Northern Leeward Islands and Puerto Rico first up for Irma impacts

Updated: 1:15 AM ET September 4

It is late – after 1am ET on September 4 now – Labor Day 2017. We are watching a powerful hurricane as it gathers strength over the ever-increasing water temps of the tropical Atlantic. It is the talk of the town for just about anyone who lives on or near the coast in the western Atlantic Basin. Indeed, Irma is coming…and first up will be the northern Leeward Islands and possibly Puerto Rico.

I do not have a lot to add in terms of where Irma ends up when all is said and done, that chapter of the story has yet to be written and won’t be for several days to come. It does, however, seem that Irma is moving more west in the model forecasts and thus the chance of it moving out to sea seems to be diminishing.

I will have a full video discussion again Monday morning and will use that to go over the details of the overnight model runs – for now, I want to focus on the northern Leewards.

Map of the NE Caribbean Sea and the northern Lesser Antilles along with Puerto Rico.

Map of the NE Caribbean Sea and the northern Lesser Antilles along with Puerto Rico.

Take a look at the map I have posted here. Those are the islands that will see the first effects of Irma in the coming days. How much of an impact Irma has in that region remains to be seen and will depend entirely on how close the core gets and how strong the hurricane is as it passes by. We will also need to watch the various reports of what the wind field is like. As Irma strengthens, it is likely to expand in size, bringing a larger area of tropical storm force winds along with hurricane force winds. This is impossible to predict in terms of absolute size but let me tell you, it is likely now that portions of the northern Leeward Islands will see hurricane conditions and maybe even the dreaded core itself.

The latest run of the GFS (Global Forecast System) shows Irma getting very close to portions of the extreme northeast corner of the Leeward Islands. If we look at the latest wind field info from the 11pm ET advisory package from the NHC, it shows:

Hurricane-force winds extend outward up to 35 miles (55 km) from the
center and tropical-storm-force winds extend outward up to 140 miles
(220 km).

This means that some of, if not all, the islands seen in the map will experience at least tropical storm conditions – winds of 39 mph or higher. Obviously, the closer Irma’s core passes to these islands, the stronger those winds will be.

GFS model run from Sunday night, 00z, showing Irma in about 60 hours or roughly 8am ET on Weds - very close to portions of the northern Leeward Islands.

GFS model run from Sunday night, 00z, showing Irma in about 60 hours or roughly 8am ET on Weds – very close to portions of the northern Leeward Islands.

Another thing to keep in mind, especially if debating whether or not to prepare for the hurricane is the fact that the core could undergo rapid changes up or down with no notice at all. It’s best to err on the side of extreme caution if you are in the area – an intensifying phase could easily bring a category higher of wind and gusts to the area – you do not want to roll the dice on that one and hope it doesn’t happen.

So for now, my best advice is simple: if you’re in the hurricane watch area – you need to assume that hurricane conditions are coming. Forget whether or not the eye will pass over you. It’s what’s around the eye – the core – that brings the horror of punishing down burst winds and extreme gusts. Ask those who live in Rockport, Texas about that. Tomorrow and Tuesday are your only days to prepare. Get it done, don’t second guess or use hope as a substitute for accomplishing the tasks needed to save your butt and your property. Irma is bad and will get worse. Be ready and follow the instructions of the local governments etc.

As for what happens next – well, let’s just say Irma is going to be remembered for a long time to come it does appear. I will go over the latest in a complete video discussion by Noon ET Monday.

M. Sudduth

 

Irma to become powerful hurricane as it aims for Lesser Antilles

8:15  AM ET August 31, 2017 – Mark Sudduth

Harvey has been downgraded to a tropical depression and is now a dying low pressure area over northeast Louisiana. It will continue to bring periods of heavy rain to portions of the Southeast as moisture streams in off the Gulf of Mexico. The feeder bands that are still set up well to the east of the gradually filling low pressure center will be capable of dumping several inches of rain where they line up and train over the same area. Everything is slowly moving east and northeast and eventually, the circulation of Harvey will fade away while the people back in Texas and parts of Louisiana continue to clean up and begin the recovery process in its wake.

I am currently in Louisiana as I travel back home to North Carolina after spending a week tracking Harvey from its landfall north of Corpus Christi to the punishing, historic rains that plunged Houston in to disaster this weekend. The data the was collected will be very helpful and the live camera feeds that were set up across Houston provided extraordinary views and even helped to motivate people to evacuate. It was a very successful field mission but I realize that I get to go home to a dry, intact house – thousands of people back in Texas are not able to and will not be able to for some time to come. Help has been arriving and there is more on the way. In time, things will get better even though it may not seem that way right now. It gives me hope, knowing what I do about how impactful hurricanes can be, that so much generosity on so many levels is pouring out to bring aid to those who need it.

The hurricane season does not stop to allow us to pick ourselves up. We saw that in 2004, 2005 and in 2008 when multiple threats and landfalls took place. Unfortunately, we may be seeing a similar pattern set up for this season.

Irma tracking map from the National Hurricane Center showing the distinct dip to the WSW by days 3-5.

Irma tracking map from the National Hurricane Center showing the distinct dip to the WSW by days 3-5.

While Harvey fades from the tracking maps, Irma is beginning to have the look of a very troubling hurricane.

The latest thinking from the NHC indicates that Irma will become a hurricane today and should continue to intensify in to a category three within a day or two from now. I personally think it will be stronger, maybe much stronger. Water temps are above normal across the entire path of Irma and the stage is set for an intense hurricane to bear down on portions of the Lesser Antilles.

Right now, Irma is moving to the west-northwest but strong high pressure to the north and east of the soon-to-be hurricane will cause it to actually lose a little bit of latitude – meaning that it will dip south some as it moves west. This is quite unusual but has happened before – most recently that I can recall was Ike in 2008. This means that the Lesser Antilles may have to deal with Irma passing through within the next week or so. It seems like a long way off and one would think that the model guidance is not that accurate but in this case, over the deep tropics with large-scale weather patterns at play, I do not see any reason to believe this southerly course change won’t happen. As such, interests in the Lesser Antilles need to monitor Irma very closely.

I know that everyone downstream from Irma will be wanting to know where it is likely to end up. Maps from the long-range global models will be posted on social media and message boards. While this is a good thing in terms of getting people to pay attention, don’t let it worry you too much – we will need at least five to seven days before we can really get a handle on whether or not Irma will impact the U.S. Right now, we need to focus on potential impacts to the Lesser Antilles.

I will post a video discussion concerning Irma and the latest on Harvey and its remnant circulation later on this morning.