It’s been a few days since my last post.  Part of the reason for the delay is because of work.  But the other reason is the lack of desire to talk about anymore snowstorms!  It’s not that I don’t enjoy forecasting and tracking snow setups, but I’d much rather talk about severe weather setups like thunderstorms and tornadoes.  I don’t think I’m alone with that notion.  The problem is it’s mid February and we are in a winter that doesn’t want to give up.  The cold keeps on coming  and it’s going to be tough for any severe thunderstorm setups of significance to occur anytime soon.

Having said that there is actually some potential for a severe thunderstorm setup on Sunday, February 21.  So I thought I’d talk about that.  The region of risk would basically cover the eastern half of Texas into the Arklatex region extending further east into the lower Mississippi Valley.

Thunderstorms are possible ahead of an arctic front that should be diving south into the Plains on Sunday.  Low pressure at the surface is expected to develop ahead of the front over Texas or the Arklatex region in response to a shortwave trough ejecting east from the Pacific.   Dewpoints in the lower 60s should advect northward from the Gulf of  Mexico into parts of east Texas and Louisiana.  500 mb  temperatures will be quite cold, approximately -20C in advance of the arctic front, which will be plenty cold to provide steep lapse rates, owing to CAPE values in the 500-1000 j/kg range.

Depending on the tilt of the shortwave and timing, there is the potential for severe thunderstorms across central/east Texas into Louisiana and possibly the lower Mississippi Valley on Sunday extending through Sunday night.  Typically linear thunderstorms and/or squall lines tend to develop ahead of cold fronts, especially arctic fronts.  But if a decent enough surface low develops over central to northeast Texas the dryline could come into play and bring the potential for more discrete storms.  There probably won’t be much, if any, directional wind shear, and right now speed shear doesn’t look that impressive.  So I tend to favor the development of a squall line right now..but it’s far too early to get into the details.

I’ll watch the computer models over the coming days and see how the timing and tilt of the shortwave looks.  But surely something interesting involving severe thunderstorms will happen on Sunday or Sunday night from Texas into the lower Mississippi Valley.

- Jim