Tropical Storm Arthur, First of the Atlantic Season, Intensifies Near Florida

Tropical Storm Arthur intensified off the coast of Florida today, with maximum sustained winds of 50 miles per hour as of 5 pm ET. The track forecast of the first storm of the North Atlantic season, while still involving a high amount of uncertainty, takes the storm northeastward off the South Carolina coast, possibly making landfall on the eastern tip of North Carolina as a Category One hurricane, and then out to sea southeast of New England.

The National Hurricane Center said areas from northeastern Florida to Virginia should "monitor the progress" of the storm, since "tropical storm and hurricane watches will likely be required this evening for portions of this area."

Because a series of cold fronts will be approaching the East Coast at the same time as Arthur will be moving northeastward at the end of the week, it's possible that the storm will serve to enhance rainfall for the July 4 holiday. This raises some flooding concerns along the I-95 corridor, although again, the amount of uncertainty is relatively high; the storm is still in an area of weak upper level steering currents, and interactions between tropical systems and non-tropical frontal systems can be difficult to predict.

The official National Hurricane Center track forecast for Tropical Storm Arthur as of 11:00 am ET on Tuesday.

IMAGE: NOAA/NHC

The presence of unusually mild ocean temperatures for this time of year argues in favor of the storm's intensification to hurricane strength all the way to a position of about 200 miles southeast of Nantucket on Friday night. The ocean off much of the East Coast is warmer than average, which could make the East Coast more vulnerable to tropical cyclones during this season, although the season is predicted to be less active than in recent years overall.

In general, though, forecasts of a tropical storm or hurricane's track have been much more reliable than intensity forecasts, something that scientists have been working to correct. The Hurricane Center expects Arthur to reach hurricane strength sometime on Wednesday, according to its 5 pm ET advisory.

The Hurricane Center (NHC) reported that the strongest winds were in the storm's southeastern section, where an Air Force "Hurricane Hunter" was forced to climb to a higher altitude due to intense turbulence. "The flight crew has been been bounced around pretty good by strong thunderstorms in that area," the NHC reported..

Sea surface temperature departures from average, with milder than average waters shown in orange, yellow, and red colors.

IMAGE: HTTP://EARTH.NULLSCHOOL.NET

Computer model forecasts, which meteorologists use to help forecast the storms' movement and intensity, show a track that would bring the worst impacts to Cape Hatteras, North Carolina, on Friday morning. This is a slight shift to the east from previous computer model runs, and more adjustments are likely as the week goes on.

Tropical storms are named using an internationally agreed upon list, once sustained winds reach or exceed 39 miles per hour. These storms become hurricanes once the maximum sustained winds strengthen to greater than 74 miles per hour. Arthur is forecast to have maximum sustained winds of 90 miles per hour

SOURCE: Mashable