qTypically
have diameters of about 100 yards but may be much larger.
q Usually a short lived phenomena lasting only
a few minutes,
but some have lasted for hours.
qMovement is
generally about 50km/hr (30 mph) over an areas about 3-4 km (2-2.5 mi) long.
qWinds may be
as low as 65 km/hr (40 mph) or as high as 450 km/hr (280 mph).
qCome in wide
range of shape and size.
q