A computer screen shows the NOAA tracking map of Hurricane Gustav.

I’ve always had a knack for remembering random tidbits of information, including memories that many would assume I would’ve long forgotten. The one I’m thinking of this week includes butterflies.

In first grade, we studied the development of monarch butterflies—from an egg to the completed, gorgeous and fluttery state. The project culminated in the release of cages of monarchs on the playground. With their wings fluttering above the blacktop where we played hopscotch, the butterflies were never to be seen again. It was sad, but also beautiful, and it’s stuck with me for a long time.

Why this memory? Out of all of the childhood memories I could possibly try to write about for work (and all of the anecdotes I’ve already included), why use this one? Hurricanes. 

In my brain, the development of a hurricane reminds me of the growth and development of butterflies, albeit with vastly different end results. (Although some may argue that hurricanes are beautiful in their own right—but I think that may be a discussion for another day and another blog post.)

Hurricanes start from humble beginnings, just as butterflies do–in a very small form.

Hurricanes start from what is known as an invest, consisting of a tropical weather system that forecasters decide to monitor for potential development. Just because forecasters monitor the area does not mean that the actual area will become a storm.1 It only means it has the potential to become one—the same way that not every butterfly egg will hatch into a caterpillar.

The (arguably) most interesting thing about invests is their naming structure. As an invest is monitored, it is assigned a number ranging from 90 to 99. Once the numbers have been exhausted, the cycle begins again.2

If an invest does become organized or strong enough, it’ll turn into a tropical depression—the more familiar younger sibling to hurricanes, like caterpillars are to butterflies. These depressions, scattered systems containing wind speeds less than or equal to 39 miles per hour,1 will lose their invest numbering and gain a different numbering system.

If sustained winds hit any point over 39 miles per hour (and less than 73 miles per hour), the depression becomes an official tropical storm1—earning its name from the long, six-year-cycling list of names determined by the World Meteorological Organization. Notably, if the storm goes back to being a depression, it will keep its tropical storm name.

The tropical storm is the equivalent to the cocoon stage of the butterfly’s development. It’s a step that is incredibly important to the process and often overlooked.

Now, it’s important to note there’s a difference between a minor and major hurricane.

Hurricanes are categorized by the Saffir-Simpson scale and assigned a number between one and five. A hurricane with a category of 3 or above, containing winds higher than 111 miles per hour, is considered major1—a larger-than-life butterfly and a true marvel. These are the storms which can cause the most catastrophic damage, the kinds of impacts you never wish to see, particularly in this field. However, they do happen. They will happen. (Notably, all storms can cause heavy damage, but it’s the major hurricanes that are the most likely to leave behind that catastrophic wind and sweeping damage from storm surge.)

As the years have gone on, hurricane prediction technology has improved, hurricane forecasts have become more accurate, and our ability to prepare for and respond to hurricanes has improved. And all of these efforts are constantly and consistently working to get better. These “butterflies” can be caught if they’re followed.

Hurricane season has already begun in both the Pacific and Atlantic basins. We will be monitoring the seas for activity and working closely all the way through the end of November, with our partners at the National Hurricane Center, in order to follow each stage of the process—from egg to butterfly.

Related Content:


  1. NHC’s Glossary of Hurricane Center Terms:
  2. NOAA Atlantic Oceanographic and Meteorological Laboratory’s Hurricane Research Division’s Frequently Asked Question (regarding invest naming structure):