Here it is in plain English: the longer you're out in the Plains the better your odds of seeing tornadoes. However, we have long recognized the fact that many folks simply cannot take off enough time to do a 10-day tour. During the first half of the storm chasing season (i.e., roughly until the third week of May), a tour length much shorter than 10 days runs the risk of ending empty-handed (i.e., no storms) due to the fact that the atmosphere can take time to reload between storm systems. Offering shorter tours is acceptable later in the season when the low-level moisture takes up quasi-permanent residence in the Great Plains owing to less frequent cold front passages. It is our perception that severe storm frequency is high enough then to justify a tour of about one week in duration. Moreover, a couple of recent studies lend statistical support to the observation that the peak of tornado season (from roughly early May to mid-to-late June) is characterized by "runs" of tornado "days" - consecutive days on which tornadoes are observed. Thus, tours offered during this 5-6 week period stand a slightly better chance of experiencing series of active weather days. For the earlier tours, we have found that the 10-day tour length strikes a very nice balance between spending enough time in the field to increase your odds to acceptable levels and the amount of time people can take off from work without depleting their annual vacation time.

So, the 10-day tour is for you if you can take off the time and want to maximize your probability of seeing a tornado. It is also cheaper on a per day basis and occurs during the time of tornado season most likely to produce violent tornado outbreaks. The 6-day version is the optimal choice for those with more limited vacation time but still want an excellent chance of experiencing intense supercell storms and tornadoes, and who wish to spend time chasing in the northern and western portions of "Tornado Alley".

The 6-day tours, offered in the late spring and early summer, are for you if you can't take as much time off but still want to have a decent shot at seeing great storms with leading storm chaser and SLT Co-owner and Tour Director Roger Hill out of Denver. As the tornado season progresses into June, storm activity migrates northwestward into the region extending from the high plains of eastern Colorado, Wyoming and Montana eastward across Nebraska and the Dakotas into Minnesota, Iowa and Wisconsin.

Here is an article explaining some of the trade-offs of chasing in the "early" versus "late" season storm chasing.

More about the 6-day summer tours:

Come chase the high plains and northern plains during their peak severe weather season of June and July. Your tour guide will be the legendary Roger Hill, widely recognized as one of the most experienced and successful chasers in the nation. Roger will be taking you through some of the most extraordinary scenic regions of the United States in search of severe weather of all kinds. Eastern Montana, the Dakotas, the high plains and upper Midwest experience a significant amount of severe weather, including supercells and tornadoes, during this time period. Each of these tours will begin and end in Denver, the heart of this chasing region. You will have 6 full days of chasing, with your tour beginning and ending on Saturdays, which are designated travel days arriving and departing Denver.  These tours are designed for those who cannot take off enough time for a 10 day tour, are looking for a later tour, or simply want a less expensive tour. Or, they are for you have always wanted to visit the northern and high plains and corn fields of the Midwest but haven't yet. Thus, if you're adamant about maximizing your odds of seeing great storms, go for one of the remaining 10-day tours or two consecutive 6-day tours (for which a fairly sizable multi-tour discount will apply). For more information please contact Dr. David Gold or Roger Hill . You won't be disappointed! Dr. Dave will be providing weather data to Roger as needed during the 6 day tours and on-call tours.