Irma shifts west, with appearance in Lowcountry Monday afternoon likely. But how strong will she be?

Looking for the lastest Irma forecast information? Today's story is here.

Hurricane Irma’s projected track on Thursday afternoon made a slight shift west with another small shift by the late evening that has the potential to change its effects on Beaufort County and the surrounding areas. But not enough to quit packing, according to the National Weather Service.

There now is a chance that Irma could continue on an inland path after making landfall in the Miami area, somewhat weakening the storm by the time it gets to South Carolina, according to National Hurricane Center and National Weather Service Charleston. However, there is a lot of “wobble” in the forecast, and earlier tracks showing the storm over water up the east coast of Florida — the so-called “worst-case scenario” for Beaufort County — could reappear, meteorologists say.

“The models have been trending somewhat to the west,” National Weather Service Charleston meteorologist Jonathan Lamb said shortly after 11 p.m. Thursday. “But it’s still several days out and ... there’s still a significant threat.”

That is why they and state officials are still warning people in the Georgia and South Carolina coastal areas there are good chances are direct and potentially devastating effects from Irma, a monstrous storm that has shown little signs of weakening since it strengthened to a Category 5 storm Tuesday and barreled through the Caribbean over the last 24 hours.

Tropical weather track

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Source: National Hurricane Center

South Carolina Gov. Henry McMaster said Thursday afternoon he expects to issue an evacuation order at 10 a.m. Saturday.

Also on Thursday, Georgia Gov. Nathan Deal issued an evacuation for coastal Georgia counties, including Chatham County, effective 6 a.m. Saturday.

“If you can leave now, go ahead,” McMaster stressed.

Beaufort County officials encouraged residents to leave, as well. Evacuations will begin between about 7 and 10 a.m. on Saturday, Sheriff P.J. Tanner said at a Thursday afternoon news conference. Local evacuation routes will be U.S. 278 and U.S. 21, which will be channeled into three parallel routes north.

Lt. Col. Neil Baxley stressed that, once Saturday comes, evacuation routes will be the only options to get out of town. Anyone planning to leave town by another route will need to leave before the evacuation begins.

“If you want to leave, if you’re ready to leave, you need to leave now,” Baxley said Thursday afternoon.

The National Hurricane Center’s latest models issued at 5 p.m. show Irma potentially traveling far west of Savannah sometime after 2 p.m. Monday. Because of its size and strength, significant hurricane force conditions would still affect much of southern South Carolina and the storm’s path is still uncertain.

Although the track has shifted from earlier forecasts that showed landfall in Beaufort County, it could easily shift back, according to NWS meteorologist Bob Bright. The chances of Irma making landfall anywhere along the southeast Georgia or southern South Carolina coasts are roughly identical.

“What we’re basically telling everyone is to prepare for a major hurricane and major hurricane impacts,” Holloway said. “A major hurricane is a Category 3 or higher. Once the eye of a hurricane moves over land it starts to weaken pretty quickly because at that point it is no longer over the warm ocean waters, which are its fuel source.”

Where is Irma?

As of late Thursday night, Irma was a massive Category 5 storm, with sustained winds of 165 mph — slower than her steady 185 mph winds previously. It is moving west-northwest at 16 mph. At 11 p.m. it was about 55 miles east-northeast of Grand Turk Island and about 585 miles east-southeast of Miami.

At its current rate, it is expected to reach the Florida Keys by mid-weekend, and the National Hurricane Center issued the first watches for the Keys and the Florida Peninsula in their 11 a.m. update Thursday morning.

Latest Caribbean view by satellite

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Source: National Hurricane Center

Irma is enormous, around 400 miles wide according to the Washington Post on Thursday, meaning it will be able to do massive damage even if the eye is not on shore. As a frame of reference, Hurricane Matthew never came ashore in Beaufort County last year but still did over $50 million in damage.

Northern turn to determine SC’s fate

A sharp northern turn in the storm is expected to happen at some point in the next few days. The exact time and location of that turn are currently unknown, but when and where it happens will be the key to its effects on South Carolina.

