Convection and Severe Weather
My research interests in convection and severe weather are concentrated in 2 areas:
Dynamics and thermodynamics of non-lake effect snow squalls (convective snowbursts)
Synoptic-scale precursors and characteristics of Mesoscale Convective Complexes (MCCs) and High-End Tornado Outbreaks (HETOs)
Dynamics and thermodynamics of convective snowbursts
Convective snowbursts are short-lived snow squalls that occur away from large bodies of water (e.g., Great Lakes) and are often associated with an arctic cold front. While snowfall accumulations are typically quite small and below warning criteria, these events often pose a large threat to life and property, particularly transportation. Visibility is typically reduced to near zero, resulting in whiteouts and very hazardous travel conditions.
My initial interest in this topic was sparked by an event in Ottawa, Ontario in January 2010, when two separate snowbursts moved through within 2 hours of each other, reducing visibility to near-zero. Radar imagery, meteograms, and soundings from that event are shown below.
Our research has shown that snowburst events are typically associated with the passage of an arctic cold front, very steep lower-tropospheric lapse rates (see soundings below), and convective and/or conditional symmetric instability (CSI) that is released by a variety of ascent mechanisms, primarily frontogenesis.
Synoptic-Scale PRECURSORS AND CHARACTERISTICS of MCCs
Our research on MCCs has to do with the large-scale mechanisms that precede and are favorable for their formation and maintenance.
MCCs are large, circular, primarily nocturnal convective systems that produce a substantial amount of warm-season precipitation in the Great Plains. They are largely dependent on the nocturnal Great Plains low-level jet (LLJ) as a source of warm, humid air. Below is an Infrared satellite animation of an MCC from June 2015. Note the very cold cloud tops.
SYNOPTIC-SCALE PRECURSORS AND CHARACTERISTICS OF HETOs
Partially supported by an Embry-Riddle Internal Research Grant, David Dillahunt (senior undergraduate meteorology major) has been examining the synoptic-scale precursors and characteristics of high-end tornado outbreaks (HETOs), such as the 27 April 2011 outbreak (see storm reports map below). Identifying these structures can lead to improved pattern recognition and more accurate medium-range forecasts of these outbreaks.
In March 2016, David presented his research results with a poster at the 20th Annual Severe Storms and Doppler Radar Conference in Ankeny, IA. Click here or scroll to the bottom of this page to see his poster!