ATL: LAURA - Post-Tropical - Discussion

[CrazyC83]

Is there any possibility that Laura stays *south* of the Greater Antilles? In that scenario, would conditions still be favorable for strengthening?

[DestinHurricane]

You can tell when a Florida landfall probably decreases, as this forum gets much less active. Tons of folks from Florida on here

Keys and panhandle are still FL the last time I checked. I know what you mean though, metro SE FL.

[Blown Away]

I wonder if that COC is reforming again? At 11am it was at 60.2W, 2 hrs later at 18mph it should be passed 61W. Looks like another circulation @17N/59W. Probably multiple vortices spinning around a very broad circulation?

[AutoPenalti]

I’m still on the “SFL should still watch” boat until about the 36 hour timeframe. LLC that Recon spotted is losing its punch and seems to be forming another one just north east of it under the convection. Any northward component and we are back to square 1. We are still roughly 3 days away from any sort of impact.


Of course, that’s assuming that it does strengthen.

[hohnywx]

Any more recon today?

Looks like two flights are scheduled for later today:

000
NOUS42 KNHC 201844
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0245 PM EDT THU 20 AUGUST 2020
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z AUGUST 2020
TCPOD NUMBER.....20-086 CORRECTION

I. ATLANTIC REQUIREMENTS
1. TROPICAL DEPRESSION THIRTEEN
FLIGHT ONE - NOAA 49
A. 22/0000Z
B. NOAA9 0313A CYCLONE
C. 21/1730Z
D. NA
E. NA
F. 41,000 TO 45,000 FT

FLIGHT TWO - NOAA 43
A. 21/2330Z
B. NOAA3 0413A CYCLONE
C. 21/2100Z
D. 18.9N 61.6W
E. 21/2130Z TO 22/0400Z
F. SFC TO 10,000 FT

FLIGHT THREE - NOAA 42
A. 22/1130Z
B. NOAA2 0513A CYCLONE
C. 22/0900Z
D. 19.6N 64.7W (CORRECTED)
E. 22/0830Z TO 22/1500Z
F. SFC TO 10,000 FT

[cheezyWXguy]

It looks pretty apparent to me that a center reformation to the east is occurring. Convergence really seems to be decreasing on that western lobe and convection looks to be increasing near the apparent center of the eastern one.

[WxEp]

I think until we have a well-defined, consistent LLC that is aligned with the MLC we are going to continue playing this guessing game to some extent. It appears convection is collapsing again, wherever it refires could be an indicator of where to look for the LLC formation or movement going forward.

[Hurricane Mike]

Any more recon today?

Looks like two flights are scheduled for later today:

000
NOUS42 KNHC 201844
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0245 PM EDT THU 20 AUGUST 2020
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z AUGUST 2020
TCPOD NUMBER.....20-086 CORRECTION

I. ATLANTIC REQUIREMENTS
1. TROPICAL DEPRESSION THIRTEEN
FLIGHT ONE - NOAA 49
A. 22/0000Z
B. NOAA9 0313A CYCLONE
C. 21/1730Z
D. NA
E. NA
F. 41,000 TO 45,000 FT

FLIGHT TWO - NOAA 43
A. 21/2330Z
B. NOAA3 0413A CYCLONE
C. 21/2100Z
D. 18.9N 61.6W
E. 21/2130Z TO 22/0400Z
F. SFC TO 10,000 FT

FLIGHT THREE - NOAA 42
A. 22/1130Z
B. NOAA2 0513A CYCLONE
C. 22/0900Z
D. 19.6N 64.7W (CORRECTED)
E. 22/0830Z TO 22/1500Z
F. SFC TO 10,000 FT

Are those the Miss Piggy and Kermit flights?

[NDG]

12z HWRF more aggressive than previous run, avoids G.A.

[Aric Dunn]

It looks pretty apparent to me that a center reformation to the east is occurring. Convergence really seems to be decreasing on that western lobe and convection looks to be increasing near the apparent center of the eastern one.

You would be correct.. at least from all the given data.. ( manually making radar loops again since the other radar loops sucks).

center appears to have consolidated and rotated a little and is heading off the wnw again.. ish..

[wx98]

Is there any possibility that Laura stays *south* of the Greater Antilles? In that scenario, would conditions still be favorable for strengthening?

In my opinion, I don’t see much of a chance of this going south of Hispaniola. Also, I would think that being on the south side would be worse in terms of land interaction and proximity to outflow from TD 14.

[eastcoastFL]

I think the NHC is just because cautionary. There’s no way a struggling system intensifies while crossing that much land. My only thinking is that they think it will be just slightly north of the islands..

If the forecast dips south even the slightest, they will probably go with either a depression or dissipation as it enters the gulf

Ya in the discussion they said they estimate that it will stay just north of the the big islands. Still low confidence on grazing islands, over them or over water.

