Dynamics of Simulated High-Shear, Low-CAPE Supercells

Wade, Andrew R.; Parker, Matthew D.

doi:10.1175/jas-d-20-0117.1

i

Dynamics of Simulated High-Shear, Low-CAPE Supercells

2021
By Wade, Andrew R. ; Parker, Matthew D.

Details

Journal Title:

Journal of the Atmospheric Sciences
Personal Author:

Wade, Andrew R. ; Parker, Matthew D.
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; NWS (National Weather Service)
Description:

High-shear, low-CAPE environments prevalent in the southeastern United States account for a large fraction of tornadoes and pose challenges for operational meteorologists. Yet, existing knowledge of supercell dynamics, particularly in the context of cloud-resolving modeling, is dominated by moderate- to high-CAPE environments typical of the Great Plains. This study applies high-resolution modeling to clarify the behavior of supercells in the more poorly understood low-CAPE environments, and compares them to a benchmark simulation in a higher-CAPE environment. Simulated low-CAPE supercells’ main updrafts do not approach the theoretical equilibrium level; their largest vertical velocities result not from buoyancy, but from dynamic accelerations associated with low-level mesocyclones and vortices. Surprisingly, low-CAPE tornado-like vortex parcels also sometimes stop ascending near the vortex top instead of carrying large vorticity upward into the midlevel updraft, contributing to vortex shallowness. Each of these low-CAPE behaviors is attributed to dynamic perturbation pressure gradient accelerations that are maximized in low levels, which predominate when the buoyancy is small.
Source:

Journal of the Atmospheric Sciences, 78(5), 1389-1410
DOI:

https://doi.org/10.1175/jas-d-20-0117.1
ISSN:

0022-4928 ; 1520-0469
Format:

PDF
Publisher:

American Meteorological Society
Document Type:

Journal Article
Funding:

Grant no. NA15OAR4590235 ; Grant no. NA16OAR4590213 ; Grant no. NA17NWS4680002
Rights Information:

Other
Compliance:

Library
Main Document Checksum:

urn:sha-512:ed72566f9ccf2395c7044793b8e55292a9781f09930ce05f2a82141b5cf59632ef3ad455aa776e5117159f662f040e0edb7ce0c1a46ba77ec1a87a7fdf11022e
Download URL:

https://repository.library.noaa.gov/view/noaa/64909/noaa_64909_DS1.pdf
File Type:

[PDF - 6.60 MB ]

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