Tropical storm Admonitions As "Perilous" Florence Draws nearer To US Drift


US Cost

By: Manoj Yadav
12 Sep 2018


Growing in size and fortifying once more, vicious Tropical storm Florence is on a direct path toward the East Drift as a "greatly hazardous" Class 4 sea tempest. Disastrous flooding and ruinous breezes are ending up likely in the eastern Carolinas north of Charleston, where typhoon alerts were issued late Tuesday.

Forecasts generally project the storm to make landfall between northern South Carolina and North Carolina's Outer Banks as a Category 3 or 4 Thursday into Friday, although shifts in the track are possible and storm impacts will expand great distances beyond where landfall occurs.

The National Hurricane Center is warning of a triple threat in the Carolinas and Virginia:

A "life-threatening storm surge" at the coast - a rise in ocean water over normally dry land.

"Life-threatening freshwater flooding from a prolonged and exceptionally heavy rainfall event" from the coast to interior sections.

"Damaging hurricane-force winds" at the coast and some distance inland.

Like Hurricane Harvey, which stalled over Texas in 2017, Florence could linger over the Southeast for several days after landfall, unloading 15 to 20 inches of rain and isolated amounts to 30 inches. The Hurricane Center said this is "likely" to produce catastrophic flash flooding.

The flooding might be similar to or worse than what the Carolinas experienced during Hurricane Matthew in 2016.

More than 1.5 million people have been ordered to evacuate coastal areas ahead of the storm, due to both destructive winds and storm surge which could place normally dry land under at least 10 feet of water.

"All interests from South Carolina into the Mid-Atlantic region should ensure they have their hurricane plan in place and follow any advice given by local officials," the Hurricane Center said.

"Even if you've ridden out storms before, this one is different," North Carolina Gov. Roy Cooper said at a Tuesday afternoon news conference, where he announced the mandatory evacuation of the state's popular and fragile barrier islands. "It's an extremely dangerous, life-threatening, historic hurricane," noting the forecast for days and days of rain.

Even before South Carolina's mandatory evacuation order for coastal areas took effect at noon, cameras showed traffic at a crawl on the main interstate connecting Charleston and Columbia. In North Carolina, Dare County officials warned that ocean overwash already was spilling onto low-lying roads and slowing evacuations there.

The monstrous storm already has forced the closing of hundreds of schools throughout the region. Because Florence's rainfall is expected to pound areas far from the coast, the University of North Carolina at Chapel Hill and Duke and North Carolina State universities canceled classes through week's end. Boeing and Volvo shut down their Charleston factories, idling thousands who build 787s and sedans. South Carolina's governor has ordered more than a million people living along the state's coast to evacuate the area ahead of Hurricane Florence.


In Virginia, officials said inland flooding was likely to be catastrophic and could test the James River flood walls in Richmond, the state capital. The Navy commander of the Mid-Atlantic region authorized an emergency evacuation order for personnel who live in the low-lying area under mandatory evacuation, and corrections officials said they had evacuated a prison in that area. The mayor of the District of Columbia joined Maryland's governor in declaring an emergency in the nation's capital.

President Donald Trump has approved emergency disaster declarations for the Carolinas and Virginia, which frees up funds for relief and recovery. "We're as ready as anybody has ever been," he said after a briefing with FEMA Administrator William "Brock" Long and Homeland Security Secretary Kirstjen Nielsen.

He also canceled campaign rallies in Cape Girardeau, Missouri, and in Mississippi.

"Florence could be the most dangerous storm in the history of the Carolinas," Long, a North Carolina native, tweeted Tuesday.

Weather:

As of 5 p.m., Florence's top winds increased to 140 mph, which "could be conservative" according to the Hurricane Center. It was tracking west-northwest at 17 mph, and about 785 miles east-southeast of Cape Fear, North Carolina.

The Hurricane Center is calling the storm "extremely dangerous," and predicts its maximum winds could still reach 155 mph at peak intensity, which is just 2 mph from Category 5. Some modest weakening may occur just before landfall, but Florence is predicted to approach the coast as a Category 3 or 4.

The storm's zone of hurricane-force winds expanded Tuesday, and extend 60 miles from the center while tropical-storm-force winds extend 170 miles outward.

Hurricane warnings were issued for South Santee River, South Carolina to Duck North Carolina and Albemarle and Pamlico Sounds. This includes Wilmington, North Carolina. Hurricane watches extended north to the North Carolina/Virginia border and south to the South Santee River, including the Charleston area.

Storm timing:

In coastal areas of the Southeast and Mid-Atlantic, heavy surf and elevated water levels are expected to arrive by Wednesday morning, and rainfall could begin by late Wednesday night and Thursday morning. The rain is then predicted to spread inland by Friday and potentially continue for days as the storm slows or stalls.

