Severe Weather Alert for Sunday 5/26/24

**nWo** · May 24

I will post information on this possible situation until late Sunday morning. My wife and I are scheduled to fly out of Lexington early that afternoon.

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SUNDAY INTO SUNDAY NIGHT ACROSS PARTS OF SOUTHEASTERN IOWA...EASTERN MISSOURI...MUCH OF CENTRAL AND SOUTHERN ILLINOIS...MUCH OF CENTRAL AND SOUTHERN INDIANA...WESTERN AND CENTRAL KENTUCKY...

Strong to severe thunderstorm development may accompany mid-level height falls across a potentially sizable area of the interior United States due to the significant potential instability associated with low-level moisture return through the warm sector of the developing cyclone, beneath at least initially capping elevated mixed-layer air. Due to variations in the model output on the synoptic and sub-synoptic developments—which might have included one or two significant clusters of convective development across the lower Missouri Valley at the beginning of the period—the specifics of this evolution are still unknown.

By Sunday afternoon, there may be a concentration of convective activity again close to the point where the outflow meets the southward-moving cold front that is passing across the eastern Missouri and west central Illinois regions. The environment is expected to be favorable for supercells initially due to the large mixed-layer CAPE and strong shear. However, an upscale growing cluster will be supported by low-level warm advection along the remnant outflow, and it is expected to propagate southeastward across the lower Ohio and into Tennessee Valley until Sunday evening. The main severe weather hazards, such as a large hail/supercell tornado risk to damaging winds and possibly a persistent QLCS tornado threat, seem likely to center around the outflow boundary/differential heating zone, even though convection may gradually increase along the southward advancing front to the southwest of the outflow boundary.

With this information, the Storm Prediction Center has a large section of Kentucky in a level 3 Enhanced Risk for Sunday. A portion of western Kentucky and around the I-75 corridor is in a level 2 Slight Risk area while eastern Kentucky is under a level 1 Marginal Risk.

**nWo** · May 24

Just received this from the National Weather Service-Louisville

Quote

We are still expecting a few strong storms this afternoon and evening. The main hazard will be heavy rainfall that could cause minor flooding, and locally damaging wind gusts. There's a small chance for hail and the tornado risk is very low today and tonight.

The worst weather is expected Sunday, when we could see organized severe weather, mainly in the late afternoon and evening. All severe hazards are on the table, including damaging winds, tornadoes, and large hail.

We will be hosting a conference call this afternoon at 230 PM EDT.

Stay weather aware this holiday weekend! We'll talk to you this afternoon.

Sincerely,

--NWS Louisville

**nWo** · May 24

I just took a look at the GEFS Ensemble model. By producing several forecasts that, when applied to the data after it has been included in the model, yield a variety of possible outcomes, GEFS quantifies these uncertainties. Every forecast accounts for a unique combination of uncertainties.

This is what it is showing for Sunday from 2 pm EDT to 7 am EDT Monday.

First, surface winds are expected to blow from the southwest at a speed of 35 to 45 mph. Around 18,000 feet, there will be 50–60 mph westerly winds. It seems that the winds will have varying directions at various altitudes. This might lead to storms rotating and producing tornadoes. Additionally, Readings of 2,500 to 3,200 J/Kg (Joule per Kilogram)of surface-based CAPE. Generally, a CAPE of 1000 J/Kg is adequate for powerful to severe storms. Generally a CAPE of 3,000 to 4,000 J/Kg or above indicates an extremely volatile atmosphere. When combined with dew points that are expected to reach the mid-70s in western Kentucky and the low to mid-60s in the majority of the state, this could create an environment where all modes of severe weather will be possible from Sunday afternoon into the nighttime hours.

**nWo** · May 24

From the conference call this afternoon:

Organized severe weather is possible on Sunday, with the threat continuing well into the overnight hours Sunday.

All severe hazards are on the table, including damaging winds, large hail, tornadoes, and localized flooding.

The greatest chance for severe weather is highlighted in orange (‘Enhanced Risk’) on the map.

All interests in the Lower Ohio Valley should stay weather-aware over the holiday weekend.

Multiple waves of storms are possible. Storms could start as early as Sunday morning and be isolated/scattered in nature.

More widespread storms would likely arrive Sunday night. The threat could extend into the early morning hours Monday.

**nWo** · May 24

I just received a email from NWS-Louisville office there will be another conference call Saturday afternoon at 3 pm EDT.

**nWo** · May 25

Kentucky is now more at risk of severe weather. There is currently a level 3 Enhanced Risk for strong to severe storms over most of Kentucky. Level 2 Slight Risk covers the locations that are not covered by level 3.