The overall weather pattern in the middle part of the country looks to become one that is more conducive to the formation of severe thunderstorms by late this weekend and early next week.
A significant trough of low pressure moves into the Rockies late in the weekend and progresses eastward next Monday and Tuesday. This will provide the upper level support needed for the possible development of severe storms. However, the surface will be a little slower to come around. On Sunday, a dryline will be established in the High Plains, but there will still be significant surface high pressure ridging across all, but the extreme western Gulf of Mexico. This will effectively limit the return of significant, deep surface moisture on Sunday. So, we end up with the prospect for some high-based thunderstorms. Still, shear will be decent, so we will need to watch the moisture and if it ends up being a little more than I think right now, we’ll have to entertain the possibility of a landspout or two. This has been the case a couple of times this season already, as the atmosphere has had the ability this year in the Plains to overachieve on quite marginal days. So, Sunday is definitely in play in terms of being a potential storm chase day.
Monday, however, looks much better. The central and western Gulf of Mexico opens up as the ridging moves east. There should be a healthy flow of richer surface moisture for about 12 hours begining Sunday night and continuing through Monday. Still, this will not be the favored Caribbean trajectory that tends to lead to major severe weather outbreaks in Tornado Alley, but moisture should still be adequate for a significant severe weather event given the favorable shear and upper level support. Nebraska, Kansas, Oklahoma and Texas are in play in terms of severe thunderstorms with large hail, damaging winds, and a few tornadoes. One thing that will need to be watched, and could impact the southern extent of the threat, will be the elevated mixed layer (EML) or cap. I think that capping is going to be an issue with most system this spring, but details will not be resoved on this until the actual day of the event.
On Tuesday, March 24th, the focus for severe weather will be shifting eastward into IA, MO, IL, IN, AR, LA and eastern TX. The best upper support lifts northeast, away from the best instability. However, I think enough instability and shear will remain to promote severe thunderstorm development from the MO Valley into the Arklatex region. This day as well appears to be a chase day for local chasers in that region, however, it is not something that I think many Plains chasers would follow unless they totally busted on Monday.
It must be cautioned that as of the writing of this blog entry, we are still four to five days away from this possible severe weather event. Timing of the system could be off by a day either way.
I will certainly be keeping a close eye on this, and posting on it regularly in the coming days.