Severe thunderstorms did not materialize as originally expected during the night of July 9th, mainly due to a push of warm air about 6,000 to 10,000ft above the surface. This warm layer essentially acted as a "cap" for storm development along the advancing cold front. As a result, little or no convection formed until the morning of July 10th when an upper-level wave tracking into the Great Lakes brought cooling temperatures aloft. Once this destabilizing influence took place, numerous showers and thunderstorms developed ahead of the frontal boundary. Thanks to copious amounts of moisture in the environment, the storms were very efficient rain-produces...resulting in rainfall rates as high as 3 inches per hour! Not all locations experienced thunderstorms, but those that did picked up some impressive amounts of rain in a short period of time. The heaviest rainfall was concentrated in a corridor from northern Sangamon County eastward into Macon County...where amounts of 2 to 4 inches were common. The highest total of 3.82 was measured by a SWOP observer 2 miles southwest of Latham in southeast Logan County where flash flooding occurred with 8 inches of water flowing over route 121 at 2000th Avenue at 10:40 am on Wednesday morning July 10. Lightning also started a house fire in Lincoln at 800 block of north Sherman at 8:03 am with a large tree branch blown down at 5th and State street in Lincoln. Shortly after 10 am numerous trees were blown down over eastern Vermilion county.
To see the rainfall map from this event, go to: http://www.crh.noaa.gov/ilx/?n=swop-precip