National Weather Service United States Department of Commerce

A Review of the March 12 Supercell

Weather Images (click images to enlarge):


Weather observations from 6 AM The image at left shows weather observations from Illinois and nearby areas at 6 am.  A frontal boundary lay across the middle of the state, as indicated by the sharp temperature contrasts (37 at Galesburg and 64 at Robinson).  Showers and thunderstorms were occurring across southeast Illinois.
Upper-air observation from Lincoln at 6 am This is the upper air observation from Lincoln the morning of March 12.  The front is still located south of Lincoln, indicated by northerly winds in the lowest levels of the atmosphere.
Upper-air observation from Lincoln at noon A special balloon launch was done at noon.  The front had lifted north of Lincoln by then, and the low levels were showing significant wind shear.
Surface map at noon The noon surface map showed the warm front lifting northward, as temperatures in the 60s had reached as far north as Lincoln, with dewpoint values also significantly increasing. 
 Upper air observation from 3 pm Another special balloon launch was done at 3 pm.  Significant wind shear continued to be displayed at the lower levels. 
Surface weather map at 3 pm By 3 pm the surface map showed that the warm front had reached roughly a Quincy to Kankakee line, with central and southern Illinois in the mid to upper 60s.


Satellite Images (click images to enlarge;  click here for satellite loop, 3.3 MB)


 Satellite image at 11:40 am This is a satellite image of the central U.S. at 11:40 am.  Keep an eye on the small patch of clouds in southeast Kansas, northwest of Coffeyville.
 Satellite image from 12:15 pm By 12:15 pm, thunderstorms were rapidly developing in southeast Kansas. 
 Satellite image from 2:02 pm This satellite image was taken just after 2 pm.  The storms in Kansas were continued to expand in coverage as they spread into Missouri. 
 Satellite image from 3:55 pm In this satellite image from 3:55 pm, the high clouds associated with the thunderstorm complex were spreading into Illinois; the storms themselves continue to move across Missouri.  Also note the small area of thunderstorms developing southwest of Kansas City; this will later evolve into the thunderstorm system that moved across central Illinois after midnight.
 Satellite image at 6:15 pm At 6:05 pm, satellite indicated the thunderstorm complex continuing to spread across Illinois, while storms organize across central Missouri.  The highest cloud tops are indicated in the lighter shades of blue. 
 Satellite image at 8:02 pm Just after 8 pm, satellite showed the supercell thunderstorm in central Illinois, while storms in Missouri become more widespread.
Satellite image from 9:45 pm By 9:45 pm, the satellite reflection of the thunderstorm complex extended from northwest of Champaign, northeast into Indiana.


Radar Images (click images to enlarge; click here for radar loop from 7-9 pm, 885 KB)


Regional radar image from 3 pm This radar image from 3 pm showed supercell thunderstorms along the Kansas/Missouri border south of Kansas City.
Radar image at 4 pm At 4 pm, an F0-strength tornado was in the supercell storm moving near Sedalia, MO.  In Illinois, severe thunderstorms in Marshall County had produced hail from penny to nickel size, and would soon grow to golfball size around Lacon.
Radar image from 5 pm At 5 pm, the two supercells in central Missouri were converging on Columbia. 
Radar image at 6:06 pm Shortly after 6 pm, the supercells were located in east central Missouri, due south of Quincy.
Lincoln radar image from 7:08 pm The two supercell storms merged into a single storm around sunset.  This radar image from Lincoln at 7:08 pm showed a hook echo on the storm as it approached the Illinois River southeast of Pittsfield.
Radar image from 7:24 pm By 7:24 pm, the hook echo had become better defined.  A tornado was moving across northern Greene County at this time.
Radar image from 7:46 pm  At 7:46 pm, the radar showed the hook echo in southern Morgan County.  A tornado was in progress, having moved into southeast Scott County around 7:30 pm and then into southern Morgan County around 7:35 pm.
Radar image from 7:56 pm  At 7:56 pm, the hook echo was approaching the Sangamon County line.  The tornado would cross the county line a few minutes later.  In addition, a second tornado developed just outside of Franklin (eastern Morgan County) at this time, and headed toward Loami, in Sangamon County.
Radar image from 8:03 pm This zoomed-in radar image in Sangamon County at 8:03 pm shows the hook echo beginning to move into the county.
Radar image from 8:20 pm At 8:20 pm, the hook echo was moving across Curran.  The tornado was between 1/2 and 3/4 mile wide.
Storm Relative Motion image from 8:20 pm This storm relative motion image from 8:20 pm shows the intensity circulation along I-72 east of Curran.
Radar image from 8:30 pm By 8:30 pm, the hook echo was moving to the I-55 corridor in Springfield.


Event Links:  Overview | Long-Track Tornado | SpringfieldFranklin/Loami | Eastern Sangamon
 Southern Logan | Greene/Scott #2 | Logan/Macon | Macon/De WittRadar&Satellite