Currently in the Atlantic - Sept. 25, 2022

There is a lot of agreement among computer models for Ian becoming a major hurricane (Category 3 or higher) by Tuesday.

by Glenn "Hurricane" Schwartz

Ian - slow strengthening - for now

The big blobs of thunderstorms are obvious. But it's hard to find the center of circulation of Ian. The most important part of the above look are the thin white, fibrous clouds extending outward in all directions. That represents the high cloud OUTFLOW, which is a sign that the wind shear preventing development is just about gone. Slow strengthening is beginning. The rapid intensification (RI) comes later.

Ian track will move over highest HEAT CONTENT

The northwest Caribbean has been historically favored for rapid intensification over the years, due to typically high water temperatures. They're even higher than "normal" now, and the warm water goes very deep. Ian should reach those reddish colors by Monday morning, and that is when the RI is expected to start.

Models agree on rapid intensification (RI)

There is a lot of agreement among computer models for Ian becoming a major hurricane (Category 3 or higher) by Tuesday. The average of the above models takes a 65-mph tropical storm to a 130-mph major hurricane in just a 36-hour period. That far exceeds the requirement to be defined as Rapid Intensification.

So, can we count on the computer models and NHC in being right about the RI?

While track forecasts have steadily improved over the decades since I worked at NHC in the 1970s, it has been a long road to improve intensity forecasting. But in the last 10 years or so, the improvement has been dramatic. Look at the sudden drop in intensity errors after virtually NO progress for decades!

Intensity forecasts dramatically improve

So far, we know these two things:

  1. Ian will strengthen by early next week and probably become a major hurricane
  2. Ian will track into the Gulf of Mexico next week and become a major threat to some parts of the U.S.

That's the easy part. Now for the WHERE question. There has been an overall trend for Ian to track somewhat farther west than we saw yesterday. The threat to the east coast of Florida has clearly gone down some (but it's not down to zero).

The European ensembles are still bunched together, showing a high chance of a track and eventual landfall in the eastern Gulf or west coast of Florida:

Now remember, Floridians, a major hurricane does NOT need to make landfall on the west coast to cause big problems. Once Ian hits west Cuba or goes through the Yucatan Channel the high winds will cause bigger and bigger waves on the east side of the storm. Enough water could build up to cause flooding on the west coast of Florida, which is highly vulnerable to storm surge (much more vulnerable than the east coast, due to the shallower water).

I learned this lesson personally with Hurricane Elena in 1985. It was my (and The Weather Channel's) first storm chase. Elena didn't come within 100 miles of Tampa, yet there was massive flooding. The airport was closed for days. And those along the Florida Panhandle and Central Gulf Coast shouldn't feel safe just because weakening may be predicted by landfall. Katrina weakened, for example. That water in the Gulf can build up like crazy, and it doesn't calm down just because winds might decrease.

Other computer models aren't as far east as the European has been. There's still a significant spread in track forecasts for next week:

Computer models agree-until Monday

More models are now showing Ian tracking through the Yucatan Channel (between Cuba and Mexico's Yucatan Peninsula). This would prevent Ian from weakening once it intensifies rapidly.

Changes in upper-air patterns over the Continental U.S. will determine whether Ian turns toward Florida west coast, continues north to the Florida Panhandle area, or even stalls like Elena did. That part of the future remains in question-for now.

Glenn "Hurricane" Schwartz  

thehurricaneschwartz@gmail.com