A Brief Recap of the May 2019 Severe Outbreak

Just two short weeks ago we posted a blog that looked into the severe weather that occurred on May 20, 2019. Little did we know that this was just the beginning! Over a 12-day period that stretched from May 17 through May 30, more than 285 tornadoes touched down across 22 states. The May storms also included hailstorms (including grapefruit-sized hail in Wellington, Texas!) and frequent heavy rainfall, sometimes at record levels, over areas that were already saturated. This led to extensive flooding and flash flooding, which frequently interfered with emergency efforts related to tornado damage.

Map of tornado warnings issued by the National Weather Service between May 17 and May 29, 2019 over the eastern United States and tornadoes confirmed and surveyed by the National Weather Service. Map produced in QGIS with border outlines from the United States Census Bureau. National Weather Service warning outlines available from the Iowa Environmental Mesonet and tornado data available from the National Weather Service. Credit: TheAustinMan

In the aftermath of the storms, states of emergency were declared in Oklahoma, Arkansas, Ohio, Mississippi, and Missouri due to the flooding and tornadoes. Pre-existing states of emergency were extended in Iowa and Nebraska as well. The mayor of Zeniolople, Pennsylvania also declared a state of emergency after the city received more than four inches of rain in twenty-four hours.

How strong were the tornadoes? While it is very difficult to measure the actual wind speeds inside a tornado since they can destroy most weather instruments placed in their paths (although storm chasers and engineers have created instrument packs that can withstand a tornado, deploying these in every tornado is essentially impossible). Luckily, in 1971 Dr. Ted Fujita (a pioneer in the field of tornado research and damage surveys) created the original Fujita scale, ranging from F0 to F5, to rate tornadoes based on the type and severity of damage that the tornado produced. However, this original scale had limitations, such as a lack of damage indicators, no account for construction quality and variability, and no definitive correlation between damage and speed. In later years, meteorologists worked with structural engineers to examine damage from many, many tornadoes. Their combined knowledge allowed for an updated scale to be created. Since 2007 we have been using that updated scale, known as the Enhanced Fujita (EF) Scale.

Explanation of EF-Scale Ratings, including examples from the April 27, 2011 outbreak. Credit: NOAA/NWS Huntsville

Fifty of the tornadoes that occurred were considered significant (meaning they were ranked as EF2 or higher). Eighteen were EF3 tornadoes, which means that the tornadoes caused severe damage. Two were classified as EF4 tornadoes (with wind speeds between 166 to 200 miles per hour) that caused devastating damage. The two EF4 tornadoes that occurred were in Dayton, Ohio on May 27 and in Linwood, Kansas on May 28. As a result of these violent storms, six people died. While any loss of life is tragic, that number is remarkably low (especially considering the massive amount and extent of destruction left in the storms’ wake) and a huge testament to how far both the science and communication have come. Furthermore, none of the six deaths were associated with the two most violent EF4 tornadoes.

Destruction in Dayton, Ohio. Credit Danny Ivers.

The threat for severe weather was first highlighted on May 12, 2019 in the Storm Prediction Center’s (SPC) 4-8 Day Severe Weather Outlook. The risk area continued to expand in the coming days. On May 14 (for the first time in the organization’s history!), the SPC highlighted an area for all Days 4-8 with a 15% or greater probability of severe weather. This is important as highlighting the risk of severe weather ahead of time can save lives. Meteorologists at local NWS Weather Forecast Offices (WFO) credited much of their success to consistent messaging, great cooperation with local media, and collaboration with neighboring NWS WFOs. Multiple meteorologists that work for the NWS had high praise for broadcast meteorologists, whom they praised for staying calm and projecting confidence to keep their communities safe.

Linwood, Kansas tornado damage. Credit: NOAA/NWS Kansas City

This severe weather season has proven that advanced warnings and clear communication can save lives. While we are hopeful and optimistic that one day tornado outbreaks will occur with no loss of life, it is clear that we are on the right path. Major kudos to all National Weather Service and broadcast meteorologists who deserve all the praise for keeping so many in their communities safe. If you know of a meteorologist who you would like to recognize for their service during the recent severe weather outbreak (or a high impact weather event that affected you!), please leave us a comment or send us an email. We would love to do a profile on some of our everyday heroes!

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