Multiple Tropical Systems Threaten Land

It seems like just a week or two ago we were saying how quiet that the Atlantic had been. Now, Mr. Dolby is right, it’s hyperactive – and so is the Pacific.

Right now, all of the media hype is centered on Tropical Storm Florence. As of 5pm EDT Saturday, Florence was centered about 800 miles southeast of Bermuda, moving toward the west at 5 mph. After reaching Category 4 strength a few days ago, Florence has weakened to a tropical storm with maximum sustained winds near 70 mph. Over the next day or two, Florence will be moving into an area where conditions will be favorable for development, plus there is plenty of warm water ahead, so the system will likely become a hurricane again. Rapid strengthening is possible over the next few days, and Florence could become a Major Hurricane (Category 3 or stronger) again over the next few days.

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There is plenty of warm water in the western Atlantic to help fuel a strong hurricane. Image provided by Weathermodels.com

The future track of Florence still has plenty of questions that can’t be answered yet, but have significant implications. A ridge of high pressure will build in to the north of Florence, sending it on a general westward track, towards the southeastern United States for the next couple of days. The questions are – How strong is that ridge to the north of Florence? How will it be oriented? If it’s strong enough, it will continue to drive the system west or west-northwestward, sending it into the Carolinas, Georgia, or possibly even northern Florida. If the high is weaker, or centered a little more to the east, it could allow the system to turn more northward as it gets close to the coastline, which could allow it to recurve out to sea without making landfall, or it could stall close to the coastline. This will obviously determine what impacts Florence may or may not have on the Southeast (as well as the Mid-Atlantic and possibly even the Northeast) later in the week. People with interests along the East Coast, especially the Mid-Atlantic states and the Southeast, should keep a close eye on the future of Florence. Rough surf ahead of Florence will impact most of the East Coast beginning on Sunday, and continuing through the week.

While Florence is gathering all of the attention (and the hype), it is far from the only system that is a threat to land right now. Newly-formed Tropical Storm Isaac was centered about 1640 miles east of the Windward Islands as of 5pm EDT Saturday, moving toward the west at 7 mph. Isaac had maximum sustained winds near 40 mph, and is expected to steadily strengthen over the next few days while crossing the Atlantic. The current forecast calls for Isaac to become a hurricane by early in the week. As we get toward midweek, if it continues on its current westward track, it could become an increasing threat to the Lesser Antilles. Many parts of this area are still recovering from getting battered by Irma and Maria last summer, and were hoping for a quiet hurricane season. This is not the news that anybody in that region wants to hear.

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A hurricane heading for the Caribbean? No, that’s not what anybody wants to hear, not after last season. Image provided by the University of Wisconsin.

To the east, Tropical Storm Helene is a threat to the Cabo Verde Islands tonight and Sunday. Tropical Storm Warnings and Hurricane Watches are in effect for the islands of Santiago, Fogo, and Brava. As of 8pm EDT Saturday, Helene was centered about 125 miles southeast of Praia in the Cabo Verde Islands, moving towards the west at 13 mph. Maximum sustained winds are near 60 mph, and additional strengthening is expected. Helene could become a hurricane on Sunday. It will bring gusty winds and heavy rainfall to parts of the Cabo Verde Islands for the next 24-36 hours. Rainfall totals of 4-8 inches could result in flooding and mudslides across the islands. Once it pulls away from the islands later on Sunday, it should continue off toward the west-northwest while strengthening a bit more. By mid-week, a turn more towards the northwest is expected, with a weakening trend ensuing as Helene moves over colder waters.

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Forecast track for Tropical Storm Helene. Image provided by the National Hurricane Center.

Think all the action is in the Atlantic? Think again – the Pacific remains active as well. Hurricane Olivia was centered about 1000 miles east of Hilo, Hawaii Saturday evening, moving towards the west at 15 mph. We know that we were more focused on Norman earlier in the week, but Norman is out of the picture, and Olivia is now the bigger threat. Olivia has maximum sustained winds near 85 mph right now. The forecast for Olivia is for a general west to west-southwest motion over the next few days, with a gradual weakening trend expected. By mid-week, Olivia should have weakened to a tropical storm as it approaches and then moves across the Hawaiian Islands. Rough surf is expected across Hawaii over the next few days, with gusty winds likely as the system approaches later on Tuesday and into Wednesday. The main threat with this system will be heavy rain, leading to flooding across the area. Hurricane Lane brought torrential rainfall and flooding to the area a few weeks ago, and this will likely renew flooding in some of the same areas that have not cleaned up yet. We’re not expecting 20-40 or more inches of rain like Lane produced, but 8 to 15 inches and locally heavier is possible, especially in the normally favored upslope locations.

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Just what Hawaii needs – more rain! Model forecasts for the track of Hurricane Olivia. Image provided by Tropical Tidbits.

Back to the east a bit, Tropical Depression 18-E has formed off the west coast of Mexico. As of Saturday evening, the system was centered about 665 miles southwest of Cabo San Lucas, Mexico, moving toward the west-northwest at 12 mph. Maximum sustained winds are near 35 mph, and strengthening is expected. The system should become a tropical storm on Sunday. The storm should head northwestward for the next 24-36 hours, before turning back towards the west-northwest. It should remain over open water, with no threat to any land areas. At this time, the system is not expected to become a hurricane before it starts to weaken over colder waters towards midweek.

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Forecast track for Tropical Depression 18-E. Finally, a fish storm that is no threat to land. Image provided by the National Hurricane Center.

We’re not done yet! Heading much farther to the west, Tropical Storm Mangkhut (not King Tut) continues to strengthen in the Western Pacific Ocean. As of Saturday evening, Mangkhut was centered a little more than 800 miles east of Guam, moving toward the west at 23 mph. It has maximum sustained winds near 65 mph, and is expected to steadily strengthen while heading westward over the next few days. It should become a typhoon on Sunday. The system is expected to move across the Northern Mariana Islands on Monday as a strengthening typhoon. Strong winds, torrential rainfall and storm surge are all threats to the islands, including the large US military presence on Guam. Considering that it’s a small island in the middle of the vast Pacific Ocean, Guam actually gets hit by typhoons quite a bit. Mangkhut should continue on a general west or west-northwest course beyond that, possibly becoming a Super Typhoon (equivalent to a Category 4 or 5 Hurricane in the Atlantic/Eastern Pacific) by midweek. Its too early to determine where it goes beyond that, but it could become a threat to the northern Philippines, Taiwan, or southeastern China late in the week.

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Forecast track for Tropical Storm Mangkhut. Image provided by the Joint Typhoon Warning Center.

Believe it or not, that’s not all. It looks like another tropical system could be developing closer to the northern Philippines. We’ll worry about that one once it actually forms. we’ve got our hands full already.

By the way, we didn’t even get to what’s left of Tropical Storm Gordon. Yeah, we’re focusing on active tropical systems in this post, but Gordon is going to bring heavy rain to the Ohio Valley into Sunday, and parts of the Mid-Atlantic and Northeast later Sunday into Monday. Several inches of rain are possible in parts of this area, with flooding expected. We’ve lost count of how many times this has happened in the Mid-Atlantic states this year. Somehow, we have a hunch that this isn’t the last time it’ll happen this year either.

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