Severe Thunderstorm

• Wind gusts in excess of 50 knots (58 mph).

• Hail ¾ of an inch in diameter or larger.

• Tornadoes.

Flash Floods

• #1 weather-related killer (146 U.S. Deaths/year)

• Can be cause by "training" of T-storms.

• Stationary (upslope) T-Storms or MCS.

Hail

• Form in synoptically-forced T-Storms.

• Begin as frozen raindrops or "graupel".

• Travel up and down many times through Cb, growing through accumulation of supercooled water ... melting and re-freezing.

• A "hailstreak" occurs when millions of hailstones break free of the updraft and fall out of the Cb.

• Largest hailstone: 1.67 pounds ... the size of a honeydew melon ... probably hit the ground at 100 mph ... Coffeyville, KS in Sept. 1970.

Microbursts

• A straight-line burst of concentrated wind with a diameter of less than 2.5 miles.

• Downdraft accelerates due to large amount of evaporational cooling or when heavy rain is exposed to entrained dry air.

• Cool air hits ground and "spreads" out ... up to 100 mph!

• Can spawn a "gustnado" ... simulates F-0 tornado damage.

• Have caused major airplane crashes at airports.