Hurricane season: Northeast outlook

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Cyclical weather patterns are shifting again, setting the stage for tropical storms to strike the region

Cyclical weather patterns are shifting again, setting the stage for tropical storms to strike the region

Is this the year Long Island is going to be hit by another major hurricane like the massive storm of 1938? And what happened to last hurricane season? All the forecasts were for another very active year, not as busy as 2005 but well above the long term average of 11 tropical storms with six becoming strong enough to be called hurricanes.

Well you can blame it on El Niño. Remember him from 1998 when everything was blamed on El Niño from a bad hair day to a drop in the stock market to a bad day of fishing? He decided to play a trick on hurricane forecasters last season by showing up late. Usually if El Niño is going to come back it shows up in the middle of winter. The tip off is a warming of the water along the equator in the Pacific Ocean (Fig. 1). Sometimes the water only warms a little, sometimes a great deal. When El Niño does come around it can last up to a year and a half. The warmer water heats the air above it and adds a great deal of water vapor to it. This warmer, wetter air creates storms that make winds that blow from the east to west across Atlantic Ocean in the hurricane season. Those winds can blow hurricanes away from the United States and can even blow the storms over, weakening them.

During the winter of 2005-’06 there was no sign of any significant warming down along the equator in the Pacific until late spring. By then it was too late; the forecasts for the hurricane season were already out. Even as the summer progressed not many forecasters thought the growing El Niño would have a great effect on the hurricane season. As it turned out, the 2006 hurricane season was very quiet with no full-blown hurricanes striking the United States. This was a break we really needed after the terrible seasons of 2004 and 2005. Damage estimates from the two seasons combined were more than $150 billion dollars. Here in the Northeast we have been very fortunate not to have had a major hurricane in the last 10 years.

There are some meteorologists and other scientists who believe global warming was responsible for the devastating 2004-’05 storms. But the truth is that global warming — or what I like to call climate change — had nothing to do with it at all. What did cause those bad years was warmer water in the tropical Atlantic Ocean. Hurricanes are engines, a little bit like car engines. Cars need gasoline to run. They take the gas, turn it into a vapor where a spark plug ignites the vapor and the explosion drives pistons in the engine to move the car forward.

A hurricane needs fuel as well. The fuel for a hurricane is hot, humid air over warm tropical oceans. That hot, moist air has a great deal of energy stored in it. When the hurricane sucks that hot humid air into its engine, the storm spins faster and faster. The more high-octane fuel, the faster the engine will run. Starting in 1995 the Atlantic Ocean warmed up. This again has nothing to do with any long-term climate change; it is caused by a 25- to 30-year cycle of warming and cooling that takes place in the Atlantic, known as the Atlantic MultiDecadal Oscillation (AMO) (Fig. 2).

When the Atlantic is in the warm phase of the AMO we see many more hurricanes and larger, broader ones too. When the waters cool we see fewer hurricanes and not as many big storms. When the waters are cool the diameter of the hurricanes are smaller as well. In the 1930s, ’40s, and ’50s the waters of the Atlantic were warm. In that time Connecticut was hit with four major hurricanes. The 1938 storm was the most damaging with winds of 120 miles per hour gusting to 160. The storm hit at high tide with a full moon, the worst possible combination. The level of Long Island Sound was lifted 20 feet higher than normal due to the hurricanes tremendous southerly wind piling water on top of itself.

If a storm of that magnitude were to return today we would be looking at $45 billion to $55 billion dollars of damage, maybe more. Some insurance companies have stopped issuing policies here because they are afraid another 1938-sized storm is in our future … someday.

In 1944 another major hurricane hit Connecticut with New London County and eastern Long Island Sound getting hit the hardest (as usual) but even Hartford had a wind gust to 109 miles per hour.

Another powerful storm hit the state in 1954, Hurricane Carol. This was another big blow for eastern and southeastern Connecticut and Rhode Island. Carol is regarded as the last major hurricane to strike the waters of Southern New England. In 1955 two weaker tropical storms struck the state within a week of each other in August and produced the epic flood of 1955.

