Active Weather Pattern Developing

After a few isolated severe thunderstorms over the past couple of days, a prolonged active weather patterns appears to be underway.

Today and tomorrow (May 20-21):
An upper level shortwave moving across the upper Great Lakes will help trigger scattered thunderstorms, some of which may be severe. Today the focus is around the Chicago area, but then the threat shifts east-southeast toward the Ohio Valley and mid-Atlantic region for Wednesday.

Thursday and Friday (May 22-23):
A developing ridge across the southern Plains and Southeast will bring hot and humid conditions to a large portion of the country. On the western periphery of this area, there will be an enhanced fire danger, along with a few isolated thunderstorms. The severe threat here appears limited at this point, but the threat is non-zero.

Saturday through Tuesday (May 24-27):
As an upper level low ejects east from the Southwest, it will interact with the ridge that was previously in place. The stage is set with hot, unstable conditions in place and increasing wind fields aloft to kick off some severe thunderstorms. It’s the slow moving nature of the trough that will stretch this threat over several days. The Euro and GFS have been coming into better agreement with how this setup may evolve. Some severe storms could develop across the eastern Rockies and portions of the western Plains on Saturday, but if I had to pick a “highest risk” day at this point, it could be Sunday. With an increasing low-level jet (winds just 5000-6000 feet above the ground) and a dryline in place, portions of the Texas and Oklahoma panhandles could see scattered severe thunderstorms. Beyond that, the threat may advance east across the Plains early next week.

It should be noted that it’s only Tuesday, so a lot can continue to change with this ever-evolving forecast. At the very least, the next week or so looks fairly active with at least a few strong to severe thunderstorms each day. It’s the upper level trough later this weekend and early next week that needs to be watched.

For a quick look at some analog guidance, mid-June of 2006 is a fairly decent match to what the current model data is predicting. That setup yielded a moderate risk (by SPC) severe event on the 16th with four tornado reports. For day-to-day comparisons, 6/15-18/2006 can be paralled with 5/24-27/2014. The June 2006 “event” began with isolated storms on the 15th, peaked on the 16th and began to weaken as it continued eastward on the 17th and 18th.