textproduct: Louisville

KEY MESSAGES

* Warm front moves north through the area, bringing widespread rain Friday morning. Building instability will create a marginal risk for severe gusty winds, a small chance of a tornado, and a flash flood threat with heavy downpours.

* Episodic bouts of showers/storms are expected to continue through the weekend and into the middle of next week. Localized excessive rainfall may result in flooding in some areas.

SHORT TERM /THROUGH TONIGHT/

Issued at 350 AM EDT Fri May 22 2026

The negatively tilted trough of an upper-level low over the northern Plains is moving towards the Ohio Valley, along with a developing surface low currently over the Gulf states. The warm front of the surface low will move from south to north over the area shortly before sunrise this morning, lifting north of the Ohio River during the early afternoon hours. Another round of light to moderate rainfall, sometimes heavy, is expected as the front moves through, and an occasional rumble of thunder cannot be ruled out.

By the afternoon, the developing surface low will move northward over the Ozarks, with a low and mid-level jet developing out ahead of it over central Kentucky. With plentiful S/SW flow in place, PW values will range in the 1.5-2" range (~99th percentile climatologically). As the front lifts to the north, some clearing may take place that could allow for additional daytime heating. With that said, most of the heating that will take place today will be mainly advection driven from the southerly flow. Given the abundant moisture in place, some diurnal heating, and forcing from the nearby surface low/upper-level trough, there is the potential for showers and thunderstorms to develop, some of which could be strong to severe.

The SPC has put central Kentucky under a Marginal Risk for severe weather today, with the main concerns being damaging winds and a potential isolated tornado. Low-level lapse rates in model soundings during peak heating are near 7 C/km, and the low-level wind shear profile is decent, with 0-3 km SRH values over 100 during the late afternoon and early evening hours. One of the limiting factors during this event would be any cloud cover that lasts following the warm frontal passage, decreasing any potential daytime heating and limiting how unstable the atmosphere could get.

With the high moisture available and multiple rounds of showers and storms expected today, there is the concern for a flash flooding threat. The most recent LREF 6-hour LPMM data continues to highlight localized areas of 2-4' rainfall totals for places that experience training storms. Given some of the recent rainfall that we have experienced this week, a Flash Flood Watch has been issued for our northeastern counties, with a more localized flooding threat possible across the rest of the CWA. We will continue to monitor the flooding threat for this event to determine if any additional counties need to be added to the watch later today. Even with limited daylight heating, southerly flow will allow temperatures to get into the low-to-mid 70s in the afternoon.

By Friday evening, the potential for severe weather quickly dissipates as we no longer have the support of daytime heating. The surface low will move by just to our west Friday night, with the coverage of showers and thunderstorms slowly decreasing as the low moves to the north and east. With decent cloud cover in place, temperatures will not fall too much during the overnight, with lows in the low-to-mid 60s forecast.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 350 AM EDT Fri May 22 2026

Moving into the Saturday period, an area of surface low pressure is expected to continue to lift northeast through northern IN/OH during the day. Broad southwest flow pattern will remain in place with PWAT values remaining in the 1.7-1.8 inch range. Waves of showers and some thunderstorms will continue to move through the region. We should see scattered convection in progress at the start of the period Saturday morning. However, model solutions show this activity moving off to the east during the day with a drier period of weather during the late afternoon and evening hours. Highs on Saturday look to warm into the 75-80 degree range with overnight lows cooling back into the lower 60s.

For Sunday, an upper level trough axis is forecast to develop over Texas with a wave in the northern branch of the jet pushing east through the Great Lakes region. We'll remain in a broad southwest flow pattern with plentiful moisture. Synoptic scale forcing remains rather weak across the region, however we'll have a remnant surface boundary in the vicinity that will serve as a focus for additional convective development. Convective coverage will likely be maximized in the afternoon during peak diurnal heating. Severe weather is not anticipated given the weak shear profiles forecast by the models. However, PWATs will remain quite high and slow moving storms will be capable of dumping quite a bit of rainfall. Highs on Sunday will range from the upper 70s to the lower 80s with overnight lows in the low-mid 60s.

Moving to Monday, aforementioned upper trough axis over Texas looks to close off into a cut off low and then eject slowly northeastward. As this occurs, flow aloft will be confluent across the Ohio Valley with a quasi-stationary surface boundary remain in place across the region. Deep moisture will also remain in place and will pool along this boundary with PWATs remaining in the 1.5-1.75 inch range. Current modeling suggests another round of showers/storms moving across the area Monday afternoon/evening. Overall shear here remains fairly marginal, so heavy rainfall looks to be the main weather hazard. Given the repeated rounds of showers/storms, we could see isolated-scattered hydro issues develop in this time frame. Highs may be a little cooler here with readings in the upper 70s to around 80 and overnight lows in the mid 60s.

Unsettled weather is likely to persist into the Tuesday through Thursday time frame as the upper level flow undergoes a fair amount of blocking and becomes highly amplified. Aforementioned cut off low over TX will lift northward and become stuck over the Plains as significant cutoff lows look to develop over the western CONUS and the NE US. An east-west axis of unsettled weather is likely to set up across the Ohio Valley during the period resulting in additional bouts of showers/storms. Convective coverage will likely be maximized in the afternoon with lesser coverage during the overnight periods. Highs during the period will average in the upper 70s/lower 80s with overnight lows in the 60s. Some drier conditions may enter the region by Friday as the models want to dive the NE US trough further south which may promote more ridging from the upper Midwest into the Ohio Valley.

Total QPF for the next 7 days looks to average between 3-5 inches from the Lower MS Valley northeast through the TN?OH Valleys. Some locally higher amounts will be possible. Excessive rainfall may result in localized flooding issues next week, and will put a serious dent in the recent drought status across the region.

AVIATION /06Z TAFS THROUGH 12Z SATURDAY/

Issued at 155 AM EDT Fri May 22 2026

A combination of MVFR, IFR, and LIFR flight categories is still ongoing across the terminals, primarily in the form of ceilings. This trend will continue through the overnight, with the exception of HNB that could see a brief period of VFR ceilings over the next few hours. The next round of precipitation will begin shortly before sunrise over BWG before spreading northward through the morning. Widespread rain showers are expected through the day on Saturday, resulting in lowered visibilities and cigs. Storm chances are possible during the afternoon and early evening hours, and were included as PROB30 groups in the TAFs. Widespread rain showers may begin to diminish near the end of the TAF period, though don't expect too much improvement in flight cigs during this time.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Flood Watch from 8 AM EDT this morning through Saturday morning for KYZ032-033-035>037-041>043-049. IN...Flood Watch from 8 AM EDT this morning through Saturday morning for INZ079.