Potentially “dangerous” system has 90% chance of tropical development

Update 2 p.m.: The National Hurricane Center is now watching three areas for possible tropical development, including one system that forecasters expect to become a tropical depression by mid-week.

Invest 97-L, noted in the two-day tropical weather outlook below with a 70 percent chance of development, is headed west-northwest at 15 to 20 mph.

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The other two systems have a low chance of development over the  next two days.

The cluster of thunderstorms and showers associated with the system in the far off Atlantic is the remnants of Tropical Storm Lisa. It is expected to merge with a cold front before it can regenerate into a tropical storm.

The third area is expected to move inland over northeastern Mexico before significant development can occur.

Previous story: A system of showers and thunderstorms about 1,100 miles east-southeast of the Windward Islands has a 90 percent chance of becoming a tropical cyclone over the next five days as it travels west-northwest at 15 to 20 mph.

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Jeff Masters, co-founder of Weather Underground and a former NOAA Hurricane Hunter, said the system is potentially “dangerous.”

“After looking remarkably unimpressive on satellite loops for the previous few days, 97-L was turning that situation around on Sunday,” Masters wrote in his blog. “The system had a large circulation at middle levels of the atmosphere, with an increasing amount of heavy thunderstorm activity.”

Part of Invest 97-L’s problem is how close it is to the equator. Tropical cyclones usually need at least 5 degrees of north latitude to get enough spin.

The GFS model takes the system along the east coast, while the European model has it staying west and hugging South America.

The GFS model takes the system along the east coast, while the European model has it staying west and hugging South America.

Masters said he expects the system to be at 12 degrees latitude by Tuesday, where it will also be in an area with 84-degree sea-surface temperatures and low wind shear.

The Washington Post’s Capital Weather Gang note in their blog this morning that models on intensity also vary from a tropical storm to a Category 4 hurricane.

“With that reduced confidence in mind, the time frame beyond five days is not very clear,” wrote Angela Fritz and Brian McNoldy for the Capital Weather Gang.

Masters said an upper-level low developing over the Mid-Atlantic states could pull 97-L more to the northwest by the weekend, putting Haiti, Jamaica, Cuba, the Bahamas and Florida in the potential strike zone.

But he stressed that it is far too early for an accurate forecast.

“Invest 97-L may pass very close to the coast of South America, which would interfere with development,” Masters said. “In addition, the southeaster Caribbean is a well-known tropical cyclone graveyard, where scores of healthy-looking storms have died or suffered severe degradation.”

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AccuWeather meteorologist Mike Doll believes the system will become a tropical depression or storm by mid week as steering currents and wind shear decrease.

“Several factors will determine if the wave strengthens as it impacts the islands and northern coast of South America later this week.” AccuWeather senior meteorologist Kristina Pydynowski wrote. “Another zone of wind shear and/or interaction with land in Venezuela could make it difficult for the wave to intensify.”

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