Tornadic  Thunderstorm Types in the Northeastern United States

Broken-S Tornado Signature

Tornadic Thunderstorm Types in the Northeastern United States

Introduction

Supercells

Appendages

Bow Echoes

Boundary Interaction

Miscellaneous Types

 Summary Table

References

McAvoy et al. (2000) noticed that several tornadoes developed along fractures in low-topped lines of thunderstorms.  The Fort Miller, New York F1 tornado (21 Aug 1994) exhibited many of the characteristics of the Broken-S tornadoes. Typically  these storms

• form at a fracture in a line of storms
  

• develop in an atmosphere characterized by high shear and weak instability
  

• are low topped 
  

• are fast moving
  

• may show weak rotation near break
  

• form in areas of high spectrum width

	Reflectivity image from the Fort Miller, NY tornado showing the broken-S signature.   (click on image to view larger picture).
	Spectrum Width Image depicting high spectrum width values at the time of the Fort Miller tornado. (click on image to view larger picture).

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