No major track changes with Maria from the overnight model runs

8:50 AM ET Friday, September 22

So far, no major changes in the overall track and future progress of the hurricane as it moves past the Turks and Caicos today – eventually turning more north with time.

In general there is a subtle shift more to the north with the track guidance rather than west although the ECMWF is perhaps a little more west than we saw 24 hours ago. The outcome seems to be the same, however, and that is the fact that Maria should turn away from the East Coast of the U.S. with time.

After Maria clears the pattern, we will begin to shift our focus to the western Caribbean where most of the long range guidance suggests a lowering of pressures and the potential for development over the coming weeks. October is notorious for powerful hurricanes originating from the western Caribbean and it will not surprise me at all to see this happen this season.

Here is the first of two video posts coming for today:

M. Sudduth

 

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Maria likely to turn out before directly impacting USA…but….

9 AM ET Thu Sept 21

Satellite photo of the western Atlantic with Jose to the north and Maria to the south

Satellite photo of the western Atlantic with Jose to the north and Maria to the south

After a devastating, crushing landfall across Puerto Rico this time yesterday, Maria is now out over the warm waters of the southwest Atlantic. The eye has become quite large with hurricane force winds now extending out from the center some 60 miles. Maria has regained category three intensity and I think it will get stronger still once it moves farther away from the island of Hispaniola.

As the people of Dominica, St. Croix and Puerto Rico labor to begin the process of rebuilding their lives and their communities, there remains one more chapter to the Maria story still unwritten. I say unwritten, though the outline sure seems to be solid at this point: Maria never makes it to the USA coastline.

All of the available track guidance suggests, at least at first glance, that Maria will turn a graceful curving path away from the Southeast coast over the next five to seven days. The closest it is likely to get to land again will be today and tomorrow as it approaches the Turks and Caicos islands – but remaining just east in terms of the dangerous core of the hurricane.

After this time period, it seems almost certain that the lack of strong high pressure over the western Atlantic, due mainly to the presence of Jose, will allow Maria to eventually lose its western progress and begin turning back towards the east and eventually on out in to the open waters of the Atlantic.

Sounds like all is well for the East Coast…except for one thing: it hasn’t happened yet.

Now I know this sounds obvious but a forecast is subject to error; whether by humans who lay out projections on a map for the center position of a tropical cyclone or by computers which use numerical prediction to guide the humans. If it hasn’t happened yet then it is only a forecast and remains under the limitations of modern weather prediction – even if it looks like a lock.

Let’s look at it from a different perspective. Instead of “why is Maria turning out to sea?”, let’s approach it from “what would it take for Maria to turn back towards the coast?”

Here is my answer: If we see more ridge (high pressure) developing north and east of Maria then it will not fade east and has a chance to continue to gain longitude (westward progress). Right now, something very important is occupying the space that would normally be filled with a dome of air and that is a tropical storm named Jose.

As a hurricane, Jose literally moved up in to and split the ridge, causing an alley-way or weakness for Maria to follow. As long as this alley stays open, Maria will turn out. This is quite likely what will happen. However, if Jose turns back west and comes inland over the Northeast or Mid-Atlantic states then what does that tell us? Why would Jose turn back to the west? Blocking high pressure. That’s why. The atmosphere is forecast to build what we call “heights” over the coming days in a fashion that would normally steer something like Maria in to the Southeast coast. But, with Jose having cut the ridge out enough, Maria is probably going to gain more northward progress with a turn out to the east with time.

Probably. Not certainly.

What we need to look for is how far west Maria tracks over the next 48-72 hours. We also need to watch what Jose does. I believe from what I have read and seen in the model guidance, that if Jose turns west and even south of west, and is driven in to the coast of say, New Jersey (however weak Jose may be it is still something to watch for), then Maria could pinwheel in as well as the models seemed to suggest yesterday. It’s a long shot but there are several members of the 51 runs of the ECMWF model that show this scenario. I cannot display that model output here as it is licensed for use by commercial weather companies. This is the advantage of having an ensemble prediction system – it allows the “what if” cards to be played. In the case of Maria, we are not yet seeing all 51 members of the ECMWF model depict an “out to sea” path.

To be fair, the 21 members of the GFS ensemble group do show 100% “out to sea” as far as USA impacts go. Which model will be correct? Wish I knew.

So the bottom line here is that while the odds favor the East Coast of the USA having to never deal with Maria directly, those odds are not 100% just yet. We’re getting close but close is not the same as there.

I’ll post a video discussion this afternoon after the 12z GFS and ECMWF models complete their runs and we’ll see if the odds have changed any.

M. Sudduth

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Speed of movement is apparently an important key for future track of Jose

11:25 pm ET Friday, September 15

I have posted a new video discussion outlining some interesting clues that the latest NHC forecast discussion yielded in tonight’s 11pm ET advisory package.

As you’ll see, the forward speed of Jose is apparently critical in terms of how soon it is able to approach the East Coast of the USA before a small but significant piece of energy dips down to sweep it eastward and away from the coast. Check out the latest video – it’s neat how it all makes sense and is shown within the 18z GFS model:

M. Sudduth

 

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GFS vs ECMWF Video Post Added

Updated: 2:45 AM ET Sept 8

Just added a new video discussion comparing the latest runs of the GFS vs the ECMWF models. I am off to bed – meteorlogist Zack Fradella will handle the early morning video and blog post. I will be back in around 11am ET with an update and plans of the day of setting up equipment around S Florida, etc.

M. Sudduth

 

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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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