Chase Region and Times
Above is what I now consider my "chase alley". I will chase some areas not included, but I don't like them. One area is northwest Missouri. I will chase there, but I'm usually wondering why. It's just a mess of hills, trees, and very twisty roads...some very very poor. Some portions north of I70 in Missouri are good though, just not the northwest ones. I try not to chase as far east as Illinois, as it just gets really grungy the further east you get. Southwest Minnesota is ok. You get east and north too far and it goes to hell(hills/trees). Eastern Oklahoma is much the same. It sucks there. I always heard how horrible southeast Oklahoma was. The one chase I had there didn't seem any worse or better than northeast Oklahoma. It wouldn't bother me if I never chase east of I35 in Oklahoma again. It goes to hell fast.
The southern areas of my Texas outline, and the northern portions along the Canadian border are more for distance than anything. I feel no desire to chase in Canada, even if there are great storms there. Same goes for that far southwest Texas area. I'm happy using that big area between the two, lol.
The further west on the plains one is, the less road options they get, obviously. Northwest Oklahoma and big chunks of the Texas Panhandle don't have data through my alltel connection. I've found that rather annoying(boy is it really easy to forget how it used to be to chase without so much info). Road options aren't exciting in some of the TX panhandle either. Same goes for western Nebraska, but it is surely worse in Nebraska. At least with this further west road option problem, one has better visibility anyway. Lack of roads to the west bothers me a whole lot less than being on roads in hill and tree filled terrains, like Missouri and eastern Oklahoma.
If I could live anywhere in the alley, I'd likely chose Grand Island Nebraska. It's just far enough west to have a short drive to most western targets. One could shoot south to the Texas panhandle in the morning and have plenty of time to reach the target. It's close to a lot of the late spring or summer northern targets. It's right in the hottest of hot zones IMO, northern Kansas, southern Nebraska(lol, yeah I know of the other "zones"....Throckmorton TX area, OKC, Harper Co KS, etc). And, it's also a short drive from any summer fun, which seems to have a home located in northern Nebraska into southern South Dakota. I've seen 2 big tornadic supercells in northern Nebraska in the month of July, and missed a lot of others. It just seems like at least once a year there's a big flying eagle radar signature out there, dropping south for hours. Having to drive through Omaha and then Lincoln to get west is getting old. Hell it's the worst once you get west of Lincoln, as it takes forever to get out of the semi and camper fun. I'm always anxious to get to the Grand Island area, as the congestion lets up a little west of there. The far majority of my chases are at least that far west. It'd also be nice ending the night on a shorter drive home. I wouldn't want to be too far west, as then you wind up having to drive east to start your chase day. I just don't like driving east to chase.
Best Time of Year to Chase
This has become a pointless question and concept to me anymore. Generally May and June are the best. 2006 and 2007 though, May and June were horrible. Horrible. Both these two years April was a much better time to be chasing. Up until these years I largely thought of April as a big waste of time. It used to be the season would start in the south around March and move north through June. Lately it seems to start north early(March 12, 2006 tornado outbreak up into northern Missouri.....March 28, 2007 I was watching wedge tornadoes in southwest Nebraska). Generally it's not good in the central plains(northern KS and Nebraska) till late April or early May(as starting points). It used to be you'd have May options and early June options including some of the southern plains. A ridged out area begins shifting north in late May into June. That seems to happen earlier and it seems to shift right on through the central states into the northern plains. South of there is often shut out till Fall.
But anyway, generally speaking, I'd think of OK and TX as late March through mid-May states. Once mid-May is here I'd be thinking northern Oklahoma on north. (again 2006 and 2007 both as examples, were rather done by May 10) Once you are into the end of June, flow over the US is really weakening and/or diverting into Canada. July and August can have their moments, but I wouldn't bank on much in those months. August and September seem like months that may give you one good system a year. When I think of July I'm thinking of weaker flow setups where a storm deviates on a boundary with extreme instability in place. Good supercells are rare by then, but they still do happen. It's just tricky making yourself go chase these setups as the ones that produce these beasts often don't look that great ahead of time.
Storm speeds are generally faster in the early spring and late fall systems. Meanwhile you can usually count on more chaseable speeds in May, June, July, August, and September.
Since catching a big tornado in central Iowa in mid-November of all times, and big ones in southwest Nebraska in late March...I don't think much of the time of year. If I think anything, right now it is to plan on chasing earlier and maybe not having anything once mid-May is here. The last two years have made me think this way(2006 and 2007). Not sure why it is so dang active early, then so dang quiet during the peak times now. If there's anything you can count on with the weather it is that it will change. Maybe that means to count on May and June being the peak again in 2008, no one knows. I'm just glad I don't have to schedule a 2 week vacation period to chase in. I used to and I always did much better on after work chases outside of that timeframe, than I did chasing during it. If you have to do this and are looking for advice on when to pick. Take a calendar, rip out April, May, and June. Place them next to each other. Place a blindfold on yourself. Spin around. Have someone point you in the general direction of them. Then throw a dart. Pick the week before and the week after the date your dart hits. As for where to chase during your vacation, don't be silly. Nothing annoys me as much as when I hear someone say, "I'm going to Oklahoma to chase next May". That's some amazing forecasting ability to pick well in advance like that. If it is May and you are coming to the plains to chase, I'd count on a state between Texas and North Dakota. If it is June you can maybe mark off Texas, maybe. If you did that in the first 8 days of June in 1995 though, well you'd probably shoot yourself. If it is April, I'd bet you can mark off North Dakota, and probably most of South Dakota.
There's a good example of what can happen early. That's the March 13, 1990 tornado outbreak. 58 reports. Just look at that track in Nebraska!
Here is a good example of a good May and June to chase in. Above are the tornado tracks from May 1st through June 30th, 2004.
Now compare that one with this one from May and June 2006. The download update to get the newer stuff says updated June 19, 2006, but I don't think they updated that comment, as I looked and there is data for all of June. So the above is really the tornado reports for May and all of June 2006. That's how sad the peak time of year was in 2006. I'd show 2007 as well, but they don't have the data for that yet.
And, since I'm messing around with this severe plot program, here is the largest tornado outbreak in US history, the April 3-4, 1974 outbreak.
I guess I don't have much else to say on where I prefer to chase, nor the time of year to do so. All there is to know is the pattern generally shifts northward from very early Spring through early Summer. That and from year to year there is no guarantee where it will be best, or if there will even be a best, nor when.