Blocking pattern holds major storm threat west Wednesday and Thursday

Severe weather hasn't been an issue for us, but over the past two days several locations across Northern Illinois have received close to, or slightly above, two inches of rainfall!

The heavy rain threat will be ending for a couple days as the jet stream takes on a different position across the Great Lakes.  Developing low pressure out west will force the jet stream to buckle across Northern Illinois and Southern Wisconsin.  This is what we call a 'ridge'.  This ridge will act essentially to block any major storm development to the west as storms fire up closer to where the strongest winds within the atmosphere will be Wednesday afternoon.  Now, an isolated storm or two does remain possible Wednesday afternoon just with a warm front nearby and an increase in moisture to the atmosphere.  But, the continuous rainfall doesn't look to be an issue for us during the afternoon.

On Thursday, the jet stream will begin to shift a little further east as the ridge breaks down.  This means areas in Northwest Illinois will hold a higher chance for developing thunderstorms Thursday afternoon.  This looks to be west of a line from Monroe to Freeport and Northwest of Dixon.

By Friday, the chance for heavier rain returns as the jet stream runs pretty much overhead and that pattern looks to be in place through the weekend.