The end of the 2002 season was surprisingly quiet in light of the fact that recently over the past eight years, the last two months of the hurricane season: October and November, have been full of activity.
On the contrary, the 2003 Atlantic Hurricane Season has already gotten underway although it is not scheduled to officially start until June 1st. Why? How so? Well, it is thanks to Tropical Storm Ana, the first named storm of the 2003 Atlantic Hurricane Season.
Ana, which originated near Bermuda as a subtropical system, acquired enough tropical characteristics to become a tropical storm with 50 mph winds. Is Ana's story a sign of things to come? It could be as the recent episode of the El Nino has subsided, and conditions are more favorable again for tropical development in the Atlantic.
Prior to the emergence of Ana, no storm has ever occurred during the month of April since records have been taken in the 1800s. Tropical Storms and Hurricanes have occurred in May, December, January, and March, but never in April.
One of these rare storms was in March, 1854 according to the U.S. Coast Survey. This particular storm came ashore near Dauphin Island, west of Mobile Bay, Alabama. Its origins apparently were in the Gulf of Mexico, and it has been referred to as "The Great 1854 Storm."
You might recall that in the last active November in 2001, there were three storms: Hurricane Michelle, Hurricane Noel, and Hurricane Olga, which lasted into the first week or so of December that year.
As previously mentioned at the beginning of our report, Ana started out as a subtropical storm in the vicinity of Bermuda. The reason why Ana was subtropical was because the storm had not acquired enough tropical characteristics.
What does it mean when we talk about having enough tropical characteristics? Well, there are several types of cyclones: 1.) Mid-Latitude or Extratropical Cyclones, 2.) Tropical Cyclones, and 3.) Hybrid Systems. Now let's take a look at these three more closely.
Mid-Latitude or Extratropical are the kind of cyclones most people in the United States deal with. These lows are spun off by the great Aleutian Low near Alaska, and ride the jet stream, a river of air that separates warm air of the tropics from the cold air of the polar regions.
Mid-Latitude Cyclones take a number of different paths, but they always end up migrating into the Northeast and New England as they approach the Icelandic Low. Extratropical storms are often termed cold core lows or systems because the core region around the center of the low consists of cold air.
On the other hand, tropical cyclones, or hurricanes and tropical storms, originate primarily off the West Coast of Africa, and ride the Northeast Trade Winds to the north of the ITCZ, the Intertropical Convergence Zone.
The tracks they take depend on the climatology at certain intervals of the season, position of the Bermuda High (subtropical high), and upper level wind patterns. Tropical cyclones are often called warm core systems by meteorologists.
Tropical cyclones are warm core systems because unlike cold core systems such as mid-latitude cyclones, these storms have warm air near the center of low pressure. Hurricanes thrive off the warm, moist air that rises from the tropical waters of the Eastern Atlantic. These storms need warm water to sustain themselves.
Hybrid systems are cyclonic systems that contain a combination of both tropical and extratropical systems, which puts them below a tropical system, or a subtropical system such as Ana in its early stages. At this point, Ana had winds of only 40 mph.
So while it was a subtropical system, it was a weak one at that. Hybrid systems can be confusing. For example, Hurricane Earl back a few years ago, was thought to be more of a subtropical storm. Nevertheless, for this time of year, it was a huge surprise to many. It totally caught the folks at Hurricaneville by surprise.
Returning to our story on Ana, the storm began to get going on Sunday afternoon, April 20th. At that time, the National Hurricane Center was about to issue a test advisory according to Ray Hawthorne at NEMAS. Hawthorne, who is the Forecaster in Charge of the NEMAS Tropical Forecast Division, indicated that there was no storm in the making yet.
However, later on that evening as folks watched the nightly local news, a subtropical storm had formed to the Southeast of Bermuda. This was the first time such an event occurred in April, and it was quite amazing to see. That is because ocean temperatures take a longer time to warm up during the course of the year because they're more massive, they mix, and have a higher specific heat capacity.
Ana wasn't through surprising though as it continued to evolve over the next 48 hours. On Monday, winds in the storm's center grew to 45 mph. Along with that, something even more interesting was beginning to occur. And that Ana was acquiring more tropical characteristics by becoming more of a warm core tropical system.
On Tuesday, that was confirmed as Ana became the first named storm of the 2003 Atlantic Hurricane Season. Now, the storm had winds of 50 mph. But, this would be as strong as the storm would get. Ana entered progressively colder waters as it headed eastward in the Atlantic towards the Azores.
Ana's little April Anomaly has definitely shaken things up around the Atlantic Basin. With the recent El Nino event dissipating, conditions that had become more hostile in the latter portion of the 2002 Hurricane Season have become more favorable now in the Atlantic.
In addition, the traditional factors such as rainfall in the Sahel region of Africa continues to be above normal just like in the very active seasons of the late 90's and early 2000s. Sea surface temperatures around the Atlantic Basin also continue to be warmer than normal.
Consequently, the highly active seasons from 1995 to 2002 with exception of 1997, which was an El Nino year, are most likely to continue this season. Is it possible that another storm could form prior to the official start of this upcoming season on June 1st? Well, the folks at Hurricaneville believe it is strongly possible.
Although water temperatures are cool this time of year, they are certainly much more warmer than usual. If that wasn't the case, Ana wouldn't have formed. The sea surface temperatures will continue to get warmer as we approach the latter portion of May into June with more intense sunlight and longer days.
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