Dr. Jeff Masters' WunderBlog

Delta done; Epsilon next?
Posted by: Dr. Jeff Masters, 15:48 GMT le 28 novembre 2005 +0
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
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51. hurricanechaser 05:47 GMT le 29 novembre 2005    
Heres one last link for satellite wind analysis ...the latest wind estimate at 0103 UTC...has 35 knots with B.P. of 995 mb....40 mph winds... both consistent with Tropical storm intensity...except its not a purely tropical system, which is why its not even categorized as a Tropical depression or subtropical depression yet.

However, the transition is underway and within the next 24 hours..it should be classified as a tropical storm as it pulls more convection in closer to its center of circulation.

I hope everyone has a good night.:)

Link
52. hurricanechaser 05:51 GMT le 29 novembre 2005    
Hey AYsZ,

Sorry about that..I had it bookedmark on the NE Atlantic...I have the same link you do and its just a visible satellite image with no shear or shear tendacies as well.
53. hurricanechaser 05:53 GMT le 29 novembre 2005    
wow..I need sleep...two quick errors..that should've been..."bookmarked":)
54. dcw 11:08 GMT le 29 novembre 2005    
Epsy looking good this morning.
55. HIEXPRESS 14:39 GMT le 29 novembre 2005    
Sorry for the misunderstanding, Snowboy. I did not mean that any here were reaching to name anything that remotely resembles a tropical cyclone to pad the statistics - since, I presume, none here are personally responsible for assigning the names. I was just poking fun at the NHC. But, thinking about it further, and also trying to understand, I visited the NHC site at Glossary of NHC/TPC terms to see what could get named:
"Subtropical Cyclone:
A non-frontal low pressure system that has characteristics of both tropical and extratropical cyclones.

The most common type is an upper-level cold low with circulation extending to the surface layer and maximum sustained winds generally occurring at a radius of about 100 miles or more from the center. In comparison to tropical cyclones, such systems have a relatively broad zone of maximum winds that is located farther from the center, and typically have a less symmetric wind field and distribution of convection.

A second type of subtropical cyclone is a mesoscale low originating in or near a frontolyzing zone of horizontal wind shear, with radius of maximum sustained winds generally less than 30 miles. The entire circulation may initially have a diameter of less than 100 miles. These generally short-lived systems may be either cold core or warm core. "

Also:
"Extratropical:
A term used in advisories and tropical summaries to indicate that a cyclone has lost its "tropical" characteristics. The term implies both poleward displacement of the cyclone and the conversion of the cyclone's primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force."

I see your point. If it spins, and has the potential to ruin someone's day, why not give it a name?

I for one, will respect the end of hurricane season, and I will not go hunting for them - don't want to get caught poaching ;)

"Not a "scientist", just stayed at a [Popular Hotel Chain]"
Member Since: 13 octobre 2005 Posts: 4 Comments: 2154
56. HIEXPRESS 14:53 GMT le 29 novembre 2005    
& so they did - Episilon!
Member Since: 13 octobre 2005 Posts: 4 Comments: 2154
57. HIEXPRESS 14:53 GMT le 29 novembre 2005    
& so they did - Epsilon!
Member Since: 13 octobre 2005 Posts: 4 Comments: 2154
58. snowboy 14:57 GMT le 29 novembre 2005    
sure enough HIEXPRESS, NHC have just issued the following:

TROPICAL STORM EPSILON ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM AST TUE NOV 29 2005

...TROPICAL STORM EPSILON...THE 28TH NAMED STORM OF THE 2005
ATLANTIC SEASON...FORMS OVER THE CENTRAL ATLANTIC OCEAN...

AT 11 AM AST...1500Z...THE CENTER OF TROPICAL STORM EPSILON WAS
LOCATED NEAR LATITUDE 31.6 NORTH... LONGITUDE 50.4 WEST OR ABOUT
845 MILES...1360 KM...EAST OF BERMUDA AND ABOUT 1395 MILES...2245
KM... WEST OF THE AZORES ISLANDS.

EPSILON IS MOVING TOWARD THE WEST NEAR 8 MPH...13 KM/HR...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH... 75 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 200 MILES...325 KM
FROM THE CENTER... ESPECIALLY TO THE NORTH AND WEST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 993 MB...29.32 INCHES.

REPEATING THE 11 AM AST POSITION...31.6 N... 50.4 W. MOVEMENT
TOWARD...WEST NEAR 8 MPH. MAXIMUM SUSTAINED
WINDS... 45 MPH. MINIMUM CENTRAL PRESSURE... 993 MB.
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About JeffMasters
Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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