Estimating chaser numbers in the Plains

Dan Robinson

Staff member
Jan 14, 2011
2,529
2,198
21
St. Louis
stormhighway.com
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.
 
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Dan Robinson

Staff member
Jan 14, 2011
2,529
2,198
21
St. Louis
stormhighway.com
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.
 
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Jun 16, 2015
459
1,053
21
32
Oklahoma City, OK
quincyvagell.com
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.
 
Jun 16, 2015
459
1,053
21
32
Oklahoma City, OK
quincyvagell.com
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.
 
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
 
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Mar 16, 2012
30
2
6
Lenexa, KS
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.
 
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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.
 
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.
 
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