Bonnie Has Become A Post-Tropical Cyclone; Locally Heavy Rain, Rip Current Risk Continues in the Carolinas

May 30,2016

Bonnie has weakened to a remnant low near the South Carolina coast as of late Monday morning. Rain, choppy surf and rip currents will continue to impact some of the beaches of the Carolinas and Georgia through this Memorial Day holiday weekend.

(MORE: Latest Impacts From Bonnie)

Highlights 

• Tropical Depression Bonnie made landfall just east of Charleston, South Carolina, on the Isle of Palms around 8:30 a.m. Sunday.
• Impacts include heavy rain, gusty winds, dangerous rip currents, some elevated surf, a small storm surge and minor coastal flooding.
• Additional rainfall accumulations of 1 to 3 inches, with locally higher amounts, are expected across eastern South Carolina, eastern North Carolina and southeastern Virginia.
• Heavy rain will spread well north of Bonnie's main circulation into portions of the Mid-Atlantic and Northeast.

(MORE: Hurricane Central)

Latest Status

Over the last several days, we watched this weather system slowly gain organization. Friday afternoon, the Air Force Reserve Hurricane Hunters found that former "Invest 91L" had both a closed circulation - enough west and northwest winds - and sufficiently robust thunderstorm activity near that low-pressure center to designate it a tropical depression.
(MORE: What is an "Invest"?)

Enhanced Satellite, Current Winds

Current Radar

(MORE: View National Interactive Radar Map
The National Hurricane Center named Tropical Storm Bonnie on Saturday evening but Bonnie weakened to a tropical depression on Sunday morning. Bonnie continued to weakend and became a remnant low Monday morning.

(INTERACTIVE: Bonnie Tracker Map)

Tropical Depression Bonnie made landfall in South Carolina Sunday morning and is expected to weaken and eventually degenerate to a remnant low. The speed at which it becomes a remnant low will depend upon its exact track, as a track farther inland would result in a faster rate of weakening.

Tropical Depression Bonnie made landfall east of Charleston, South Carolina on Sunday morning.

Bonnie Impacts

The main impacts from this system will be poor beach and boating conditions, along with locally heavy rain, this weekend.
Bands of heavy rain caused flash flooding in South Carolina on Sunday. Part of Interstate 95 southbound was closed for the majority of the day Sunday. Parking lots were flooded and numerous cars were stranded near Archdale, South Carolina. Water also entered a residence near Ridgeland, South Carolina and near Switzerland, South Carolina.
Here are a few rainfall totals:

• 8.20 inches near Ridgeland, South Carolina
• 5.75 inches near Okatie, South Carolina
• 5.20 inches near Charleston, South Carolina
• 4.85 inches near Milbury, Georgia

Wind was not a major issue with Bonnie. A wind gust of 40 mph was measured at the Charleston International Airport just before 9 a.m. Sunday morning.
There is also the potential for rip currents and high surf for parts of the Southeast coast through the Memorial Day weekend.
Rip currents, a particular concern in generally good weather when more beach-goers might be tempted to swim, were already spotted Saturday and Sunday along the Georgia and the South Carolina and North Carolina coasts.

Dangerous surf is likely through Monday along the Southeast coast.

Monday's Forecast

A moisture plume will be pulled north, then northeast along the East Coast into Monday from the same upper-level steering winds channeling this system into the Carolinas.
(FORECAST: Virginia Beach | Hatteras | Myrtle Beach | Daytona Beach)
While not directly related to the tropical cyclone itself, this could wring out areas of locally heavy rainfall up and down the Eastern Seaboard from parts of New England to the Carolinas, with local flash flooding possible.

Rainfall Forecast Through Monday Night

Southeast Coast is Typically an Early Season Area to Watch

This map shows the typical formation areas and tracks for named storms in June.

The area off the Southeast coast, as well as the Gulf of Mexico and northwest Caribbean, is a part of the Atlantic basin where early-season tropical or subtropical storm development is most likely.
That said, it's not a very active time of year for storms to form compared to the peak August-October period. For example, only one named storm forms during June every other year, on average.
(MORE: Where June Storms Develop)
Recent seasons have had activity before the start of June.
Last May, Tropical Storm Ana formed off the Southeast coast before making landfall near Myrtle Beach, South Carolina, with minor impacts.
In 2012 two named storms, Alberto and Beryl, formed during May off the Southeast coast. Beryl would go on to make landfall in northeast Florida, while Alberto moved out to sea.
(MORE: When Hurricane Season Starts Early)

MORE: Hurricanes From Space - Satellite Imagery