Sunday, September 1, 2019

Hurricane Dorian may not make Florida landfall, but will eye Carolina coast

By Alex Sosnowski, AccuWeather senior meteorologist




With an inland push across the Florida Peninsula now unlikely, the risks of damage related to wind, coastal flooding and rainfall will increase in parts of Georgia and the Carolinas from dangerous Hurricane Dorian later this week.
Changing conditions surrounding Dorian, most notably a pair of non-tropical storms from the Midwest, will pull on the hurricane in such a way to allow it to track along the Georgia and Carolina coasts.
Dorian Track AM update 9-1
The first Midwest storm is likely to give Dorian a northward nudge on Monday. A second storm from the Midwest is expected to pull Dorian northward and northeastward from Tuesday to Thursday.
It is possible that Dorian takes a similar track to that of Matthew in 2016, where the hurricane may brush or bounce along the immediate coast of the southeastern United States.
Matthew track
However, all hurricanes and their track are different, no matter how similar they appear due to infinitely different weather conditions from one storm versus the next. Matthew traveled northward between Cuba and Hispaniola, while Dorian traveled northward across the U.S. Virgin Islands.
A brief landfall or brush of the outer eyewall cannot be ruled out from Cape Canaveral, Florida to Cape Hatteras, North Carolina.
Dorian PM update sep 1
This satellite images shows Category 5 Hurricane Dorian making landfall across the northern Bahamas with maximum sustained winds of 185 mph on Sunday afternoon, Sep. 1, 2019. (NOAA/GOES-East)
Dorian will spend the majority of the Labor Day weekend at Category 4 or 5 strength. A Category 4 hurricane is very dangerous, and has maximum sustained winds of 130 mph to 156 mph. A Category 5 hurricane is catastrophic, with maximum sustained winds of 157 mph or more.
Dorian will likely weaken as it makes a north, then northeastward turn near the coast, due to frictional effects and increasing southwesterly wind shear.
The current AccuWeather RealImpact™ Scale for Hurricanes for Dorian is a 5 on the Bahamas but a 2 on the mainland U.S.
AccuWeather RIS
While the increasing wind shear is likely to increase the forward speed of Dorian, a significant period of high winds, coastal flooding, battering waves and heavy rain is in store from southeastern Georgia to the southeastern portions of South Carolina and North Carolina.
Dorian Risk pm Sun update
Hurricane-force winds are likely on the barrier islands, as well as locations along the immediate coast of the mainland.
People along the coasts of Georgia and the Carolinas should be prepared for widespread power outages with downed trees and some property damage that a Category 1 to 3 hurricane would inflict. This means that gusts ranging from 74 mph to 129 mph can occur.
Dorian Wind 9-1 update
"Because of the initial slow-moving nature of the hurricane, seas and surf will build days ahead of the storm's arrival," according to AccuWeather Senior Meteorologist Rob Miller.
People spending time at the beach ahead of the storm this weekend and into early next week should anticipate building surf with an increasing risk of strong rip currents from Georgia to North Carolina.
"Coastal flooding is likely to occur and build with each high tide cycle well in advance of the storm, perhaps by two days ore more ahead of tropical-storm winds," Miller said.
Dorian TS Winds update 9-1
Some of the barrier islands may be shut off for a time as roads close.
"At the very least, some low-lying access roads on the barrier islands and shorelines of the bays and harbors may go under water," AccuWeather Meteorologist Tiffany Fortier said.
Cities such as Charleston, South Carolina, which are vulnerable to flooding, should expect flooding from this storm situation. The city recently experienced flooding during the king tides in lieu of any storm and mere effects from the new moon.
Areas that typically get flooded during the approach of a hurricane should expect the same conditions.
The long-duration event, lasting days, will cause considerable wear and tear to the beaches in the region.
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If prompted, people should evacuate the barrier islands as soon as possible. If the power goes out, it may be days to a week or more before it is restored in all areas due to the vast stretch of coastline that Dorian will impact in the southeast U.S.
Since Dorian is not anticipated to push inland over Florida, nor well inland over Georgia and the Carolinas, a worst-case scenario of widespread flooding of streams and rivers over central and northwestern areas of Georgia and the Carolinas is not likely.
However, some of the rivers and low-lying areas along the Coastal Plains in these same states have the potential to receive torrential rain, which can lead to significant flooding.
At this time, AccuWeather meteorologists are forecasting a general 4 to 8 inches of rain with locally higher amounts along the immediate coast of the southeastern U.S. with an AccuWeather Local StormMax™ of 15 inches.
The AccuWeather Local StormMax™ of 24 inches is anticipated for the northern Bahamas.
Dorian Flood 9-1 pm update
The situation could be made worse in these areas due to the slow-moving nature of Dorian, and the persistent onshore flow that causes water to rise over the western ends of the bays and estuaries and back up over the coastal rivers.
Only a track that takes Dorian on a curved path farther out to sea might avoid problems related to heavy rainfall and significantly less potential damage and power outages from wind.
Just as non-tropical storms from the Midwest that travel to the Northeast states will help to pull Dorian northward, then curve the hurricane northeastward along the Carolina coast, a third such non-tropical storm should protect the upper mid-Atlantic and New England from a direct hit from Dorian. However, Dorian may track close enough to the coast to deliver a period of heavy rainfall, strong winds and coastal flooding.
People taking advantage of lower hotel rates after Labor Day weekend should be prepared for building surf and rip currents with the potential for dangerous surf conditions by next weekend.
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