There is still a chance that Irma might miss the Lowcountry, according to Holloway, who said that when forecasting four and five days in advance, the hurricane center’s track can be off by anywhere from 175 to 225 miles. That uncertainty is why the cone in the forecast widens the further into the future it looks.

It is worth noting that because of its size, the storm’s effects will be felt many hours before it actually arrives and that, in a way, even if it misses the Lowcountry, it will still hit the area.

“That prediction of where the center will be is the best forecast, but don’t just focus on that center point, because it could be anywhere within that cone,” said Holloway. “But it is such a big storm that the impacts are going to extend away from the center many hundreds of miles.”

Meteorologist Carl Barnes noted that “any wobble could shift it back offshore” if Irma begins an inland course into Florida in the coming days. Since the projections are still a few days out and slight changes can cause major changes in the prediction, the weather service is urging everyone to treat this as a major hurricane.

What to expect

The potential effects on the Lowcountry won’t be clear until “a day or so” before the hurricane hits the area, Lamb said. Even if Irma should maintain an inland path over Florida and into Georgia, he said, the threat of “significant storm surge” still looms. The bulk of the storm is projected to reach Beaufort County and the surrounding areas Monday afternoon and evening. Tides will begin to rise Friday and gradually increase with each passing high tide.

Flash flooding, tornadoes, at least tropical storm force winds and storm surge are all threats that Beaufort County could face even if the eye of Irma misses us according to Holloway, who advises that people should still prepare as if there is going to be a direct impact.

“Some fluctuations in intensity are likely during the next day or two, but Irma is forecast to remain a powerful category 4 or 5 hurricane during the next couple of days,” according to the hurricane center.

If Irma does hit as a Category 3, major storm surge is expected, though precise estimates are not yet available. You can use this tool to see what storm surge would look like in your area during a Category 3 hurricane.

The most recent frame of reference that Beaufort County residents have for comparison to Irma would be Hurricane Matthew, which grazed the Lowcountry last October. According to Holloway, such comparisons fall woefully short of what the Lowcountry should expect.

“Let’s say that it follows the expected (2 p.m. Thursday) forecast track exactly, that is basically a major hurricane making direct landfall into the Tybee Island and Beaufort County area,” said Holloway. “There really is no comparison to Matthew. This would be a much more significant storm with much stronger winds and much more significant storm surge issues.”

If you need advice on how to prepare for the coming storm, would like to better understand the conditions that Irma might bring, the National Oceanic and Atmospheric Administration has teamed up with the National Weather Service in Charleston to create a hurricane preparedness guide.

Watches and warnings

Hurricane watches have been issued for the Florida Peninsula from Jupiter Inlet around the peninsula to Bonita Beach, including the Florida Keys, Lake Okeechobee, and Florida Bay. A storm surge watch has been issued for these areas as well.

Hurricane warnings are in effect in Haiti from their northern border with the Dominican Republic to Le Mole St. Nicholas, as well as the southeastern, central and southeastern Bahamas, the central and northwestern Bahamas, the Turks and Caicos Islands and the Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus and Villa Clara.

Hurricane watches have been issued for the Jupiter Inlet southward around the Florida peninsula to Bonita Beach, the Florida Keys, Lake Okeechobee, Florida Bay, and the Cuban provinces of Guantanamo, Holguin, Las Tunas and Matanzas.

Tropical storm warnings have been issued in Haiti from south of Le Mole St. Nicholas to Port-Au-Prince and the Cuban provinces of Guantanamo, Holguin and Las Tunas.

States of emergency have been issued for Florida, Georgia, South and North Carolina.

An emergency was also declared in Beaufort by Mayor Billy Keyserling. The mayor’s order will be in effect through Tuesday afternoon unless called off by the mayor before then.

This story was originally published September 7, 2017 at 5:42 AM with the headline "Irma shifts west, with appearance in Lowcountry Monday afternoon likely. But how strong will she be?."