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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Hurricane Patricia a record setting event

It’s been quite a year for tropical cyclones globally. After several years in a row with few intense hurricanes and typhoons, 2015 has seen a remarkable turnaround. The latest is Patricia, now poised to strike Mexico near Manzanillo later today, and it is about as intense as they come.

There is not much I can say in terms of preparedness actions. Simply put, people in the path of this hurricane need to leave, period. If they haven’t done so already, they need to get moving. That being said, there’s actually some good news.

Patricia is NOT a 100 mile wide or 60 mile wide EF-5 tornado. I’ve seen people saying this on social media and it’s just wrong. Let me explain…

A hurricane like Patricia is very rare, obviously. One thing we do know because of the recon flights that have provided incredible in-situ data is that the radius of maximum winds (RMW) is very narrow. In fact, the ENTIRE extent of hurricane force winds, 74 mph to 200 mph in this case, is ONLY 30 miles from the eye. This is extremely important because it limits the amount of real estate that will have to deal with those winds. In other words, if you live just 40 miles from the eye, you would hardly notice as the core passed by. Move 20 miles closer to the eye and it’s a terrifying siege of flying debris and flesh-stripping wind. So while it will be awful for those who have to endure the core, it’s not like we’re talking about 100 miles of coastline laid to waste.

Another aspect of the small RMW is the storm surge. Katrina had a storm surge of 28+ feet in some locations due to its enormous RMW – more than 90 miles at one point. The result was a surge of water pushed onshore from Louisiana to Florida. In the case of Patricia, it will be a small area, maybe 10 to 20 miles, that receives a possible catastrophic storm surge. Wind drives the surge and the wind is only 200 mph very close to the eye.

I bring this up because it is important to keep the facts straight and not let the historic moment become clouded with information that is simply incorrect. Patricia is bad enough on its own and for those who remain in its path, today will be one not soon forgotten.

Texas to receive Patricia remnants

What happens after Patricia makes landfall? First, it will weaken extremely fast over the higher terrain of interior Mexico. Sadly, there will be potential for loss of life due to the flash flooding and mudslides as the torrents of rain impact those same mountains.

Info-graphic concerning the threat to parts of Texas from the remnants of hurricane Patricia

Info-graphic concerning the threat to parts of Texas from the remnants of hurricane Patricia

Interestingly, it looks as though the low level center will be stripped away but the mid and upper level energy will remain fairly intact. This means that there is a slim chance that once the remnants reach the warm Gulf of Mexico, some regeneration could take place. While this is NOT being forecast by the NHC right now, it would not surprise me to see it happen over the weekend or on Monday. What is more likely to happen is that Patricia’s energy leads to more of a non-tropical low pressure area to develop and bring gale force winds and extremely heavy rains to a large part of Texas. All of this will combine with a frontal boundary draped across the region and will help to focus the moisture feed, dumping excessive rain over a large swath of Texas.

In addition to the rain, coastal flooding is a real possibility with the strong onshore flow that is forecast to develop. Water levels could rise several feet in typical flood-prone areas away from the Galveston Seawall. In short, Patricia will leave a mark, even if only indirectly, long after its historic landfall in Mexico.

I will have a video discussion posted this afternoon that will highlight the landfall of Patricia and what to expect after tonight for Texas and vicinity.

M. Sudduth 9:40 AM ET Oct 23

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New storm developing in southeast Pacific, Atlantic remains quiet

A new tropical storm is likely developing in the southeast Pacific not too far off the Mexican coastline. The National Hurricane Center will almost certainly begin advisories on the system later today (right now it is designated at invest area 97-E). The development of this soon-to-be-storm is important for a couple of reasons.

First and foremost, it will have a direct impact on the weather across portions of Pacific Mexico over the next few days. Heavy rain with the usual threat of mudslides and flash flooding will an issue due to the fairly close proximity to the coast.

Model plots for 97-E in the southeast Pacific

Model plots for 97-E in the southeast Pacific

Computer models indicate that a track to the west with a gradual bend back to the northwest and eventually northeast is probable over the coming days. This means that there is the threat of a hurricane making landfall in Mexico as the system is forecast to intensify significantly over the very warm waters of the southeast Pacific. Interests along the coast of Mexico should pay close attention to this developing storm. It would not surprise me at all to see a hurricane watch posted for a portion of the Mexican coastline by sometime tomorrow.

The other interesting aspect of this system is where it developed. Right now it is situated just south of the Gulf of Tehuantepec which is itself not far from the Bay of Campeche in the extreme southern Gulf of Mexico. If you remember your geography, the strip of land that separates the two bodies of water is called an isthmus. The developing storm is on the Pacific side of the isthmus and likely precluded any development from taking place in the southern Gulf of Mexico. It is rare to have two tropical cyclones going at the same time so close together – and as such, the Pacific disturbance took over and is now on its way to becoming yet another hurricane for the region.

However, something very interesting may happen down the road. Tropical cyclones are incredible heat engines, driving their convective bursts with warm water. The transport of this energy in to the subtropics can often times lead to larger storms that have part hurricane, part mid-latitude cyclone characteristics. There is a chance that we see that happen with the Pacific system after it makes landfall in Mexico.

WPC precip forecast over the next 5 to 7 days indicating a lot of rain possible for parts of Texas and New Mexico

WPC precip forecast over the next 5 to 7 days indicating a lot of rain possible for parts of Texas and New Mexico

Some of the global models are indicating that at least some of the remnant energy will survive the trek across Mexico and combine with an upper level low coming out of the Southwest to produce a potentially heavy rain event for Texas and New Mexico. While the rain is needed, we could be faced with another instance of too much, too soon. The latest forecast from the WPC (Weather Prediction Center, formally known as the Hydrometeorological Prediction Center) suggests that a wide swath of Texas and part of eastern New Mexico could receive several inches of rain beginning later in the week. The timing of when and where is tough to call this far out but your local NWS office will have the best info concerning local impacts from this rain event.

Remember back in April and in to May, parts of Texas were inundated by very heavy rain as wave after wave of energy moved across the region dumping incredible amounts of water, resulting in widespread flooding issues. While this storm will not be nearly as prolonged, there is potential for more flooding so please pay close attention as the week wears on.

As I mentioned in the headline, the Atlantic Basin remains very quiet right now. I do not see any solid evidence of development happening anytime soon. It appears that a slow moving MJO pulse will eventually make its way in to the region as we get in to early November and it’s possible that we could see more activity flare up at that point, probably in the western Caribbean Sea. We’ll deal with that when and if the time comes.

I’ll have more in the developing storm in the southeast Pacific on my video discussion later today.

M. Sudduth 8:45 AM ET Oct 20

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