Tropical Storm Irene forms in Atlantic

Well, that didn't take long!

Less than an hour after writing that a tropical depression or storm could form this evening, the National Hurricane Center began issuing advisories on Tropical Storm Irene.

At 8 p.m. Saturday, its ill-defined center was at 14.9 degrees North and 58.5 degrees West. That puts it about 200 miles east of Guadeloupe and Dominica. The storm has top sustained winds of 50 mph.

Meteorologists say one key factor will play a huge role in whether Irene becomes a strong hurricane and whether it will directly impact the United States -- the track.

The National Hurricane Center's initial track carries the storm over the island of Hispaniola (Dominican Republic and Haiti), and that's usually death for a tropical system. The mountains on that island tend to disrupt the circulation in a tropical system.

What's left of Irene also would brush the north coast of Cuba, and the Hurricane Center's initial prediction shows a tropical storm -- not a hurricane -- approaching south Florida on Thursday afternoon.

What everyone will be watching over the next 24 hours is exactly where the storm's center forms, and which direction it goes.

If the center forms a bit north of where it is now, or if Irene tracks a bit farther north than expected, it would miss the big islands and have a clear aim at the Bahamas and the Southeast coast. The reverse is true -- a track farther south would carry the storm into the Gulf of Mexico.

One thing is for sure -- Irene is a big storm, and Puerto Rico will take a pounding Sunday, with flooding rains and gusty winds.

Beyond that, we shall see.