And, finally, in 1960 Hurricane Donna smashed ashore in September with more damage and flooding, mostly in central and eastern Connecticut and Rhode Island. Once again it was the waters of eastern Long Island Sound that bore the brunt of the storm.

Through the 1960s, ’70s, ’80s and into the ’90s the waters of the Atlantic Ocean cooled. During this time Connecticut was hit with only one modestly sized hurricane, named Gloria, on Sept. 27, 1985. Another moderately strong hurricane struck Southeastern Connecticut, Rhode Island and Massachusetts in 1991, Hurricane Bob. In the 22 years from 1938 to 1960 Connecticut (and especially the southeastern Connecticut coastal waters) was hit with four large hurricanes and a massive flood from two weaker tropical storms. In the 45 hurricane seasons since 1960 we have only seen two modest hurricanes strike southern New England head-on.

Hurricanes come and go in cycles. The water of the Atlantic Ocean started to warm again in the mid-1990s and will likely stay warm until 2020 or so. The reality of that means we are in the same ocean temperature pattern of the 1930s, ’40s and ’50s, yet we have had no hurricane make a direct hit here since the water warmed.

Knowing the past is the key to understanding and predicting the future. Hurricanes will return to southern New England — it is only a matter of time. The size and forward speed of the storm will have a great deal to do with how much damage there is.

Hurricanes need to live over warm water, at least 80 degrees. That is the reason these greatest of all storms are born in the tropics. Sometimes the winds in the atmosphere grab onto a hurricane and scoop it up to New England. The water temperature north of Cape Hatteras, N.C., is usually a few degrees shy of 80 in August and September. That means that a slow-moving hurricane will begin to weaken as it plows to the north over those waters.

But if the winds scooping up the hurricane are fast enough they can lift the storm up from the tropics so rapidly that the storm loses little of its power and can even gain strength because it is flying so fast to the north. The 1938 hurricane was moving at nearly 60 miles per hour when it hit the state during the afternoon of Sept. 21.

So what about the 2007 hurricane season? We know the water of the Atlantic is warm. But now the Pacific ocean is cooling off. The Pacific also has a 25- to 30-year warming and cooling cycle. This is called the Pacific Decadal Oscillation. The Pacific was cool through the 1950s, ’60s and ’70s. In the late 1970s the Pacific warmed up and stayed warm through 2006. Now it appears the Pacific is reverting back to the cool phase again. Because of this, last winter was Alaska’s coldest in 30 years. Cooler water in the Pacific means fewer El Niños and more La Niñas. La Niña is the term we use when the water along the equator cools for a year to a year and half. La Niñas help reduce the amount of wind over the Tropical Atlantic during the hurricane season. That means the storms can grow taller, broader and stronger without interference from the winds of El Niño.

This hurricane season the Atlantic waters will be warm, the Pacific waters will likely be cool and we may have a La Niña in place along the equator. Those ingredients add up to a very active hurricane season.

However it’s where the hurricanes go that matters, not how many there are. There is no way to tell if Connecticut or any other part of southern New England will have a hurricane this year or not. But based on what has happened in the past with similar water and atmospheric patterns, we should be ready to take a step back into the weather of the past, and maybe soon.

It’s a fact that most of southern New England’s major hurricanes have hit during La Niña hurricane seasons. Be ready and have a plan of action before the warnings are issued. Peak season for hurricanes in southern New England is August and September. The greatest threat period is focused on the four-week period from late August until late September.

Meteorologist Art Horn appeared for many years on NBC30 as a television weather forecaster. He is from Groton, Conn. He has a degree in meteorology from Lyndon State College. After 25 years in television he started his own business, The “Art” of Weather, in 2005. Art speaks at adult communities, libraries, museums, condo associations, schools as well as clubs and organizations across in New England and Florida. www.theartofweather.com