Thursday morning Irma went through rapid intensification going from a Tropical Storm to a Category 2 Hurricane in just five hours.
Just a few hours later, Irma strengthened to a CAT 3 Thursday afternoon and the storm will continue to strengthen to a CAT 4 with 140 mph sustained winds by Tuesday (9/5/2017) or sooner.
Given the location of this hurricane, over 1,800 miles from the Lesser Antilles, there’s a TON of uncertain on where it will go. For the immediate forecast, it will continue to track westward towards the Caribbean while maintaining major hurricane status.
The main thing we have to monitor with this storm will be the steering currents involved.
Right now, the Bermuda High is very strong which is forcing Irma to the west & south. Both the 12z GFS and 12z ECMWF agree with this forecast.
The other steering current is a developing trough in the U.S. that would pick up the storm and push it north and east.
The 12z GFS model shows a stronger trough over the U.S. leading to Irma taking a sharp northeast turn away from U.S. landfall by next Thursday/Friday.
On the other hand, the 12z ECMWF model shows a weaker trough over the U.S. allowing Irma to drift farther west and move into The Gulf Of Mexico. Even though these are the two most respected long-range forecast models we use, they are currently showing ~800-mile difference on where Irma will be at 4 p.m. Saturday, September 9, 2017.
Again, it is way too early to know if Irma will make U.S. landfall given how many days out we are from this being a possibility. We will continue to follow the latest on Irma, and keep you informed. Some other things to watch over the next week with Irma would be:
1. Does it make landfall in the Caribbean or does it stay over water the entire time? If it remains over water then it is more likely to continue to strengthen or maintain major hurricane status. If Irma makes landfall, then it’s more likely for the storm to weaken. However, once it’s over water again, it will regain intensity given the warm waters and low shear environment.
2. The consistency with models. Will we continue to see model agreement or will the uncertain become greater.
3. New data. The Hurricane Hunters will make several flights into the Irma collecting life-saving information, so that meteorologist can better predict what the storm will do. One major difference between Irma and Harvey is the duration of warning people will have along the coast IF Irma does make landfall on U.S. soil. Aside from Irma, we are watching the possibility of another tropical system developing in the Bay of Campeche. This cluster of storms has a 20% chance of developing into a tropical system over the next 5 days. REGARDLESS of the strength of the storm, any additional tropical downpours along the Northwest Gulf Coast would be catastrophic.
Keep in mind hurricane seasons peaks September 10 and continues through November 30, so the early predictions of an above average hurricane season seem to be coming true.