Wednesday, July 18, 2012

Cumulus Field Becoming Agitated in Southern Wisconsin

The cumulus field over southern Wisconsin into extreme northern Illinois is becoming agitated this hour, with storms potentially forming over the next few hours.

With the movement of the cold front north, a mesoscale convective system (MCS) is now moving east southeast, as shown by the latest Storm Prediction Center Mesoscale Discussion. As soon as the storms fire, you can find it here.


Threat of Microbursts Present in Lower Great Lake Today

DISCLAIMER: Some microbursts can be deadly. These POTENTIAL microbursts would most likely
NOT be life-threatening.

Shown above are the values of Downdraft CAPE at the time of publishing (1:18 PM CDT) across the Midwest. The image above does show elevated values along the lower Great Lakes and into the Ohio Valley of downdraft CAPE.

But what is downdraft CAPE in the first place?
Essentially, downdraft CAPE can determine how strong a downdraft can be. A downdraft is also known as a gust front or outflow boundary, and is a pool of cold air that has been shot from the storm onto the ground.
Downdraft CAPE measures the potential strength of these downdrafts. The higher the downdraft CAPE, the stronger an outflow boundary may be, and an increased number of downdrafts in general.
If the downdraft is strong enough and has enough downdraft CAPE behind it, those ingredients can come together and form a microburst, which is a strong downdraft that can be deadly. However, as mentioned in the disclaimer, today's microbursts do not look to be life-threatening.


Severe Weather Strikes Great Lakes

Severe weather is targeting the Great Lakes today, as a cold front sags south and ignites potentially severe storms in the midst of warm temperatures and a very humid environment.

Analysis of current conditions shows an eroding capping inversion over the western portion of the risk area, with over 5000 j/kg of instability being forecasted to develop in the highlighted area, especially in Iowa and Illinois.

Severe thunderstorm watches have been issued all over the Great Lakes today, with storms not far behind.