State of the chase season 2020

Randy Jennings

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May 18, 2013
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Too soon to start a 2021 thread, but there is now a La Nina watch and there has been some studies that suggest an increase in southern plains tornadoes and hail storms in La Nina Springs.


 

Dean Baron

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Sep 25, 2006
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I think it's safe to say Canada has taken first place in photogenic tornadoes this year. Still a couple weeks left for some stuff to happen in the northern plains but that is far from a guarantee.
 
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Jul 5, 2009
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^ Not sure why they say “chances not that good,” probability is 48% which is not that much worse than a coin flip. True it’s more likely than not there will be a tornado before year-end, but there is still a significant chance there won’t be.
 
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Aug 9, 2012
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There have been some decent outbreaks in October/November in that part of Kansas in previous years (Nov 27 2005 cold core comes to mind) and then October 6 2016 as well. There was a big outbreak back in 2001 as well in October. So I don't think its out of the cards that we could still see some tornado activity in the ICT area before 2020 ends. Its not ideal and doesn't do much to improve our perspection on this chase season, but hey its something to look forward to.
 

Mark Blue

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You took the words right out of my mouth Ethan. We still have the second season before we write 2020 off but I'm also not too confident that it'll change. Climatological persistence has a way of negating what us chasers want in the form of patterns that aren't conducive to severe weather. Fingers crossed at this point!
 
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Drew Terril

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You took the words right out of my mouth Ethan. We still have the second season before we write 2020 off but I'm also not too confident that it'll change. Climatological persistence has a way of negating what us chasers want in the form of patterns that aren't conducive to severe weather. Fingers crossed at this point!
This has been my hope. I generally do well in second season as it is, so I'm hesitant to give up at any point through the end of the year. One thing that I'm hopefully will help is the amount of rain that we've had this summer. I don't remember the last time we were mowing weekly this late in the summer in Oklahoma, usually the grass is nearly dead by now. So there should at least be moisture to work with as we get further towards second season.
 

Jeff House

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Well the NAM shows a mini-sup fest in West Tenn. It's Friday at 57 hours, so maybe LOL, but surely too early to call the season over.

Other models have similar favorable wind fields, and cells turning slightly right of the mean low level flow. Clearing for a quasi-dry area and instability is the question Friday.
 
Jan 7, 2006
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As we slide into the beginning of the so-called second season, an abysmal pattern dominated by deep eastern North America troughing looks to take hold starting next week, right on cue.

Through all the discussion of worst years on record this spring, there were a lot of comparisons to 2006, and people frequently mentioned that the fall was relatively active that year to help compensate. By this point, we'd already seen a well forecast regional outbreak in SD and MN on August 24:

There were at least couple more respectable Plains tornado days on September 16 and 21, plus the KS cold core event in late November.

Regardless, it looks likely that we'll miss out on any easily-forecast tornado events during the late August/early September period that can sometimes feature high CAPE and slow moving storms more in the vein of June setups. The march toward "worst year since 1988" for Plains setups that can be foreseen and chased without biting on every 2% chance is very much on track, in my opinion.
 

Jeff House

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South-Central Kansas is close to a record low tornado activity. Guess covid year is a good one to use on such a severe wx anomaly.

Separately the Dixie Alley above anomaly is not really welcome. Tornadoes here seem to impact people so much more.

Next trough is really squirrelly. I had high hopes for something in the Midwest; but, looks like a poor evolution. Still have time to improve.

There's always Dixie recurving TCs. Hate to wish for hurricanes, but hey we don't control it. Remnant low needs to be moving east like Harvey or Laura. Anything still going northwest I pass.
 
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Todd Lemery

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I haven’t seen this map before. It does confirm what we all knew was going on in Kansas this year. Nothing. It’s surprising to me that SD and Minnesota are running below average too. It seemed like it had been a pretty busy place this year.
Looking farther out past this weekend, I’m really not seeing anything coming down the pipe that’s getting my hopes up. GFS is showing this moisture getting cleared out of the plains until the middle of the month. Ugh
 
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Oct 10, 2004
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So, what happened?

PDO has finally gone negative which for a long time was chalked up as the big reason we couldn't get a proper central US tornado season for most of the 2010s. ENSO has been hovering cool neutral to weak La Nina although its influence on tornado potential is nebulous (some say La Nina is favorable and point to years like 2008, 2010 and 2011, others say it's unfavorable because it leads to drought).

For most years after 2011 (which wasn't spectacular in the Plains, either) large portions of the spring were wasted to a locked-in unfavorable longwave pattern (either lingering E CONUS trough/Polar Vortex/extended winter; or gigantic death ridge primarily in 2012). In 2019, we got the much-anticipated favorable longwave pattern in the second half of May, but the setups were consistently borked by subtle (unresolvable by models in the medium to long range) synoptic scale quirks that led to issues with initiation timing, storm mode, and capping.

