May 18th Severe Weather Ramping Up

We use rather strong language in the title of this post but we feel by the end of the post you will understand the reasons why. 

1. First we have a warm to hot air mass out ahead of a cold front that is pressing off towards the east. This is one ingredient needed for severe weather to occur.

Temperatures are in the 80s and 90s. 

Secondly we have a trigger which is a cold front with two areas of low pressure. One over western Kansas and one over the border of the Dakotas with a trough pressing to the east and a dry line setting up from the low over Western Ks southward thru Eastern Tx..

Using the NAM we have quite the parameter field set up over quite a broad area...

CAPE which is convective available potential energy is quite high with values ranging at 4000-5000. In addition to this we have a lot of lift in the atmosphere...

We have lift indexes as low as negative 13 which helps to support an unstable atmosphere.

Perhaps more importantly is the EHI or the Energy Helicity Index that the NAM is showing..

If this EHI becomes a realized factor it means we could see tornados in Oklahoma, Nebraska, Kansas, Eastern South Dakota. 
Shear is greatest in the areas to the north with around 40 knots plus..

Perhaps the one positive to take away from the whole over all severe scenario is that the Helicity is not all that high across the region..

Never the less with it being 200+ in combination with the EHI we think this just enhances the potential for tornados across the areas that were mentioned.
The Helicity also does increase as the night goes along...

We think the state of TX will most likely be influenced by a strong CAP in place but with the CAPE as high as it is ..we have to include them in the outlook if that CAP were to break.

All aspects of severe weather can be expected today from Large Hail to strong gusty winds to the chance for tornado's mentioned in the areas that we covered above.

If you are out and about stay tuned to your National Weather Service and heed any warnings that may be issued and take cover and shelter immediately should you be in a tornado warning . 

So with all the above mentioned this is the outlook. We did not put a moderate risk area but pretty much you can figure from above where we would put it if we were to..