Tropical Storm Watches Issued For Portions Of The Keys Ahead of Elsa

A Tropical Storm Watch has been issued for the Florida Keys from Craig Key westward to the Dry Tortugas. Tropical Storm conditions are possible as soon as Monday in the Keys and is likely to spread northward into South Florida late Monday into Monday night.

Original article from 11 AM Saturday:

Elsa weakened to a tropical storm less than 50 miles south of the coast of the Dominican Republic Saturday morning.

Elsa is rapidly churning west-northwestward through the Caribbean, where conditions were expected to deteriorate along the southern coast of Hispaniola Saturday. The mountainous terrain of the island is likely to enhance rainfall totals in spite of the storm's fast forward motion. Rainfall amounts of 4 to 8 inches, with locally higher amounts in excess of one foot, are likely to cause life-threatening flash floods and mudslides. Similar rainfall amounts are possible Sunday into Monday in Jamaica and Cuba.

The storm's forward motion has been occasionally in excess of 30 mph from the flow around a strong high pressure ridge over the subtropical Atlantic Ocean. Such a fast motion makes it difficult for Elsa's circulation near the ocean's surface to be vertically aligned with its mid-level circulation some 10,000 to 15,000 feet above the ocean. There is also some wind shear from the northwest which is preventing the storm from intensifying.

Elsa is forecast to reach the outer skirts of the high pressure ridge on Sunday. As it does so, its forward motion is expected to slow down considerably, perhaps at half the speed it is moving on Saturday. Meanwhile, a strong trough of low pressure is moving off the Southeast coast of the United States. This trough is responsible for a front slipping unusually far south into North Florida for early July. The trough will leave behind what is called a "weakness" in the subtropical ridge. Tropical storms and hurricanes move toward the path of least resistance -- toward these weaknesses in the flow. That will cause Elsa to turn more toward the north, in the general direction of the Florida Peninsula early this upcoming week.

This forecast path will take Elsa near or directly over the high terrain of Hispaniola and eastern Cuba, in particular. Elsa's core circulation is small, so it is highly susceptible to weakening if it interacts with this rugged terrain, which is becoming increasingly probable.

Regardless of Elsa's precise strength, heavy rainfall is becoming more likely over the Florida Peninsula and Big Bend starting on Monday and lasting until midweek. Rainfall totals of 2 to 5 inches, with locally higher amounts, may fall near the path of Elsa. Since many areas are already receiving heavy rain this weekend from a cold front, there will be a heightened risk of flash flooding. If Elsa does not spend as much time over the islands of the Caribbean or is able to move over the Gulf of Mexico, it may also be able to produce tropical storm force winds over parts of the state.

Heavy rainfall may spread as far north as coastal Georgia and the eastern Carolinas Wednesday and Thursday as the storm accelerates toward the northeast.