21st Conf. on Severe Local Storms

3.1

Probing Rotationally Dominated Mesoscale Convective Systems

Christopher A. Davis, NCAR, Boulder, CO

The Bow Echo and MCV Experiment (BAMEX) will investigate the dynamics of long-lived mesoscale convective systems (MCSs) with two primary foci: severe wind producing bow echoes and MCSs producing long lived mesoscale convective vortices (MCVs). Both are examples of organized convection with strong mesoscale rotation about a vertical axis. The overall objectives and observing strategies of BAMEX will be briefly reviewed.

It has recently been found that (MCVs) which persist many hours beyond the decay of the mesoscale convective system (MCS) that gave rise to them are commonly observed features in the mid-troposphere during the warm season. Estimates of 20-40 cases per season over the Central U.S. now exist. To the extent that MCVs induce mesoscale ascent and other factors affecting subsequent convective development, better understanding and prediction of MCVs will have an important affect on warm season rainfall and flood forecasts. In recent years there have been numerous insightful modeling studies of MCSs producing MCVs, but there are scant observations to confirm that models are adequately simulating the cloud-scale and mesoscale processes within MCSs that lead to long lived vortices. BAMEX is designed to acquire high-quality datasets that will address outstanding issues related to the maturation of primary MCSs and development of secondary convection near MCVs. Specific questions are:

How do long-lived MCVs form and what distinguishes MCVs which persist well beyond the decay of the parent convective system from those that do not?

How do MCVs help induce new convection? What is the relative importance of processes within the boundary layer versus above the boundary layer?

Why does new convection sometimes reintensify MCVs, leading to a multi-day MCS/MCV cycle, while other times the MCV appears to decay immediately following the organization of new convection?

Can focussed situ measuments, combined with radar information, improve the predictive skill of weather associated with long-lived MCSs and MCV?

In this talk we will further describe the overall rationale of BAMEX and elaborate further on the above research questions and the observations needed to address them.

extended abstract  Extended Abstract (152K)

Supplementary URL: http://www.mmm.ucar.edu/bamex/science.html

Session 3, Bow Echo and MCV Experiment (BAMEX) Symposium
Monday, 12 August 2002, 4:30 PM-6:00 PM

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