textproduct: Louisville

KEY MESSAGES

* Dry through tomorrow, except a low (20-30%) chance for an afternoon or evening storm mainly over southern Kentucky. Daily storm chances begin to increase on Thursday.

* Rain and thunderstorm chances peak Friday into Saturday, especially during the afternoon and evening hours. Slow-moving storms will be capable of locally torrential rainfall, lightning, and gusty winds.

* Outside of storms, heat indices will peak in the 97-103 degree range each afternoon through at least Friday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 315 PM EDT Tue Jul 14 2026

Tuesday afternoon, between a ridge of high pressure over the Midwest/Great Lakes and a cutoff low across the Deep South, easterly flow was in place across central Kentucky and southern Indiana. The northern extent of deep layer moisture was evident in the more extensive cu field across southern Kentucky where RAP mesoanalysis revealed 1500-2500 J/kg SBCAPE. Fortunately, effective bulk shear in these areas was only 20-25 kt, with the higher shear values displaced to the north. Even so, the steep low level lapse rates and increasingly dry mid levels across the area are resulting in DCAPE values of 900-1300 J/kg (highest in western KY), which would support gusty outflow winds with any thunderstorm that manages to fire this afternoon and evening. Fortunately, the probability of storms over our area is low; HREF neighborhood probabilities for >40 dBZ peak around 20-40% between 5 and 11 pm EDT this evening across areas south of an Everett to Burkesville line.

Tomorrow looks like a similar set up, though with the ridge sinking south over the Ohio Valley subsidence should limit storm coverage even more compared to today. Still, around a 10-20% chance for a pop-up storm will exist area-wide during the afternoon and evening when strong surface heating may result in convective temperatures (around 88-91 degF) being reached.

Shower and storm chances will increase slightly on Thursday as ridging weakens and remnant energy from the aforementioned low begins to move back towards our area from the southwest. The Rapid Ensemble Forecast System (REFS) mean brings PWATs up to around 2 inches across the area Thursday afternoon, while keeping 0-6km bulk shear generally under 15 kts. This suggests that any storms that develop will be both efficient rain-producers and slow-movers, capable of dropping locally heavy rainfall - though storm coverage will still be relatively low at around 25-40%.

Outside of any afternoon and evening storms, it'll be seasonably warm and increasingly humid the next couple days with afternoon highs in the upper 80s to low 90s and overnight lows in the low to mid 70s. Daily heat indices will peak in the upper 90s to around 103, resulting in minor to moderate heat risk - suggesting an increased chance of heat related illness among vulnerable populations.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 315 PM EDT Tue Jul 14 2026

===== Friday - Saturday =====

A gradual weakening of the upper level ridge begins Friday and continues into next week. A weak, mid-level shortwave disturbance is forecast to drift over the Lower OH Valley Friday into Friday night. Meanwhile, the first in a series of stronger shortwave troughs will drop southeast over Canada before rotating across the Great Lakes this weekend.

We'll have a very warm, moist airmass and weak low-level SW flow in place ahead of the mid-level impulse. LREF mean PW values are forecast to approach 2 inches Friday and Saturday, above the climatological 90th percentile. Forecast soundings show plenty of diurnal instability and weak flow through the column. Scattered to numerous showers and storms are likely Friday afternoon and evening, with coverage diminishing overnight. Slow-moving, pulse convection will pose a threat for torrential rainfall, lightning, and microbursts. Excessive rainfall could lead to localized flooding. Highs on Friday should reach the upper 80s to near 90 in most places.

We'll have a very similar environment in place on Saturday. A somewhat stronger wave will be rotating southeast across the Great Lakes by this time, dragging a cold front south through the Upper Midwest and Great Lakes. A round of scattered, pulse convection appears likely Saturday afternoon and evening. Outside of these showers and storms, temperatures are forecast to rise through the mid/upper 80s during the afternoon hours.

===== Sunday - Tuesday =====

A weak cold front appears likely to drop south into our region by Sunday. This should be enough forcing interacting with the warm, humid airmass for at least isolated to scattered showers and storms.

Increasing model spread lowers forecast confidence in the details heading into next week. However, the general pattern will likely continue to feature NW flow aloft and a deepening upper level trough over the eastern US and Canada. A deepening low pressure system will track east across Ontario Monday into Tuesday, and this system should drag a somewhat stronger cold front into the Ohio Valley. This will bring us one more chance for showers and thunderstorms Monday into Tuesday, before drier air filters in from the northwest through the middle of next week.

AVIATION /00Z TAFS THROUGH 06Z THURSDAY/

Issued at 750 PM EDT Tue Jul 14 2026

High pressure moving into the region will help to keep skies clear and ease winds through the period, but it could help lead to fogging tonight. Signals are mixed, but chances look better towards the east, affecting LEX and RGA. The other sites are expected to remain VFR.

LMK WATCHES/WARNINGS/ADVISORIES

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