Wednesday, March 14, 2012

Strong Storm System Poised to Create Severe Weather Event Early Next Week

I am becoming increasingly concerned for the residents of the Southern Plains as the 12z GFS digs the storm system in question deeper than ever and emphasizes the ridge in the east stronger than ever.

First, let's take a look at the storm system. It is signified by the strong areas of vorticity in parts of the South Plains. There are things that make a storm stronger or weaker, and that is classified in tilts. A negative tilt is the most conductive for severe storms, in how a negatively tilted storm has cold air running over it. As we know, warm air at the surface rises in air cooler than the surface to make instability. If there is cold air running over the storm system, it increases instability and thus increases severe weather potential.
One can determine if a storm is negatively tilted by seeing the way the lines on this map are positioned. In this scenario, the storm system is negatively tilted, because the storm is almost trying to point to the southeast, according to the lines trying to point southeast.

Next, let's look at another big player in this potential severe weather outbreak, the ridge. For those who are unfamiliar with weather terms, a ridge is basically the fancy name for high pressure systems. Today, in comparison to yesterday's 12z GFS run, the ridge is stronger and further north. The increased strength means that more warm, moist air will be rushing north, meaning more potential to develop instability. This ridge is particularly strong and is nothing to fool around with.
Something I want to look for is a parameter called theta-e. In the simplest terms, theta-e indicates instability in higher values. There is a very large difference in theta-e between the system and the air being influenced by the ridge. This high gradient (difference) worries me, as high temperature gradients can often be the focus of severe thunderstorm boundaries.

Thirdly, I want to discuss wind shearing. As we all know, two objects being smashed together makes friction. This is as textbook as it gets- a storm system rubbing up against a strong ridge. When a strong storm system and a strong ridge clash, there is bound to be something 'interesting'. We will deal with that later. However, relating back to the friction part, the friction discussed earlier equates to wind shear in the weather world. Just checking out the wind barbs makes me know that this environment will have ample wind to make for a potentially tornadic situation. There are very high wind barbs present between the ridge and storm system. When you get lines on the image above shown in a vertical pattern, it is a very showy indicator of high wind speeds in the area.
There is one more piece on wind shearing I need to discuss with you. It is called Deep layer Shear, and is necessary for tornadoes. Basically, it is the difference in wind speeds between the 500mb level and the surface. I glanced over DLS forecast values in this timeframe and am honestly very concerned- values over 90 knots are possible. That is extreme. This just enhances the tornado potential in my eyes, which, judging by forecast rotation in the atmosphere, is worrisome.

You can see my new tornado forecast by clicking here to see the new TRIAD Tornado Model.


Long Range Severe Weather Risk Issued by SPC

The Storm Prediction Center has issued a Day 5 severe weather risk for the storm system I talked about in yesterday's post. Day 5 actually means 4 days away from today, since the National Weather Service and government agencies classify Day 1 as today, Day 2 as tomorrow, etc.
A thing I find pretty cool is how in line this is with what I predicted yesterday. Take a look:
I will have a full discussion out at 4:00 PM CDT Today.