[Jr0d]

So far I have not heard any official statement or plan of action from Monroe county or the City of Key West.

This was posted a little while ago:
https://www.nbcmiami.com/news/local/monroe-county-announces-emergency-order-evacuations-ahead-of-tropical-storm-lauras-potential-track/2281350/

I missed that part of the meeting I suppose, had to download the Facebook to watch it . Mobile homes, RVs, and liveaboard vessels are under an evacuation order. Nothing for tourists yet. I expect that to happen tomorrow morning unless the models continue to shift South(unlikely in my amateur opinion).

[SFLcane]

I’m still on the “SFL should still watch” boat until about the 36 hour timeframe. LLC that Recon spotted is losing its punch and seems to be forming another one just north east of it under the convection. Any northward component and we are back to square 1. We are still roughly 3 days away from any sort of impact.


Of course, that’s assuming that it does strengthen.

Doupt that.. As you can see by the HMON and the HWRF even if takes off to a Cat 3 they still keep it way south of the mainland near Cuba. That ridge seems to strong.

[ThetaE]

I just mentioned in the TD 14 thread that according to the CIMSS vorticity maps, Laura appears to not be very well stacked into the mid-layers. In particular, Laura has a decent 500 mb, and to a lesser extent 700 mb, vorticity signature that is displaced to the ESE of the center by quite a ways. The position of the 500mb vorticity appears to be inducing or associated with a northerly mid-level shear on the system:



This could explain a few things about Laura today: the center position/reformation further south than expected, and now the potential reformation to the east so as to become better vertically aligned.

[psyclone]

You can tell when a Florida landfall probably decreases, as this forum gets much less active. Tons of folks from Florida on here

That's definitely part of it. But beyond that there are bigger forces at work when a storm in zeroing in on a location. it's rather fascinating to watch and you'll see it in action this season
A.) as a storm heads for an area and it becomes clear more areas are off the hook, people in those areas peel off. most folks only have an interest in a storm that poses some risk to them. (that's not a knock..it makes sense people are interested in their area)
B.) those still in the hot zone need to get off message boards and secure their property. so many of those folks peel off for a different reason.

The net effect can be a message board that gets rather quiet as a storm makes landfall. It's counterintuitive until you think about it and then it makes perfect sense. I personally take extended outlooks with a big grain of salt...even from the pros. it isn't a knock on them, we're just not good enough. extended outlooks on Dorian showed a high probability of significant impacts for me. thankfully it didn't happen. I was in the hot zone on the early outlooks for this year's storm I. again zilch. This one also looks like an extended swing and a miss. We will see. The net effect for me is to take extended outlooks with a big grain of salt. We will see what Laura does. the shredder is less of a risk when there's nothing to shred and we have plenty of examples of disturbances that transited the GA and went on to become something significant thereafter. For me the takeaway is this...we do not need a long runway to build a significant storm in peak season.

[HurricaneEnzo]

New center 59.5W 17N ? Boy that will throw a monkey wrench in some stuff.

https://tropicaltidbits.com/sat/satloop ... roduct=vis

[HurricaneEdouard]

I'm getting Hurricane Frederic vibes from this. My thinking hasn't changed from three days ago; I'm still expecting Laura to be our first major hurricane of the season (likely in the Gulf), and track more westward than was the track consensus over the last few days, into the Caribbean at least briefly.

Been a Form lurker for many years.

Question =>
Currently NHC is showing TD13 (Laura) and TD14 both making landfall approximately 300 miles from each other at approximately the same time.

Wouldn’t each TD interact with each other and effect the tacking direction of each other. How do the Hurricane Spaghetti Tracking Models account for the close proximity of each other?

They would, yes; this is called a Fujiwhara interaction, in which they begin to revolve around a point between them. This should affect track insomuch as the eastward system (Laura) would move further north, and the more westward system (Fourteen/Marco) would move further west. Intensity-wise, the stronger system tends to shear the other (although they can shear each other about equally if they are of similar strength, as we saw in the multiple Fujiwhara interactions in 1995). The forecast models do account for this proximity - the forecast models are either global models, which model weather and steering currents across the entire planet, or hurricane models which are higher-resolution grids embedded within the global models - but, historically, the precedent is that models are bad at nailing Fujiwhara interactions, so I'd say track uncertainty increases past day four.

[gfsperpendicular]

New center 59.5W 17N ? Boy that will throw a monkey wrench in some stuff.

https://tropicaltidbits.com/sat/satloop ... roduct=vis

I think you're right and that's almost 1.5 degrees east of the 2pm advisory position (but coincides well with the mid-level vorticity). That would give it a lot more time to gain latitude before reaching the GAs (and Florida).

[Kazmit]

New center 59.5W 17N ? Boy that will throw a monkey wrench in some stuff.

https://tropicaltidbits.com/sat/satloop ... roduct=vis

How would an east center relocation affect its path?