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.