Hurricane Irma is coming – I just don’t know where it’s going

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.

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.

M. Sudduth

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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.

 

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Hurricane watch posted for portions of the Texas coast has Harvey becomes a depression once again

http://www.nhc.noaa.gov/storm_graphics/AT09/refresh/AL092017_5day_cone_no_line_and_wind+png/145443_5day_cone_no_line_and_wind.png

NHC track map showing the forecast for Harvey over the coming days. It will be a slow moving system with the potential for widespread flooding due to excessive rain.

The NHC has begun issuing advisories once again on TD Harvey with the expectation that it will strengthen in to a tropical storm and eventually a hurricane. As such, a hurricane watch has been issued from just north of Port Mansfield to San Luis Pass. This means that hurricane conditions are possible within about 48 hours.

Harvey is currently in the organizing stage and is beginning to slowly take on a more classic tropical storm look. The NHC says that it will likely be a slow process at first followed by the potential for a “quickly strengthening cyclone” as it approaches the Texas coast Friday.

Storm surge flooding of 4-6 feet above ground level is forecast from Port Mansfield north and east to High Island. This is life-threatening and evacuations will be needed. Do not wait it out to see if it really happens – remember Ike!

I have prepared an in-depth video discussion of the current situation with Harvey and it is posted below. I will have another video later tonight once I get to Houston and begin preparing for Harvey along the Texas coast.

M. Sudduth 11:45 AM ET

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Harvey not gone – likely to strengthen again over Gulf, threaten Texas as a hurricane

Remember tropical storm Harvey? It made its way across the open Atlantic as a tropical wave and became a tropical storm just before reaching the Windward Islands a few days ago – bringing flooding rains to Barbados especially. Then, it died away, almost.

The low level energy associated with Harvey has remained very much intact and is now over the Yucatan peninsula, poised to emerge in to the Bay of Campeche later tonight. From there, computer models strongly suggest that it will strengthen and perhaps to hurricane intensity. This is concerning since it will be doing so while moving towards land, possibly Texas and/or northeast Mexico. The time frame from it becoming a depression again to hurricane strength may be short and people along the coast may not realize what’s coming.

I have produced a video discussion covering this topic plus a look at 92L (which is not likely to do very much in the coming days). Check out the video below and note that I will have another one posted early this afternoon:

M. Sudduth 10:15 AM ET Aug 22

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