A lot of people have asked about our app – it is called Hurricane Impact and is available on the iPhone App Store. Search Hurricane Impact
8 AM ET September 2, 2017
I am back home in North Carolina after a 10-day saga in Texas dealing with hurricane Harvey. That story is still very much ongoing, obviously, as the early stages of clean-up and recovery begin. The Harvey field mission was very successful with wind and pressure data being collected in Corpus Christi and several unmanned camera systems being deployed during both the hurricane impact and the flood impact.
Now it is time to focus on Irma.
Hurricane Irma five day forecast points plotted over upper ocean heat content map. The future track takes Irma over increasing sea surface temps as well as increasing upper ocean heat content – which will result in significant intensification. Click on image for full size.
Right now, the hurricane is fluctuating between category two and category three intensity as it moves over water temps that are just warm enough to sustain the heat engine. In a couple of days, the water temps will increase quite a bit, providing more fuel for a much stronger version of Irma than we see now. Fortunately, it will still be far away from any land areas.
The first region to consider for potential impacts, either direct or indirect, will be the Leeward Islands, especially the northern Leewards.
So far, the official forecast track from the NHC keeps the core of Irma to the north of all of the northern islands and presumably Puerto Rico. However, it is too soon to know if this will verify or not. The ECMWF model is fairly close to the islands while the GFS is notably farther to the north as Irma passes by. We are going to need another 48 hours or so to work out the details of this portion of the track for the hurricane and in my opinion, the west-southwest dip that is forecast will be the key here. The longer Irma remains at the latitude of the islands when the high pressure to its north eases up and allows the hurricane to gain more latitude, the greater the risk for a direct hit. Interests from Dominica to Puerto Rico should be paying very close attention to Irma over the next few days. In this case, timing will be everything – the later that turn back out of the WSW dive the more the risk increases.
After the next five days, the focus will shift to the Bahamas and the Southeast coast, including Florida. This part of the future track of Irma remains very uncertain. Both of the major global models, the GFS and the ECMWF, suggest a possible threat to the region in about a week to ten days. Here too, it will be all about timing and position.
As Irma moves westward, steered by a strong Bermuda High, a trough of lower pressure in the atmosphere will dig in to the nation’s mid-section, bringing a wonderful shot of fall weather to a good deal of the eastern U.S.
This trough will push on and erode the western portion of the Bermuda High. This will allow Irma to gain latitude once again – presumably. It all depends on how far north Irma is once the trough digs in. A more northerly and faster west track would place Irma closer to the weakness that the trough will create – allowing for a chance to turn north and then maybe northeast and out to sea.
On the other hand, if Irma if farther south and east, the trough digs in, then lifts out a few days later, allowing the Bermuda High to build back in – sending Irma on a NW track towards the Southeast. There are multiple variations of this scenario but the overall idea is, in my opinion, going to come down to how far west and north Irma is when the trough begins to lift out.
Since we are talking about at least seven days from now, it is impossible to know what will happen. For this reason, everyone from the Bahamas to Florida to the Canadian Maritimes should be keeping tabs on Irma every day. There’s no reason to worry just yet in any particular location. Right now, as I am doing with my family, just add a little more to your supplies each time you visit the store. An extra gallon or two of water, maybe have your generator checked if you’ve used it anytime in the past. Do these small things now before the stress and anxiety ramps up next week – which it very well might for some people.
We have time right now to watch and react at a steady pace. Maybe it will be ok and Irma will turn out to sea. If not, luck favors the prepared and my advice is: start preparing a little more each day from here going forward. You just might need it.
I will have a video discussion posted later this afternoon which will go over the latest from both the GFS and the ECMWF.