textproduct: Louisville

KEY MESSAGES

* Scattered showers and thunderstorms will develop again this afternoon and evening. A few strong to severe storms will be possible, especially across southern KY. Damaging straight-line winds are the main severe threat.

* Isolated swaths of 2+" of rainfall this afternoon and evening may lead to flash flooding. Additional chances for heavy rain on Sunday may lead to additional flooding. The Flood Watch is now in effect for portions of central KY through Sunday afternoon.

* A cut-off low will keep daily storm chances around for Monday with less storm coverage Tuesday afternoon. Daily storm chances though continue the rest of the week with highs in the upper 80s.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 245 PM EDT Sat Jul 11 2026

This Afternoon through Tonight...

At this hour, 1015 mb sfc low pressure is centered just east of St. Louis with a quasi-stationary front extending to the east just south of the I-70 corridor across Indiana and Ohio. Aloft, a 500 mb trough is nearly vertically stacked over the sfc low and is gradually drifting to the southeast per latest mid-level WV imagery. To the east of this upper trough axis, the Ohio Valley sits within a belt of relatively strong mid- and upper-level westerlies, leading to approximately 25-30 kt of 0-6 km shear which should continue through this afternoon and evening. As far as instability is concerned, a gradient is noted in sfc dewpoints across the lower OH and upper TN valley, separating mid-to-upper 70s dewpoints across TN and southwest KY from low-to-mid 70s dewpoints across the rest of southern IN and KY. South of this gradient, approximately 2500-3000 J/kg of SBCAPE are present, with around 1500 J/kg to the north.

This afternoon, expect intervals of sunshine to allow temperatures to warm into the low-to-mid 80s across the area. This heating, combined with convergence ahead of the sfc front and sfc low as well as mid-level PVA should spark scattered showers and thunderstorms. Recent hi-res guidance suggests the potential for two main areas of convection: one parallel to the sfc stationary front sinking southward across southern IN/northern KY, and another which should develop closer to the sfc low/upper trough across southern IL that will ride the instability gradient to the southeast into southern KY and TN this evening. While strong storms with gusty winds will be possible across the area, the greater threat for damaging winds should be with the latter area referenced above. As mentioned in the previous paragraph, seasonably strong shear should support some organized multicell clusters, with any bowing segments leading to a locally enhanced wind potential. The main window for storms should be from 4 pm this afternoon until around 10 pm tonight, with activity tapering off after that.

While storms should be fairly progressive this afternoon and evening given faster flow aloft, training of storms will continue to support some flash flooding threat. 12Z HREF guidance shows several 6-hr localized probability-matched mean QPF swaths across the area in excess of 2", with ensemble maximum QPF values showing a few bullseyes exceeding 4". While the intensity of convection should diminish late this evening, there may still be a lingering flood threat as the sfc low spins into western KY. Convergence bands along the quasi-stationary front could keep showers developing through much of the overnight hours, though this is somewhat dependent on how worked over the environment is after this evening.

Otherwise, low-level moisture should settle into a low stratus and/or patchy fog layer early Sunday morning. Temperatures should bottom out in the upper 60s and low 70s.

Sunday and Sunday Night...

The aforementioned sfc low is expected to drift along the KY/TN border during the day on Sunday, with light NE flow spreading across much of the CWA. This will start to bring slightly drier air into the northern part of the area; however, HREF progs continue to feature 1.8"+ PW through the day on Sunday along and south of Ohio River. Ample low level cloud cover should cause a slow rise in temperatures Sunday morning, and highs tomorrow afternoon are only expected to reach the low 80s for most of the area.

Still, with ample low-level moisture present over the area, instability (on the order of 1500-2000 J/kg SBCAPE) should be sufficient for some scattered convection Sunday afternoon and evening. Wind shear will weaken tonight and remain weak through the day on Sunday, with less than 10 kt of 0-6 km shear expected. As a result, the severe storm potential is very low tomorrow, with garden- variety summer storms expected. Since the forcing mechanisms for storms should be less well-defined Sunday afternoon, expect coverage to be on the isolated to widely scattered side. However, a few slow moving storms will still support a localized flooding threat, especially across southern and eastern KY. Given the lingering flooding potential, and after collaborating with surrounding WFOs, the Flash Flood Watch will be extended through Sunday evening for much of central KY.

