TIMELINE: Here's what you need to know about Tuesday’s severe weather threat

It's a 9 First Warning Weather Alert Day
Severe Weather Threat Tuesday
Posted at 5:26 PM, May 02, 2022
and last updated 2022-05-03 13:52:54-04

CINCINNATI — Today is a 9 First Warning Weather Alert Day due to the potential of strong and severe storms during the afternoon and evening.

A low-pressure system is moving through the Great Lakes region afternoon and will bring the threat of strong & storms storms here to the Tri-State. The center will stay just to the northwest of the Ohio River Valley putting us in the “sweet spot” for severe weather the evening commute.

Tornado Watch
Tornado Watch in effect until 9 p.m. ET

The Storm Prediction Center has highlighted much of the Tri-State in its outlook for severe weather Tuesday afternoon. We are included in a Slight risk (Level 2 of 5) for storms. Don’t let that “lessened” category fool you, we still have the potential for severe storms but there are still a few variables that are in question. Let’s get into it.

Severe wind gusts of 60+ mph remains our primary threat during the afternoon, however we will also have potential for a few isolated tornadoes. Large hail, of 1 inch in diameter or greater, may also be possible, but it is the lesser of our three threats today. All of these threats are more likely if supercell storms develop. Right now, the better threats for super cells will be in Northern Kentucky and southwest Ohio.

Tuesday's Severe Storm Impacts
Tuesday's Severe Storm Impacts

Heavy rain and flooding is also a threat, but that remains low. Storms this morning dropped 0.25" to 0.75" of rain to most communities. Localized stronger storms will have potential to drop 1 to 2 inches of rain this afternoon, which would increase a flash flood threat through the evening.

We are nearing our time of storm "initiation" where we are starting to develop a few cells which will strengthen over the next couple of hours. Our biggest threat will develop after 2 p.m., but it is the 4 p.m. to 7 p.m. window which it looks best for supercell storms.

Storms will originally start out as individual cells before likely merging into a line of storms, squall-line, as it moves towards the east. It is at this time, where storms are individualized, that our tornado threat looks greatest.

2pm Future Radar
2pm Future Radar
4pm Future Radar
4pm Future Radar

Storms will last through the evening commute before moving out of our area around 8 to 9 p.m. Shortly thereafter we will see the passage of the cold front, which will cut off any threat for storms.

6pm Future Radar
6pm Future Radar

When forecasting storms we look for many ingredients, but there are four main factors that really determine severe weather. I use the acronym of S.L.I.M. This covers Shear, Lift, Instability, & Moisture. Shear is a measure of the spin in the atmosphere, which you need for storms to turn and strengthen. Lift is what helps these storms develop with an upward motion to push the storms higher in the atmosphere. Instability measures the energy in the atmosphere for storms to feed off of. The higher those level get, the stronger storms are able to become. Lastly, Moisture. You can’t have storms without moisture, but the higher the levels, the better the threat for strong storms & tornadoes.

The biggest question for Tuesday afternoon will be whether or not we are able to destabilize enough after the morning rounds of showers and storms and if so, will there be enough shear/twist in the atmosphere at the same time.

Potential atmosphere rotation Tuesday afternoon
Potential atmosphere rotation Tuesday afternoon

If the morning rain lasts longer than expected, or we don’t see as much warming through the middle of the day, that will limit our daytime heating which drastically could drop our energy levels. A benchmark value for energy is around 1,000 J/KG. Levels of 2,000 J/KG have been popping up in future forecasts, which would be ample amount of energy. The warmer we continue to get, the more energy will be available.

Expected available energy for storms Tuesday afternoon
Expected available energy for storms Tuesday afternoon

Another question we have had is whether or not we have enough moisture available for the storms. Dewpoints of 65°F and greater are usually the target for severe storm potential. If we see an influx of higher moisture, then our instability will also increase which would amplify our threat for storms. Right now, the better variables look to be across Southwest Ohio and Northern Kentucky. Either way, the threat is there and needs to be monitored.

Expected Dewpoints for Tuesday afternoon & evening
Expected Dewpoints for Tuesday afternoon & evening. The measure moisture in our atmosphere

As always, make sure to stay weather alert Tuesday. We will have coverage for you on-air when need, but you can also stream coverage this afternoon on your WCPO Phone App as well as on our streaming app on your Roku, Amazon Fire, and Apple TV devices. Keep checking in for the latest updates as we get closer and closer.

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