SGB
Beach Fanatic
The following is an excerpt from Jeff Masters' blog at weatherunderground.com. It's looking good for us for the rest of this season! (knock on wood!!)
http://www.weatherunderground.com/blog/JeffMasters/show.html
While the lack of wind shear would seem to favor an active hurricane season, what wind shear we have had has been of exceptionally high quality. The jet stream has spun off a continual series of upper level "cold lows" over the Bahamas and central Caribbean that have brought hostile wind shear to any tropical waves or tropical storms that have tried to approach. This jet stream pattern has been in place since early June, and shows no signs of changing through the end of September.
Dry air and vertical instability
Hurricanes like plenty of moist, unstable air. This has been lacking this year, thanks to an above-average amount of dry Saharan air coming off the coast of Africa. For example, take a look at the instability plot for the eastern Caribbean, where many of last year's fiercest storms formed. Instability has been well below normal this year. Model projections through the rest of September show no change to the basic atmospheric pattern over the Atlantic, and I expect lack of instability will continue to inhibit hurricane development.
Steering pattern
The large scale jet stream pattern and associated positioning of the Bermuda High has remained unchanged since early June, and is forecast to remain the same through the end of September. This pattern puts a trough of low pressure over the U.S. East Coast, which will act to recurve storms approaching the U.S. or Caribbean. Now that we are entering late September, the troughs are getting stronger and extending farther south, making recurvature even more likely. The current pattern has been for tropical waves that form into tropical storms to emerge from Africa at about the latitude of the Cape Verde Islands (12-15 north latitude). This is far enough north to make recurvature very likely. This pattern is forecast to continue through the end of September, and I don't expect any of these African systems will be able to avoid recurvature. We will probably get two or three more of these recurving storms before the usual end to the African tropical storm season in early October.
Summary
Given that the current jet stream pattern that favors recurving storms and shear-producing upper level lows over the Bahamas and central Caribbean is forecast to continue until the end of September, plus Bill Gray's September 1 forecast of only two named storms and one non-major hurricane in October, I don't believe any major hurricanes will affect the U.S. or Caribbean the remainder of hurricane season. I expect one or two tropical storms or Category 1 hurricanes will form in October from the remains of old cold fronts that push off the coast of the U.S. A hurricane of this nature is most likely to affect the west coast of Florida or the Outer Banks of North Carolina, and rarely has enough time over water to make it to Category 3 status. In total, I expect 5 more named storms, 3 hurricanes, and 1 major hurricane this season.
http://www.weatherunderground.com/blog/JeffMasters/show.html
While the lack of wind shear would seem to favor an active hurricane season, what wind shear we have had has been of exceptionally high quality. The jet stream has spun off a continual series of upper level "cold lows" over the Bahamas and central Caribbean that have brought hostile wind shear to any tropical waves or tropical storms that have tried to approach. This jet stream pattern has been in place since early June, and shows no signs of changing through the end of September.
Dry air and vertical instability
Hurricanes like plenty of moist, unstable air. This has been lacking this year, thanks to an above-average amount of dry Saharan air coming off the coast of Africa. For example, take a look at the instability plot for the eastern Caribbean, where many of last year's fiercest storms formed. Instability has been well below normal this year. Model projections through the rest of September show no change to the basic atmospheric pattern over the Atlantic, and I expect lack of instability will continue to inhibit hurricane development.
Steering pattern
The large scale jet stream pattern and associated positioning of the Bermuda High has remained unchanged since early June, and is forecast to remain the same through the end of September. This pattern puts a trough of low pressure over the U.S. East Coast, which will act to recurve storms approaching the U.S. or Caribbean. Now that we are entering late September, the troughs are getting stronger and extending farther south, making recurvature even more likely. The current pattern has been for tropical waves that form into tropical storms to emerge from Africa at about the latitude of the Cape Verde Islands (12-15 north latitude). This is far enough north to make recurvature very likely. This pattern is forecast to continue through the end of September, and I don't expect any of these African systems will be able to avoid recurvature. We will probably get two or three more of these recurving storms before the usual end to the African tropical storm season in early October.
Summary
Given that the current jet stream pattern that favors recurving storms and shear-producing upper level lows over the Bahamas and central Caribbean is forecast to continue until the end of September, plus Bill Gray's September 1 forecast of only two named storms and one non-major hurricane in October, I don't believe any major hurricanes will affect the U.S. or Caribbean the remainder of hurricane season. I expect one or two tropical storms or Category 1 hurricanes will form in October from the remains of old cold fronts that push off the coast of the U.S. A hurricane of this nature is most likely to affect the west coast of Florida or the Outer Banks of North Carolina, and rarely has enough time over water to make it to Category 3 status. In total, I expect 5 more named storms, 3 hurricanes, and 1 major hurricane this season.
