Why The Uptick In Severe Weather? HUGE recap

Hailstone from April 15 storm in NE Ohio

Since the beginning of March, the overall pattern across the central US/Ohio Valley/Southern Great Lakes has been unsettled with frequent storm systems, heavy rain and multiple severe weather events. How did this pattern evolve?

The jet stream across the Pacific has been very strong going back to late February. A persistent low near Hawaii produced record setting rainfall. The warm, moist air was transported to the Pacific Northwest where diabatic heating occurred (the transfer of heat through the system as water condenses -- latent heat). This heating strengthened the upper level ridge through compression which causes more heat and dry conditions at the surface. As the ridge strengthened out west, low pressure systems traveled up and over the ridge intensifying as they moved through the central US/Ohio Valley.  Think of it like building up speed as you ride a roller roaster up and over the top.

Here is a great article that compares the March 2026 pattern evolution which created the heat out west to the June 2021 event. It also discusses the climate change connection:

In more technical terms from the article:

"Warm, moist air ascended rapidly within the cyclone’s warm conveyor belt, the river of air that rises from the boundary layer ahead of a cold front. As the air ascended, water vapor condensed, releasing enormous quantities of latent heat. That heating reorganized the potential vorticity (PV) structure of the atmosphere: below the heating maximum, PV was enhanced (strengthening the cyclone), while above it, anomalously low-PV air was produced and transported into the upper troposphere. This low-PV outflow spread poleward, displacing the jet and amplifying a downstream ridge over western North America. The ridge then drove intense subsidence and adiabatic warming at the surface."

The ridge expansion is illustrated nicely in this animation:

By late March, the ridge strength was at levels usually seen in mid summer. Notice that as the ridge deepened (warm colors), the trough across the central US/Great Lakes also deepened (blue areas). This trough fed the development of each one of the storm systems which traveled up and over the ridge.

Upper level pattern evolution across the northern Pacific and North America since early February in 7 day increments. Warmer colors indicate high pressure. Colder colors low pressure.

This pattern created record heat across the much of the US.

This ended up being the warmest March on record beating out 2012:

March temperature ranks

Interestingly, as the US set records, most of Canada and Alaska was experiencing record cold for March.

Heavy snow across northern Michigan over a three day period between March 14-17.

Rainfall in March across the Ohio Valley was well above normal normal.

Some of strongest wind gusts in the last 50 years in northern Ohio were felt on March 13:

Rainfall from March through April 16 versus normal:

Number of severe thunderstorm warnings for Ohio is now at 92 through April 15. Here is the data since 1995.

Coverage of severe thunderstorm warnings across Ohio this year vs 2025:

Now we add the tornado warnings to the map.

Just northern Ohio.

Surprisingly, the number of lightning strikes across Ohio, Indiana, Illinois, Kentucky, Michigan, Iowa and Wisconsin between March 17 and April 16, 2026 was 31% lower vs the same period in 2025!  402,955 vs 275, 970

Compare this year to years past for all of Ohio.

Compare this year to years past for Ohio, Indiana, Illinois, Michigan, Wisconsin and Minnesota.

Will this pattern continue throughout the spring and summer?  More ahead.

 

Ohio Tornado Recap Through April 30

So far this year, the Ohio tornado count has been record setting.  Preliminary numbers put the total at 43 although official tornado track analysis puts the exact number closer to 35. Either way, we haven't had a year anywhere close to this since...well, last year. 

Ohio counties that have been under a tornado warning at some point this year: 55 of the 88 counties.

Here are the totals year by year since 1950. Red bar represents total tornadoes through April 30.  The green bar are the EF2 or greater tornadoes each year.

Here is the average number of tornadoes per state through April 30:

Here is the actual number this year through April 30:

Why so many tornadoes this year?

First, we have been transitioning out of a very strong El Nino period and rapidly heading into a La Nina. These changes in the equatorial Pacific have impacted the jet stream across the central US. Throughout the winter, the storm track was absent across the US as evident by below normal snowfall across the central US.

Notice how the jet intensity was abnormally strong in mid March and April across the mid-west. Warmer colors indicate well above normal jet intensity.

The lifted index (degree of instability) was extremely favorable for rising air and storms across the Ohio Valley in mid March. Colder colors indicate rapidly rising air.

