23rd Conference on Severe Local Storms


Archetypes for surface baroclinic boundaries influencing tropical cyclone tornado occurrence

Roger Edwards, SPC/NWS/NOAA, Norman, OK; and A. E. Pietrycha

Tornadoes that occur within landfalling tropical cyclones (TCs) may be strongly associated with the presence of surface thermal gradients, either pre-existing before the incursion of a TC, or developing in situ as the result of differential diabatic processes. Based on their relative influences on buoyancy and/or shear characteristics, four basic types of subjectively analyzed baroclinic boundaries are identified, illustrated and proposed as archetypes that distinguish areas associated with the presence or lack of tornadoes within the TC envelope. The archetypes are: 1) Buoyancy limiting (favorable shear on both sides, buoyancy on one), 2) Shear limiting (favorable buoyancy on both sides, strong shear on one), 3) Optimal overlap (most favorable shear on one side, buoyancy on the other, juxtaposed close to the boundary) and 4) Unfavorable (baroclinic boundary -- failures in buoyancy, shear and/or storm mode). An ideal example will be presented for each type of boundary from four different landfalling TCs.

extended abstract  Extended Abstract (404K)

Poster Session 8, Tropical and Nonmesocyclone Tornadoes, Lightning, Pulse and Multicell Storms
Wednesday, 8 November 2006, 3:00 PM-4:30 PM, Pre-Convene Space

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