Keep Your Guard Up: Secondary Hurricane Season Begins
Even though the peak of hurricane season has passed, there is sometimes a second pulse of tropical storms and hurricanes during October.
While it may seem the door has shut in the Atlantic Basin for this season, there are still some reasons to keep up the guard.
There have been 15 named tropical systems this year in the Atlantic and there has recently been one of the longest-lived tropical systems on record, Nadine.
AccuWeather.com meteorologists do not expect a big new crop of tropical storms and hurricanes for the remainder of the season, but they are monitoring a couple of areas in the Atlantic during week two of October.
One is an area of disturbed weather east of the Bahamas. While this system is not likely to develop, it will merge with a cold front and bring heavy rainfall to Bermuda Thursday and Friday.
Another is a tropical wave over the Central Atlantic.
According to Expert Senior Meteorologist Dan Kottlowski, Head of AccuWeather.com's Hurricane Center, "There is a chance that this feature, which moved off the coast of Africa days earlier, could develop into an organized tropical system next week."
The system is likely to travel in the neighborhood of the Leeward Islands, the Virgin Islands and Puerto Rico spanning late this week into early next week.
"Strong westerly winds aloft currently exist where the system is heading, but they may weaken next week, allowing for some development," Kottlowski said.
Showers and thunderstorms will enhance from east to west from the Leeward Islands to Puerto Rico this weekend into early next week. While there is a risk from flash and urban flooding and potentially gusty squalls, the region is in need of rain.
People from the northeastern Caribbean islands to Bermuda will want to keep an eye on the system and be prepared for potentially adverse weather conditions.
Why a Second Spike in Atlantic Tropical Storms, Hurricanes?
Hurricanes need warm water, weak upper-level winds and moist air to develop.
During October, ocean waters begin to cool and upper-level winds begin to increase. However, water temperatures often remain just warm enough for development. In addition, strong upper-levels winds can still be absent long enough to allow development.
During the peak of hurricane season, September, most tropical systems are born from disturbances moving westward off the coast of Africa. The disturbances are called tropical waves. While the number of waves tends to decline during October, there are still enough remaining to cause trouble occasionally.
Plenty of moist air also remains over the Atlantic well into autumn.
Scientifically, the main function of hurricanes, typhoons, etc., is to transport heat from the tropics to higher latitudes.
"During October, we begin to see more fronts move to and stall over the Gulf of Mexico and just off the Atlantic coast of the United States," Kottlowski said.
The fronts offer a means to spawn thunderstorms, which can then gradually develop into a tropical system.
"We also tend to get more frequent, large areas of high pressure building over the United States," Kottlowski said, "The circulation around these fair weather systems can help to spin up tropical systems to their south and east over the warm Gulf and Atlantic waters."
While westerly winds aloft tend to strengthen and guide many tropical storms and hurricanes away from North America moving forward through the autumn, every once in a while, these winds back around and allow a tropical system to plow inland or parallel the coast.
There have been very costly October hurricanes in terms of lives lost and destruction to property.
1954's Hazel was one of the worst October hurricanes on record. The storm claimed over 1,000 lives (most of them in Haiti) and caused over $400 million (1954 dollars) in damage. Hazel was captured by strong upper-level steering winds and drawn northward at amazing speed along the Atlantic Seaboard of the U.S.
According to AccuWeather.com Chief Meteorologist Elliot Abrams, "The highest winds ever recorded, 94 mph, at Philadelphia International Airport, occurred as Hazel passed to the west. Hurricane-force winds occurred as far inland as Toronto, Canada, on the shores of Lake Ontario."
1964's Hilda curved in from the Caribbean, turned northward over the central Gulf of Mexico and slammed into Louisiana with 135-mph winds and tremendous storm surge. More than 35 people died in the storm.
Dangers from the tropics not only come from hurricanes, but also from tremendous moisture from a tropical storm or depression. As these tropical systems move into a cooler environment, they can no longer hold their moisture and release it in the form of tremendous rainfall and the risk of flooding.
1985's Juan dropped nearly a foot of rain on the north-central Gulf Coast. As many as 48 people died as a result of the storm. Damage approached $3 billion.