US severe thunderstorm activity to escalate, warns Guy Carpenter

US severe thunderstorm activity and severe convective weather looks set to escalate as we move into the second-half of March, reinsurance broker Guy Carpenter has warned.

A multi-day period of severe weather is forecast for the US south and southeast, which the reinsurance broker warns has the potential to bring damaging severe thunderstorms, as well as other convective weather effects such as large hail and tornadoes.

Beginning today, Tuesday March 16th, Guy Carpenter warns that a low pressure system moving across the country from the Desert Southwest will bring severe thunderstorms to Oklahoma and Texas today.

The forecast then suggests that conditions will be more favorable for widespread thunderstorms that are capable of producing large hail and multiple tornadoes on Wednesday, as the weather event moves further east across the lower Mississippi River Valley and Southeast US.

Additionally, the window for severe weather conditions continues into Thursday, across much of the Southeast US, Guy Carpenter warns.

Impacts are possible for major urban areas, with NOAA’s Storm Prediction Center having raised a “significant severe” possibility for either hail or tornadoes for the following metropolitan areas:  Memphis, TN, Birmingham, AL, Montgomery, AL, Little Rock, AR, Jonesboro, AR, Pine Bluff, AR and Tuscaloosa, AL.

The reinsurance broker highlights that the “significant severe” level of the SPC’s warning “indicates that there is greater than a 10% chance within 25 miles of these cities to see either 2″+ hail or tornadoes of EF2 or greater intensity.”

We’re now moving firmly into the accepted beginning of the peak convective storm and severe thunderstorm weather season in the United States.

Given the La Nina conditions and the state of ENSO in the northern hemisphere Spring of 2021, it had been anticipated that the US tornado and severe thunderstorm season could be a more severe one.

In fact, forecasts for convective storm activity have suggested the potential for an above average year due to La Nina and ENSO and the second-half of March is when that activity typically ramps up.

Guy Carpenter said that, “Traditionally March marks the start of the severe weather season and lasts into May. A below average start to March 2021 is transitioning into what looks to be multiple bouts of severe weather every 3-5 days through the end of March across the the southern half of the central and eastern US.”

That’s an ominous warning and with the insurance-linked securities (ILS) market holding significant levels of exposure to convective weather, severe storms and in particular hail and tornado events, it suggests ILS funds may be on watch as we move into the peak time of year for this peril.

The catastrophe bond market holds exposure to this peril as well, particularly the aggregate and multi-peril US cat bond transactions.

Currently, we count almost $6.3 billion of US multi-peril cat bonds on-risk in the market, with well over half having some exposure to severe storms and convective weather losses.

Keep an eye on the trends in US tornadoes, severe thunderstorms and convective weather as they develop throughout the season over on our U.S. tornadoes and severe thunderstorms page.