textproduct: Louisville

KEY MESSAGES

* Strong to severe storms are possible today. Multiple waves of storms are possible, which could lessen the severe threat overall. Damaging winds are the most likely severe hazard, with spin-up tornadoes and hail also possible.

* Cooler and quieter weather expected Thursday through Saturday.

* Another chance for rain, and possibly storms, returns by late this weekend before temperatures turn sharply colder early next week.

SHORT TERM /THROUGH TONIGHT/

Issued at 316 AM EDT Wed Mar 11 2026

Synopsis...

This morning, broad upper-level troughing is present across the central CONUS, with deep SW flow stretching from the TX Gulf Coast all the way into the NE US. Currently, the upper flow pattern is still split between a northern stream wave and associated jet max ejecting across the northern Plains and a southern stream trough over the southern Plains which has gradually been overtaken by the stronger northern wave. This upper pattern has supported the development of an expansive sfc frontal zone, which as of this morning extends from the Rio Grande Valley up into the lower Great Lakes. To the southeast of this frontal zone, a broad warm sector is present from the Gulf up to the lower Great Lakes. Showers and thunderstorms have developed over the past 6-12 hours in the vicinity of the frontal zone, and should push across our region later today as the coupled upper trough and sfc front eject to the east.

Now through sunrise...

As of 06Z, area radars are quiet, with the majority of the convection remaining to the NW of the Ohio Valley. Air temperatures are in the upper 60s and low 70s, with dewpoints generally in the low-to-mid 60s. While there is about 1000-1500 J/kg of MUCAPE aloft, ACARS soundings show a robust capping/warm layer around 800-850 mb, resulting in around 100 J/kg of MLCIN. However, over the next few hours, a surge of llvl moisture from the SW along with weak mid- level height falls should begin to help erode the cap. At the same time, convection currently crossing the Ozarks should cross the Mississippi Valley, which could help to spark new convection downstream. While the recent trend in hi-res guidance has been less robust with storms before sunrise, would still expect isolated to scattered development between 6-8 AM EDT, especially along and north of the Ohio River. While strong deep-layer shear and low-level helicity would support an all-hazards threat if discrete cells develop, the fact that most hi-res guidance shows line segments or multi-cell clusters developing would support damaging winds as the primary hazard this morning.

Evolution of the Severe/Flooding Threat Today...

It still looks fairly messy with the convective evolution today, with multiple waves of showers and storms, some of which could be strong to severe, expected. There's a fairly consistent signal in the NAM/RAP showing a mid-level speed max/shortwave crossing Indiana during the mid-to-late morning hours before moving into Ohio by early afternoon. Think that this could spark convection across the northern half of the CWA ahead of the front, with this wave of activity pushing off to the northeast by early afternoon. After this first wave, it is uncertain how much instability will be diminished, and if the atmosphere can destabilize again ahead of the cold front which should generally cross the area between 21Z and 02Z this evening. If, as in recent HRRR/WRF-ARW runs, there is persistent messy shower/storm activity, then the severe threat in the afternoon and evening would be lower. We'll still have to watch southern KY, as it is less likely that these areas will be impacted by morning convection, leading to a more robust wave in the afternoon and evening.

As mentioned above, all hazards are on the table with today's severe threat given ample shear and reasonably impressive instability for early March (1000-1500 J/kg in the unperturbed warm sector). The strongest veering/SRH in the lowest 1 km of the atmosphere is expected this morning, with the near-sfc flow gradually becoming more SW during the afternoon and evening hours. Given a SW'ly oriented 0-3 km shear vector on the order of 40-45 kt, any line segments which develop a more NW-SE orientation could carry a spin- up tornado threat, as well as a damaging wind threat. Overall, given the amount of uncertainty in convective evolution (and the possible failure modes) today, agree with the maintenance of a Level 2/SLGT risk across the area. Think damaging winds in multicell clusters and line segments will be the main risk, with spin-up tornadoes a secondary risk and severe hail a tertiary risk. Any lingering storm threat should end with cold FROPA, with severe chances ending from NW to SE between 21Z-01Z this evening (though it very well may end before that!).

For the most part, showers and storms will be progressive in nature today, with limited residence time of heavy rainfall expected. However, there could be some areas which receive multiple rounds of heavy rain, with 00Z HREF LPMM showing a few swaths of 1.5-2" QPF in 6 hr. While most of the CWA should be able to handle these amounts with little more than nuisance flooding, these amounts could cause some issues across southern IN.

Strong Gradient Winds Today...

With short range models consistently showing 40-45 kt of SW'ly flow at 925 mb during the late morning and afternoon, there is certainly potential to get advisory-level wind gusts down to the sfc today across the area. The main source of uncertainty is how deep we will mix given persistent cloudiness and intermittent showers and storms, though BUFKIT soundings do support scattered 35+ kt gusts later today. Have decided to go ahead and issue a Wind Advisory in the area where stronger low-level flow will be more persistent today. While advisory-level gusts may be scattered within this area and will likely not persist through the entire effective period, still wanted to message the potential for strong wind gusts outside of storms today.

Rain Lingers this Evening, then Cooler Tonight...

Behind the cold front, a few hours of light rain will be possible, though showers should end for most by around midnight. Breezy NW winds will usher in strong cold advection tonight, with temperatures likely tumbling from the 70s to the 40s in ~6 hours. Lows by Thursday morning are expected to settle in the 30s across the area, with skies beginning to clear from the NW by around dawn.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 316 AM EDT Wed Mar 11 2026

Thursday through Saturday...

