Large-Hail-Producing Thunderstorms over the Midlands of South Carolina

on October 21, 2005

Dan MillerNWS Columbia, SC

SC 25-Year Large Hail (1.75”+) Climatology

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J F M A M J J A S O N D

SC Hail Events(1.75"+) since 1980

Meteorological EnvironmentKey Points

• Warm and moist low level air – Surface temperatures and dewpoints about ten

degrees above normal, enhancing instability.• Dry air aloft

– Seen on water vapor imagery and soundings, aiding parcel buoyancy and lowering wet bulb zero height.

• Upper level disturbance– PVA enhancing lift, and cooling temps aloft

steepening lapse rates/instability.• Jet streak

– Left front quadrant enhancing divergence aloft/lift• Low level convergence/boundaries

– source of lift

Jet Streak250mb Height/Wind Speed

18Z 21-Oct-05

Jet Streak250mb Height/Wind Speed

00Z 22-Oct-05

Upper Impulse500mb Heights/Vorticity/Temps

18Z 21-Oct-05

Upper Impulse500mb Heights/Vorticity/Temps

00Z 22-Oct-05

Surface Analysis12Z 21-Oct-2005

LAPS Sounding Clarendon Co. 18Z

Clarendon County Severe Cell

Thank You!

Dan MillerNational Weather Service2909 Aviation WayWest Columbia, SC 29170

daniel.miller@noaa.gov803-822-8133