Walking a fine line this weekend

Increasing cloud cover can be expected this afternoon ahead of the remnants of Hurricane Isaac.  As I mentioned Thursday morning, there's likely to be a very tight rainfall gradient from north to south with who sees significant rain/flooding to who squeezes by with only a couple tenths of an inch. 




 

Here's the latest QPF (rainfall map) from the Hydrometeorological Prediction Center.  Areas just south of I-88 could stand to receive several inches of rain whereas areas to the north will receive less.  The rain continues to fall through central Missouri and just to the north of St. Louis, MO.  Here's the latest thinking on when the rain will begin tonight:  Look for rain to spread north near I-88 by this evening and into northern Illinois by daybreak Saturday.  Rainfall along the I-88 corridor will be steady and likely heavy through the day Saturday and possibly even heavier to the south of that.  Far northern Illinois could receive up to an inch of rain through the weekend with southern Wisconsin possibly only receiving a half an inch or less.  A slight shift in the track will shift the heavy rain north so we'll continue to watch the progression of the low as inland tropical systems can be torrential rainfall producers.

While rain during a drought is often times a relief it can also produce flooding if there's too much of it.  If several inches of rain were in fact to fall this weekend a flooding concern will arise.  Even though the ground is dry the rain is not able to absorb and sink in like it should because the soil is so hard that the rain almost 'bounces' off of it causing runoff and flooding.  The latest drought monitor hasn't shown much improvement except in the counties lying just to the south of Lee and DeKalb from what fell last Sunday.  The dairy state has pretty much remained the same from last week to this week as well.