Hurricane Barbara has transitioned into a post-tropical cyclone, but a new tropical storm has formed in the eastern Pacific – Cosme. Cosme is no threat to land, and appears to have a short life ahead of it with no significant strengthening. However, in the Atlantic, a trough currently inland over the United States could eventually spawn a low pressure system in the Gulf of Mexico next week, which needs to be watched for possible tropical development.

As of 8:00 a.m. PDT (11:00 a.m. EDT), Tropical Storm Cosme was centered near 15.6°N 115.7°W, and was moving west-northwestward at about 14 mph. Maximum sustained winds were 45 knots (50 mph), with an estimated minimum pressure of 1001 mb. Moderate wind shear is currently taking its toll on Cosme, with the center of circulation partially exposed to the west of the convective mass. Although shear is expected to decrease based on the SHIPS model, Cosme is expected to move over sea surface temperatures cooler than 26°C (78.8°F) on Saturday afternoon, which should induce a weakening trend. The HWRF model interestingly brings Cosme to near hurricane strength, but the rest of the model consensus is weaker. Cosme is no threat to land and should become post-tropical by next Tuesday.

Tropical development possible over the Northeastern Gulf of Mexico late next week

A trough of low pressure, currently centered over western Tennessee, is expected to slowly drift southeastward, and eventually turn westward into the Gulf of Mexico. If this system emerges into the Gulf of Mexico, a low pressure center may form. Sea surface temperatures over the Gulf of Mexico are very warm (about 29-30°C/84.2-86°F), but it remains uncertain how favorable the upper-level wind environment will be. If shear is low enough, it is possible we may see some faster organization of this system. A smaller system would also likely be able to organize quicker than a larger one. The 12z ECMWF and UKMET models developed this system into a tropical storm, while the 12z GFS and CMC models did not show any development. The National Hurricane Center (NHC) gives this system a near zero percent chance of development within 48 hours, and a 20 percent chance within five days. The next name on the Atlantic naming list is Barry. The North Atlantic basin is still yet to see a fully tropical cyclone form this season; Andrea in May was a subtropical cyclone.

Another eastern Pacific system to watch next week

Finally, there is one last system to watch in the eastern Pacific: an area of low pressure is expected to form early next week southwest of Mexico. The NHC gives this system a near zero percent chance of development within 48 hours, and a 20 percent chance within five days. Model support for this system is quite limited, and if it develops, it will likely not pose a threat to land.