Visible light satellite image, courtesy of NASA, taken in the morning of 13 August 2011
As we had anticipated the 2011 Atlantic Hurricane Season has shifted into a higher gear and on 13 August 2011 we have Tropical Storm FRANKLIN, the 6th named tropical cyclone of the season, and three tropical waves with potential for cyclonic development, all active in the Atlantic basin.
FRANKLIN was some 300 – 400 kilometers northeast of Bermuda at 0645 EST moving east by northeast, in the general direction of the Azores Islands in the North Atlantic. Because of its track and the fact that it is already moving over much cooler waters. where sea surface temperatures are below 26 Celsius, it is difficult to predict how the intensity of the storm may evolve over time and although it is expected to to decline over the next 24-48 hours it is also possible for some intensification to occur in the near term.
The National Hurricane Center is investigating tropical waves designated as 92L, 93L and 94L, which in the early morning of 13 August 2011 were respectively located at 20N-50W, 12N – 34W and 26N – 58W. All of these tropical waves are showing signs of organization and potential for cyclonic development in the next 24 – 48 hours.
Satellite image of the northwestern Atlantic on 13 August 2011 showing the four tropical systems active in the basin
As we monitor these active systems it is important to also pay attention at several cells of disturbed weather marching west over equatorial Africa, which may become the next tropical waves to emerge over the eastern Atlantic in the next 12 – 36 hours.
Color-enhanced infrared satellite image on 13 Augsut 2011 showing several tropical waves and cells of disturbed weather over equatorial Africa and the eastern Atlantic
In observing this current tropical activity in the Atlantic basin it is interesting so see how the typical “belt of tropical activity”, that typically circles the Earth near the equator, has been disrupted by strong weather fronts and ridges marching generally east by northeast over the USA and the northern Atlantic. This is shown in the composite satellite image below:
Full-disk composite satellite image of Earth's western hemisphere on 13 August 2011 showing the current disruption ot the "belt of tropical activity" around the planet
As of 10:45 p.m. on 13 August 2011 the tropical activity described in this post continues to evolve; Tropical Storm FRANKLIN has weakened and it is now a Tropical Depression, while what was tropical wave 94L has initiated cyclonic generation and it is now Tropical Depression #7 of the 2011 Atlantic Hurricane Season, and Tropical Wave 92L continues to show signs of possible cyclonic development in the next 24 – 48 hours. We need to continue monitoring Tropical Wave 93L and those other that continue to emerge over the eastern Atlantic. Watching this cyclonic activity in the Atlantic basin we are reminded that in 1992 the first tropical cyclone of the season, one of historical proportions, only became a hurricane on 22 August 1992; this was the infamous Hurricane Andrew.
It is now Sunday 14 August 2011 and Tropical Depression #7 is now Tropical Storm GERT, the 7th named tropical cyclone of the 2011 Atlantic Hurricane Season. At 4:45 p.m. today GERT was some 200 kilometers south by southeast of Bermuda moving north by northwest at approximately 12 kilometers per hour. Also today and following in GERT’s wake Tropical Wave 92L is well organized and could potentially become a tropical cyclone in the next day or so. In summary, the 2011 Atlantic Hurricane Season is maintaining a high level of activity and the prognosis appears to be for more of the same in the near term. Consequently all interest around the larger basin must continue to pay attention, be prepared and foster the practice of mitigation. We all need to be well aware that while most of the recent cyclonic activity has taken place over the open waters of the Atlantic, far away from the continental USA, it only takes one hit to cause substantial and possibly catastrophic damage.