2018 severe wx/chase season discussion

[JamesCaruso]

Well I guess some data have come in to support the message: https://www.wunderground.com/news/2018-02-06-winter-severe-weather-least-in-years

The good news is the article also mentions how active the previous year's winter was, and we all know the 2017 chase season sucked, so when looking at this winter hopefully there is an inverse relationship to chase season, or (at worst) no relationship at all.




Sent from my iPhone using Tapatalk

 

[Jonathan Beeson]

There may be an awakening ahead on the Euro for areas E of I-35. Not exactly optimal chasing terrain, but this may be the first decent setup of the year. Very sharp trough with a well positioned SE ridge coupled with a strong LLJ response..

[Broken External Image]:http://maps1.pivotalweather.com/maps/models/ecmwf/2018021500/120/500h.conus.png

[Broken External Image]:http://maps1.pivotalweather.com/maps/models/ecmwf/2018021500/120/850w.conus.png

 

[Jeff Duda]

The good news is the article also mentions how active the previous year's winter was, and we all know the 2017 chase season sucked, so when looking at this winter hopefully there is an inverse relationship to chase season, or (at worst) no relationship at all.

You would be best to assume there is little to no correlation between general t-storm/svr activity during the winter and during the subsequent spring. You're not going to be able to make any skillful predictions based on this. Too much noise in the signal, and too many other factors that impact severe weather activity in both seasons that themselves are not strongly correlated (between seasons).

 

[Drew Terril]

I looked at some past drought monitor maps, and it appears there is little correlation between Plains precip through mid-February and the quality of the following chase season. You could say that no-drought conditions might increase the odds of a good season (IE 2010 and 2016), but 2013 and 2011 don't fit that mold. Source: http://droughtmonitor.unl.edu/Maps/MapArchive.aspx

View attachment 16620

View attachment 16621

This is great info Dan! Thanks for posting this as I'd always thought there was more of a correlation between the two. Clearly my thinking was wrong.

 

[Andy Wehrle]

Well between tomorrow and later next week, looks like things should at least be picking up to where they should be for the end of Feb./early March with modest to moderate severe potential from the lower MS Valley east to the mid-South/Dixie Alley

 

[Taylor Wright]

So far through Feb. 25th, preliminary counts show us riding somewhere around 30th percentile. Looks like a slow start but GFS shows that could change soon with more southeast junk in the coming weeks.

 

[Jeff Duda]

Noise vs. signal. Tough to tell with so small a sample size and so early in the year. It only really takes one event to launch the seasonal count from the 25th to the 75th percentile at this time of year.

 

[Robert Pickard]

I've only had one thunderstorm here, and one tornado warning(at night) for the northern part of the county, (which I avoided because at night you can't see anything). Only 5 lightning strikes all year lol...
It'll pick up, I hope..

 

[Jeff House]

If Birmingham does a survey we can tack on 1-2 more tornadoes in northwest Alabama Feb. 28th. Low levels did not looked backed enough but the two cells were turning hard right. Somebody over there documented and tweeted TOG. It was oddly close to my Aug. 31, 2017 intercept mile marker 30 Alabama I-22.

 

[Todd Lemery]

http://www.ustornadoes.com/2018/03/01/spring-2018-seasonal-tornado-outlook/

This is just another bone to throw on the pile. I’m feeling pretty positive

 

[Andy Wehrle]

They note 2006 as a "notably active exception" but that is almost universally reviled as one of the worst overall chase seasons since the turn of the millennium. Most of that activity was in the jungles, and it shut down after April 15. May was dominated by a cool eastern trough.

Based solely on my arm chair knowledge of meteorology/climatology, ENSO is overrated as a predictor of US tornado activity and chase season quality. PDO/PNA seem to play a far bigger role, although the details as to how and why are beyond the scope of my knowledge.

 

[Andy Berrington]

They note 2006 as a "notably active exception" but that is almost universally reviled as one of the worst overall chase seasons since the turn of the millennium. Most of that activity was in the jungles, and it shut down after April 15. May was dominated by a cool eastern trough.

Save 2013, the years listed in that analog composite are basically a smorgasbord of generally terrible chase seasons, especially in May. Also, the stubborn +PDO has been on yet another rising trend over the last three months.

 

[Brandon Centeno]

Here’s hoping the upcoming (big) decline in AAM will yield quality events. Quite the signal there for a propensity for western US troughing.

 

[Jeff Duda]

Moderator note

Since this thread is evolving into the typical "state of the season: YYYY edition" type thread, I have gone ahead and renamed it thusly. Keep the good discussion going!

 

[Brandon Centeno]

Interesting, if not impressive agreement from a week out on western US troughing by the GFS, ECMWF, and CMC.



Obviously each of the three have their differences, but there should be relatively high confidence in some degree of severe threat evolving over some portion of the plains, especially due to the increasing confidence low-level moisture will be in abundance. Looks like an eastern Great Plains event could be on the way.

From an analogue sense, there seems to be a signal of enhanced predictability, given spatial probabilities associated with fcst pattern:

Lines up nicely with where the threat area likely will be should the major models hold. Using a threshold of a minimum of 1 tornado report:




Certainly, this event bears watching. Even though the upcoming amplification of the east coast pattern blasts the gulf with a cold front, the extremely warm gulf SSTs, and more importantly, a favorable large-scale pattern evolution looks to allow an abundance of moisture into the plains. When you get favorable moisture return in the early season paired with an impressive mid-upper level system, big things can happen.