The best time and place to chase (revisiting an old question with stats)

[Dan Robinson]

Most of us already know that to see tornadoes, ideally you have to "jump" when the atmosphere says "jump" - that is, chase when the conditions come together. It's also already common knowledge that late May is the climatological peak, but how useful is that to the fixed-date vacationer that has to schedule his or her chase trips many months in advance?

I have kept stats on tornadoes and tornado days per state, month and year, and thought I would share how these numbers confirm the climatological "prime time and place": May 15-31 in Kansas. I keep a stats page here: http://stormhighway.com/tornado_chasing_stats.php

Kansas in late May blows away every other state and calendar period in every one of my personal tornado metrics: total number of tornadoes, total number of tornado days, total photogenic tornadoes and overall success rate (number of tornado chase days that resulted in a tornado day). The whole point of this is to suggest to the chasers who have to plan ahead and/or only have a limited number of days to use: fly into Kansas City or Wichita, and take your vacation during the last half of May.

Some years, of course, this period will bust (2006, 2009, 2012, 2014, etc). However, if you are able to chase for at least three seasons, the late May period in Kansas should virtually guarantee that you'll get at least one high-quality day (providing you target correctly).

Again, this isn't news to longtime chasers - but might be helpful for newcomers.

 

[Michael Snyder]

I have to pick my chasecation for the most part, in October of the previous year.
I also choose late may, this year I'm taking three weeks, and going for late May into early June. I've seen great Tornado days: Eads, Colorado, Moore Oklahoma, Lacrosse Kansas, and chased May 21-26 this year (12 Tornadoes) all picking Chasecation dates the previous fall,
so it can be done.

 

[Jeff House]

Second half of may is hands down the best time to chase. Hard to express how strongly I agree with May 15-31. Days like Pilgner or the oil rig video make one think about June, and some states peak June; however, the places than peak in May peak higher. June beauties are often spawned in more subtle weather patterns, great for avoiding crowds but it does not offer the highest odds of success for the individual. May offers better chances of synoptic setups. Second half of May in particular can offer a lovely hybrid synoptic and subtle. This year was not unique the week of May 22. I like weeks with 1-2 synoptic waves and subtle days in between, you know in case of synoptic debacles like Thursday May 26, lol!

If one has 3 weeks of vacation I would use them the last 3 weeks of May. Sure first week of May could have a synoptic beast but probably just 1-2 days. If one has 2 weeks of vacation I would use them the last two weeks of May. One could argue the two weeks ending Friday before Memorial Day to avoid crowds, but going weekend to weekend uses vacation more efficiently.

Best deal of all is a floating vacation which my manager lets me do. Thankfully Plains tornado season is a slow time at work here. Floating of course offers flexibility for the 2003 early May sequence or a late blooming first week of June. However odds strongly favor May 15-31; last two weeks of May is king.

 

[Ethan Schisler]

This is a reason I'm glad I live in Illinois. Illinois sees severe thunderstorms almost year round when conditions favor such. I've been able to observe ~11 tornadoes this year with only one of them coming outside of the state of IL (4/29 in S OK). While only a couple of these were what I would consider to be quality tornadoes, the point is that if I lived somewhere else, my stats for such a year may not nearly be as significant. The only downside to this is that you are still looking at a significant drive westward (8+ hours) when conditions warrant. Others have mentioned May 15-31 as being the most favorable time to chase and I can't disagree with this at all! June although is my favorite time period to chase and Nebraska/South Dakota/Colorado being the states in which I prefer doing so, if I'm making a trip westward.

I should also note that I don't have very good luck when it comes to picking "chasecation" dates. My most successful week being May 5-11, 2015, I managed to see around 10 tornadoes over the course with the most success being had on May 8-10, as I screwed up the earlier parts of the week, so definitely could have been more successful!

 

[JamesCaruso]

Actually even though I am a long-time chaser those statistics are quite helpful Dan. I always knew that the peak was centered around the last week of May but I always anecdotally felt it was a toss-up on either side of that, i.e. third week of May vs first week of June. In fact I usually have a general preference to do the last week of May and first week of June, basically the weeks on either side of Memorial Day. I always feel that coming back before June starts is too early, like I'm going to miss something in early June. If I had a third week I would definitely use it for the first week of June, surprised to see Jeff's recommendation to use an available third week to instead go earlier in May (starting second week of June) but I'll have to take that under advisement if I'm ever lucky enough to have a third week!

The last few years I have been able to keep things floating within a three-week period but can only chase for two weeks. Usually my strategy is to plan a start around 5/15, but if the pattern doesn't look favorable for that week I push my start date back. I generally head out by 5/22 no matter what, because usually my latest possible date to return to work is already set so I want to make sure I get my full two weeks in (but often I'll return early if it's dead, like I did this past year).



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[Dan Robinson]

It's always tempting to shift my bias to other locations and times of year when events like Simla or Pilger happen (for example, vowing I'll start choosing Colorado upslope targets instead of the Kansas triple point/OFB, or shifting my chasing more into mid-June). To list a few in this genre:

- Colorado
- Northern Plains
- Midwest
- the Caprock/"Panhandle magic"
- June

All of those have a place in chasing lore due to a few memorable events, but when you look at it objectively, they really aren't good things to bank on year after year. I'll stop short of saying that they're overrated, but certainly not things I'd want to start doing exclusively. For example, the Panhandle got a legendary reputation after 1995, but we really haven't seen a comparable season since. Similarly, Colorado and the Northern Plains will do something amazing once every 5-10 years or so, but you have to sacrifice a lot of better setups either earlier in the season or to the east and south before you score the Simla, Campo or Pilger.

