Category 5 Irma Update – 09-07-17 [12:30 AM ET]

12:30 AM ET
Irma [19.6N / 67.0W]

A little MET101 lesson and potential ray of hope for SoFla.

Let’s get some facts together before we dive in:

1) Hurricanes are generally steered by what’s going on in the middle and upper levels of the atmosphere. Lower levels have little to do with the direction the system will move, so NO, turning all the East Coast fans on at the same time just won’t work.

2) Winds move clockwise around a high pressure, and counterclockwise around a low pressure.

So now observe a few things on the attached gif, which consists of current Infrared Satellite (“sees” infrared values of heat from clouds) and the mid-level wind streamlines (green lines) off the Florida East Coast, around the Central Atlantic High pressure (CATL-H), and further extending off the West Coast of FL.


Irma’s trajectory is about the competition of who’s steering flow will dominate and coax Irma’s movement. The CATL-H looks primed to snatch Irma out of her current driving forces. The steering pattern off the SW Coast of the Floridian Peninsula, associated with the incoming trough over the SE, is rather weak in comparison.

Putting these pieces together, it’s QUITE possible that Irma will indeed shift further E overnight, pulling a Miami/Fort Lauderdale landfall off the table. What’s good for us, means bad for someone else. Depending on IF and HOW extreme the shift is, this could put our friends up in Central/North FL or GA under the gun.

Of course, the CATL-H may:
1) maintain it’s current hold (sorry South Florida)
2) slightly retreat eastward (opening up Irma to being influenced by the incoming trough’s steering flow) – or-
3) build even further westward and force the track to shift slightly back westward (through the FL spine or along the Western half/Gulf side.

Regardless of who will win out, the northerly turn is a pretty sure thing, it’s just about who wins this tug-of-war for Irma’s attention. So basically, with many potentials still out there, keep preparing, keep paying attention, and be ready for whatever happens!

And lastly, no matter whether you evacuated, prepared, or didn’t, consider this a lesson learned for the next time these scenarios come around. Based on the preparations and reports from all over social media, it’s INCREDIBLE how seriously Floridians took this threat. In NO way should anyone feel their course of action was overreacting. You took these warnings seriously, and THIS is what keeps meteorologists going.

More to come…