Variability of Surface Outflows, Cold Pools,
and Downdrafts
in a Large Parameter Space Study of Convective Storms
D. J. Perkey, Cody Kirkpatrick*, and E. W. McCaul, Jr.
Poster presentation at the 2008 AGU Fall Meeting, abstract A13A-0226. *Presented by C. Kirkpatrick.
Submitted Abstract
Using results from a large set of three-dimensional cloud
resolving model simulations, we investigate the sensitivity of storm outflows,
downdrafts, and cold pools to background environmental conditions. The dominant
right-moving storm in each of over 200 unique experiments is analyzed, and its
properties averaged during the second hour of 2 h simulations, to assess the
general relationships between storm outflow characteristics and environmental
parameters.
The strongest surface wind gusts and largest areas of outflow
are produced when convective available potential energy (CAPE) and bulk
tropospheric wind shear are large, these being environmental conditions that are
hallmarks of vigorous, organized convection. Strong winds are also more
widespread when the atmospheric precipitable water (PW) is large, which permits
greater production of precipitation aloft, and when the lifted condensation
level (LCL) is raised, allowing increased evaporation of falling hydrometeors in
the downdraft. Storm cold pool temperature deficits and areal coverages exhibit
more complicated relationships, but cold pools are generally larger and
relatively colder in warm environments (i.e., high PW) and when CAPE is large.
These findings help clarify the environmental conditions that influence the
surface ``sensible weather'' produced by deep, moist convection.
This is a low-resolution reproduction of all the panels on the poster. If you would like to examine any of the figures in more detail, please email me at the link on the previous page for a copy.