March 31 "Rainbow Chase" in Madison and Macoupin Counties, IL, by John Farley

I headed out for a while this afternoon in Illinois north of the St. Louis area hoping to see some strong cold-core storms and maybe if I really got lucky some cold-air funnels. With the pressure quite low, the sun back out, and the dewpoint still above 50, I thought the possiblity was there despite being well-behind the cold front and nearly 20 degrees cooler than yesterday. The low to our NNW was so wound up that the wind was almost straight from the south, even behind the cold front. SPC led me further in the direction I was already thinking when they added southwest Illinois to the slight risk area in the 19Z outlook, indicating possible large hail and damaging gusts in stronger storms. My daughter, who I don't normally take on chases, talked me into taking her along, to which I agreed because I thought the chance of encounterning anything really dangerous was fairly remote.

Between 3:30 and 6:00 in nothern Madison Co. and southern Macoupin Co. we saw lots of convective showers/squalls, a few cold-core thunderstorms, and half a dozen great rainbows, but nothing severe. With the cells moving at 45 mph toward the NE they were hard to keep up with, at the least. As we had to break off and return home around 5:30, they seemed to be strengthening as they moved out of northern Macoupin Co. - ragged base and scud very evident under one updraft. TWC later reported the storms produced 1/2 inch hail as they moved on through central Illinois. Like I said, we saw nothing severe but did get some very nice pics of the rainbows and brightly lit cb towers and precip shafts as they raced away from us. BTW, as the last band of convection passed by, there was a marked shift of the wind from S to W, suggesting a surface trough or secondary front.

John Farley

Return to John Farley's Weather Photos page. Some photos of the clouds and rainbows observed on this chase appear there.

Return to John Farley's Home Page.