By sunrise Thursday, the region will be well within the post-frontal air mass as the upper trough passes east of the area during the morning hours. Broad subsidence in the wake of the trough should bring clearing skies Thursday morning, with NW winds gradually easing during the daytime hours as sfc high pressure sets up from TX into the Ohio Valley. Temperatures should be roughly 25 degrees cooler across the area Thursday, with highs expected to range from around 50 in the northern CWA to the mid 50s near the TN border.

NW'ly mid- and upper-level flow will continue through Friday and into the beginning of the weekend. This upper flow pattern will bring a compact shortwave through the upper Midwest and Great Lakes Thursday night into Friday morning, with an associated sfc cold front expected to approach the Ohio Valley on Friday. Given the relatively compact nature of the trough, and the fact that it will largely remain north of the region, moisture return will be limited ahead of the front. Increased mid- and upper-level cloud cover and strong SW winds should be the main impacts with the Friday system, with most likely peak wind gusts expected to range from 30-40 mph across the area.

By Friday night, the upper trough will begin to leave the remnants of the sfc cold front behind as weak high pressure noses into the region from the north. As we head into the day on Saturday, the upper pattern is expected to become more zonal as another trough begins to drop south out of the Canadian Prairies. This should allow the remnants of the cold front to begin to lift north through the area Saturday afternoon and evening, with milder return flow beginning again over the region. All in all, quiet weather is expected Saturday, with mostly sunny skies and SE winds expected. A somewhat stronger than normal temperature gradient should be in place thanks to the remnants of the front, with highs currently expected to range from the low 60s in the north to the low 70s in the south.

Saturday Night into Early Next Week...

The next potentially significant system to impact the Ohio Valley is expected during the second half of the weekend, with showers and thunderstorms, some of which could be strong to severe, expected to move through ahead of a strong cold front. Saturday night, an upper- level shortwave is expected to amplify over the Dakotas, with a broad area of sfc low pressure expected to deepen over the Central Plains. Continued southerly flow into the Ohio Valley should keep temperatures mild Saturday night into Sunday morning, with above normal temperatures continuing into the day on Sunday.

As the upper trough pushes east and continues to amplify during the day on Sunday, deepening of the sfc low will continue, with current medium-range progs depicting a near- or sub-990 mb low tracking across the lower Great Lakes Sunday afternoon and evening. The strong sfc pressure gradient will support strong gusty winds again during the day on Sunday, with the ECMWF Extreme Forecast Index signal continuing to show medium-to-high confidence(EFI ~0.8) in strong wind gusts, especially across northern KY and IN. Current NBM most likely maximum wind gusts do reach advisory levels Sunday across portions of the area, so we'll continue to monitor this potential over the coming days.

In addition to the potential for gusty gradient winds, we'll have to monitor the late weekend system for the potential for strong to severe storms as well. Given the highly amplified/sheared flow over the region, wind shear will be more than sufficient for organized convection. The main uncertainty at this time appears to center around how robust the moisture return and destabilization is ahead of the cold front Sunday afternoon and evening. Current medium-range progs show dewpoints rising into the mid-to-upper 50s ahead of the front, which could support at least a marginal threat for severe storms. AI/ML severe convection guidance signals remain over the Ohio Valley on Sunday, though the signals continue to be modest, likely reflecting uncertainty as it relates to the amount of instability. At this time, there is relatively good agreement on the timing of cold FROPA/greatest storm threat Sunday evening, generally lasting from the late afternoon hours into the early overnight hours.

Cold FROPA is expected to be quite sharp Sunday night, with temperatures plummeting into Monday morning as strong cold advection overspreads the area. There is still the potential for post-frontal showers to mix with or change to snow by Monday, though confidence and expected impacts are on the lower end at this time. For the rest of the first half of next week, upper troughing should persist over the eastern CONUS, with a pattern shift to below normal temperatures likely through the middle of next week. As the upper trough axis begins to work to the east by the middle of next week, there could be some additional chances for precipitation from NW flow/clipper systems, but signals remain unclear at this time.

AVIATION /06Z TAFS THROUGH 12Z THURSDAY/

Issued at 129 AM EDT Wed Mar 11 2026

Quite an active period of weather is expected over the next 24 hours, with multiple impacts from CIGs, VIS, winds, and TS possible at all forecast sites. Over the next 3-6 hours, would generally expect VFR conditions with wind gusts gradually increasing toward dawn. Between 08-10Z, would expect scattered SHRA/TSRA to begin to develop along and north of a HNB-SDF line. Through the remainder of the daytime hours on Wednesday, rounds of showers and storms will be possible across the area, with reduced CIGs, VIS, and gusty winds possible in any storms. Outside of storms, SW winds will be strong, with sustained winds of 15-25 kt and gusts of 25-35 kt likely during portions of the day today. By this evening, a cold front will push through the region from NW to SE, with winds veering sharply to the NW behind the front. Lower CIGs and SHRA will be possible behind the front, with conditions generally improving after 03-05Z Thursday.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Wind Advisory from 8 AM EDT /7 AM CDT/ this morning to 7 PM EDT /6 PM CDT/ this evening for KYZ023>043-045>049- 053>057. IN...Wind Advisory from 8 AM EDT /7 AM CDT/ this morning to 7 PM EDT /6 PM CDT/ this evening for INZ076>079-083-084- 089>092.