Friday, March 30, 2012
Severe Storms Possible Northwest of Dallas
There is a conditional chance of severe storms across parts of North Texas and Southern Oklahoma this afternoon. Forecast sounding near Wichita Falls show showing an extreme amount of instability that could lead to explosive thunderstorm development later this afternoon. The one ingredient lacking to prevent this from being a major severe weather outbreak is forcing to give lift to surface parcels which would in turn cause the storms to develop.
A dryline will be advancing eastward across northwest Texas later this afternoon. This could provide enough forcing to allow one or two isolated storms to develop, especially near the intersection of the thermal axis and moisture axis.
We can also see that surface moisture is forecast to be converging along the dryline which give added belief in the threat of thunderstorms development.
Now all of the area is under extreme instability with LIs running between -11 and -14 across all of north Texas and southern Oklahoma.
Over the same area however, there is a small cap. The lid strength index is positive over most of the area, greater than 0°. Usually a lid strength index less than 2° shows there is a chance the cap will break and allow scattered storms to develop. However, with the extreme lack in forcing the cap could very well win out today. There is forecast to be a small upper level disturbance move across this region later this afternoon. This could be just enough lift to take advantage of the extreme instability available.
Many times a weakness in the cap develops near the nose of the low level lapse rate axis. If this occurs today isolated storms could develop very close to Wichita Falls later this afternoon.
If storms do develop they will do so in an environment that is not only conducive for very large hail, overall high instability, but they could also produce an isolated tornado. The amount of 0-3km CAPE is approaching 200 J/kg in a few areas which will provide plenty of stretching potential of Strom Relative Helicity which could lead to tornadogenesis.
There does appear to be just enough low level storm relative helicity to introduce a tornado threat as well. So the next few hours will determine what if any storm can develop and whether or not I will be making the four hour drive to see what Mother Nature has to offer.