Slight Risk of Severe Weather Tomorrow

There is a slight risk of severe weather tomorrow over northern Illinois and eastern Iowa as a cold front moves in to ward off unusually hot temperatures for that region of the country.

Instability is forecast to be on the high end, not surprising for 100 degree heat. The Storm Prediction Center does mention the potential for 4000-5000 j/kg of instability, which is indeed very high. The NAM indicates a small area of enhanced rotation potential over northern Illinois, slanted more towards the area south of Chicago, IL going into extreme northwest Indiana. Over the general lower Great Lakes region, there could be a widespread weak capping inversion, which would likely be crushed by at least 3000 j/kg of instability currently being projected by the NAM.
The GFS is bullish on instability, placing over 5000 j/kg of potential energy over northern Illinois, whereas the NAM centers the instability into the Upper Midwest. Additionally, the GFS disintegrates capping potential in Northern Illinois, opting to place any inversion to the south of a line roughly following Interstate 80. There looks to be some shearing in southern Wisconsin and areas west, igniting potentials for some supercellular structures of which the Storm Prediction Center does find plausible. Precipitation values off the GFS at roughly 7:00 PM CDT tomorrow do indicate what could be a small cluster of storms, or an area of cells in northern Illinois. These could reach severe limits and will have to be watched in future forecasts.

Andrew

Ominous Heat Wave to Expand North Tomorrow

Heat related advisories are up as the nation prepares for a bout with menacing 100 degree heat tomorrow. There are excessive heat warnings in action in eastern Kansas and western Missouri, where the center of the heat should be placed. Heat index values could flirt with 110 degrees. In dark maroon, in northwest Illinois and east Iowa, an excessive heat watch is in effect, meaning that there is the potential that those areas could see an excessive heat warning out of this. Much more common on the map is orange, which signifies heat advisories. Chicago, IL, St. Louis, MO, and Indianapolis, IN are among the major cities in the heat advisories. I would not be surprised to see St. Louis go under an excessive heat warning for this event, with highs flirting with 110.

Forecast high temperatures for tomorrow extend an arm of 100 degree heat from Kansas through the Midwest and edging into the Ohio Valley. A swath of near-100 degree heat will also be present in the southern Mississippi valley into portions of the Southeast. 90 degree readings look to be in place throughout the Northern Plains and East Coast tomorrow as well.

In order to limit health-related illness risk tomorrow, it is advised that you:
-Drink plenty of water at all times.
-Do as little high labor activities outside as possible.
-Check on elderly neighbors.
-If you have pets, keep them in a cool area with a water source.

Tomorrow is not the day to go run a 5K or bike several miles in the afternoon. This heat will pose a threat to life, but can be avoided if you keep hydrated and don't do high energy activity.

Andrew