Being in hot water is really bad for lobsters, but it is great for tropical storms!
Hurricanes are fueled by the energy from hot water. This means the current trend of the Northern Atlantic Ocean growing warmer is creating more strong hurricanes, weird subtropical storms and flooding extratropical storms like Sandy! Officials are scrambling to figure out how to warn and prepare people adequately for the new era of storms.
The National Hurricane Center is designing newer and better warnings for surge damage. Source: NOAA
What has happened is that the Atlantic is in a natural warming pattern, called the warm phase of the Atlantic Multidecadal Oscillation (what a mouthful!) or AMO. After 35 years of a cool AMO, it switched to warm in 1995. This warm phase will probably last at least 20 more years. Yikes!
Unfortunately, most of the science and warning systems were designed when the Atlantic was cool. The hotter waters produce different storm conditions than cooler water. The storms started changing in 1995 and the science is scrambling to catch up.
How subtropical storms are born. Source: Browning Newsletter
Subtropical storms − Sometimes a cold front will drift off the coast, hit hot waters and turn into a subtropical storm. The bottom of the storm turns into a dangerous tropical storm while the top is still a cold front. These used to be rare, now they are more common. Finally, in 2002, the National Hurricane Center started naming these storms and issuing storm warnings.
Hidden hurricanes − Other times, hurricanes can get caught up in a cold front. Think of them as hidden hurricanes. They look like cooler extratropical (no longer tropical) storms, but they create fiercer rains and snows and more floods. Like the Perfect Storm or Hurricane Sandy, they are deadly. However, once a storm stopped being tropical the National Hurricane Center stopped reporting on it. Information became scattered. There were no hurricane warnings posted north of North Carolina for Sandy!
Hurricane Sandy merging with a cold front. Source NASA
Last week, the National Hurricane Center announced changes in their warning systems. They will continue to issue warnings on a storm until it hits land, even if it becomes extratropical. They will warn people how deep storm surges will be and where they will hit. (Surges can flood areas even 50 miles inland.) Information will become clearer, timelier, and more centralized.
A warmer Atlantic is marvelous for swimming, but science and coastal cities must cope with the fact that hotter water can be dangerous. Just ask a lobster!
Evelyn Browning Garriss, historical climatologist, is a longtime writer for The Old Farmer's Almanac. She is also editor of The Browning World Climate Bulletin  and has advised farmers, businesses, and investors worldwide on upcoming climate events and their economic and social impact for the past 21 years.