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Chris’ Weather Corner - “Major Hurricane Lee Strengthens in the Atlantic”

By Chris Gilberti | September 11, 2023

Visible satellite imagery of Hurricane Lee from the GOES-16 satellite at 18:45 UTC (Coordinated Universal Time) Sept. 8, 2023

Photo Credit: Tropical Tidbits

Major Hurricane Lee has rapidly intensified to a category 5 hurricane in the Atlantic Ocean as we head through the peak of hurricane season. Lee formed quickly from a cluster of thunderstorms that moved off the coast of Africa into a tropical depression on Sept. 5, and strengthened to a dangerous category 5 just two days later on Sept. 7.

Hurricane rapid intensification is defined as strengthening wind speeds by 35 mph or more over a 24-hour time period. In this case, Hurricane Lee strengthened by 80 mph in 24 hours, completing a double rapid intensification. Hurricane Lee is expected to maintain major hurricane strength as it continues its movement across the Atlantic to the north of Puerto Rico in the coming days, though it is still too early to forecast its exact track and whether it will make landfall on the east coast.

As Lee continues its movement across the Atlantic, it will be steered by a high-pressure ridge to its north. Wind around high pressure rotates clockwise, which will push Lee towards the northwest in the coming days. Many tropical storms and hurricanes at Lee’s position would simply curve north before getting close to the Caribbean islands or the United States, but with this high pressure in place, Lee will be forced closer to the United States – which has garnered the attention of meteorologists monitoring its potential impacts to land.

Whenever a hurricane like Lee rapidly intensifies, it catches the eyes of meteorologists anywhere. What has made this storm special is its potential to maintain this strength while tracking toward the United States. Meteorologists at the National Hurricane Center have many tools to make their forecasts of Lee’s future track and intensity, including not only individual model runs but also ensembles, which are the same model being run many times with slight differences in the initial conditions they start with. By using ensembles, meteorologists can get a good idea of how likely a given track or intensity is. While most model ensembles keep the storm off the coast, some bring it much closer or even predict a landfall in the northeast United States.

Given that this storm has the potential for major impacts if it tracks a certain direction, it is important here to distinguish where there is high confidence in this storm’s forecast and where there is not. Firstly, there is high confidence that Hurricane Lee will remain a strong and dangerous hurricane through the beginning of the week as it continues its movement across the Atlantic. There is also decent confidence that as it does so, it will likely remain to the north of islands such as Puerto Rico, Turks and Caicos, and the Bahamas. Where there is less certainty, however, is where it will travel and how strong it will be after it moves north of these places.

The high pressure steering Lee closer to the United States is expected to begin weakening during the middle of the week. At the same time, a low-pressure storm system from over the United States will begin to push off the coast. The timing of each of these features will be crucial in determining what, if any, impacts the United States could see from Lee.

If the high pressure weakens quickly and the low pressure moves eastward and off the coast faster, this could help force Hurricane Lee to turn north before it gets to the East Coast, meaning that the East Coast would avoid most or any impacts. If the high-pressure sticks around longer, and the low pressure moves slower, that would allow Lee to continue towards the east coast and not turn north until it has already made landfall. Any potential impacts from this storm are still around a week away, so it is unfortunately still too early to make a definitive forecast on where the storm will track exactly or how strong it will be.

National Hurricane Center forecast cone for Hurricane Lee as of 11 AM AST Sep. 8, 2023. Figure Credit: NOAA National Hurricane Center

Although it is too early to forecast exactly what impacts the United States could see from Hurricane Lee, there should be a much better idea in the coming days thanks to hurricane hunters who are flying planes fitted with meteorological instrumentation into the storm. As of Sept. 8, Lee was close enough that hurricane hunters could fly their aircraft into and through the storm to get real measurements of what is happening within the storm. This information is invaluable in forecasting storms like Lee, as weather models rely on data observations to initialize their forecasts. Given that data over the ocean is so sparse, the data collected by Hurricane Hunters can be fed into weather models over the coming days to help get a more reliable forecast.

Monitoring trends in model data over the coming days will be crucial to determine where impacts from Lee will be located. As the storm moves closer we will continue to get a better idea of what is happening within it, and how the high and low pressures that will steer it towards or away from the coast will interact. With this, we will have much higher confidence in the storm's path.

Current model guidance has shown at the very least a considerable potential for the storm to track close enough to the east coast that it could impact coastal New England. Trends in the models (how they change each time they are run) have maintained or even increased confidence that those who live anywhere along the East Coast of the United States should continue to keep a close eye on this storm, especially over the next couple of days as a more definitive, more confident forecast will be made. Even for inland locations such as Albany, tropical storms and hurricanes can cause very heavy rains and strong winds so it is important for everybody to keep an eye on this forecast. While it may be still too early to tell exactly where the storm will impact if it tracks along the coast, it is never too early to be prepared.


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