Laura and Marco: 2 Options

This is one of the most difficult tropical forecasts I’ve ever worked with. We’ve been saying from the beginning that the models don’t have a good understanding of these systems and what they’re going to do. Models are always wrong - every single time. The key to being a good forecaster is figuring out why they’re wrong, what degree they’re wrong, and correcting for it. So, that’s what we’re going to try to do for you in this blog post.

Above are the official tracks from the National Hurricane Center for both Laura and Marco. Laura starts off by Puerto Rico on the east side of the map. Marco starts off between the Yucatan and Cuba on the west side of the map.

I don’t like this forecast at all. There’s simply no way Laura is going to run directly across the mountains of Hispaniola and then run the entire length of Cuba and survive. It won’t happen. Storms don’t do that. What’s more, if Marco makes the left hand turn the NHC is showing, then Laura would end up further west.

Essentially, I don’t like these forecasts from the NHC because I think they are trying to hedge their bets between two options. They don’t know which option is going to happen right now, so they’re putting out a forecast that’s trying to cover both options at the same time. The problem is this forecast simply isn’t going to happen, but one of the other two options might.

Why is there so much uncertainty? It all has to to with the Bermuda High. That’s a persistent area of high pressure that sits off the coast of Florida, between Florida and Bermuda. The winds will flow in a clockwise direction around that high pressure and will steer the tropical storms (especially Laura). But, the big question right now is how strong is that Bermuda High. A weak Bermuda high will allow Laura to come further north and east. A stronger Bermuda High will force her south and west.

Here’s what I think is Option 1. Notice I’ve shown the area of high pressure in the upper right hand corner. That’s the Bermuda High. If it backs up north and east, then it will allow a path for Laura to go north of Cuba (not along the length of Cuba as the NHC is predicting). The weaker Bermuda High will also allow Marco to go due north. This option puts Marco on a path for New Orleans, arriving on Monday as a hurricane, and potentially a major hurricane. Laura would then go underneath Marco, and seek out warmer waters to Marco’s west, meaning there’s a landfall for Laura near Lake Charles. She would also probably be a hurricane, although maybe a bit weaker since she’d have to travel across waters that had been cooled by Marco just 24 to 48 hours earlier.

But, what if the Bermuda High is stronger? What if, instead of backing off towards the northeast, it stays closer to Florida and the Bahamas. In this scenario, Laura is pushed south of Cuba. She would likely hug the southern coasts of Hispaniola and Cuba, and would struggle to become a hurricane until she gets into the Gulf. Marco would also be pushed further west, and wouldn’t be able to make a run for New Orleans. In this option, Marco would head northwest, and would miss a trough that would have allowed him to escape towards the north. This option is why you see the leftward turn in the NCH’s forecast, but I believe if that’s actually what happens, then Marco would be closer to Corpus or Brownsville than Houston. It also seems likely that Marco would only be a Cat 1 or 2 Hurricane, not a major hurricane. That would leave plenty of warm waters in the Gulf of Mexico for Laura to tap into, and she could become the bigger storm and make landfall between Corpus and Lake Charles.

So, which option is more likely. I honestly don’t know. The models don’t either. And, I believe that’s why the NHC’s forecast is the way it is. They’re running Laura the length of Cuba, even though they know she’s not going to do that because they’re not sure if she’s going to be on the north side or the south side and their current forecast is an attempt to cover both options.

The key to this forecast, as it always is with tropical systems, is, “How strong is the High?” When the models start to get a better handle on the answer to that question, the forecast will finally come into better focus. Until then, we’ll keep sharing what we’re seeing with you here at Storm Guides.

Afternoon Update:

With this afternoon’s model runs in, it’s looking more and more like Option 1 is the more likely scenario. And, the NWS’s forecasts this afternoon are more in line with that thought process. So, Marco is looking like he will make landfall over the New Orleans area on Monday Afternoon. Laura will ride the northern side of Cuba, come into the Gulf, swing under Marco and make landfall between Houston and New Orleans on Wednesday Afternoon. We’ll keep watching these for updates and to see if the models continue in this trend.