Less than 24 hours remain before the first Tropical Storm force winds will blow along the North and South Carolina shores ahead of Hurricane Florence. In Myrtle Beach, SC, Wednesday afternoon certainly did not have the look of imminent danger. The live-camera frame below, courtesy of EarthCam, portrays what would normally be a beautiful beach day. Cumulus clouds from Florence gently floated along the horizon,  but otherwise it was bright and sunny, with a cooling breeze from the ocean to mitigate the sub-tropical heat.

But at closer glance, there’s something quite jarring about this picture. The beach and boardwalk are both completely devoid of people. That’s because the entire stretch of coastline between Edisto, SC and Hampton Roads, VA are under mandatory evacuation orders ahead of catastrophic impacts from Hurricane Florence. We’re about 24 hours out, so let’s take a look at what’s new.

Time is dwindling to make preparations before the, to put it simply, destruction  of much of the Carolina, Virginia, and Georgia coast and inland flood plains. As of 5pm, Florence was a Category 3 Major Hurricane with maximum sustained wind speeds of 120 and minimum central pressure of 949 mb. As expected, the storm continues to barrel northwestward toward the North and South Carolina coasts at 16 mph.




Though Florence has weakened since this morning, her wind field has expanded considerably. Hurricane Force winds now extend 70 miles from the storm’s center, while Tropical Storm force winds extend an incredible 175 miles out. Satellite imagery below depicts the storm’s immense size. Bright red imagery depict very tall clouds that have grown out of the enormous release of latent heat. The storm’s robust outflow can be seen expanding to the south.

Some numerical guidance has shifted southward over the last day, but most models have gradually converged on a particularly gruesome track. There is unanimous model consensus that Florence will continue northwestward until early Friday morning. It will trek just offshore the North and South Carolina border before grinding to a crawl upon encountering strong high pressure. Florence will subsequently swing southwestward and hug the coast, briefly before making landfall Friday night or Saturday morning while wrapping around high pressure. Upwelling of cold water and slight vertical wind shear will weaken the hurricane as it approaches the coast so it will make landfall as a Category 2 or strong Category 1 Hurricane. Florence is expected to make landfall somewhere between Wilmington, NC and Charleston, SC. Since the storm will have slowed drastically, this weakening will be insufficient to prevent widespread disaster.

Although there is relatively little spread in numerical guidance through Florence’s landfall, the cyclone’s ultimate fate upon storming ashore is highly uncertain. The determinisic global and hurricane models appear to have a strong handle on the storm’s ultimate path, but peering into the ensembles tells another story. The messy scribble over the Southeast on the ECMWF spaghetti plot below, courtesy of weathernerds.org, is the suite of possible “tracks” of Florence as she begins to disintegrate. While a westward progression towards the mountains seems most reasonable based on the near consensus of the deterministic models, the ECMWF ensemble should not be entirely discounted. Alongside the torrential rain over the Southeast, an abundance of data will flood the model assimilation system upon reaching the coast, which could result in stark changes to the storm’s path.

Regardless of where Florence travels upon landfall, she will quickly begin the process of extra-tropical transition as the storm interact’s with nearby fronts. The heaviest rain will migrate toward the northern side of the circulation, inundating much of the southern Appalachians. Eventually,  Florence will be picked up by the jet stream, which will carry her remnants towards the Northeast.

Florence is an extremely treacherous storm. The entire coastline from Savannah to Norfolk and the corridor from the North Georgia Mountains through the Blue Ridge Mountains will experience crippling impacts from Florence in some fashion. Given its immense wind field and slowing propagating speed, impacts will be long-lasting. Tree-toppling tropical storm and hurricane force winds, torrential rain and continuously building storm surge will literally annihilate the Carolinas, southern Virginia and eastern Georgia. We don’t say this is to stoke fear, we say this to help: lives will be lost of those who do not heed warnings and evacuation orders from local emergency management officials. The destruction this storm will bring cannot be understated.

The most perilous impacts will be along the South Carolina and southern and central North Carolina coasts. Inundation of storm surge will submerge barrier islands and travel up bays, rivers, and estuaries such that even cities like Wilmington, NC, which is protected from the immediate coast by barrier islands and estuaries, will experience significant damage. In conjunction with wind gusts in excess of 120 mph, the storm surge will destroy structures in its path along the immediate coast. Popular beach destinations like Hatteras Morehead City, Carolina Beach, and Myrtle Beach will face widespread destruction.




Biblical quantities of rain will douse the Southeast. The most rain will reside north of the storm’s center, though immense rainfall will fall elsewhere. Southeastern North Carolina and far northeastern South Carolina are likely to receive over 2 feet of rain in just three days. Over a foot of rain will overwhelm the soil elsewhere in South Carolina and southern North Carolina. Babbling brooks will transform into raging rivers. Rivers will overflow their banks, generating vast swaths of inland seas. Eastern North Carolina and the South Carolina low country,  landscapes peppered with with swamps, are especially susceptible to flooding. Tropical Storm force sustained winds and hurricane force wind gusts will penetrate areas not considered “coastal.”. Winds may not topple buildings as they will along the coast, but severe structural damage, toppled trees, and widespread power outages will nonetheless ensue.

Further west less rain will fall, but the threshold of rain necessary for destruction is lower. Copious quantities of rain will race down mountainsides and accumulate in valleys. Mudslides become an issue here. The terrain makes emergency response and evacuation difficult already. Toppled trees  and debris will pile on roads alongside overflowing creeks, making matters worse.

Florence is an extremely dangerous hurricane, unlike anything the Carolinas have ever experienced in a long time. All warnings must be taken seriously. There is very little time left to prepare for the upcoming devastation. Protect lives and property as soon as possible. Encourage friends and family who live on the coast or in flood plains to evacuate while they still have a chance. Countless lives are at stake. Coastal areas may lose power by tomorrow evening.

As always, WeatherOptics will continue to provide updates as the situation unfolds.



Author

Josh is a lifelong nature and weather enthusiast as well as the Head Meteorologist at WeatherOptics. He began regularly forecasting for New Jersey, Long Island and New York City in 2014 on social media, contributing to community pages such as SBU Weather. He holds degrees in Physics and in Atmospheric and Oceanic Sciences from Stony Brook University, from which he graduated in 2018. In the Fall of 2018 Josh will start graduate school for his M.S. in Marine and Atmospheric Sciences at Stony Brook, continuing his research on approaches to non-convective wind gust forecasting.

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