Radar Image from April 3, 2008...

Here is a reflectivity image from LZK (little Rock) at 0136z. This is a mature supercell with a hook echo, inflow notch, and some intense rainfall. This tornado formed in a severe thunderstorm watch, but conditions were still potent enough for tornado formation. Here are some useful indicies I looked at where this tornado formed:

Surface dewpoints: 63-64 degrees
LCL's: 1000 meters
LFC: 1400-1600 meters
0-3km Capes: 50-100 J/kg
MUCAPES: 1500-2000 J/kg
Significant Tornado Potential (STP): 3-4
0-6km Shear: 60 knots
Effective Bulk Shear (EBS): 60-65 knots
1km EHI: 1
3km EHI: 1 (these values would have been higher if there was higher cape)
1km SRH: 250-350 M2S2
3km SRH: 300-400 M2S2
9-11 km storm relative winds: 35 knots (high precip/almost classic supercell winds)
1km shear was also favorable at 30-35 knots.

This supercell storm occurred as nocturnal cooling was beginning, but this goes to show that it doesnt take much for the atmosphere to work with what it has. Always look at the whole picture when trying to figure out whats going on. You dont have to have a tornado watch for tornadoes to form, as illustrated.

-Howell
April 4, 2008