 

[joel ewing]

For years, my plan has been to be able to fly into the alley on a very short notice from mid-May thru all of June. I much prefer June, as I love chasing my native Nebraska more than any other place in the alley....and they get the majority of their activity in June. The last several years I've traded in my airline miles for a round-trip ticket to Omaha from my home in Tucson. I make sure I purchase a ticket that does not issue me a penalty if I change my flight date. I'll keep my options open until I see a string of days where it appears we'll have action somewhere in the alley, and fly into Omaha right before that time. I rent my vehicles, and base out of Nebraska. My co-pilot / long-time chase partner Doren Berge is out of Massachusetts, and we coordinate to land in Omaha together.
Personally, I'd much rather chase deep into June, as there are FAR LESS chasers out there, the daylight hours are the longest, and the northern alley is much more green and beautiful than it is in mid-May. Frankly, Doren and I try our best to stay out of the crowded-chaser areas such as Oklahoma and the Tex. Panhandle, anymore. Oh, we'll chase there for sure, but not on real iffy-days. We love chasing east / northeast Colo, Nebraska and the Dakotas, as well as eastern Wyoming and eastern Montana too. Obviously....we like our "elbow-room" when we chase. Many of you have read my chase accounts in StormTrack before and know that we take pride at having a "Plan B" in place in case of a bust, regardless of where we happen to be. By that I mean, we'll have a good idea of what place we want to visit or where we wish to go sight-seeing in the event we suffer a bust. For example, two seasons ago we were in Montana, and ended up at the Little Big Horn Site (Custer's Last Stand). We'd never been to Montana before, but a bust forced us into our "Plan B"....and it was just the COOLEST place to check out! Man it couldn't have been better! It's awesome to chase in an area that is new to you, because you can always find something neat to check out or experience when the situation forces you to do so.

 

[James Hammett]

- June

Bold move to put June in that list as a lot of us prefer to chase that month for the aforementioned reasons, myself included. But I've missed several great events over the years because of my bias against chasing when and where the crowds are the thickest. This year I banked on June and June was horrible. Lowest prelim tornado count (92) since 1985. Other years June has been pretty reliable for great setups somewhere. I think a lot of folks get their fill in May and shut down ops somewhat for June or at least get a lot more selective. For sheer concentrated numbers though I agree you can't beat the "old faithful" 2nd half of May in the central plains.

 

[James Hammett]

Tornado counts usually pull hard through June and early July but this year outside of May (in the plains) we've been coasting toward the minimum:

 

[James Wilson]

Western Kansas Eastern Colorado have been my bread and butter the last two year ... gold mine of amazing tornadoes. May obviously is the best time.

 

[Paul Knightley]

Always last 2 weeks of May for me - as much as anything it's so ingrained now that I think I would go mad through April if I didn't know it was just a short time away!

 

[samuel stone]

For years I've chased KS, OK, and southern NE and other than a few days, May has yielded most of my success. especially the "20s" of May in Kansas. It's almost a sure thing.

 

[James Hammett]

I've identified a few "clusters" of tornado dates in the years I've been chasing. I'm counting 2+ consecutive (E)F1+ tornado days in my favored chase areas (western to central plains with a northern bias) so your mileage may vary.
Late May: 5/21-5/29 (2004,2008,2010,2012,2013,2016)
Early June: 6/2-6-7 (2005,2008,2009,2014,2015)
Mid June: 6/9-6/18 (2004,2008,2010,2011,2014)

There are also less significant clusters in early May (5/4-5/8) and late June (6/19-6/21). I'm sure some of this would smooth out to random noise if you averaged out a larger sample of data (30+ years). But it's interesting to see how reliable that late May peak has been in recent years. June is clearly the bigger month in my favored areas but the events (and the chasers!) do tend to be more spread out.

 

[Greg Flint]

Joel - it's cool to see/hear of another fellow mass chaser who heads out to chase during prime time (even if it is just your chase partner).

My friend and I are late 30's early 40's and will embark on our 4th year in a row heading out to the plains. We typically fly into Dallas mid May, and start there. Often times the setup brings us North into OK/KS, so we just plan out a killer BBQ runway right along the way.

In 2015, we drove from RI straight through to Lamar CO and saw brief tornado. Ended up crisscrossing MO following days chasing anything that came close to resembling a base. That Took too much out of us, and then driving back to MA/RI with nothing to show for it really sucked.

I'm thankful there is data proving late May is most plentiful as that's our 1 week out of the year we can do it.

I'd be curious to know if there is any data from last 20 years that suggest what chase season might look like during El Niño or La Niña year: in terms of areas and months.

 

[James Hammett]

I tend to neglect late April after hitting the early setups and deciding to "wait until May". But climatology says it's pretty hot so I've added it to my tornado date cluster list:

Late April: 4/22 - 4/26 (2007, 2008, 2009, 2010, 2012, 2015)