these areas where there will be better chances for pop-up showers and storms, with weak forcing aloft probably limiting coverage to isolated or widely scattered at best. Deep-layer shear around 10 knots should result in slow-moving garden-variety showers and storms, and severe weather is not expected. High temperatures this afternoon should be fairly seasonable for early August, generally ranging from 86-91 across the area.

Tonight, any lingering convection should subside soon after sunset, though additional showers and storms will be ongoing overnight to the west of the area. This activity is not expected to make it into the area as ridging aloft should hold firm. Another mostly dry and mild night is expected tonight, with patchy fog again being possible before sunrise Thursday morning.

Thursday and Thursday Night...

Another seasonably hot and humid day is expected on Thursday with isolated to widely scattered showers and storms (20-30% coverage) expected to develop in the afternoon hours. Once again, much of central KY and southern IN will be in between two features which would support greater coverage of storms: better forcing from a mid- level shortwave across IL/IN and a pool of greater low-level moisture across eastern KY. Additionally, any lingering convective debris clouds from upstream convection could also limit destabilization Thursday afternoon. Recent guidance depicts a broader pool of 1000-2000 J/kg MLCAPE Thursday afternoon, which should be sufficient for some convective activity. Where (if) storms develop, there will be somewhat stronger flow aloft along/north of the Ohio River, resulting in 15-20 kt of deep-layer shear. Still, the instability-shear parameter space supports typical summertime storms Thursday afternoon and evening.

Mid-level shortwaves/vort lobes will continue to move across the mid- Mississippi Valley Thursday night into Friday morning, initiating additional waves of showers and storms. These waves of showers and storms may make it into our northern/western counties overnight Thursday into Friday morning; however, confidence in this solution is still fairly low.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 305 AM EDT Wed Aug 5 2026

Friday and Saturday...

By the end of the week, baggy mid- and upper-level troughing will be in place over much of the Midwest, with ridging placed on either end of the trough across the intermountain West and the western North Atlantic. This will allow a sfc cold front to sink toward the region by Friday; however, the lack of amplification of the upper trough will likely keep the front from making its way through the Ohio Valley. Nevertheless, ahead of this boundary, ensemble mean PWATs around 1.8" (~75th percentile of climatology) should keep a moist and unstable environment in place across the region. A more focused chance for showers and storms is favored to arise as one or two mid- level shortwaves/vort lobes rounds the base of the trough Friday into Saturday. Timing will be important to the better chances for rain, as passage during peak heating would maximize shower/storm chances either day. Given somewhat better forcing, a strong storm or two can't be completely ruled out during this period, and there is a modest signal in NCAR AI Severe Convection Guidance Friday into Saturday. Temperatures should trend fairly steady over this period, with highs in the upper 80s to around 90 and lows in the upper 60s and low 70s.

Sunday through Early Next Week...

A brief decrease in precipitation chances is expected for the second half of the weekend as the upper ridge over the western CONUS broadens out. Height rises and slightly lower PWATs on Sunday should suppress convective coverage, with temperatures remaining seasonably hot in the upper 80s and low 90s.

As we head into early-to-mid next week, a gradual retreat in the positive height anomalies is expected as persistent troughing over Hudson Bay digs back to the southwest. How quickly this occurs is still uncertain, but it will bring better shower/storm chances and a slight fall in temperatures to the area when it does happen. At this time, the upper ridge is likely to continue to dominate on Monday, with it potentially being the warmest day of the upcoming period with widespread low 90s for highs. As we head into Tuesday and the middle of next week, the pattern should become more unsettled, with increasing chances for (at least) afternoon and evening showers and storms.

AVIATION /18Z TAFS THROUGH 00Z FRIDAY/

Issued at 148 PM EDT Wed Aug 5 2026

Showers and thunderstorms have begun to develop east of I-65 this afternoon and could impact LEX and RGA through the early evening hours. Any thunderstorms that do occur could briefly reduce visibility due to heavy downpours. Chances for showers and storms will quickly decrease by sunset, with VFR conditions prevailing across the terminals through the remainder of the TAF period. Patchy fog may develop tonight, primarily near BWG, though any reduction in visibilities should remain above VFR levels.

LMK WATCHES/WARNINGS/ADVISORIES

KY...None. IN...None.