Delta done; Epsilon next?

Delta is now a formidable non-tropical (also called extra-tropical) low-pressure system over the far eastern Atlantic. Delta has merged with a cold front approaching the coast of Africa, and this cold front will sweep Delta's remnants through the Madeira Islands today and into the Morocco on Tuesday, battering those areas with a ferocity rarely seen. Winds should reach 50-60 mph, accompanied by rains of 3-6 inches and a storm surge of 2-4 feet. Welcome to the Hurricane Season of 2005, northern Africa!

With Delta's demise today, there is a possibility that the Hurricane Season of 2005 is finally over. However, spinning to the west of Delta over the mid-Atlantic Ocean is the next system to be concerned about, a large non-tropical low pressure system near 30N 50W. This low is over waters of about 26C (79F), which is right at the threshold where tropical storm development can occur. Already, the storm has winds of tropical storm force (40 mph) in a band to the west of the center, according to a 5am EST pass by the QuikSCAT satellite. This cyclone is expected to move slowly west towards Bermuda the rest of the week, and may gradually acquire enough tropical characteristics to be classified as Tropical Storm Epsilon. The storm has little chance of affecting any land areas except Bermuda, and I expect the storm will recurve back to the east before it reaches Bermuda.


Figure 1. Visible satellite image from 8:30am EST today showing Delta approaching the Madeira Islands and Morocco. To the west of Delta is a non-tropical low that may transform into Tropical Storm Epsilon later this week.

December storms
What are the chances of another tropical storm in December? Wind shear levels in the Caribbean are forecast to remain high this week, so development there is unlikely until next week at the earliest, but I wouldn't count out the Caribbean quite yet this year. Development in the mid-Atlantic area after Epsilon leaves is a possibility. Nothing that develops in either of these areas is likely to develop into a hurricane and affect any land areas, however. Shear levels are probably too high and the oceans too cold to allow a significant hurricane to develop.

Historically, the odds do not favor December tropical storm formation. Between 1871 and 2004, only eight tropical storms formed. Three became hurricanes. Two years had two December tropical storms each--2003 and 1887. Hurricane Alice of 1954 was remarkable in that it formed on December 30, and struck the Lesser Antilles islands of St. Kitts and Barthelemy as a Category 1 hurricane on January 2, 1955. Over $100,000 in damage was caused on the islands, and the rains ended a severe drought in Puerto Rico. The head of Puerto Rico's weather station noted:

"This storm has aroused considerable interest. People were somewhat skeptical and slow in believing that a hurricane had actually formed. Already historians have expressed their opinion as to whether this was, or not, the first of its kind in the area. In Puerto Rico a controversy centers about a storm that affected this island in the year 1816; one historian maintaining that it occurred in the moth of January while another holds that it occurred in September."

Alice was not the only winter hurricane to affect the Caribbean; an unnamed Category 2 hurricane moved through the northern Leeward islands on March 8, 1908.

Tropical Storm Odette was the only December tropical storm to kill anyone--it claimed eight lives in the Dominican Republic due to floods when it struck on December 6, 2003, with winds of 65 mph. Odette downed trees and power lines, and damaged buildings, bridges, and large areas of agricultural land. Approximately 35% of the Dominican Republic's banana crop was destroyed.

So in summary, I do expect we'll get at least one and possibly two more tropical storms this season, but they will not be a threat to cause significant damage to land areas.

Jeff Masters