25th Conference on Severe Local Storms


Tornadoes within weak CAPE environments across the continental United States

Jared L. Guyer, NOAA/NWS, Norman, OK; and A. R. Dean

Given the well-established importance of buoyancy in conjunction with vertical shear for severe convective storms, tornadoes occurring within weak buoyancy regimes can pose unique challenges to operational forecasters. A preliminary climatology of tornadoes estimated to have occurred with weak buoyancy, as defined by Mixed-Layer (ML) CAPE of 500 J/kg or less, is presented for the continental United States for 2003-2009. Estimated MLCAPE values were derived from a 40 km gridded dataset of the Storm Prediction Center's hourly Mesoscale Analysis archive, which is based on a blend of surface METAR observations and RUC analysis fields. The comprehensive SPC relational database of severe events and environmental data contains more than 2500 tornadoes that have occurred with MLCAPE < 500 J/kg. Seasonal, temporal, geographic, EF-scale climatologies are presented, in addition to relational examination of these events to common convective indices and general synoptic/mesoscale patterns. A number of prior research studies have identified common scenarios for tornadoes within weak CAPE regimes (i.e. tropical systems, "cold core" mid-latitude closed lows, low-topped California storms, Gulf Coast cool season), but this study may help further document the frequency of occurrence with such patterns.

extended abstract  Extended Abstract (464K)

wrf recordingRecorded presentation

Session 1, Severe Weather Climatology I
Monday, 11 October 2010, 9:00 AM-10:20 AM, Grand Mesa Ballroom F

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