Stormy Outlook Across Midwest & Southern U.S. in March After Cold February Conclusion

After the regional severe weather event that brought a few tornadoes and big hail to parts of the Ohio Valley on Thursday, February 19th, we've slipped back into a familiar winter pattern across the Central and Southern U.S.

Ridging in the west with troughing in the east has sent another wave of cold air spilling into the Midwest, feeding into a Nor'easter that delivered blizzard conditions to New England. I'm happy for East Coast snow weenies, but after tasting the warm inflow of a supercell thunderstorm last week I'm not so tickled by the flurries being blown around in a chilly Wind Advisory out my window this morning. Another clipper system has the potential to deliver a stripe of 1-2" of new snow across the area tomorrow night.

Forgive me for looking into the future a bit this morning...

Long-range forecast models are beginning to hone in on the first 1-2 weeks of March as a period of transition where we may see an upper-level disturbance currently located over the Pacific Ocean slowly progress eastward into the southwest U.S. coinciding with an expanding area of high pressure colocated over the Northeast U.S.

Ridge west, trough east = shots of cold air, dry conditions across the central U.S.

Upper-level low over the Pacific moves ashore in the first days of March.

Some influence of approaching upper-level trough in the first days of March, but more significant impacts probably begin after March 5th.

Southwest flow around the first weekend in March, but how intense? How impactful?

Current ridge west, trough east alignment sends cold fronts crashing down to the Gulf Coast keeping the Central U.S. dry.

Troughing sneaking back into the western U.S. with high pressure moving east would open the Gulf back up to northward moisture transport.

I'm a little skeptical about the current look, where it appears this trough is somewhat displaced from the main northern branch of the jet stream running across North America as this introduces some uncertainty around timing, the speed of the trough ejection, and the reliability of its ability to dramatically influence the pattern across the U.S. An eventual link between this southwest U.S. trough and troughing over northern and western Canada could lead to a more permanent, and more significant feature leading to a prolonged period of stormy conditions across the highlighted region deeper into March. Failure to link, and a weaker sub-tropical jet influence may limit northward moisture transport and the overall efficacy of this trough.

That being said, across the board long-range guidance from the EPS, GEFS, the European and GFS weeklies, and the European and GFS AI models are highlighting increasingly wet conditions from the Red River to the Ohio River, or from Texas to the Great Lakes in the first ten days of March.

Diving into the ensembles a bit more it looks like this transition may trickle to a start, with a gradual ramp up in storminess in the first week of March, perhaps culminating with a bigger system or two around the first weekend of March, or March 6-9. A not insignificant amount of the individual ensemble members from the EPS and GEFS are really opening up the Gulf to northward moisture transport and are depicting some rather volatile, unstable warm sectors associated with these hypothetical waves. Diving into individual ensemble members has its limitations, but can be nice for taking an early look at "okay, if this happens, what sort of environments are we talking about?" and the early look is "if this happens, we could be talking about seasonally volatile environments that have plenty of instability which combined with seasonally strong wind shear and upper-level dynamics could result in significant, widespread severe weather risks".

You don't make plans based on individual ensemble members, but you definitely take note when multiple members are lofting volatile warm sectors with 2000+ j/kg of CAPE northward into the Midwest ahead of a dynamic storm early-season system.

So, without getting too hung up on specifics it is simply worth pointing out that as we get closer to early March the signal for wetter than normal conditions continues to increase, and I'm starting to see some early signs pointing toward a potential run of severe weather events from the Southern Plains into the Lower & Middle Mississippi Valleys in early March with the potential that this risk could linger deeper into the month.

If I had to call my shot, I'd watch the period from March 5-10 for a return to organized severe storms from Texas to the Great Lakes.