The Atlantic basin remains active, with Tropical Storm Grace entering the Caribbean Sea as well as the remnants of Tropical Storm Fred are expected to re-develop into a tropical depression by Sunday. In addition, there is an area of low pressure north of Bermuda being monitored for potential tropical development.

As of 8:00 p.m. EDT Saturday, Tropical Storm Grace was located near 16.6°N 61.5°W, and was moving westward at about 23 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1010 mb. Grace is a disorganized tropical storm, likely a result of its fast forward speed. A NOAA Hurricane Hunter aircraft investigated Grace today, and struggled to close off a well-defined center at 850 mb. However, surface observations in the Lesser Antilles seem to suggest that Grace’s surface circulation is at least barely closed. The mission left us with a lot of questions, as it did not sample the strongest convection, where some cyclonic turning was noted on radar images. The National Hurricane Center has revised its estimated center position north of previous estimates, which could suggest that northward adjustments in the forecast track are possible. No additional reconnaissance missions are scheduled for Grace until Sunday afternoon. Grace’s future track and intensity remains highly uncertain, with a wide range of possibilities. Until we get more clarity on the position of the low-level center and how well-defined it is, we will likely continue to see adjustments in the track. The 00z GFS-based SHIPS guidance suggests that Grace’s forward speed will slow from 19 kt to near 12 kt in about 24 hours as it nears Puerto Rico. In addition, the model suggests wind shear will be relatively light, less than 15 knots, with sea surface temperatures warmer than 28.0°C (82.4°F) and mid-level moisture also increasing slightly over the next 24 hours. This should allow for Grace to gain some organization and possibly develop a better-defined circulation. What happens after that point is highly uncertain, as Grace’s exact track will have significant implications on its future. If Grace moves directly over mountainous central Hispaniola, it is likely the storm’s weak circulation will be disrupted significantly. If Grace manages to slide just south or just north of the island, it would likely have a better chance of being a significant tropical cyclone long-term. A Tropical Storm Warning is currently in effect for the Leeward Islands, the U.S. and U.K. Virgin Islands, Puerto Rico, and the eastern coast of the Dominican Republic. A Tropical Storm Watch is in effect for the southern and northern coasts of the Dominican Republic. Interests in these regions should be prepared for tropical storm conditions. It remains too soon to predict if Grace will impact the continental United States, but it remains a possibility at this long lead time.

As of 5:00 p.m. EDT, the remnants of Tropical Storm Fred were centered near 24.0°N 84.6°W, and were moving west-northwestward at about 13 mph. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1013 mb. Although the National Hurricane Center does not typically issue advisories for a remnant disturbance without watches or warnings active, the center decided to keep advisories active since redevelopment is likely and watches and warnings will likely be required for the United States Gulf Coast. NHC gives the remnants of Fred a 90 percent chance of re-development, both within 48 hours and five days. The 00z GFS-based SHIPS guidance indicates that environmental conditions will be relatively favorable up until the system makes landfall in about 48 hours or so, somewhere between southeastern Mississippi and the Florida Panhandle. The guidance suggests wind shear will be light to moderate, around 15-20 knots, with sea surface temperatures near 30°C (86°F) and 700-500 mb relative humidity values of around 65-70 percent. Although this environment is expected to be favorable for redevelopment, Fred will take time to redevelop a well-defined circulation, and it currently appears unlikely that Fred will be anything more than a moderately strong tropical storm at landfall. Regardless, interests along the northern Gulf Coast should watch Fred closely, as watches and warnings will likely be issued soon.

The National Hurricane Center (NHC) is monitoring a small area of low pressure north of Bermuda for tropical cyclone development – designated Invest 96L. The NHC gives 96L a 20 percent chance of development within 48 hours, and a 30 percent chance within five days. As of 00:00 UTC Sunday, Invest 96L was centered near 36.0°N 63.5°W. Maximum sustained winds were 25 knots (30 mph), with an estimated minimum pressure of 1015 mb. The 00z GFS-based SHIPS guidance indicates that environmental conditions are somewhat conducive for development for the next 2-3 days, with sea surface temperatures near 28°C (82.4°F), wind shear less than 15 knots, and a marginally moist 500-700 mb environment with relative humidity values near 55 percent. However, the guidance suggests wind shear will increase significantly, to greater than 30 knots, in about 4 days, which will likely inhibit additional development. The 12z ECMWF model run suggested that 96L would do a clockwise loop while developing slightly, and pass near Bermuda. Interests in Bermuda should monitor the progress of 96L, but it appears unlikely to affect any other land areas at this time.