TS Arthur a rarity on Florida's Atlantic coast

The Palm Beach PostJuly 1, 2014 

WEST PALM BEACH -- Tropical Storm Arthur drew attention Tuesday not only because it is the 2014 season’s first named storm, but also because tropical storms aren’t usually seen off Florida’s east coast this time of year.

Declared a tropical storm Tuesday morning just off the Treasure Coast, Arthur brought rain to Palm Beach, Martin and St. Lucie counties in the afternoon before moving north. It was expected to become a minimal hurricane Thursday somewhere off North Carolina’s Outer Banks, and ruin more than a few July Fourth picnics along the mid-Atlantic seaboard.

At 5 p.m. Tuesday, the storm had top sustained winds of 50 mph, and a tropical storm watch remained in place for Florida’s east coast from Fort Pierce to Flagler Beach, north of Daytona Beach.

In South Florida, heavy rain fell in some spots, but it was the same or even less than would be produced by a typical summer thunderstorm. Palm Beach County Emergency Manager Bill Johnson said there were no reports of serious damages or flooding.

A total of 1.03 inches fell just between 2 p.m. and 3 p.m, at Palm Beach International Airport, according to the National Weather Service. Rainfall totals for 8 a.m. to 4 p.m. included 0.72 inches at Forest Hill High School in West Palm Beach, 0.67 inches in Lake Worth, a half-inch in the Caloosa neighborhood west of Palm Beach Gardens, and none in Boca Raton, according to South Florida Water Management District gauges. Treasure Coast totals also ranged between a quarter and two thirds of an inch.

The formation of a storm off Florida’s east coast this early in the season is relatively unusual.

Beryl struck Jacksonville May 28, 2012, as the strongest tropical storm on record ever to hit land before the start of the season. But at this point last year, two tropical storms had formed, neither near Florida; Andrea June 5 in the central Gulf of Mexico and Barry June 17 off Panama.

National Hurricane Center records for 1851 to 2009 show only five storms formed off the east coast of Florida from June 21 through July 10, with 25 in the Gulf of Mexico and nine in the Caribbean.

And according to a “historical hurricane tracks” database operated by the National Oceanic and Atmospheric Administration, records for 1877 to 2012 show, in the month of July, only three came within about 230 miles of West Palm Beach. They included a 1981 tropical depression and an 1878 tropical storm, both of which passed through Palm Beach County. There also was Tropical Storm Ana, which was a tropical depression when it traversed Broward County in 1981.

The reason for the paucity of storms in the western Atlantic is the temperature of the water. While things already have warmed up by early July in the Gulf of Mexico, essentially a giant, shallow bathtub surrounded on three sides, waters are more tepid in the massive Atlantic, which covers a big open chunk of the globe from pole to pole.

“The waters in the Atlantic take a little longer to really get to a higher temperature,” Jeral Estupinan, science and operations officer for the National Weather Service office west of Miami, said Tuesday.

He also said wind shear, the collision of crosswinds in upper and lower parts of the atmosphere that tends to bust up tropical circulation, is much higher in June and July.

But Estupinan said it’s no accident that when storms do form in June and July, it’s along the coast. That’s because of the Gulf Stream, the current of year-round warm water that hugs the eastern seaboard.

Arthur formed this early, Estupinan said, because it started on land, as an area of low pressure over the Carolinas that later moved southward over the Gulf Stream.

Had it not done that, he said, “it never would have happened.”

The water management district said Tuesday afternoon because its 16-county area recorded nearly-average rainfall in June, it had the capacity to handle the stormwater from Arthur.

It said for June, an average 8.09 inches fell districtwide, with Martin and St. Lucie counties averaging 9.57 inches.

Lake Okeechobee still stands below its historic average for this time of year; it was at 12.98 feet Tuesday, 0.41 feet below average.

The National Weather Service’s 2014 forecast for the wet season -- mid May to mid October -- calls for near or slightly below-average rain, with June potentially being the wettest month compared to normal totals.

Staff writers Julius Whigham and Christine Stapleton contributed to this story.

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