Heavy rainfall could lead to flash flooding

9:50pm Update: Latest model guidance suggesting the heaviest rain holding off until just before dawn Tuesday morning.  A few showers/storms are likely from 1am to 5am, but most of the rain arrives by sunrise.











A Flash Flood Watch has been issued for Northwest Illinois for Jo Daviess, Stephenson, Carroll and Whiteside counties beginning 10pm Monday evening and lasting through Tuesday night.

Monday evening has been dry following showers that moved through during the morning.  But all that is expected to change after midnight as low pressure moves through Iowa and into the Great Lakes by Tuesday afternoon.

The threat will turn from severe weather in the central Plains, to heavy rainfall for northern Illinois by Tuesday morning.  The heaviest rain is expected to fall through the early morning commute, tapering off after 10am.  Additional thunderstorms could develop Tuesday afternoon along a cold front with drier and cooler air moving in by Wednesday. 

Widespread 1" to 2" of rain will be common, with locally 2", or more, falling from Forreston west and southwest through Mt. Carroll, Dixon and the Quad Cities.

Excessive rainfall could lead to rises in small creeks and streams, along with water ponding on roadways impacting Tuesday morning's commute.