UPDATE: Tropical Storm Katia forms in the far eastern Atlantic, set to become major hurricane

MIAMI (BNO NEWS) — Tropical Storm Katia formed in the far eastern Atlantic on early Tuesday morning and is expected to become a major hurricane later this week, forecasters said.

Forecasters at the U.S. National Hurricane Center (NHC) have been following the weather system since Saturday evening when it emerged as a large area of showers and thunderstorms off the west coast of Africa. It became better organized on Sunday in association with a low pressure area when it was classified as a tropical depression.

“The convective pattern of the cyclone has improved overnight, with a large area of cold cloud tops now situated to the west and southwest of the estimated center location,” NHC senior hurricane specialist Michael Brennan said on Tuesday, adding that intensity estimates showed the system had strengthened. “On this basis the cyclone is upgraded to a tropical storm.”

As of 5 a.m. AST (0900 GMT), the center of Katia was located about 535 miles (855 kilometers) west-southwest of the southernmost Cape Verde Islands. It is moving toward the west-northwest at a speed near 17 miles (28 kilometers) per hour, a general motion which is expected to continue during the next few days.

Maximum sustained winds of Katia have increased to near 40 miles (65 kilometers) per hour, with higher gusts. “[East-northeasterly] shear should decrease in the next 12 hours or so, and after that time steady intensification should commence as the cyclone moves over progressively higher ocean heat content,” Brennan said. “Katia is expected to be near hurricane strength within 36 to 48 hours with continued strengthening to near major hurricane status by the end of the period (week).”

Tuesday’s forecast showed Katia will be just north of Puerto Rico by Sunday, but this could change as the most recent 5-year average errors at this forecast time is about 250 miles (402 kilometers). Forecasts later this week will better determine which countries, if any, are at risk.

Katia was added to this year’s rotating storm roster to replace Katrina which killed more than 1,800 people in August 2005 when it made landfall near the Louisiana-Mississippi. Storm names are retired if they caused a large number of fatalities.

Katia is the eleventh named storm of the 2011 Atlantic hurricane season, following Tropical Storm Jose which formed south of Bermuda on late Sunday afternoon. Jose passed west of Bermuda, causing minor damage but no casualties.

According to figures released earlier this month, NOAA’s Climate Prediction Center is expecting an above-normal hurricane season in the Atlantic this year. The outlook calls for 14 to 19 named storms, with seven to ten becoming hurricanes and three to five expected to become a major hurricane (category 3 or higher).

An average Atlantic hurricane season produces 11 named storms, with six becoming hurricanes and two becoming major hurricanes. The Atlantic hurricane season runs from June 1 through November 30, with peak activity in September.