Hurricane activity in both the Atlantic and Pacific Oceans really begins to pick up intensity at the beginning of August, building up to the peak of the seasons in the middle of September. Right on cue, we have our seventh named storm in the eastern Pacific—possibly threatening Hawaii—while the Atlantic Ocean is dead quiet.

The only storm on the stage at the moment is a hurricane named Guillermo, which is teetering on the edge of category two status as it chugs west-northwest through the eastern Pacific Ocean. The storm is encountering warm waters and a favorable environment that should allow it to strengthen over the next couple of days, after which time the National Hurricane Center expects it to begin weakening.

However, their latest forecast also shows the system coming very close to Hawaii as a strong tropical storm in the middle of next week. This is still five days out and hurricanes are notorious for not doing what model guidance and forecasters expect them to do, but when you see a tropical system aiming right for the Hawaiian islands, it’s time to take notice.

The scenario is similar to what played out last August when Hurricane Iselle formed in the eastern Pacific, crossed into the central Pacific, and hit Hawaii as a strong tropical storm. If the storm plays out as currently forecast, it will keep the name Guillermo even though it’s crossing into the area that’s covered by the Central Pacific Hurricane Center in Honolulu (which uses its own list of names).

If you live on the Hawaiian islands or if you’re visiting there within the next week or two, keep a close on the developments of this storm and have a plan if you need to evacuate or need to change your travel plans in a hurry. Don’t blow off forecasts and warnings from local officials because you’ve saved up for years to take this vacation—the only thing worse than a group of smug locals is a group of smug tourists.

The National Hurricane Center in Miami will continue issuing advisories on Guillermo until it crosses 140°W—after that, responsibility shifts to the Central Pacific Hurricane Center in Honolulu.

Atlantic Ocean


In the past week, we’ve seen two areas highlighted by the National Hurricane Center for tropical development—the first one you probably heard about non-stop on The Weather Channel this week, which had the potential to form from a stalled front draped across Florida and the coastal waters off the southeast. Most of the tropical systems we see early in the season form from decaying frontal boundaries near land, and this had the potential but the environment was too harsh.

Farther out in the Atlantic, there’s one disturbance near Africa that’s desperately trying to develop—you can even see a swirliness to the clouds if you look near 15°N, 20°W on the satellite image above, but here too the environment is too hostile for any meaningful development.

Africa is to blame (or to thank, depending on your outlook) for the storm’s dusty demise. Dry, dusty air coming off the Sahara Desert is a death sentence for tropical systems in the Atlantic, and it’s why many potential storms have fizzled out over the years. Add this to the strengthening El Niño in the eastern Pacific—which tends to increase wind shear and kill storms in its own right—and we’re still on track to see below-normal activity in the Atlantic.

Not that that’s a bad thing, of course.

[Images: NOAA, author, NOAA, WeatherBELL | Corrected to reflect that the NHC hands storms over to the CPHC at 140°W, not 120°W as I originally stated.]

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