A FLASH FLOOD WATCH has been issued for parts of northern Illinois beginning Thursday evening and lasting through Friday morning. Rainfall totals ranged between 1.0 and 2.5 inches Wednesday night and Thursday morning (areas shaded in blue). We’ve had a little break in the rain activity Thursday afternoon with skies remaining mostly cloudy, although there are a few breaks beginning to develop as the thick cirrus cloud deck overhead begins to thin some.
Most of the instability for the rest of this afternoon and evening will remain focused across southern Iowa and central Illinois as the rain this morning helped to push the frontal boundary a little more to the south. Having said that, moisture continues to stream into northern Illinois with dew point temperatures quickly rising into the low to mid 60s.
Thunderstorms are expected to develop to the southwest late Thursday evening, quickly lifting northeast into northern Illinois Thursday night. The biggest concerns locally will be heavy rainfall, especially following the heavy rain from early Thursday morning. Stronger thunderstorms may be capable of strong wind gusts as well. Another one to two inches of rain will be possible by Friday morning, with rainfall totals over two inches along and south of I-80. Flash flooding will be possible, especially in the areas highlighted under the flash flood watch, later tonight. Quick river rises may also occur with the additional rainfall Thursday night. Those in flood prone areas, or along any of the local rivers, should watch for flooding.