August 2020:

[sau27]

12Z Euro ensemble still has Laura as a possible threat for us. All of the stronger members are in Texas while the weaker ones go to Louisiana.

[Andrew]

Models are going to continue to have difficulty with the track as both storms remain rather disorganized. The big reason for the change this afternoon on the 12z runs is the expected intensification from Marco that leaves enough of a weakness behind for Laura to follow. Let's see what the overnight runs show because additional swings are possible.

[sau27]

Just saw a post from Jack Sillin saying that a stronger Marco moving north actually could help expand/strengthen the SE ridge due to additional heat release from the storm. Never thought of that.

[snowman65]

Just so happens that 3 years ago today we were tracking a little fellow by the name of harvey.....not to far off from the same position as Marco...

[Texashawk]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

[sambucol]

Is southeast Texas in the clear? I’m seeing comments on other pages that everything is now shifted way East and Texas isn’t in play. Is this correct or will the track shift back west? I’m confused. Thank you.

[tireman4]

Is southeast Texas in the clear? I’m seeing comments on other pages that everything is now shifted way East and Texas isn’t in play. Is this correct or will the track shift back west? I’m confused. Thank you.

One word. No

[Cpv17]

Is southeast Texas in the clear? I’m seeing comments on other pages that everything is now shifted way East and Texas isn’t in play. Is this correct or will the track shift back west? I’m confused. Thank you.

It could still shift back west. Shear is hitting it now and tearing it apart.

[Cpv17]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

Yes. A weaker storm would go more west.

[Kingwood36]

Wx57 has it going to the mouth of Mississippi before noon on monday...no texas hit

[Texashawk]

Wx57 has it going to the mouth of Mississippi before noon on monday...no texas hit

Wow. That’s quite a shift for him. He was saying Freeport this morning. Interesting

[Andrew]

Just saw a post from Jack Sillin saying that a stronger Marco moving north actually could help expand/strengthen the SE ridge due to additional heat release from the storm. Never thought of that.

With the size of Marco and the proximity to Laura, I think the more immediate impact will actually be more of a temporary weakness along the Central Gulf Coast. That is what models, among other things, were showing in the 12z suite of runs.

[Cromagnum]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

Yes. A weaker storm would go more west.

I dont understand this. If there is a high pressure system to the east, why would a weaker storm go more west? I always thought stronger storms get pushed by ridges more than weak ones

[Cpv17]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

Yes. A weaker storm would go more west.

I dont understand this. If there is a high pressure system to the east, why would a weaker storm go more west? I always thought stronger storms get pushed by ridges more than weak ones

Stronger storms are more influenced by the steering currents than weaker ones. They’re basically a lot more sensitive and can feel ridges/troughs from miles upon miles away. Something like that.

[don]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

Yes. A weaker storm would go more west.

I dont understand this. If there is a high pressure system to the east, why would a weaker storm go more west? I always thought stronger storms get pushed by ridges more than weak ones

There is a trough over the south that is pulling Marco north. And the stronger Marco is the more he feels the troughs tug.

[Kingwood36]

Honestly I'm over both of them at this point..go where ya wanna go

[unome]

This line from the earlier NHC discussion stuck out for me:https://www.nhc.noaa.gov/archive/2020/MARCO.shtml

Large-scale guidance generally agree that any binary direct or indirect interaction, while both systems are in the gulf and at near equal latitude, is unlikely at this point.

[Andrew]

Marco does not look impressive at all. Frankly looks like it’s already getting sheared away to the NE. Would that affect the track?

Yes. A weaker storm would go more west.

I dont understand this. If there is a high pressure system to the east, why would a weaker storm go more west? I always thought stronger storms get pushed by ridges more than weak ones

For Marco, there is an upper-level trough extending from the Western Gulf Coast, northeast to parts of the Ohio Valley. When a tropical system intensifies it also grows deeper vertically and can feel the impacts of that upper-level trough more. While mid and lower level steering would push it more to the west (under the ridging you mentioned), a stronger system would "feel out" the trough and upper-level steering flow to push it more north. So really it's about looking at the vertical column and seeing how different levels of the atmosphere could impact the system.

[snowman65]

If Marco decides to go up the Mississippi river, is Laura more likely to follow him?

[Andrew]

If Marco decides to go up the Mississippi river, is Laura more likely to follow him?

There may be some lingering weaknesses from it, but it's more of an indication that ridging over the Western Atlantic and SE U.S. is not as strong. That is why Laura is able to gain latitude and track into Louisiana.