Fiona is still a Category 4 hurricane... it passed west of Bermuda and is now headed for Nova Scotia. Gaston is still a tropical storm, drifting around the Azores, Invest 98L was upgraded to Tropical Depression 9 on Friday morning, and Invest 90L was upgraded to Tropical Depression 10 on Friday morning.
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| Overview of Atlantic tropical cyclones and Invests, courtesy of Tomer Burg. |
Unfortunately for eastern Canada, Fiona has not unexpectedly weakened or deviated from the forecast track. It is set to make a historic landfall early Saturday morning... perhaps as the strongest storm the area has ever experienced. Although the storm will transition to an extratropical cyclone before reaching Canada, the impacts will remain the same; it will be an extratropical cyclone with sustained winds of 100 mph or so. The storm surge and resulting coastal flooding will be significant in coastal areas east of the center.
Not only it is a Category 4 hurricane now, it will gain energy from interaction with a trough, a process known as "baroclinic enhancement". This process is fairly typical for high-latitude storms, but this is going to be an exceptional example. You can find a radar loop of Fiona's encounter with Nova Scotia and Newfoundland at http://bmcnoldy.rsmas.miami.edu/tropics/radar/
Similar to yesterday, Gaston is a mid-rage tropical storm, now in the midst of the Azores and expected to stall for the next 2-3 days, then draft was toward the west as it weakens and loses its tropical characteristics.
Invest 90L, the one that was on the coast of Africa yesterday, was upgraded to TD10 today, based on rare but valuable aircraft reconnaissance by the NASA DC-8 aircraft based in Cabo Verde for a field program. Although this could become a tropical storm very soon, its future is limited and is expected to dissipate by the end of the weekend.
As I wrote yesterday, I found just three other examples of this happening (a wave coming off of Africa, developing, and turning north, all before reaching Cabo Verde): Tropical Storm Becky in 1962, Tropical Storm Ginger in 1967, and an unnamed tropical storm in 1988.
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Finally, Invest 98L, the wave that left the African coast back on September 15, was upgraded to Tropical Depression 9 early Friday morning and is now centered about halfway between Venezuela and Hispaniola. It's still experiencing hefty vertical wind shear -- in this satellite animation, you see all of the thunderstorm activity getting pushed to the southwest, leaving the low-level center completely exposed.
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The bad news is that the wind shear is forecast to become quite low starting on Saturday and lasting through Tuesday. At the same time, it will be passing over incredibly favorable ocean conditions in the western Caribbean. There is the potential for some very rapid intensification over the weekend as it passes near Jamaica on Sunday morning then into western Cuba midday Monday.
The NHC forecast as of 11am EDT Friday brings it to Category 2 intensity when it's near Cuba, then Category 3 intensity when it's near south and central Florida on Tuesday night into Wednesday morning. But that all assumes it won't rapidly intensify over the western Caribbean this weekend. For anyone in western Cuba and south/central Florida, I'd take this threat very seriously.
Tropical storm force winds could arrive in Cuba midday Monday, Tuesday morning in south Florida, and Tuesday afternoon in central Florida. You want to have all outdoor preparations complete by then.
The next two names on the list are Hermine and Ian, and it will be a race between TD9 and TD10 for which name goes to which storm.
Thanks to Fiona, the season's total ACE (Accumulated Cyclone Energy) got a huge push, bringing it up to about 82% of average for the date. So far, that single storm has contributed 43% of the total, and it's still going.
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