June Tornado Climatology
Based on long-term data, the peak of US tornado activity occurs in June.
The advantage of June over May is that warm, moist air from the Gulf is far better established over the Plains which means less down days than May. The atmosphere is better able to recover after frontal passage and reestablish periods of instability for severe storms.
During June, we have seen some of the most magnificent supercells ever, with pronounced striations in addition to tornadoes and other visually impressive features. This is due to the fact that most of the storms we see in June occur on or close to the High Plains region where the air is clearer and storms are stripped of their low plains obscurities. June really is the gem of storm chasing.
Below, you will see a map (top) indicating probabilities of severe weather for mid-June. Note the wide spread nature of the intense activity which stretches along and east of a line from about Plainview, Texas to Denver, Colorado. The bottom map depicts average tornado days per year from 1980-1999. Note the climax over northeast Colorado where most of our June tours are based. SOURCE: NSSL
Question: Isn't May the best month for storm chasing?
Answer: Not exactly. May and June are the top two months, on average, for storm chasing on the Plains. April and July can also be quite good. Meteorologically, there is almost no difference between May and June other than the slight advantage June has over May for consistent thermodynamics. However, May tends to see more headline news since significant tornadoes are more common along and east of the highly populated Interstate 35 corridor. We think this has led some to believe that May is a better storm chasing month.
Other advantages June has over May are:
More nature. Chasing in more rural, natural areas.
Better photographic light. The light and visibility on the High Plains is better than it is on the lower, hazy areas to the east.
Longer days. June offers a larger intercept window prior to dark.
High Plains magic. Supercells and tornadoes need less to develop on the High Plains.