Mesoscale observations of an extended heat burst and associated wind storm in Central Oklahoma



On 13 May 2009, 13 surface-based observing stations within central and western Oklahoma recorded maximum wind speeds in excess of 22.5 m s−1, along with gusts exceeding 28 m s−1 in isolated locations, during a localized wind storm that lasted in excess for over an hour. These wind speeds were associated with an enhanced mesoscale pressure gradient that developed during the late evening of 12 May 2009 and early morning hours of 13 May 2009, which then slowly propagated from west to east. Ultimately, the event produced localized wind damage in northern portions of Oklahoma City. Analysis of the synoptic and mesoscale conditions present at each stage of the event revealed that specific parameters associated with heat bursts occurred during the event, but with the inclusion of varying mesoscale and microscale influences. As such, a close examination of the mesoscale pressure field indicated that a dynamically variable mesoscale convective system (MCS) produced a mesohigh/mesolow couplet that ultimately created the strong pressure gradient. The result was a prolonged period (in excess of 1 h) of enhanced wind speed values across a swath approximately 300 km in length and 50 km in width that were not directly associated with the anomalously warmer and drier conditions that occurred due to the heat burst. Copyright © 2011 Royal Meteorological Society