Severe Weather July 18 2013

For the past several days we have had a Bermuda High Pressure in control and the result has been a very hot and humid air mass across the vast majority of the country. Temperatures have been in the 90s and real feel temperatures have been even higher. With an air mass in place like this to get severe weather you need  a cold front with a temperature difference behind that cold front and when you have these two air masses colliding one with another it brings about the chance of severe weather.. We have a cold front that will be dropping south and east from the Canadian Border and this front will serve as the necessary trigger for severe weather to occur. We expect today that all modes of severe will be possible ...

As we noted the temperatures are hot across the vast majority of the region with temperatures in the 80s and the 90s and the real feel temperatures in some locales will be between 100-105 degrees.

Factor in dew points in the 60s and 70s and once again you have the recipe for some very hot weather.
Moving on to the severe parameters that will be in place....

Convective Available Potential Energy or CAPE is essentially fuel that gets thrown on the fire. This will range from 1000 to as much as 4000

Lift in the atmosphere or the Lift Index will be from about negative 2 to negative 8..

Wind Shear with this system coming down across the lakes is essentially from 35 knots to 60 knots. 

Energy Helicity Index is relatively high across Northern Minnesota and across Northern Wisconsin and Upper Michigan . In tandem with this the HELICITY is also on the higher side...

So these areas mentioned above are the regions that we think have the potential for Tornadoe's. Elsewhere we think the main threats will be heavy rain, damaging winds and the potential for Hail...

So this is the zone we have highlighted...

Keep in mind that over the next couple days that this front will be moving south and east and this means that the severe potential will also move south and east .

For those that are in the areas that are extremely hot ... we want to stress that you should drink plenty of liquids and if at all possible stay indoors and in the Air Conditioning. If you must venture outdoors take Water with you and wear light colored and loose fitting clothing...