Tropical Moisture to Bring Heavy Rain to South Carolina This Week
Update Tuesday afternoon: A Flash Flood Watch remains in effect through Tuesday evening for southeastern parts of the Upstate and southwestern Midlands region. A band of moderate to heavy rainfall, associated with Invest 98L, will continue to remain near stationary over the region delivering rainfall rates of 1 to 2 inches per hour. A total of 1 to 3 inches of rain has already fallen around the region with an additional 2 to 4 inches possible through Tuesday evening.
The heavy rainfall rates accumulating on saturated soils could produce a rapid rise in stream levels. Flash flooding could develop quickly along streams, rivers and low-lying locations repeatedly affected by heavy showers and thunderstorms through Tuesday evening. Additional heavy showers and thunderstorms are expected to continue overnight into Wednesday and likely Thursday as Invest 98L crosses over the Carolinas and exits into the Atlantic.
Original story Monday evening: A disturbance over the Southeast could develop into a tropical system if it moves back over water near the Mid-Atlantic states Wednesday or Thursday. At the very least, it will produce several days of rain across the Palmetto State this week.
Forecasters at the National Hurricane Center are also watching a second tropical wave in the Central Atlantic and Tropical Storm Edouard southeast of Atlantic Canada.
Widespread rainfall has been prominent across the southeast United States over the holiday weekend thanks to a weak front that has stalled allowing for an influx of tropical moisture. A small low pressure system formed along this boundary Sunday in the eastern Gulf of Mexico, and it moved into Georgia Monday. The disturbance is forecast to grow into a larger system as it moves toward the coast of the Carolinas by midweek. This is when chances of development are expected to increase as it moves back over the Atlantic beginning Wednesday.
The National Hurricane Center is giving this disturbance, which is referred to in the meteorology community as Invest 98, a 40% chance of intensifying into a tropical or subtropical system over the next five days. Gulf moisture will continue to surge into South Carolina ahead of Invest 98, aiding in the development of numerous showers and thunderstorms each day lasting through at least Thursday. Heavy rainfall and flash flooding is possible where multiple rounds of the thunderstorms move over the same areas in the coming days. Heavy surf, rip currents, and strong winds are likely along the coast as Invest 98 pushes offshore.
A second tropical wave is being monitored southeast of the Lesser Antilles in the tropical Atlantic. This disturbance was producing disorganized showers and thunderstorms Monday, but was not expected to develop. This is because the tropical wave is forecast to enter a hostile environment by midweek, where strong upper-level winds and drier air will likely prevent further organization. However, the wave could produce heavy rain and gusty winds across the Lesser Antilles Tuesday.
Finally, late Sunday night, Tropical Storm Edouard formed in the far North Atlantic, northeast of Bermuda. The storm poses no threat to the United States and, as of Monday morning, is moving quickly northeast at 45 mph. Edouard may not be a threat to any immediate landmass but it did break a record. Tropical Storm Edouard became the earliest fifth Atlantic named storm on record. The previous record was set by Emily, which formed on July 12, 2005.