In the Atlantic, Tropical Depression Two fighting a losing battle

Enhanced satellite image of TD2 at 9:15am EDT today.  High clouds are white, and low clouds appear yellow. (NOAA)

Enhanced satellite image of TD2 at 9:15am EDT today. High clouds are white, and low clouds appear yellow. (NOAA)

At 4 p.m. EDT on Monday, an area of strong thunderstorms located in the central Atlantic was upgraded to Tropical Depression 2, based on satellite appearance.  This morning, the tiny swirl is centered about 950 miles east of the Windward Islands and is moving toward the west-northwest at 16 mph.  That motion is expected to continue, which will bring it near the southern Leeward Islands on Thursday.  However, there may not be much left of it by then.

dashboard-hurricaneTropical Weather Dashboard
System type: Tropical Depression
Intensity: 35 mph, 1012 mb (updated 11 a.m. EDT)
Location: 950 miles east of Barbados
Intensification potential: Low (confidence: high)
Landfall potential: Low (confidence: high)
Days from possible landfall: 2
Zones to watch for possible landfall: Lesser Antilles (confidence: high)
Will if affect VA/MD/DE beaches? No (confidence: high)
Will it affect D.C.? No (confidence: high)

dashboard-hurricane 

There are a few factors working against this small tropical cyclone.  The sea surface temperature is currently warm enough to sustain a stronger storm, but barely.  The vertical wind shear, which inhibits cyclone development and strengthening, is also low enough to allow a storm to intensify, but it will be increasing notably by tomorrow. Finally, and most importantly, there is a lot of dry air surrounding this tropical cyclone embryo.

Precipitable water (top) and water vapor (bottom) images near TD2 this morning.  In the PW, the cooler colors are drier, and in the WV, the  browns/blacks are dry. (CIMSS and NOAA)

Precipitable water (top) and water vapor (bottom) images near TD2 this morning. In the PW, the cooler colors are drier, and in the WV, the browns are drier. (CIMSS and NOAA)

This depression formed from an easterly wave, which had its origins over eastern Africa back on July 12 (ten days ago!).  It made the long trek across Africa and exited the west coast on July 17.  As we head into August, these African easterly waves typically become the favored mechanism for hurricane formation in the Atlantic.  Over the next three months, a continuous train of easterly waves will be generated over eastern and central Africa.  Some will have “the right stuff” and become tropical cyclones, but the majority will never organize into anything worth mentioning.  The figure below shows all of the points of origin for tropical storms in the Atlantic during the July 21-31 period.  The red dots are where storms formed between 1851-2009, while the green dot is the current position of Tropical Depression 2.

Points of origin for all tropical storms from 1851-2009. (NOAA)

Points of origin for all tropical storms from 1851-2009.  The green dot shows where TD2 is today for reference.  (NOAA)

IF this system should develop further and become a tropical storm, the next name is Bertha.  As I pointed out yesterday, Bertha is one of the names from the original set of six lists started in 1979.  It was first used in 1984, so this year will be its sixth time around, though it may have to wait for the next opportunity if TD2 doesn’t make it.

And for another bit of trivia, 80 of the original 126 names (6 lists with 21 alphabetical names each, omitting Q, U, X, Y, Z) are still in use, while 53 names have been retired.  Want to guess which letter has had the most retirees?   This year’s list contains 12 of the original 21 names, and five of the six lists still have their original “B” name too!

(If you guessed “I” for the letter with the most retired names, pat yourself on the back!  Since 1979, there have been eight “I” names retired, while “F” comes in second place with six.  The only letter with no retirees is “V.”)

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