Tropical Storm Isaias Turns Toward the Carolinas

Tropical Storm Isaias turned toward the Carolinas on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Isaias was located at latitude 30.7°N and longitude 80.1°W which put it about 220 miles (350 km) south-southwest of Myrtle Beach, South Carolina.  Isaias was moving toward the north at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 998 mb.

A Hurricane Warning was in effect for the portion of the coast from South Santee River, South Carolina to Surt City, North Carolina.  Tropical Storm Warnings were in effect for the portions of the coast from Altamaha Sound, Georgia to South Santee River, South Carolina and from Surf City North Carolina to Watch Hill, Rhode Island including Albemarle Sound, Pamlico Sound, Long Island and Long Island Sound.  A Tropical Storm Watch was in effect for the portion of the coast from Watch Hill, Rhode Island to Stonington, Maine including Block Island, Martha’s Vineyard and Nantucket.

Tropical Storm Isaias seemed to begin another cycle where the thunderstorm activity pulsed down during the overnight hours.  However, visible satellite and radar images seemed to indicate that thunderstorms were starting redevelop on Monday morning.  A band of thunderstorms appeared to be wrapping around the northern side of the circulation.  Thunderstorms were also increasing in bands in the northern and eastern parts of Isaias.  Bands in the southern and western sides of Isaias consisted primarily of showers and lower clouds.  The circulation of Tropical Storm Isaias could be pulling in some drier air around the southern and western parts of the storm.  That is a fairly typical occurrence with tropical systems moving up the East Coast of the U.S.  Winds to tropical storm force extended out 125 miles (200 km) in the northern and eastern quadrants of Isaias.  The winds in the southern and western parts of the circulation were mostly at less than tropical storm force.

Tropical Storm Isaias will move through an environment somewhat favorable for intensification during the next 12 hours.  Isaias will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the Central U.S. will produce southwesterly winds which will blow toward the top of Isaias.  Those winds will cause moderate vertical wind shear which will inhibit intensification.  The wind shear is expected to decrease slightly later on Monday, which could allow Isaias to strengthen into a hurricane.

The upper level trough will steer Tropical Storm Isaias toward the north-northeast during the next several days.  On its anticipated track Tropical Storm Isaias will make landfall near Myrtle Beach, South Carolina on Monday night.  Isaias could be a hurricane when it makes landfall.  Isaias will bring gusty winds and a storm surge of 3 to 6 feet (1 to 2 meters) to the coast near and to the east of where the center makes landfall.  The center of Isaias will move across eastern North Carolina and it could be near Norfolk, Virginia on Tuesday morning.  Tropical Storm Isaias could pass near New York City later on Tuesday.

Tropical Storm Isaias will bring gusty winds to the East Coast of the U.S. from South Carolina to Maine.  Isaias will also drop locally heavy rain from eastern South Carolina to New England.  The National Weather Service has indicated that a Moderate Risk of flash floods exists for the region from eastern South Carolina to eastern Pennsylvania.