Extended Abstract (320K)P1.5
Evolution of a mesoscale convective vortex over Northern Arizona
David O. Blanchard, NOAA/NWS, Flagstaff, AZ
The development of mesoscale convective systems (MCSs) and mesoscale convective complexes (MCCs) has been extensively studied in the literature over the past two decades. Considerable advances have been made in understanding the initiation, maturation, and decay of these systems .
Less well understood and documented are mesoscale convective vortices (MCVs), an occasional feature of MCSs and MCCs. MCVs are often identified on visible satellite imagery after the MCS/MCC has dissipated and the thick anvil shield has either thinned or moved downstream. Then the residual circulation can often be identified by the spiral bands associated with the mid-level circulation.
There have been a few published climatologies of MCV environments. In these studies, the area of focus was limited such that systems over the relatively flatter terrain of the central United States from Texas northward to the Canadian border were examined. MCVs that occurred outside this domain were not documented. The climatologies indicate that the majority of North American MCVs occur south of 42.5 ° N and west of –87.5 ° W. No southern or western boundaries are given but are assumed to be the Gulf Coast and the Rocky Mountains.
Although MCVs are considerably less common outside of the central United States, they do occasionally occur. On 20 August, 2001, a MCS developed in northern Arizona and southern Utah. As this system matured, an MCV developed that persisted long after the original convection had weakened. Satellite imagery, Doppler radar data, surface METAR reports, and upper air rawinsonde data were analyzed to assist in the documentation of this system.
The evolution of this MCV is similar to those that have been documented in the central portions of the United States. However, unlike some of the midwestern systems, this MCV was not responsible for subsequent regeneration of convection along its leading edge. It is believed that local subsidence from other, stronger convection associated with the Mexican monsoon circulation was instrumental in preventing new convection from developing.
Poster Session 1, Mesoscale Convective Systems and MCVs
Monday, 12 August 2002, 3:00 PM-4:30 PM
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