Severe Weather Outlook for April 9th 2013

The first main severe weather event of the season should start to take shape tomorrow evening into the overnight hours. An arctic cold front will be making its way to the south and to the east along with its associated trough. Air out ahead of this cold front is warm..

As you can see by looking at the first image the air behind the front is colder ..of course it will not be that cold into the south. However .. the front will cause temperatures to drop from the warmer levels.

Timing. Timing of the front looks to be in the over night areas and should be pass the Falls region of TX by 12 Z wednesday or 8 AM wednesday morning.

During the day across the south we will be dealing with a CAPPED environment. You can see this when you look at the CINH which is an inhibitor to severe weather.

So we are really expecting nothing to fall across that area thru about 8 PM. The guidance is in good agreement with this as well..

The above is what falls by 2 AM.. and there after by 8 AM (which is when the front will have passed thru NC TX)

So lets take a look at the severe parameters that will be in place. And the first one we are going to look at is the shear. There is no doubt about it that the shear would certainly support a severe weather event with shear as high as 100 Knots.. Keep in mind though there is a CAP thru about 8 PM

CAPE is greatest at 30 hrs and again this is when things are just starting to get going in the south around the TX area. As you see they develop over the Falls to Jacks County area ..  So this is the CAPE for 30-36 hrs ..

Now you can see here by 33 hrs the CAPE has shifted east away from the Falls region and is very minimal at about 250 .. 

And by 36 it continues to shift further to the east.  So the CAPE is supportive of severe weather and especially in areas to the east. 

Next Parameter we are going to look at is the Lift Index which again there is plenty of lift in the atmosphere..

The final parameters we are going to look at is the EHI and the Helicity index. These are the parameters that are specifically used to look at what areas are likely to see tornadic activity.

You can see by these images that the EHI is greatest to the east of the Falls region and the areas that are above 1 stretch as far north as Iowa.

Just as the CAPE progressed east so does the EHI. Lets look at the helicity quickly..

Now this is at 33 hrs ..and remember by this point the EHI has shifted east so the Helicity while in place to the west is no longer lined up with the Greatest EHI but it is further to the east and stretching to the North as well.

So we have severe parameters in place that will create a severe weather event. With the CAP in place across the south till at least 8 PM and the timing of the precipitation being in the over night hours we think areas across the west in Tx with the parameters decreasing will end up having the risk of Large Hail and gusty winds. It is to the east and then north where the greatest CAPE, EHI, and Helicity is that we anticipate all modes of severe from Winds to Hail to Tornado potential.
The front will cross the south by about 8 AM wednesday morning but the area will continue to see rain falling across the region.

So with all the above stated...this is the day 1 outlook for the 9th

We will be monitoring the situation later in the afternoon and all evening long!