Exciting news

I have been able to snap some pictures of a supercell-style storm cell near my house. Pictures will be posted tomorrow!

Severe Weather Outbreak Possible Early Next Week

I am increasingly becoming worried over the potential for a serious severe weather outbreak early next week as a strong storm system will eject into the Southern Plains and crash into a mega-ridge of high pressure.

The 12z GFS is really pushing on the storms to become elevated, with over 40 knots of deep layer shear evident over the storms breeding grounds. At the same time, at screaming jet stream, speeding along at over 100 knots, will be overhead, greatly aiding in the tornado threat. What is also a big player is the Low level Jet stream (LLJ). The LLJ will be going at over 60 knots directly overhead the storms, which worries me because this would likely enhance the tornado threat.
Instability on the 12z GFS is kept to 2000 j/kg tops, with a better likelihood of 1250-1500 j/kg of instability. This is considered sustainable for severe storms, but not the strongest of them. A potential weakener of the storms is a cap of warm air that is called CINH, or Convective Inhibition. The 12z GFS is printing about 100 to 300 J/kg of CINH, which would likely hamper some storm development. However, a sharp surface theta-e temperature gradient should be sufficient to ignite thunderstorms without too much intervention from any CINH.

The NAM is printing EHI values (a good tornado indicator) at over 3 in Texas, which is astoundingly high. I am not surprised, as the TRIAD Tornado Model has been predicting this to be a pretty dangerous situation for the past couple days.

I have been poking around in the Storm Prediction Center's SREF ensembles, and have come to find that this afternoon's TRIAD tornado model looks pretty in line with the other models and ensembles. You can click here to see the latest output.

Sunday will definitely be a Storm Action Day. I can tell you that now.
I am also considering running a special TRIAD model run for Sunday's storms. It would be focused in on the Plains and run every few hours.

-Andrew

Notices for March 15, 2012

- There will be no new post on the potential severe weather in the South Plains today. The one from yesterday is still valid today.

-There will, however, be a new TRIAD Tornado Model forecast out at 4:00 PM CDT.

Info on TRIAD Tornado Model

As mentioned on the Facebook page, I have added a key and indicated that a new forecast will be issued once a day. The forecasts will be issued at 4:00 PM CDT on weekdays, with TBD times on weekends.

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.

-Andrew