With the 2017 chase season very likely wrapped up, I want to look back at how abysmal the year was for me. I had one real chase with just some structure to show for it. On the only other good chase days of the year nearby (May 18th and 19th), I was busy and unable to chase. May 18th (a High Risk bust in KS/OK) produced a brief tornado in Wabaunsee County, and May 19th featured multiple tornadoes in the heart of the Flint Hills. Go figure. Although 2017 has had 1,363 confirmed tornadoes so far (the most since 2011), there were only a few that were chase-worthy, and Kansas especially underperformed in terms of memorable tornadoes. I made a post at the beginning of 2017 about analog years and how 2017 might end up looking like, and had 1999, 2004, 2006, 2008, 2009, and 2012 as possibilities. 2009 and 2012 seemed to be similar years in terms of chasing, as there were very few chase-worthy events, especially here in Kansas. I’ll be making a post about the Top 5 Chase Days in 2017 later, but to give you a hint, only one was in May, which is the prime chasing month. Suffice to say, the 2017 chase season was quite disappointing for everyone, but for me in particular.
Now, let’s see what 2018 has in store.
The analogs seems to be conflicted, with some very good Plains years next to some terrible ones. Through the winter of 2016-17, we had a weak La Nina with a positive PDO. This upcoming winter looks to have a weak Nina with a neutral to perhaps negative PDO. The PDO going negative would be the best news for next year so far. The difference between the two winters is where the La Nina is located. Last winter, it was a “Modoki” Nina, where the coolest surface waters are closer to the central Pacific. This time, the coolest waters are much further east. It is hard to determine the effects this will have on our weather, but it could lead to a colder winter for areas north of the Mason-Dixon line, with warm and dry conditions for the Southeast.
Last winter was very active in terms of tornado events, with significant outbreaks occurring on November 29th-30th, 2016, January 21st-22nd, 2017, February 7th, and February 28th-March 1st. It was one of the most active cold seasons in recent memory. This winter does not look quite as active at the moment. There was a decent event on November 5th in Indiana and Ohio, but the rest of the month looks quiet for now. It wouldn’t surprise me if there was an event somewhere in the December 5th-20th timeframe, as the persistent eastern troughing may take a break, leading to a tornado-friendly west trough/east ridge configuration. However, it appears that an eastern trough through the winter may be common, with cold conditions for the eastern half of the country.
The question is this: How long does the eastern troughing hold? Does it break down in February or does it hold into late March or early April? This is one of the keys to the tornado season. The longer it holds, the less likely we are to have a good chase season. I feel that March and April will be the deciding months to the season; if the early part of the season is active, it will be a successful season, as it is entirely possible that May is anemic again.
My top 5 analogs for the season are: 1990, 1991, 2002, 2013, 2014. Brett Roberts, a storm chaser, created a ranking for chase seasons based on several factors (http://skyinmotion.com/weather/chase_season_rankings/). Using his rankings, we can group these in the three groups: Great, OK, and Bad.
1990 and 1991, and 2013 were great chase years. 1990 and 1991 both featured all-time great chase events, with both March 13, 1990 and April 26, 1991 among the most impressive Plains outbreaks on record. Both years also had other good events to keep chasers busy. 2013 featured one of the best 15 day stretches of chasing ever (May 15th-31st) with the 15th, 18th, 19th, 20th, 27th, 28th, and 31st all featuring well-documented strong/violent tornadoes. Although Roberts has 2013 as below average, the May 15th-31st stretch makes it into my “great” category. It’s interesting to note that the 2013 tornado season was far below average until late May, and the chase season was terrible both prior to May 15th and after May 31st. Any chaser would take 1990, 1991, or 2013 in a heartbeat, and in fact, on Roberts’ rankings, 1990 and 1991 were two of the four best years in chasing.
2014 was an OK chase year. The year was very quiet until April 27th, which had the infamous Vilonia, AR tornado, along with several more chaseable tornadoes in SE KS. May 2014 was abysmal. However, June 16th-18th made up for it. The mesmerizing Pilger, NE tornado family of June 16th was an unparalleled spectacle. June 17th featured a monstrous, slow-moving tornado near Coleridge, NE, while June 18th had multiple tornadoes in eastern SD, including the scary-yet-beautiful Alpena, SD EF4. If you chased June 16th-18th, it was a great year, but if you didn’t, it was an awful year.
2002 was pretty bad. April 17th featured a decent event in NW OK, but most of the month of April was pretty quiet. May 5th and 7th both had good events in KS and TX, but again, it was not the best month. June 23rd had the only violent tornado on the Plains, near Aberdeen, SD. Overall, 2002 was pretty quiet with a few decent events here and there, making it into the “bad” category.
As of now, my thoughts for both the cold season and the Plains chase season are as follows: mid-December could see a tornado event, perhaps in the mid-Mississippi valley. January will be largely quiet, with a return to tornadic activity in February, but probably not too significant. March and April could be pretty active, while May could be below average. June will be a month to watch, as above-average activity may make the season. Overall, I’m not very optimistic about 2018, but until June, hope remains.