31 August 2010

Danielle out of the picture, Earl heading for the US East Coast, Fiona forms...

NHC ceased writing advisories on Danielle at 03Z as it completed its extratropical transition and entered the hurricane graveyard that is the north central Atlantic.  It was a named storm for 10 days and didn't affect any land.

Earl, on the other hand, is still a powerful Category 4 hurricane and is finally moving away from the Leeward and Virgin Islands.  There are radar loops (from 3 different sites) available at the link below.  At 15Z today, the storm is located 1070 miles SSE of Cape Hatteras, NC and heading WNW at 12kts.  The intensity is 115kts and 939mb, and is forecast to intensify further as it makes its way toward the east coast.  The hurricane is undergoing a concentric eyewall cycle now, where a small eyewall gets replaced by a new larger eyewall over the course of about 12-18 hours.  This can be a temporary disruption to intensification, but the end result is often a more intense storm than before.  Hurricane-force winds extend 60 miles out from the center on the NE side of the storm, and the wind field will expand after the eyewall cycle completes.

The forecast is for Earl to remain a major hurricane for at least the next 3 days.  Today and tomorrow it will brush by the eastern Bahamas, then head NW toward North Carolina.  The official forecast keeps the center of the storm offshore, but not by much, and the distance is within the typical 3-day track forecast error.  The closest approach (or landfall if that should happen) would be during the early morning hours on Friday.  Even if the eyewall doesn't hit the coast, eastern NC will experience tropical storm and possibly hurricane conditions for several hours.  After that encounter with the coast on Friday morning, eastern MA will be affected on Friday evening, then Nova Scotia on Saturday morning.

At 21Z yesterday, the easterly wave we've been tracking for a week was finally upgraded to TS Fiona, the 6th named storm of the season.  Fiona is not in a very favorable environment, as as such, is not forecast to intensify much.  It's currently 35kts, and located 440 miles east of the Leeward Islands.  As I mentioned before, this system will affect the same islands that Earl just did, and there are already Tropical Storm Warnings and Watches for the northern Leeward Islands... again.  The long-term forecast is for very slight intensification and recurving by 70W, not getting too close to the US east coast, but perhaps getting uncomfortably close to Bermuda this weekend.

Now that we're at the end of August, it's a good time to re-evaluate where the season stands compared to an average season.  We have had 6 named storms, 3 hurricanes, and 2 major hurricanes.  An average season by this date has 5 named storms, 2 hurricanes, and 0 major hurricanes.

Please visit my tropical Atlantic headquarters.

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