Storm activity keeps meteorologists busy

A TROPICAL disturbance that just left the African coast yesterday has become the hurricane season’s ninth named storm over the eastern tropical Atlantic Ocean.

The National Hurricane Center declared that Tropical Storm Irma had formed at 11am eastern time, and it was expected to strengthen. It is many days away from any land, but should be monitored by interests in the Caribbean and US.

Meanwhile, a tropical system that could form in the western Gulf of Mexico near Louisiana and Texas early next week bears watching.

Irma was positioned 675km west of the Cabo Verde Islands on Wednesday, with maximum sustained winds of 80km/h. It was tracking west at 21km/h. Computer models are in complete agreement that this storm will intensify in the coming days and could reach hurricane intensity by Friday or this weekend.

It is still very far east – 3 400km east of the Leeward Islands – so there is plenty of time keep a watchful eye on it.

Through the next four or so days, models also agree on where it will track.

But beyond that, some potentially important divergence sets in. The farther north it goes, the more likely it becomes that it will recurve to the north and away from land.

But if it stays further south, away from weaknesses in a large area of high pressure in the subtropics (to its north), it can keep cruising toward the Caribbean, Central America, Mexico and possibly the US.

Historically, over the past 50 years, the ninth named storm has formed on September 30, on average, so Irma is exactly one month early. Accumulated Cyclone Energy, or ACE, is another useful metric we commonly use to assess how busy the hurricane season is.

It is a single value that integrates information about all of the various storms’ intensities over their entire life span.

The ACE so far this hurricane season is at only about 92% of average, despite Harvey.

Harvey’s rampage in the Gulf of Mexico and south-east Texas aside, the hurricane season is still young and just approaching its peak.

Another area we continue to monitor is the north-western Gulf of Mexico.

Just days after Harvey moves out, another tropical disturbance or tropical cyclone could move in. It does not yet exist, but models have consistently been hinting at a disturbance developing in the Bay of Campeche and tracking towards Texas by Wednesday.

The latest run of the US GFS model produces 25-40cm of rain in a swath spanning south-east Texas through southern Louisiana.

There is still a lot of uncertainty with this system, but given the potential, it is important to be aware of it. If it develops but tracks a bit further east, the Texas coast could be spared. – Washington Post

COMPUTER MODELS ARE IN COMPLETE AGREEMENT THAT THE STORM WILL INTENSIFY IN THE COMING DAYS