Hurricane Eugene in the East Pacific has rapidly weakened today as it has entered a more stable environment with decreasing sea surface temperatures, and is likely going to be downgraded to a tropical storm at the next advisory. In the Atlantic, the remnants of Tropical Depression Four are continuing to be monitored for possible regeneration, and there is still a low, but decreasing, chance that a tropical wave could develop east of the Lesser Antilles. There is now also a new area of interest in the East Pacific that could develop over the coming days.

Eugene rapidly weakening, likely to become a remnant low tomorrow or Wednesday

Cool sea surface temperatures below 25°C (77°F) and dry, stable air have caused Hurricane Eugene to rapidly weaken from its category 3 peak yesterday. At 2:00 p.m. PDT (5:00 p.m. EDT), Eugene was centered near 19.4°N 117.8°W. Maximum sustained winds were 65 knots (75 mph) with an estimated minimum pressure of 983 mb. Eugene is likely to continue on its northwestward path for the next several days, and should become a remnant low by Wednesday, if not late tomorrow. Eugene is no threat to land, aside from possible high seas along the western coast of Mexico.

Despite the cooling sea surface temperatures, low wind shear has allowed Eugene to remain well-organized this evening. Deep convection continues to burst near the center of Eugene, which is unusual for East Pacific tropical cyclones north of the 26°C (78.8°F) isotherm. Regardless, the eye has disappeared, and the deep convection should begin to wane overnight or tomorrow as the cyclone moves over progressively cooler waters. Eugene is likely to be downgraded to a tropical storm in its next advisory based on the Automated Tropical Cyclone Forecast (ATCF) intensity of 60 knots (70 mph) with a minimum pressure of 990 mb.

Remnants of Tropical Depression Four could regenerate near Bahamas or in Gulf of Mexico

The remnants of Tropical Depression Four are being monitored by the National Hurricane Center (NHC) for possible redevelopment, although it has not yet been mentioned in the Tropical Weather Outlook. This morning, the NHC designated the remnants of Four as an invest, which means that model guidance is now running on the system. The NHC has scheduled a reconnaissance mission to investigate the remnants of Four tomorrow, scheduled to investigate from 4:30 to 8:30 p.m. EDT. However, if the remnants of Four do not look healthy in the morning, the flight will likely be cancelled.

Deep convection has been bursting most of the day with the remnants of Four, but the convection is not well organized. Wind shear today remains fairly strong, but is expected to decrease to below 10 knots by late tomorrow. There are currently no indications that a well-defined, closed circulation exists. As of 00:00 UTC Tuesday, the remnants of Four were centered near 22.5°N 66.1°W, with maximum sustained winds of 25 knots (30 mph) and an estimated minimum pressure of 1014 mb. Four is likely to continue on a westward path for the next few days, before eventually likely entering the Gulf of Mexico and turning to the northwest. Sea surface temperatures are expected to remain very warm at 29-30°C (84.2-86°F), but relative humidity values of less than 50 percent will likely suppress development. The 12z ECMWF model run, as well as several EPS and GEFS ensemble members, indicated the possibility that the remnants of Four could regenerate in the Gulf of Mexico in about six days. Tropical cyclones in the Gulf of Mexico can spin up fast, and with wind shear expected to remain low, I would keep an eye on this system if you are a resident of Florida, Alabama, Mississippi or Louisiana. I currently give the remnants of Four a 30 percent chance of regeneration over the next week.

Decreasing chance of African wave developing, another area of interest in East Pacific

A tropical wave located several hundred miles southwest of the Cabo Verde Islands has a low chance to develop into a tropical cyclone. Models have backed off development, and the 18z Monday GFS model run barely predicted any development of this wave. The 12z Monday ECMWF, CMC, and UKMET model runs did not predict any development of this wave at all. Regardless, it is still worth watching, since it has an impressive vorticity signature. The NHC has decreased its five day development chance from 20 percent to 10 percent at their 8:00 p.m. EDT Tropical Weather Outlook, and it is possible the system could be removed from the outlook very soon. 48-hour development chances remain near 0 percent. Conditions are only expected to be marginally conducive, and it is expected that strong trade winds and Saharan Air Layer (SAL) will likely not allow this wave to develop. The wave will likely also be close to the coast of South America to develop. I am lowering my 10-day probability of development from 50 percent to 20 percent.

In the East Pacific, an area of low pressure is located to the Southeast of Hurricane Eugene, and is given a low (10 percent) chance of development within 48 hours. It is given a 20 percent chance of development within the next five days by the NHC. The 12z Monday ECMWF model run predicted this system would develop into a tropical cyclone later this week and eventually emerge into the Central Pacific basin. The 12z Monday CMC model predicted development as well, while the 18z Monday GFS and GFS-Para model runs predicted no development. I give this system a 40 percent chance of development during the next five days, because the ECMWF tends to be more conservative with tropical cyclogenesis than the GFS.

I will be back tomorrow for an update on these systems.