I've been thinking about the possibility of forecasting chaser numbers.

Based on observation, the theory is that storm chaser numbers increase when the following conditions are in place:

- Weekend or Holiday

- Proximity to a city

- Southern Plains region

- Fewer target storms

- High-end SPC categorical risk

Formula for calculating expected CTI:

(M+C+R+S+D)-(T-1) = CTI

- Where (M) is Month value:

July-February = -1

March = 0

April = 1

May = 2

June = 1

- Where (C) is proximity to a city:

Within 100 miles of major city = 2

Within 200 miles of a major city = 1

More than 200 miles from a major city = 0

- Where (R) is the geographic region:

Southern Plains (northern Texas, Oklahoma, southern Kansas) = 2

Central Plains (northern Kansas, Nebraska) = 1

Northern Plains (Dakotas) = 0

Midwest, South, Atlantic Coast = -1

- Where (S) is the SPC categorical risk:

General, 2% tornado = -1

Slight, <=5% tornado = 0

Slight, 10% tornado = 1

Moderate, 15% tornado = 2

Moderate, <=10% tornado = 2

High, <=15% tornado = 2 (wind event)

High, >=30% tornado = 3

- Where (D) is the day of the week:

Weekday = 0

Weekend or Holiday = 1

- Where (T) is the number of dominant, mature tornadic supercells within the risk area.

The maximum theoretical CTI would then be 10, which would occur:

- on a weekend or holiday

- in May

- inside of a SPC high risk

- close to a major city

- in the southern Plains

- one dominant supercell

The minimum would be zero (even if the calculated CTI was below zero).

I know this isn't perfect, but would be interesting to refine and see how it validates.

Any comments or observations?