textproduct: Louisville

KEY MESSAGES

* Isolated/Scattered showers and storms are possible this afternoon and evening. A few strong storms can't be ruled out with gusty winds, intense lightning, and torrential rainfall.

* Seasonable temperatures (mid-upper 80s) and daily chances (20-40%) for afternoon-evening thunderstorms are forecast throughout the upcoming work week. The risk for severe weather appears low through at least Wednesday.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 306 PM EDT Sun Jul 5 2026

Afternoon satellite imagery shows mostly sunny skies across much of the region. The exception would be over far southern KY where some higher convective cloud top debris has spread northward. Temperatures at mid-afternoon were in the middle 80s across the region. We'll likely see temps top out in the 84-88 degree range this afternoon before temps settle back into the upper 70s this evening.

Radar has been rather quiet this afternoon. However, we expect isolated to scattered storms to develop in the next few hours as we hit convective temps, which are around 87 to 88 degrees. Initially, best chances of precipitation will be across our far northern row of Indiana counties, where a small area of surface convergence was located. A band of light to moderate showers has developed just north of the CWA. If current convective trends continue, the showers will move into portions of Scott/Jefferson counties in Indiana in the next few hours. Additional isolated/scattered convection may develop across the remainder of the region later this afternoon. Latest suite of CAMs wants to further develop convection over central TN and push it north. Convective cloud debris spreading northward into southern KY may limit additional heating in the Lake Cumberland region. It is possible that the more favored convective region may end up once again in the I-165 corridor if the HRRR is correct. is considerably less than it has been in the last few days. Model soundings still show skinny CAPE profiles with weak shear and PWATS up around 1.8-1.9 inches. Still think main threats would be gusty winds, intense CG lightning and torrential rainfall with any storms that develop.

Convection should decrease in the mid-late evening with the loss of heating. A few showers may persist into the late night hours. Combination of clearing skies, light winds, and ample moisture may result in fog formation in the low-lying and typical fog prone areas. Lows will cool into the upper 60s and lower 70s.

For Monday, upper trough axis will hang over the Ohio Valley during the period with a weak frontal boundary dropping southward into the region. A rather stagnant, but moist airmass will remain across the region. Model soundings for Monday afternoon continue to exhibit skinny CAPE profiles with weak vertical wind shear. Typical summertime pulse-driven convection looks to be the convective mode of the day with a 30-40% coverage area. Highs on the day will be a little cooler with highs in the 83-88 degree range with Monday night lows dropping into the upper 60s/lower 70s.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 306 PM EDT Sun Jul 5 2026

At the beginning of the forecast period (Tuesday morning), a positively tilted trough will stretch from the Lower Mississippi River Valley to New England, fostering weak cyclonic flow over the local area. This, combined with modest (1000-2000 J/kg SBCAPE) diurnally driven instability, should be sufficient to support a couple scattered (20-40% coverage) afternoon-evening showers and storms. Deep layer wind shear should be weak (REFS ensemble max is 15-20 kt), suggesting the probability of severe/sustained storms is low, but with the EPS ensemble mean maintaining PWATs of 1.7-1.9 inches and forecast soundings depicting a deep (~12kft) warm cloud layer, any showers and storms will prove efficient rain-producers. Both the NAMNest and RRFS advertise very localized pockets of hourly rainfall over 1.5 inches beneath the heaviest cells, which is approaching Flash Flood Guidance (FFG) - the threshold around which we become concerned about hydrological problems. Outside of storms, it'll be a seasonably warm and humid day with high temperatures in the mid 80s and dewpoints in the low 70s.

Global models don't agree on precisely when that trough will shift off to the east, but forecast experience would make one lean towards a later departure, which suggests Wednesday will be virtually a repeat of Tuesday - seasonably warm and humid with pop-up (20-40% coverage) afternoon-evening storms that could dump very localized heavy rainfall but pose little risk for severe weather. Eventually, the GFS, ECMWF, and CMC agree that a more pronounced feature will pass through the Midwest/Lower Great Lakes Regions, potentially serving as a focus for organized convection, though they disagree on details such as precise track, strength, and especially timing. At this point, the best overlap between shear and instability among the long-range ensembles is Thursday night into Friday, when the Low Resolution Ensemble Forecast (LREF) system gives a 20-35% joint probability for 0-6km wind shear > 25 kt and MUCAPE > 1000 J/kg; this corresponds to our highest (60-80%) probabilities of precipitation (PoPs) in the 7-day forecast.

Thereafter, empirical orthogonal functions (EOFs) of 500mb heights suggest uncertainty increases in the synoptic pattern, with a dipole in EOF1 suggesting this is driven mainly by position uncertainty in ridging over the Intermountain West/Great Plains and troughing over the Northeast/Great Lakes. "How does this influence our local weather?", one may ask. A more expansive upper level trough over the Northeast/Great Lakes (40% chance) would result in less warm and humid conditions, along with continued diurnally driven showers and thunderstorms; meanwhile, a ridge that builds further east into the Ohio Valley (60% chance) would favor increasingly warm and muggy conditions with low daily rain chances by next Sunday (7/12).

AVIATION /12Z TAFS THROUGH 18Z MONDAY/

Issued at 1258 PM EDT Sun Jul 5 2026

VFR conditions are expected across the region this afternoon. Isolated/scattered showers/storms will be possible this afternoon between roughly 05/20-06/02Z. For now, have enough confidence to add a PROB30 at BWG and HNB for now. The storms will dissipate with the loss of heating and we'll see light/variable winds. A weak cold front will drop into the region from the north. May see some patchy fog and low clouds affect KHNB after midnight tonight.

LMK WATCHES/WARNINGS/ADVISORIES

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