Early Thoughts on the 2021 Storm Observation Season

Some early ideas on 2021 storm season, copied over from social media.

La Nina/PDO- combination means we're in for a banger, right? Adding AMO+ (or removing AMO-, rather) leaves us with some eye-popping analog years, and the composite background state certainly has some similarities when compared against the top 3 severe weather producing seasons of the last 20 years. But, there are problems with the 2021 = 2011 comp. Call it a 2011 PRO or 2021 CON, but the anomalously strong, sustained SW flow of 2011 is not likely to be repeated in 2021. In fact, a peek at current SST brings up questions with the strength of the PDO- impact in 2021.

Getting to the point, I think there are reasons to think the 2021 spring storm season is active at least in spurts especially in the red highlighted region of the Ohio and Lower/Mid Mississippi river valleys. The Gulf of Mexico figures to be open for business & the sub-tropical jet is coming to life.

It's the warm tongue in the Pacific that sets 2021 apart from being a clear-cut La Nina/PDO- screamer to me. We're almost certainly staring at periods of split-flow and a weaker polar jet. Open Gulf + sub-tropical jet life + the polar jet at times playing nice gives me hope for bursts of life.

The first such burst of life could be just around the corner with some early active signals appearing in mid to late March. Perhaps split-flow concerns are removed in coming weeks, perhaps they're validated. For now, I'm hopeful, but still mostly just curious.

"Final" thoughts next week.

Indeed, ensemble forecasts continue to point toward a period of favorable conditions for severe storms in the central United States in mid-March. I'm growing keen on the March 10th - 20th frame.