Question:
It is the third time a hurricane forms in Campeche coast in Mexico. What are the conditions for this to happen? What made Milton hurricane lose power before going inland, and reduce from a category 5 to a category 3?
Answer:
Atlantic and Gulf hurricanes can form anywhere in the tropics from the western African coast to within the Gulf of Mexico, as shown on the Scijinks site (scroll down below the top video to see the relevant graphic).
A hurricane requires specific conditions to form and strengthen. Broadly: warm sea surface temperatures, high amounts of water vapor in the air, and weak upper air winds that allow these “spinning tops” to continue unimpeded by outside winds (aka low shear). There’s not a lot of surface roughness (which can slow down storm winds near the lowest levels of the troposphere) over open ocean compared with land, which is part of the reason tropical storms can get so intense (read: stronger winds within and lower pressure centers) over water.
As for frequency of hurricane formation in the Atlantic Basin and Gulf of Mexico, the number is increasing slightly as climate change (a mixture of natural cycles and human-induced warming) occurs. As far as I can tell, meteorologists today can’t give a specific percentage of each process causing this increase – we have weather and climate models to help us to narrow down the numerous variables in the real atmosphere so we can figure out what has the greatest impacts on formation. The environment is far from stationary (and more complex than our improved models), so what’s true one year may not be the next – that’s why long-term climate pattern research is essential.
What researchers generally agree upon in the Atlantic/Gulf of Mexico:
- Anything that warms the oceans in this area increases sea surface temperatures and water vapor in the air – so climate warming like we are experiencing has an impact on tropical storm formation on top of natural variability.
- Storms are likely to become more intense and drop high amounts of rain over areas, with areas on land seeing far more flooding like we saw in North Carolina.
- The general path of hurricanes hasn’t changed much, but the number of hurricanes HAS increased slightly in the past 40 years. 20 years ago, there were an average of 12 storms each year. Today there are an average of 14 or more storms a year. As with anything in science, we need more decades of modern data to really understand this.
- The strength of hurricanes appears to be increasing, with fewer Cat 1-3 storms and more Cat 4-5 intensities. By how much exactly, researchers are still studying.
- Whether we will see more land-falling hurricanes in the future is uncertain, as there are several complex factors in storm paths.
For more technical details on our current understanding about hurricanes and climate, see https://www.gfdl.noaa.gov/
As for why Hurricane Milton weakened from Cat 5 to Cat 3: one of the ingredients it needed to remain Cat 5 – low shear – changed. The hurricane encountered higher shear (stronger winds with height that can reduce the storm engine’s efficiency) from nearby frontal boundaries and a strong jet stream aloft before landfall.
