The National Hurricane Center (NHC) unveiled a new product Sunday afternoon with the initiation of advisories on Potential Tropical Cyclone Two (formerly Invest 92L). Potential TC Two is given a high (90 percent) chance of development within 48 hours by the NHC, and is expected to become Tropical Storm Bret tomorrow. Invest 93L in the Northwestern Caribbean Sea remains disorganized this evening, but the NHC gives 93L an 80 percent chance of development within 48 hours and a 90 percent chance within five days. 93L will likely develop into Tropical Storm Cindy by Tuesday – and the Atlantic will likely have simultaneous June named storms for the first time since 1968.

Potential Tropical Cyclone Two: poised to become a small Tropical Storm Bret

Potential Tropical Cyclone Two had advisories initiated by the NHC at 5:00 p.m. EDT Sunday afternoon. This season, the NHC has the option to issue potential tropical cyclone advisories, if tropical storm watches or warnings are required. As of 8:00 PM EDT Sunday, Potential TC Two had maximum sustained winds of 30 knots (35 mph) and a minimum pressure of 1007 mb. Two was centered near 7.7°N 51.4°W, and was moving westward at 23 mph. The appearance of Potential TC Two has improved during the past several hours, with a small persistent central dense overcast-like feature developing. Two is very close to tropical cyclone status, if it is not one already.  Two is a small system, and is likely developing a tight core. The tight core could allow Two to strengthen into a moderate to strong tropical storm before wind shear increases in the eastern Caribbean Sea. However, the small size of Potential TC Two will also make it more likely to quickly weaken due to the wind shear. Wind shear is currently favorable, less than 10 knots, but it is expected to increase to over 20 knots by Tuesday. Two is embedded in a fairly moist environment, which favors intensification. Tropical Storm Warnings are in effect for Barbados, Trinidad and Tobago, St. Vincent and the Grenadines, and Grenada. NHC expects Two to strengthen into a 50-mph tropical storm by Tuesday, although this could be conservative based on the small size of the system.

Invest 93L: Central Gulf Coast looking like most likely landfall location

Invest 93L in the Atlantic continues to remain disorganized. However, it is producing tropical storm force winds well east of the center. As of 00:00 UTC Monday (8:00 PM EDT Sunday), 93L had maximum sustained winds of 35 knots (40 mph), with an estimated minimum pressure of 1004 mb. 93L lacks a well-defined center of circulation. Earlier today, there was a burst of convection well east of the estimated low-level center, but this convection has waned. 93L will likely take time to organize, and will not be a well-organized cyclone assuming development does occur. In fact, it could even develop characteristics of a subtropical cyclone, with a large wind field and the strongest winds occurring far from the center.

Models continue to remain in good agreement that 93L will develop, but the landfall location remains uncertain. However, there is slightly more confidence than yesterday. The 18z Sunday GFS predicts 93L will make landfall in Louisiana. In contrast, the 12z Sunday ECMWF model continues to predict a landfall in northern Mexico, while the 12z Sunday CMC run predicts a Texas landfall. Most of the model guidance is clustered towards a Louisiana landfall. Based on current model trends, I think a landfall in Louisiana or East Texas is the most likely scenario. However, 93L will likely be a sheared system with the strongest winds and rainfall well east of the center. A moderate tropical or subtropical storm (around 50 mph) is the most likely intensity of 93L at landfall. We will have to keep watching the further evolution of 93L’s track – the track of this system has higher than normal uncertainty.

I give a near 100 percent chance that we will see Tropical Storm Bret form and a 75 percent chance that we will see Tropical Storm Cindy form during the next few days. I will be back for another blog post tomorrow on these systems.