Tropical Storm Dorian: What you need to know about this cyclone

Wednesday, July 24, 2013
Tropical Storm Dorian continues to move west across the deep Atlantic tropics today. The big question everyone wants to know is: Will this storm threaten the Caribbean islands, Bahamas or possibly the United States?

So let’s discuss.

As of noon the storm had 50 mph sustained winds, and it’s not expected to strengthen rapidly in the near future. That’s partly due to sea surface temperatures that aren’t entirely favorable for development. The map below shows sea surface temperatures in the Atlantic, and the location of Dorian’s center of low pressure.

Temperatures above 26.5 degrees Celsius (80 degrees Fahrenheit) are helpful for storm development, but Dorian won’t be in waters that warm for a couple of days. However, if it does hold together for another five days or so, it will come over warmer waters as it approaches the Leeward Islands.

Of course another significant factor in storm development is wind shear, and that’s expected to slightly increase along its path during the next couple of days, forecasters say.

There’s a fair amount of uncertainty in intensity forecasting, but the bottom line is that conditions are not overly favorable for hurricane development during the next five days.

The forecast models are in good agreement over the next four or five days because Dorian is moving along the southern edge of a strong high pressure system.

Typically westward moving storms begin to curve to the northwest as they approach the United States, so the long term track suggests Dorian, if it holds together, may begin to pose a threat to Florida in about one week’s time, or perhaps the U.S. East Coast a little bit after that.

However those of you who follow storms recognize there’s a lot of uncertainty in storm track forecasts after about five days time, so the final fate of Dorian remains in question.

Dorian is the fourth tropical storm to form this season, and it comes about a month earlier than when the “D” storm typically comes during an Atlantic season.

It’s a good reminder that seasonal forecasters expect a busy year in the Atlantic. The time to make preparations — i.e. getting a kit, determining whether you need to evacuate — is now.

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