|Above: Potential Tropical Cyclone 10 off the coast of Georgia and South Carolina, as seen by the GOES-16 satellite at 5:30 pm CDT Sunday, August 27, 2017. Image credit: NOAA/RAMMB. GOES-16 data are considered preliminary and non-operational.|
A Tropical Storm Watch is posted for portions of the coasts of South Carolina and North Carolina, thanks to the increasing development of an area of low pressure (formerly called 92L) located about 135 miles south-southwest of Charleston, South Carolina at 8 pm EDT Sunday. This system was designated Potential Tropical Cyclone Ten (PTC 10) by NHC on Sunday afternoon. Satellite images on Sunday evening showed that PTC 10 had a modest amount of heavy thunderstorm activity that was gradually becoming more organized, but high wind shear of 35 - 45 knots was hindering development. The system was stationary on Sunday evening, but is expected to move to the northeast on Monday and Tuesday, very close to the Southeast U.S. coast. PTC 10 will bring heavy rains of 2 – 4” and rough surf to the coast of South Carolina on Monday, and to North Carolina and Virginia by Tuesday. The best chances for development into a tropical or subtropical depression or storm may come on Monday evening, when wind shear is expected to drop to 25 - 30 knots, according to the 0Z Monday run of the SHIPS model. In its tropical weather outlook issued at 8 pm EDT Sunday, the National Hurricane Center gave PTC Ten 2-day and 5-day odds of development of 90%. The storm is unlikely to gain sustained winds any higher than 45 mph as a tropical or subtropical cyclone, and will merge with a cold front and move to the northeast, out to sea, on Wednesday.
The next African tropical wave may develop
A tropical wave emerging from the coast of Africa on Sunday night is expected to develop into a tropical depression by Friday over the central tropical Atlantic, according to the 12Z Sunday runs of our top three models for predicting tropical cyclone genesis--the European, GFS, and UKMET models. The wave is predicted to head west to west-northwest at 15 – 20 mph, reaching the northern Lesser Antilles Islands no earlier than Tuesday, September 5. However, the storm is emerging from Africa fairly far to the north, and has a good chance of turning more to the northwest by the weekend and missing the Lesser Antilles Islands entirely. In its tropical weather outlook issued at 8 pm EDT Sunday, the National Hurricane Center gave this new wave 2-day and 5-day odds of development of 0% and 40%, respectively.