Observations of an Unusual Wind Storm in Oklahoma City

During a nearly 5-hour period on May 13, 2009, a swath of severe winds developed across west-central Oklahoma and propagated through northern portions of Oklahoma City and into east-central Oklahoma. Over the nearly 200 km length of the swath, numerous Oklahoma Mesonet and Oklahoma City Micronet (OKCNET) stations recorded speeds winds in excess of 25 meters per second for over an hour (with gusts over 30 meters per second). Specifically within Oklahoma City, numerous reports of structural damage were reported due to the persistent severe winds. Analysis of the event revealed that a mesohigh pressure area formed due to a mesoscale convective system while a mesolow pressure area formed just to the north creating a very strong pressure gradient between the two mesoscale features. Observations from the OKNCET data revealed that during the height of the event in Oklahoma City, the pressure gradient was 12 mb over a 30 km distance and the winds were characterized by gradient flow. Further, the severe wind event occurred in the absence of convective precipitation and significant synoptic features.