State of the Chase Season 2021

[Michael Gavan]

For the last few years I've done a forecasting video based on analogs, patterns, sorcery, etc. Here's a not-so-serious forecast for what could happen in the plains this year and the deep south.

TL; DW: 2011, 1971, 1965, 1955 are my primary analogs. Very active along the I35 cooridor east all the way to Georgia. High plains are 50/50, leaning toward less active or even downright quiet.


Side note. If we make it to May 21, 2021 without an EF5, it will break the record for longest F/EF5 drought. (May 3 1999 to May 4 2007)

 

[Andy Wehrle]

Well, certainly if any set of analogs is primed to break that drought, that's the one!

 

[Andy Berrington]

Regardless of any positive signs, man the climate models for AMJ are just resoundingly bad. Not even going to bother posting them, but the consensus from the ECMWF/NMME/CANSIPS/etc. is for another very dead season with a poleward retracted jet (even starting in April this time) along with some serious drought problems given torching temperatures and a lack of precip.

 

[adlyons]

Regardless of any positive signs, man the climate models for AMJ are just resoundingly bad. Not even going to bother posting them, but the consensus from the ECMWF/NMME/CANSIPS/etc. is for another very dead season with a poleward retracted jet (even starting in April this time) along with some serious drought problems given torching temperatures and a lack of precip.

Definitely seeing some not great signs on the jet position from the long term models. The one plus is it looks like a good bet for Gulf of Mexico and western Atlantic SSTs to be well above normal again. A stronger Atlantic ridge might not hurt. I still think this year ends up as a crap shoot. Im sticking with my gut which says below normal numbers again this year. The one thing I can say for certain is theres not going to be anything to chase for at least a few weeks with this cold air death surge. Damn Canadians! jk.

 

[Andy Berrington]

Definitely seeing some not great signs on the jet position from the long term models. The one plus is it looks like a good bet for Gulf of Mexico and western Atlantic SSTs to be well above normal again. A stronger Atlantic ridge might not hurt. I still think this year ends up as a crap shoot. Im sticking with my gut which says below normal numbers again this year. The one thing I can say for certain is theres not going to be anything to chase for at least a few weeks with this cold air death surge. Damn Canadians! jk.

I know I'm a tornado history guy and all, but it'd be nice to have some... you know... current tornadoes to analyze and/or chase.

 

[Andy Wehrle]

I know I'm a tornado history guy and all, but it'd be nice to have some... you know... current tornadoes to analyze and/or chase.

Right?!

 

[adlyons]

Just posting for visibility and discussion. Accuweather and company seem to be hedging towards a traditional la Nina spring with the drought taken into consideration. As others have mentioned this is a bit of a 'tweener Nina' in terms of strength and the rapid sring decay. So not sure I buy the 2011 comparison as much, but interesting nonetheless. https://www.accuweather.com/en/weather-forecasts/accuweathers-2021-us-spring-forecast/893237?utm_campaign=accuweather&utm_content=&utm_medium=social&utm_source=twitter

 

[Todd Lemery]

The link isn’t working for me. Anybody else?

 

[Warren Faidley]

Correct me if I'm wrong, but I believe Accuwx incorrectly predicted an active spring (tornadoes) last year?

 

[Jeff Duda]

Off-topic, but I see AccuWeather's seasonal forecasts as akin to throwing shit against the wall and seeing what sticks.

I don't think there's any reliable way to predict activity level of the spring tornado season beyond aggregate statistics, but we're heading into spring with massive drought in the southwest (although, parts of NW TX, W OK, and W KS have escaped the bad stuff), so that can't be great. Could be looking at strong caps.

Worst part is the synoptic pattern, though. That's what hosed 2018 and 2020. I don't see how that can be predicted at this length.

 

[Warren Faidley]

It's important to consider there are multiple chase seasons, not just "one size fits all."

I break them down into: "Winter season," generally in the SE states in January February and early March. "Early spring season" starting in late March to Mid-April. "Mid-spring" (the traditional chase season) from late April though early June. "Late-spring and early summer" running through mid-July. There are isolated events for the remaining months and one could argue for a "Canadian season" since things seems to be shifting further north every year.

Each season has it's own climatology and "x-factors," complicating "broad-brush" forecasts. I've seen seemingly "bust" seasons saved by robust Colorado-sets up in June. I've also seen insane set-ups in Western Texas killed repeatedly by strong caps. Trying to forecast, for example, when and if the Hudson Bay Low will form or recovery times for Gulf RH is impossible this far out.

2021 is likely going to be another year where you have to remain flexible if you can, picking out the few early gems (e.g., Midland last year), and rolling the dice for an active week in May or June. Or, move to Canada.

 

[Jeff Duda]

I disagree with the notion that there are distinct seasons for severe weather. There is a distinct peak of severe weather/tornado activity in the spring months across the US with a monotonic increase and decrease leading to and going away from that time. The "fall hump" is statistically barely distinguishable from the rest of the year's annual cycle. What actually changes other than the frequency of severe weather is where it occurs. If you want to argue that seasonality is implied by region, then fine. But the transitions are smooth, statistically speaking.

 

[adlyons]

The link isn’t working for me. Anybody else?

Sorry, I messed up the link here it is. https://www.accuweather.com/en/weather-forecasts/accuweathers-2021-us-spring-forecast/893237

 

[adlyons]

Off-topic, but I see AccuWeather's seasonal forecasts as akin to throwing shit against the wall and seeing what sticks.

Pretty much my thoughts about it lol. Posted more for fun than anything else.

 

[Andy Wehrle]

Off-topic, but I see AccuWeather's seasonal forecasts as akin to throwing shit against the wall and seeing what sticks.

I don't think there's any reliable way to predict activity level of the spring tornado season beyond aggregate statistics, but we're heading into spring with massive drought in the southwest (although, parts of NW TX, W OK, and W KS have escaped the bad stuff), so that can't be great. Could be looking at strong caps.

Worst part is the synoptic pattern, though. That's what hosed 2018 and 2020. I don't see how that can be predicted at this length.

Perhaps that strong EML, while resulting in a "too strong" cap for the Southern Plains, could result in a more "ideal" EML further north/east (AKA MBY and parts of IA/IL/MN) where a more common failure mode is the lack of a sufficient one to prevent early initiation/MCS mode. But, that still requires we not flip right from "extended winter" in April, to the jet being in Canada.