The center of cooler drier Canadian-source high pressure will move from west to east over the Chicago area Saturday, taking us back to mid-June when normal highs are around 80-degrees with dew points in the 50s. An on-shore wind out of the north-northeast will keep readings in the 70s along the Lake Michigan shoreline. Conditions will rapidly change on Sunday as the high pressure moves off to the east and southwest flow up the backside of the departing high pressure will allow a warm front to surge back north over our area, bringing temperatures and dew points back where they were on Friday – highs in the mid to upper 80s and dew points in the upper 60s to lower 70, along with an increasing probability of showers and thunderstorms later in the day and overnight.
Very warm humid conditions with periods of showers and thunderstorms will prevail most of the workweek ahead – temperatures peaking in the mid-90s Wednesday and possibly Thursday. For the week ahead rainfall totals look to range from 1 to well in excess of 3-inches, as is the nature of summertime showers and thunderstorms.