What's it gonna take to get another year like a 1979, 1981, 1991, 1995, 1999, 2003-04, 2008 or 2010? With at least sporadic bursts of activity throughout A/M/J, spread throughout the Plains and Midwest?
 

Jeff House

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Next spring the Plains needs a proper TNI Trans Nino Index. The TNI has been shown to correlate better than straight La Nina.

Proper ocean SSTs would be Nina lingers over most of the Tropical Pac. Little warming by South America, but keep the Basin overall Nina.
 
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Jul 5, 2009
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What's it gonna take to get another year like a 1979, 1981, 1991, 1995, 1999, 2003-04, 2008 or 2010? With at least sporadic bursts of activity throughout A/M/J, spread throughout the Plains and Midwest?
When I first read that sentence my thought was to look at when I started chasing (1996) and count the good years listed - and felt disgusted that there were only 5, out of 20+ years of chasing.

But the 20 year span from 1979-1999 also only has 5. So is it no worse than it's ever been, and it's only our collective impression based on recency bias? Or is it just that, yeah, there's always only 5 great years out of every 20, but the 1979-1999 span still had many more decent seasons than 2000-2020 span? I don't know enough about the 1979-1999 stretch to answer that.
 
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Jan 7, 2006
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The consensus NWP forecast for OKC's temperature at 7pm next Wednesday is currently around 50 F, including a 48 F vote from the ECMWF.

models-2020090412-f132.sfct.us_sc.gif

Meanwhile, the record cold high for the date is 67 F, based on over 120 years of records. If it were occurring one day earlier, the record to beat would be 73 F. If the guidance is even in the right ballpark, this record will be shattered by a margin of 10-15 F.

While purely anecdotal, it is remarkable how often lately, despite the background of a warming global climate, we have seen truly anomalous cold during the warmer portions of the transition seasons in the central U.S. This has certainly been a common anecdotal complaint in our commiseration threads the past few years. I believe the CO contingent has been especially vocal about this, and they may be about to see a disruptive snowstorm at Denver's elevation before September 10.

It's so early in the fall that there's theoretically plenty of time for moisture recovery and a pattern change prior to the late September-mid October timeframe, the historical peak for second season setups in NE/KS/OK/TX. Regardless, it's depressingly stunning how easy it's been to come by big anomalies (whether synoptic or seasonal in time scale) that work against us.
 
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While purely anecdotal, it is remarkable how often lately, despite the background of a warming global climate, we have seen truly anomalous cold during the warmer portions of the transition seasons in the central U.S. This has certainly been a common anecdotal complaint in our commiseration threads the past few years. I believe the CO contingent has been especially vocal about this, and they may be about to see a disruptive snowstorm at Denver's elevation before September 10.
I hope this is not too far off topic, but there are several research articles that conclude a warming earth, particularly the Arctic, leads to a "wavier" jet. I would conclude that based on those findings, we would experience more frequent, anomalous weather swings like one forecast this upcoming week, and I would also think that would generally be more favorable for severe setups over time, but that really hasn't been the case...

I know that it takes more than an active jet to produce an ideal setup, but you'd think things would fall into place more than they have been. Either it's just a streak of "bad luck", or there's something bigger afoot, as has been alluded to in other threads and earlier in this one, I think.
 

Jeff Duda

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The broad consensus I have seen on various listservs and on social media is that this upcoming pattern shift is largely the result of Rossby wave amplification resulting from the extratropical transition of one or two Pacific tropical cyclones. As soon as their "energy" is "absorbed/used" the pattern appears to settle back down somewhat. In fact, I wouldn't be at all surprised to see a return to the existing dominant summertime pattern two weeks from now.

So this seems to be more of a chance event rather than a sense of a longer-term signal.
 
Oct 10, 2004
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I believe the synoptic pattern that led to the November 2013 tornado outbreak was partly attributed to the recurvature of a WPAC typhoon (possibly the infamous Haiyan). Obviously this setup isn't expected to lead to anything like that. Haiyan also tracked much further south than Haishen is, striking the Philippines/Vietnam rather than Japan/Korea.
 
Apr 23, 2016
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Not a whole lot to like about heading into winter with a spatially expansive western drought and enso drifting back into a weak nina, neither of which seem to bode well for the following plains season. Years that headed into the winter with these conditions were overwhelmingly poor(notable examples from the past decade include 2018, 2014, 2012, and 2017 to an extent) and do not have me optimistic for good plains activity in 2021. Weak ninas seem to favor BA plains activity in general, whether or not drought is present during the preceding winter. This is the earliest I think I've ever really talked about an upcoming season and as such, this is a very obtuse analysis that is barely scientific, but something I thought might be worth sharing regardless.

Those are the key features I'm watching over the winter. How the nina evolves(where I think a stronger nina probably ends up being better in general) and the extent of the drought. My guess is that due to the nina, no matter it's strength, the current expansive drought struggles to weaken and probably expands markedly, but who knows.