Tuesday, May 5, 2015

(Sort Of) Tropical Storm Ana To Form This Week?

One forecast depiction of a possible
subtropical storm named Ana later this week.
This is just one scenario. Forecasters
are uncertain where this storm will go,
how strong it will get and even
whether it will form.  
Well, some of us have suddenly made the leap from winter to summer and skipped over spring.

After what had been a reluctant spring, temperatures soared into the mid-80s around my hacienda in northwestern Vermont.

The 86 degree reading in Burlington, Vermont Tuesday was the first 80 degree reading of the year and the hottest day since Sept. 5, 2014. Still, the hot day fell short of the record high of 89 degrees set in 1944.

The rest of the week will bring more above normal temperatures to the Northeast, including Vermont.

Our basking in the heat is not the only summer like thing going on. An early subtropical storm might form off the southeastern United States coast in the next couple of days.

Tropical systems are normally creatures of the late summer and fall, and Atlantic hurricane season doesn't officially start until June 1, but weather systems don't always follow the calendar or schedules or appointment books.

A few tropical storms or subtropical storms have formed in the past in the Atlantic in May or even April. So this is not unprecedented. Just odd.

True tropical storms and hurricanes have a warm core, as opposed to "traditional" storm systems that have cold cores.

Sometimes you get subtropical storms, which are often "normal" storms and low pressure systems with colder centers that then begin to get some complicated tropical characteristics, like spiraling rain bands and some tall thunderstorms surrounding the center of the system.

This happens when these systems are over warm ocean water. Tropical storms and hurricanes must form over water, and almost always the temperature of the water has to be at least 78, 79 or 80 degrees or warmer.

This warm water helps create these "warm" thunderstorms near the center of the storm, turning a plain old storm into something subtropical. Sometimes the subtropical storm entirely completes a transition to a tropical storm or even hurricane.

The current system is forming as a "normal" low pressure system along an old weather front in the Bahamas.

It might start to acquire some of the properties that characterize tropical storms as it moves north, making this thing a subtropical storm.

Subtropical storms still get names from the National Hurricane Center, and if this one gets going, it will be named "Ana"

It's still not entirely certain if "Ana" will form, and if so, where it will go. The system is going to move slowly, as it will be trapped south of a strong high pressure system that will be giving the Northeast its summery weather over the next several days.

People living in the southeastern U.S. coast from North Carolina to South Florida should be aware would-be Ana could come close enough to the coast to cause heavy rain, gusty winds, and long periods of battering surf that could do a real number on beaches and coastal structures.

The possible early formation of Ana doesn't really say anything about how busy the Atlantic hurricane season will be.

There is an El Nino going on, which is a warm area of water in the Pacific Ocean. When there is an El Nino, there tends to be fewer tropical storms and hurricanes in the Atlantic Ocean than usual.

But a few still form, and if one gets big and hits the coast, then you're really screwed. For instance, 1992 was a quiet hurricane year, but one of those hurricanes was Andrew, which devastated South Florida.

Ana most certainly won't be a powerhouse like Andrew. But it's still a reminder for people living along the U.S coast that we're overdue for a major hurricane, and it could come later this summer or autumn.

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