Tropical-storm-force winds could reach the coastline as early as Thursday morning, at which point all outdoor preparations should be completed.

Extremely dangerous hurricane-force winds could batter coastal locations by Friday. Hurricane-to-tropical-storm-force winds could extend well inland, depending on the storm's track.

Storm hazards:

Like a bulldozer, the storm's winds and forward motion will push a tremendous amount of water onshore when it makes landfall. The storm surge, or rise in water above normally dry land at the coast, could reach up to more than a story high, or 13 feet, if the maximum surge coincides at high tide.

Jeff Masters, the meteorologist who pens Weather Underground's Category 6 blog, reported a maximum surge of 15 to 20 feet is possible which would rival heights from hurricanes Hugo (1989) and Hazel (1954).

The biggest surge should occur just to the north of where the eye of the storm comes ashore, which the Hurricane Center projects in southeast North Carolina.

The surge will result in inundation of roads, homes and businesses.

Storm surge warnings were issued from South Santee River in South Carolina to Duck, North Carolina. The Charleston area is under a storm surge watch.

The Hurricane Center projects the following surge heights above normally dry land, if the maximum surge coincides with high tide:

--Cape Fear to Cape Lookout, including the Neuse and Pamlico Rivers: 9 to 13 feet

--North Myrtle Beach to Cape Fear: 6 to 9 feet

--Cape Lookout to Ocracoke Inlet: 6 to 9 feet

--South Santee River to North Myrtle Beach: 4 to 6 feet

--Ocracoke Inlet to North Carolina/Virginia Border: 4 to 6 feet

--Edisto Beach to South Santee River: 2 to 4 feet

Rain

Models have come into agreement that a northward turn before reaching the United States is unlikely and that a building high-pressure zone north of the storm will cause it to slow or stall once it reaches the coast or shortly thereafter. Where exactly the zone of heaviest rain will be is a big uncertainty. It could reasonably occur anywhere between the mountains and the coast.

If the storm stalls, some areas could see feet of rain, especially if downpours focus over the higher terrain in western North Carolina and southwestern and central Virginia.

However, some of the latest forecast models suggest the heaviest rainfall could focus on the eastern Carolinas.

If the storm drifts into Virginia, this region will be particularly susceptible to flooding because of far-above-normal rainfall in the region since May. In addition, because the ground is likely to be saturated, trees will be vulnerable in strong winds.

Parts of the Mid-Atlantic, especially from Virginia to Pennsylvania, have received 150 to 300 percent of their normal rainfall since May.

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Wind

The strongest winds will occur where and when the storm makes landfall in a ring around the calm eye of the storm known as the eyewall. If the storm makes landfall as a Category 4, these winds will be destructive, sustained at up to 130 mph or so with higher gusts.

The zone where these intense winds occur will be narrow, but the effects will probably be devastating, similar to a strong tornado. The Hurricane Center describes the types of damage associated with Category 4 winds:

Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

Outside of this zone of destructive winds, damaging winds are still likely, even some distance inland from the coast, which will lead to minor structural damage, downed trees and widespread power outages.

If the storm stalls in eastern Carolinas as or just after the storm makes landfall, these wind impacts will be magnified.

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The latest path projections

Where the storm makes landfall has implications for where the strongest winds and biggest rise in water at the coast occurs, but strong winds and extreme rainfall could occur at great distances from the landfall location. Keeping this in mind, here is the likelihood of landfall at different locations based on our evaluation of model data:

--80 percent in the Carolinas

--10 percent offshore

--5 percent between northern Florida and Georgia

--5 percent north of the Carolinas

Even in the unlikely event that the storm center remains just offshore, it will almost certainly come close enough to bring dangerous wind and flooding to coastal areas. Areas farther to the north and west may be somewhat spared in this scenario.

While the storm is expect to unleash its worst effects on the Carolinas and Virginia, residents farther north in coastal and inland areas in the Delmarva Peninsula, New Jersey, Pennsylvania and New York should also monitor the storm and prepare in case the forecast shifts to the north and east after landfall.

Florence's place in history

In the event that Florence makes landfall as a Class 4 in North Carolina, it would be the most grounded tempest to come aground that far north on record.

On the off chance that a noteworthy tropical storm (Classification 3 or higher) makes landfall along the Southeast drift, the uncommonness of such an occasion is pertinent. Since 1851, just 10 noteworthy tropical storms have done as such, and the latest was Fran in 1996, 22 years back. Hugo in 1989 was the one preceding that and was a Classification 4 at landfall. No storm has made landfall as a Classification 5 in this locale on record.

Numerous individuals in the Southeast and Mid-Atlantic most likely have not encountered a tempest of the potential extent of Florence.