The MJO might have been a factor. Higher amplitude phase 4-6 in mid March. Moderate amplitude phase 8-1-2 in late March. However, according to this paper, the connection in March and April might be smaller. Bold print below is important:

The physical mechanism proposed in this study cannot explain the MJO–U.S. tornadogenesis relationship in the boreal early and middle spring months (March and April). Compared to MJJ, the Pacific jet is strengthened and shifted southward in March and April, but the anomalous subsidence over the northeast Pacific is very weak in March and April. Therefore, it is more likely that the relationship between MJO and U.S. tornadic environmental parameters in March and April is largely influenced by extratropical stationary Rossby waves forced by MJO-induced diabatic heating anomalies over the Maritime Continent. Thus, it is also likely that natural atmospheric variabilities originated from high latitudes such as North Atlantic Oscillation (e.g., Lin et al. 2009) and Artic Oscillation (e.g., Zhou and Miller 2005) interfere with the MJO-induced extratropical teleconnection to the United States in March and April, and thus may weaken the relationship between MJO and U.S. tornadogenesis. Additionally, in March and April, tropical Pacific sea surface temperature anomalies associated with El Niño–Southern Oscillation (ENSO) are of key importance in modulating the spatiotemporal variability of U.S. tornadogenesis (e.g., Weaver et al. 2012; Lee et al. 2013, 2016; Barrett and Gensini 2013; Allen et al. 2015; Lepore et al. 2017; Molina et al. 2018; Chu et al. 2019).

Speaking of high latitudes, check out the height anomalies in the higher latitudes since early 2024. Heights rise, Arctic Oscillation drops. Frequent troughs track across the mid latitudes. Notice all but one of the top 7 tornado days occurred when the northern height anomalies were high. 

Here are the mid latitude 500 mB heights vs normal on those top 7 tornado days with SPC storm reports for each period:

#1 - April 26-27 (143 tornadoes)

#2 - April 1-2 (97 tornadoes)

#3 - March 14 (36 tornadoes)

#4 - April 16 (24 tornadoes)

#5 - February 27 (24 tornadoes)

Gulf of Mexico water temperatures were well above normal in March especially. Some cooling has occurred since but overall temperatures are still above normal. 

We also transitioning out of El Nino and into La Nina territory over the last 2-3 months. Notice the warmer water eroding away along the equator. This probably played a factor in the overall jet stream direction and intensity changes across the central US.

Historic August Rainfall/Severe Weather Recap

The clean up continues after the second round of heavy rain/severe storms across northern Ohio.

17 school districts closed due to damage and power outages:

Here is the COMPLETE radar loop from August 23 at noon through early August 25 before sunrise. Warnings, watches and lightning are included for northern Ohio.

I separated the 2 day rain event into 3 separate radar loops starting at 9pm August 24 through August 25 at 3am:

August 23 - 12:30PM through August 24 - 5AM

August 24 - 5AM through August 24 9AM

August - 9PM through August 25 - 5AM

Historic rainfall over 48 hours with two separate large clusters of rain/storms:

Another vantage point shows the heaviest rain from southern Michigan through Ohio and western PA.

Since August 1, most of northern Ohio has received 200-400% of normal rainfall:

Severe storm warnings were widespread. Most of northern Ohio was under a severe thunderstorm warning at some point between August 23 and early August 25.

4 tornado warnings. 12 tornadoes. COMPLETE NWS RECAP

The EF-1 that occurred on the east side of Cleveland was the first tornado that occurred within the Cleveland city limits since July 12, 1992 per NWS Cleveland. That tornado occurred near Hopkins Airport.

Here are ALL of the tornadoes from 1950 to 2022 in Cuyahoga County

Why did this heavy rain occur?  What were the factors that lead to this?

The huge ridge of heat in the central US has been a fixture for at least a week. 

Where high pressure resides, low pressure has to follow either down or up stream. Disturbances rode up and over the ridge and down through the Great Lakes.  

Great lakes radar loop from Wednesday through Friday: The excessive heat watches/warnings are shown in red.

Couple this with the high humidity (dewpoints above 75) and you have the recipe for heavy rainfall.

Interestingly, the historic Derecho in 1969 on the 4th of July produced MORE rainfall!

Here are the final rainfall numbers between August 23-25 using the same perspective as the 1969 map above (for comparison)

Oh and almost 75,000 lightning strokes over the 48 hour period across Ohio!