Severe Weather Possible This Saturday, April 26

Ingredients may come together to produce significant severe weather on Saturday across Texoma. There is some uncertainty with regards to the forecast so I do not want to hype the situation but do want to make all of you aware of the possibilities. 

First, a strong jet stream and upper level storm system will approach Texoma on Saturday afternoon as shown in these two images. 

Saturday evening jet stream forecast

500 mb level vorticity map

A vigorous upper level trough of low pressure will become negatively tilted with time which is favorable for producing sufficient lift to develop thunderstorms. The jet also acts to evacuate air from the updraft of thunderstorms and tilting the updraft which can promote stronger thunderstorms. 

*The timing of these features is critical to the development of storms and their strength. If it speeds up a bit or is in a favorable location during peak daytime heating, severe storms become more likely. If it is slower to approach, the severe threat would be lower and/or storms may not be as strong if capping in the atmosphere holds. Models do differ with this solution so we will be watching it closely over the next few days. 

Here are some severe weather parameters including the measure of instability which we call CAPE. This is anywhere between 1-3,000 J/kg depending on which forecast model you choose. This would be moderate levels of instability and enough to build and sustain storms. 

CAPE values valid Saturday evening

We also look at other parameters such as a supercell composite forecast which can help us determine where the greatest chance of rotating supercells are and to what degree the risk is. These values of between 4-10 are pretty significant so the primary type of storm would be supercells.

Supercell composite forecast valid Saturday evening.

Lastly, we will continue to track forecast soundings through this weekend since this helps to give us an idea how the atmosphere will look above our heads if parcels of air were released. It shows temperature, winds, and dewpoints and how a parcel would react if lifted in that particular atmosphere. This forecast sounding shows favorable winds shifting from SE at lower levels to SW at upper levels which can promote healthy, rotating updrafts. It also shows a slight lid on our atmosphere which may work to inhibit convection. However, I believe the jet stream energy will work to break this cap and we will get convection to initialize.

NAM forecast sounding valid Saturday evening for near Lawton, Oklahoma

Here's what you need to know...

Timing: 2PM-overnight. Tornado threat greatest from 4-9PM. Large hail & damaging wind threat possible anytime.

We will likely see a broken line of supercells develop just to the east of the dry-line then track northeast. Any stronger storms may turn east a bit more.

All of Texoma has a chance of seeing severe storms.

*Have a severe weather plan in place in case a storm heads towards your location. Stay with SkyWARN 7 weather for updates through this weekend. We will have extra hands in studio and I will be out storm chasing while streaming video.

A few links to help you out.

http://www.kswo.com/
My SkyWARN 7 Radar Online
My Facebook Page
National Weather Service Norman