Sunday, April 2, 2017

Heavy rain expected this week could cause flooding problems

Over an inch and a half of rain came down in northern Illinois and southern Wisconsin late last week.  An additional two inches of rain could fall for some this upcoming week.

Two significant storm systems will pass through Illinois this week.  The first will arrive late Sunday night and Monday, and the second moves in Wednesday and Thursday.

Low pressure in Texas Sunday afternoon has brought severe weather to east Texas and Louisiana.  This low will lift north through the mid-Mississippi River Valley Sunday night and into central Illinois by Monday afternoon.  Light rain has been falling already with a little break expected through the evening and early overnight.   Not much is expected to accumulate.  A more steady rain will arrive late morning and throughout the afternoon Monday as the surface low moves closer.  Northern Illinois and southern Wisconsin will remain on the 'colder' side, but the system's warm front won't be that far away.  As the low lifts north, it will pull an incredible amount of moisture northward with it.  The amount of available moisture in the atmosphere, or what meteorologists refer to as 'Precipitable Water' will be near one inch.  That means if all the moisture in the atmosphere where to fall as rain, it would add to up a little over an inch.  Rainfall totals by Monday night will range from half an inch up to at least one inch, to possibly an inch and a half if thunderstorms develop.

Once that low passes, another one quickly moves in by the middle of the week bringing with it the potential for an additional inch of rain.  The rain on Wednesday will be a cold rain with temperatures only expected to be in the 40's.  And I can't completely rule out the possibility of some snowflakes mixing in with it.  More on that in the next post.

With an already saturated ground and swollen creeks, streams and rivers the additional rainfall could cause localized flooding, especially where the heaviest rain occurs.

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