Our "storm meister" is Cruise Critic senior contributor Steve Faber, who, like many of our members, also happens to live in the "zone." Steve came to the study of meteorology out of necessity, learning the skills out of an aversion to death and dismemberment -- his own! For years he was a private pilot with ratings in single engine, instruments and gliders, and for those endeavors understanding weather is a basic survival skill.... More
The tropical season has gone from zero to a likely two in less than a week since our last dispatch.
Tropical Depression Four developed on Monday, August 21. This was the first storm to be born in the Cape Verde spawning grounds, typical for this point in the season. What was unusual, however, was how far into the Cape Verde region TD4 developed: It was even east of the Cape Verdes, forming between them and the coastline of Africa. This is significant for two reasons, lessening this storm's ultimate potential. First of all, when severe weather actually intersects with the African coastline, fine dust is kicked up into the atmosphere, which can filter the sunlight shining on the warm ocean water -- very much like turning down the heat under the boiler of a steam engine. Also, because they have so far to travel to reach our longitudes on the west side of "the pond," there is much that can happen to them along the way; wind shear, cooler water and retaining a tightly enclosed circulation for a longer period of time are factors that tend to limit the chance of reaching our shores as a major hurricane.
Of course, it is equally possible that the storm may pass through areas more conducive to tropical development, but when that happens early in a storm's life the storm often develops instability from "overdevelopment." For this reason, few hurricanes can remain at Category Five for very long.
Between August 22 and 23 TD4 became Tropical Storm Debby. Because the 48 hours subsequent to that strengthening took Debby over relatively cooler water, intensity was expected to decrease, and the amount of intensification thereafter was downgraded. That is in fact what transpired, and current forecasts predict that Debby will never exceed tropical storm level.
One characteristic of tropical cyclones in our hemisphere is that they all have a tendency to eventually turn pole ward. This is due to summer trade wind patterns in the southern Atlantic. The point at which a storm turns north is determined by a number of factors, but mostly by the mid-Atlantic ridge, also known as the Bermuda High. This feature keeps cyclones on a generally westerly track until they either reach the end of the ridge or a weakening somewhere along the ridge's length. Last year the ridge was strong and persistent, and extended from the mid-Atlantic all the way to the Eastern Seaboard. That is one reason so many storms made landfall, especially in Florida, and so few went up the mid-Atlantic "chute." Debby has demonstrated to us that -- at least for now -- the ridge is a less significant feature, and Debby turned toward the pole even before reaching Bermuda's longitude. Because it will be moving sooner into cooler water, it is now predicted that Debby will not reach hurricane strength.
As of August 24, Tropical Depression Five formed near the Windward Islands, relatively close to the equator, quickly passing over Barbados. The depression became the fifth named storm of the season just this afternoon, and is an extremely fast moving storm; although it has slowed down a bit, it was moving initially west-northwest at more than 20 miles per hour. Storms which move that fast are less likely to intensify into major hurricanes as are those which move at a more leisurely pace over warm water, revving up their storm "engines." Ernesto is also encountering strong westerly shear. Yet it remains vigorous and refuses to get torn apart, so the expectation is that after a day or so at tropical storm level, Ernesto will become a Category One hurricane, its position just south of Jamaica. The current thinking is that it will be slow to turn pole ward, which is not good news for the beleaguered Yucatan Peninsula.
As for sea state conditions, Debby will be too far east to affect any sailings other than trans-Atlantic crossings, which can easily be rerouted to avoid the worst. Hurricane Ernesto could be making life miserable for Western Caribbean cruises by the end of the weekend, with 12-ft. seas and winds of 65 knots gusting to 80 knots likely between Cuba and the Yucatan.
What a Difference a Year Makes
As I'm sure nearly all of you have heard through the news media, on August 23 last year, Tropical Storm Katrina roared into existence near the Bahamas, and, after passing over the Florida Peninsula, rapidly developed into the most destructive hurricane in U.S. history.
At the same point this year we have yet to see our first hurricane.