Rain chances should decrease quickly after sunset Sunday, with mainly dry conditions expected Sunday night into Monday morning.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 245 PM EDT Sat Jul 11 2026

***** Monday - Wednesday *****

By Monday morning, skies remain at least mostly cloudy as the cut- off low from this week is expected to meander slowly towards the south-southwest. Chances for storms bringing lightning and heavy downpours increase in the afternoon (60-70%) in communities south of the Ohio River. Persistent mid-level vorticity maxima and higher PWATs ranging 1.6-1.9" means that storms will refire with afternoon heating, keeping the flash flood risk around for one more afternoon of summertime convection. Average precip totals are rather light, but generally range 0.25-0.5" in a NE-SW oriented line from the Bluegrass region towards Bowling Green, KY. Everywhere else on average should see <0.25", with dry conditions expected north of the Ohio. Though considering the amount of moisture left in the atmosphere, storms could dump an inch or more in some communities, but for now, chances of anyone seeing more than an inch are low under 10%. Highs depend on storm coverage, but will be highest in the drier areas north of the Ohio in the mid 80s to low 80s across the southeast CWA.

By Tuesday morning, current trends indicate a high pressure will try to build in mid to low levels across the Upper Plains. A Rex blocking pattern will setup across the Central US as the cut-off low retrogrades towards the west and will even cause easterlies at mid- levels. This cut-off low will then move towards the lee of the Rockies and may even strengthen as it arrives in west Texas. For our area, how far south and east the high over the Upper Plains can increase subsidence over KY/IN will dictate how warm and dry we get for later this week. For Tuesday afternoon, a surface high trying to build over the southern Great Lakes may finally push storms off to our south. Reintroducing PoPs though across our southern CWA can't be ruled out as PWATs remain high within close proximity from the lift associated with Monday's low. Regardless, highs on Tuesday will reach the upper 80s and lows in the low 70s.

For Wednesday, as the cut-off low slowly strengthens as it moves away, this may counteract the weak high pressure at the surface with moisture transport from the south. This means storm chances increase yet again for another typical afternoon of summertime convection. It is important to note though that shear up until now will remain modest at best and any severe threat will be limited to gusty winds and heavy downpours. Highs will once again be in the upper 80s or a few low 90s in the typical hot spots.

***** Thursday - Saturday *****

The rest of the week seems unsettled as the Rex blocking pattern breaks down with troughing returning over the eastern CONUS. Seems that the high pressure over the Upper Plains will begin to weaken or at least move further westward allowing for bursts of energy from shortwaves traveling along the trough over the east to bring daily storm chances again. There is still considerable uncertainty with storm chances that will be rooted out once these days approach. If the trough is too far east, then hotter temperatures and dry skies will prevail. For now, expect daily afternoon storm chances with highs in the upper 80s to a few low 90s each day.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 135 PM EDT Sat Jul 11 2026

Progressively deeper mixing should allow all sites to return to VFR conditions this afternoon as the SCT-BKN cu field lifts. Winds should be out of the W/SW this afternoon, with speeds mainly between 6-12 kt. The main potential impact through this evening should be scattered thunderstorms which may bring brief IFR VIS, MVFR CIGs, and 30+ kt wind gusts. The best chances for TSRA appears to be at BWG/HNB, though at least PROB30 mention will be at all sites into the evening hours.

Tonight, light and variable winds are expected. Low-level moisture is expected to sink into a low stratus layer after midnight, with IFR CIGs and lower VIS likely, especially between 08Z and 16Z Sunday. Isolated showers and storms will remain in the area overnight, though confidence and coverage is too low to include in the current forecast. Flight categories should begin to improve late Sunday morning, though sub-VFR conditions are favored through mid- afternoon tomorrow.

Overall forecast confidence is low-medium, mainly driven by uncertainties in TSRA this afternoon and evening.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch until 2 AM EDT /1 AM CDT/ Sunday for KYZ023>043- 045>049-053>057-061>067-070>078-081-082. IN...Flood Watch until 2 AM EDT /1 AM CDT/ Sunday for INZ076>079- 083-084-089>092.