PS: Also, these are not independent events so those long tail odds are likely way off base.
Using 1 as the first number in the ratio makes people think of it like a comet, once you see it you won't see it again for the given period (and will not live to see another).
Using 4 in 100,000 would be an attempt to get more people to reason clearly about what the odds mean.
Rates like HDD failures, Diseases, Homicides, Accidents, are often described as X:100,000.
Odds on the other hand apply to specific events such as the Redskins winning the next Supper Bowl. The difference is when talk about a wide range of things you speak in terms of rates. Thus, the odds of getting this much snow next year that's ~1:26,000. But, the rate of years with this much snow is better described as 4 per 100,000 years.
In the end it's because they described it as events:years they should use a round number of years. But if they had said said the odds that this happens next year then 1:X should be reasonable.