Dolly, the fourth named storm of the year, could develop off the northeast coast

The National Hurricane Center said it has been watching the system for a few days and it has now has become well-organized enough to be considered a depression.

The forecast is for the subtropical depression to reach tropical storm strength -- sustained winds of 39 mph or above -- by midday Wednesday.

If it does get this strong, the storm will become Dolly.

"Depression 4 forecast to get named in 12 hr - which would make it 2nd earliest on record," Colorado State University research scientist Phil Klotzbach tweeted on Monday.

The depression is 310 miles southeast of Nantucket, Massachusetts.

"The good news is that the storm is expected to be around for only a brief period of time and is moving away from the US into the open waters of the North Atlantic," CNN meteorologist Taylor Ward said. All the models are in agreement that it will move east-northeastward Monday night and then turn northeastward on Tuesday.

By Tuesday afternoon or evening, the storm should begin weakening.

The storm system should be absorbed by a larger extratropical low or dissipate on Thursday, the National Hurricane Center said.