Heat and Humidity Continue to Fuel Scattered Thunderstorms

Temperatures Saturday and Sunday warmed into the mid and upper 80s, with the heat index rising into the low 90s Sunday afternoon. Most of the weekend was dry, however, there were heavy rain producing thunderstorms that occurred for some Saturday evening. The heat and humidity will be cranking up a little in the days to come with temperatures rising close to 90 degrees Monday afternoon. Unfortunately the rise in the temperature will also come with an increasing dew point temperature - amount of moisture in the atmosphere. Sunday afternoon dew points were in the upper 60s and low 70s. Monday afternoon dew points are forecast to rise into the low to mid 70s - meaning a very tropical air mass - which could push the heat index close to 100 degrees, especially if temperatures do reach the 90s. If we end up with a little more cloud cover to start the day, then the air temperature might not be quite as warm, however it'll still feel muggy.

A weak stationary boundary is expected to lift back to the north Monday morning, moving right over northern Illinois during the afternoon. Scattered showers and thunderstorms will be likely as the boundary interacts with the moisture, leading to localized heavy downpours. The severe threat is low Monday, but some of the stronger storms could have gusty winds with them. Those gusty winds and heavy rainfall will be our biggest threats with any storms that develop over the next several days.

Scattered thunderstorms will occur once again Tuesday and Wednesday as an upper level disturbance moves in from the south. By Thursday and Friday the wind direction shifts more to the east and northeast thanks to high pressure building in to the north. While this won't bring our heat down, as highs are still expected to remain in the upper 80s, it will knock the humidity down a little. Beyond Friday it does look like a strong ridge of high pressure will begin to build and slowly slide east into the fourth of July weekend. That building ridge could bring temperatures well into the 90s for Saturday and Sunday, assuming we stay rain free during that time.