Thunderstorms exploded to life Wednesday afternoon as daytime warming destabilized
the atmosphere, encouraging humid air near the surface to ascend and building vast
cumulus clouds that reached 40,000 feet into the atmosphere. Concentrated downpours
from the towering thunderheads drenched Wrigleyville with 1.48 inches of rain and
produced brief flooding in spots. Midway Airport's 0.84 inches of rain through late
evening pushed the city's spring rainfall tally to 13.41 inches-re-establishing the
season to date as the wettest on record here.
Lots of lightning
The first flashes of lightning with Wednesday's fast developing storms occurred
around 1 p.m. on the Mississippi River between Iowa and Wisconsin. Storm development
was so rapid, lightning was arching across Chicago skies only three hours later. A total
of 5,183 cloud-to-ground strokes had been recorded over the six-hour period through
8 p.m. within a 200-miles radius of Chicago. 38% of them especially high amperage
"positive lightning". Typically only 10 percent of lightning bears a positive charge.
