Estimating chaser numbers in the Plains

[Dan Robinson]

Yesterday's (May 17) global Spotter Network beacon count peaked at 1,104 at 5:20pm. Early in the morning, there were 389 beacons, only about 12 of which were in the Plains. So, it can be assumed that those are non-chasers. Subtracting that baseline yields a maximum count of 715 likely Plains beaconers. Stormtrack & Twitter polls suggest only 7 to 10% of chasers don't beacon. Using a higher 30% non-beacon rate (accounting for the "I refuse to associate or identify with the chase community in any way, shape or form, even a Twitter poll") yields an estimate of 1,021 Plains chasers.

This number obviously needs refining, as it is possible many chasers, spotters and weather enthusiasts outside of the Plains also beacon in the afternoon. I have archived the SN placefile at several points through the day and will do some detailed analysis to get a better estimate of numbers in each target.

 

[Jeff Duda]

So...roughly 1000 chasers spread out from W NE/NE CO through KS and down into SW TX? That's honestly not bad at all. What's bad is when those 1000 are all concentrated on one storm headed up I-44 towards OKC or towards ICT or near some other large city.

 

[JamesCaruso]

I am one of the 7-10% that does not beacon

 

[Dan Robinson]

Data suggests chaser numbers are strongly tied to SPC categorical risk. Yesterday's numbers started out lower than they had all week (362 at 11:30AM), but spiked suddenly after the Moderate Risk / 15% hatched tornado upgrade to a peak of 1,414 at 7:30PM. So, it looks like we can say that "SPC Chasers", not the core "dedicated" group, are a big part of the numbers on the higher end days.

 

[Quincy Vagell]

For what it's worth, my poll on Twitter finished with the following percentages in terms of who/when chasers report their location with 231 votes:

29% Yes, most times
23% Yes, when on/near a storm
16% Sometimes, but usually no
32% No (rarely or never)

There are a few ways to interpret this poll. At the very least, 32% of respondents rarely or never report their location. I would argue that you could add in the 16% category and go with a split of 48% of chasers usually don't report and 52% of chasers usually do. I've had discussions with some chasers online and many have stated that they used to report more often, but that they do so less and less with time. Many of them don't report at all anymore.

 

[Dan Robinson]

Tony Perkins has been doing some data analysis on this by filtering out the dots that do not move past a certain threshold throughout the day. Here is his Twitter response:

https://twitter.com/x/status/1131674412443414533

 

[Quincy Vagell]

That's a good consideration too. Some dots on spotter network are simply left on all of the time. I suppose a lot of those are just general weather/storm enthusiasts who probably do not move much or at all. Those can definitely be removed from the data set. I also bet that you have a lot of people in the Plains who don't really chase, but activate their location when there's a threat for storms.

 

[Tony Perkins]

Here are some comparisons of notable dates this season. The threshold used below is about a 60 mile radius of distance moved during the day (1 degree of lat or lon). That should eliminate people who look at Radarscope at both home and then again elsewhere like work. Also this data is national, not just tornado alley, so you can potentially take a non-chase day as a baseline for general non-chasing but active activity.

May 7 (Tulia TX): 395
May 14 (Non Chase Day Baseline): 56
May 17 (NE, SW OK): 494
May 18: (OK) 478
May 19: 172
May 20: (High Risk): 752
May 21: 285
May 22: (OK) 447
May 23: (Panhandle) 383

 

[Eric Matthews]

We chase with 2-3 people in a vehicle most days. Very seldom do we have on more than one beacon. I wonder if the results above more closely reflect the number of vehicles or the number of chasers?
I don't know that this adds anything to the discussion, but thought it may impact the chaser count vs chaser vehicle count.

 

[Sean Ramsey]

I stopped at Loves at the junction of I-40 and Panhandle exit the day before yesterday and it was filled to the brim with people who would be chasing, they were just waiting for intiation. I say "people who would be chasing" instead of "chasers" because there were obviously chaser vehicles, but also tour vans full of people, what looked to be students chasing in large groups, and field research teams in the area, which all would be technically, chasers. I can't imagine the 50-100 people in that parking lot would all have beacons on when they chased.

 

[Willoughby Owen]

Comparing a marginal slight risk setup from mid May 2010 over Midland to Fort Stockton and mid May 2017 over the same area and I reckon that chaser numbers have easily doubled, if not tripled during that time period.

 

[John Farley]

I think I you are.way underestimating the number of chasers who do not beacon. I have never participated in SN because I nearly always chase solo and setting up SN just seems like another bother. If I see something significant that I do not have reason to believe the NWS already knows about, I just call it in. And I have never been on Twitter and never will because it's word limits promote oversimplification. So I could not participate in the Twitter poll. I would guess that its 50 percent who usually don't beam is a floor, and the true amount is higher. Just from my own experiences, there are a LOT of people out there. Certaily more than 7-10 percent more than the SN number.