The anomalously active July has come to a close over the Atlantic basin with a record-breaking 6 tropical cyclones, 5 of which became named storms (tying the record from the 2005 season) and 2 of which have become hurricanes. Hurricane Isaias is slowly strengthening over the central Bahamas, and may still be a hurricane when it approaches the coast of Florida and eventually the Carolinas on Sunday and Monday. In the far eastern Atlantic, a small area of low pressure has developed into Tropical Depression Ten.

As of 11:00 p.m. EDT Friday, Hurricane Isaias was centered near 23.3°N 76.4°W, and was moving northwestward at about 15 mph. Maximum sustained winds were 70 knots (80 mph), with an estimated minimum pressure of 987 mb. Although Isaias is located over sea surface temperatures near 30°C, the SHIPS guidance indicates that westerly shear of greater than 20 knots (25 mph), as well as mid-level humidity values of about 50-55 percent, should limit significant additional intensification. None of the reliable intensity guidance brings Isaias to Category 2 intensity. Some slight intensification is still possible, but there are already indications on recon and radar data that the eyewall may have opened up on the southern side. This is good news for the southeastern United States, suggesting rapid intensification is unlikely. Isaias is expected to continue moving northwestward through Sunday morning, when it is expected to turn to the north and eventually north-northeast on Monday. Chances are increasing that Isaias will make landfall in southeastern Florida, possibly as a Category 1 hurricane. It is interesting to note that many of the global models weaken Isaias to a tropical storm during the next 36 hours as it approaches the coast, possibly as a result of the increased shear and dry air. A Hurricane Warning is currently in effect from Boca Raton to Volusia-Brevard County Line in Florida, as well as the Northern and Central Bahamas. A Hurricane Watch is currently in effect from Hallandale Beach to south of Boca Raton, Florida. A Storm Surge Watch is currently in effect from Jupiter Inlet to Ponte Vedra Beach, Florida. The recent model guidance has shifted somewhat westward, and chances of a direct landfall in Florida are increasing. Isaias making landfall in Florida would likely weaken the storm and decrease the chances of a hurricane landfall in the Carolinas. It is quite possible, though, that Isaias could make landfall in southeastern Florida, re-emerge into the southwestern Atlantic, and make a second landfall in North Carolina, as many recent model runs suggest. The situation with Isaias is changing quickly, and I will be back with a more detailed update tomorrow.

In the far eastern Atlantic, a small area of low pressure associated with a tropical wave has developed into Tropical Depression Ten. As of 2:00 a.m. Cabo Verde Time (11:00 p.m. EDT), the depression was centered near 17.1°N 21.1°W, and was moving northwestward at about 14 mph. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1007 mb. Normally, at this location this early in the season, sea surface temperatures are too cool to support tropical cyclogenesis. An earlier convective burst is beginning to wane as the depression moves over cooler waters, and it is likely that the depression will become a remnant low on Saturday. TD Ten is no threat to land.