Thursday morning severe weather update

It'll be a busy weather day today as thunderstorms, strong winds, and possible record setting heat will move in through the afternoon today. Through this morning though we're seeing the warm front with this system pass through, which has sparked a few showers this morning to our west but all we're seeing is increasing cloud cover briefly and warmer temperatures.
 

Two different air masses are moving through the state line this morning as well. For locations off to the north and east of Rockford cooler lake air from Lake Michigan has moved some fog onshore once again today while keeping temperatures in the upper 50's. To the west though the previously mentioned warm front is lifting north bumping up temperatures into the mid 60's. As this warm front moves north though, cooler air will slide back onto the lake.

Our main concern today continues to be the *conditional* severe weather threat we'll see into this afternoon. As it looks now, our previous concern about thunderstorm development being if thunderstorms develop seems to be in better agreement for a few isolated thunderstorms to develop. Within this large, enhanced risk the main risks we'll be looking out for will be large to very large hail (possible 2 inches+), damaging wind gusts, and possibly an isolated tornado.

Breaking down the severe hazard types today large and hail and wind gusts look to be our main concern through the afternoon. Thunderstorms are expected to develop near I39 today and quickly intensify. However, as thunderstorms form the bases of the thunderstorms will start higher due to lower dewpoints and higher surface temperatures. These conditions will allow for drier air to be transported down to the surface allowing for a few stronger wind gusts, this along with strong vertical winds will allow for large hail development.

Moving onto the tornado risk today, it's a bit lower than the hail and wind threat but an isolated tornado cannot be ruled out this afternoon. Going back to the high thunderstorm bases this will initially keep the tornado threat lower. As thunderstorms approach Lake Michigan though, higher dewpoints and a bit stronger low level wind field will increase tornado chances. As it stands now, eastern portions of the state line including Boone, McHenry, and Whitworth counties look to have a bit higher of a tornado threat.

Timing those thunderstorms out, showers are expected to develop along the cold front from 2-4 p.m. this afternoon. These showers and thunderstorms will erupt quickly though as a large amount of atmospheric instability will be present as these storms form. Storms will quickly race east into the afternoon but will obtain severe status quickly with such a potent environment. As previously said early on, thunderstorms will mainly carry a wind and large hail risk but as the mature east the tornado threat has the potential to ramp up.

By 7-8 p.m. though thunderstorms will move east of the state line bringing any chances for thunderstorms tonight east as well. Into the night cooler and drier conditions will move in until we warm up back into the 80's tomorrow morning!