Threshold for conv outlook to target several chase days in a year, within my area

[Mike Darling]

My wife and I live in the Metro Detroit area (SE Michigan.)

We run our own business, so instead of scheduling a chasing vacation in advance, we're (somewhat) able to watch the weather and decide on short notice to go.

We are hoping to stay within Michigan, Ohio, Indiana, Illinois, and possibly eastern Iowa or southern Wisconsin. We would love to head out to the plains sometime in the future, but aren't planning on doing that this year unless there's another forecast for a severe outbreak. (We couldn't head out in April.)

We're hoping to see a tornado this year, but understand that limiting our chase area and number of days could very well mean that doesn't happen. We also understand the randomness and variance involved, and that a reasonable looking threshold might indicate no chase days, or cause us to miss events we could have gotten to.

I'm wondering if you were trying to operate under these restrictions, what would your rules of thumb be?

I know there's a lot more to it than looking at convective outlook/CAPE forecasts and meso discussions, but that's probably what we're starting with.

Ideally, I'd love to know how many times each year my given area sees each probabilities, and pick the highest probability category that I could still expect to happen a few times a year. (I know past results aren't necessarily going to predict this year's results.)

For parts of Michigan, Ohio, and Indiana that we can get to fairly quickly, what day 1 tornado probability would you be looking for to jump in the car given our restrictions? I understand the percentage is for any point in the area to have that weather within a 25 mile radius, so heading to targeted areas while watching live GR3 data greatly increase our chances beyond those chances. My initial thought is to look for a 10%+ tornado probability. But, I have no idea how many of those days I should generally expect, and whether that's too rare or too common for my area.

For the wider area that we'd need to travel to the day before, what day 2 probability would you be looking for? My initial thought is to look for a hatched 15% area with decent forecast text discussion.

 

[Jon Strebler]

I would say you need to do some more research before just basing everything off of convective outlooks. If you just wait for a day with high probs then you're going to miss some good days. If you really want to chase, then go chase anything that has a chance, even a 2% area. I don't think you're going to see all that many 10%+ days in that area, a few, but not too many. I think just looking at the outlooks for chasing opportunities is going to leave you in the dark about what is going on, and cause a lot of driving for nothing. Research more about the overall synoptic scale of the event, and work your way down. Are you going to play a warm front, dryline/cold front, are there any boundaries over the forecast area? If you're just looking for a 10%+ tornado area, do you just plan on driving into the middle of it and waiting? You're going to be playing A LOT of catch up if you just drive into a risk area without a specific reasoning for a target.

 

[Travis Davis]

I've honestly had better luck on 2 and 5 % days then Mod / High risk setups. I even got a couple tornadoes on < 2% days.