Livin' on the edge

The lack of rain and the persistent hot weather has almost become the norm across the country with record breaking heat and ongoing drought conditions in the Midwest.  This all looks to be changing as we could be dealing with several rounds of thunderstorms before the weekend gets here.

A little over a month ago the storm track was along the U.S/Canadian border keeping the heavy rain threat closer to Minnesota and Wisconsin.  Now with the position of the jetstream over us this week there will be an increase in the storm threat beginning this evening and lasting through the end of the week.  Weekend Meteorologist Eric Nefstead had discussed in an earlier post a 'Ring of Fire' pattern beginning to set up which usually favors heavy rain and severe storm potential. 

The image on the left is the current water vapor and it really tells a lot this morning.  The darker areas are where sinking air is present and you can easily see where the ridge of high pressure is.  It's located in the center of the country.  Moisture within the atmosphere is flowing up over the ridge from the southwest into the Great Lakes.  This is also where the jetstream is located (blue arrow).  With the placement of the jetstream almost directly overhead any storms that form upstream will hold a greater chance of moving into northern Illinois and southern Wisconsin.  As low pressure moves into eastern Canada a trailing cool front will move south out of Wisconsin later this evening.  A series of upper level disturbances will move from northwest to southeast this week pushing the front south and then lifting it back north by the middle of the week.  A fairly moisture rich environment is in place and with each disturbance that moves across the boundary the threat for rain increases with the first round arriving tonight.  While an isolated thunderstorm may develop this afternoon storm chances increase through the overnight and into Tuesday morning with locally heavy rainfall possible.  Along with an increase in the heavy rain comes the potential for severe weather; the first of which may occur tonight.  While widespread activity isn't anticipated if thunderstorms grow large enough strong winds may become a concern.  Timing out the storm potential continues to remain a challenge, but the way it looks right now the greatest threat appears to be overnight tonight into Tuesday morning, Tuesday night into Wednesday and then again Wednesday night into Thursday.