ATL: LAURA - Post-Tropical - Discussion

[CrazyC83]

Have there been any synoptic flights ahead of this thing yet?

None. With fewer commercial flights and less sampling, I think we need the G-IV out there sooner.

[Hurricane Mike]

Have there been any synoptic flights ahead of this thing yet?

None. With fewer commercial flights and less sampling, I think we need the G-IV out there sooner.

Darn. With those tight models I wanna verify, because if they stay this tight, we could have a very serious problem in Southeast Florida on Monday.

[ConvergenceZone]

Personally, I think there is a good chance that this ends up missing FL to the east, given that models are underestimating short-term as well as long-term organisation. The key is that the ridge to its north is going to be narrow. Any changes in either the size/intensity of 98L and/or the orientation of the ridge axis relative to the numerous shortwave impulses will make a tremendous difference, since 98L will be nearing the Bahamas and FL at an angle, heading WNW or even NW. This puts us in yet another Matthew-, Irma-, or Dorian-type scenario, with potentially large ramifications. Note that the global models show persistent northwesterly flow over the Northeastern U.S. This kind of pattern normally would favour a sharp curve at some point, especially if one is contending with a powerful major hurricane. Of course, uncertainty is still high at this stage, but climatology and the upcoming setup combined would normally favour a track missing FL, especially if we are dealing with a major hurricane.

CMC
ECMWF
EPS

If that were the case, I would think that the NHC would be picking up on it. They don't mention "recurve" in any part of their discussion, and they usually don't shy away from that word if they think it's a possibility...

[Blinhart]

Have there been any synoptic flights ahead of this thing yet?

None. With fewer commercial flights and less sampling, I think we need the G-IV out there sooner.

Yeah I was going to ask if Gonzo was going to be flying anytime soon to sample all the upper air situation all over the GoM, and over the Bahamas.

[ozonepete]

You really have to put a plainly visible disclaimer on a forecast like that (or any really) that it's a non-professional opinion.
There are a lot of people on here who might panic after seeing your forecast and spread it to other people.

Unrelated, but remember 10+ years ago when people had their own forecast threads with regular “advisories”? And the pro-Mets has their own forum for their personal advisories? Good times...

Lol yeah. God only knows how many freaked out and fled to Canada for a tropical storm.

[Hurricaneman]

Looking at this, the LLC is just south of the new convective blowup, could be wrong though

[psyclone]

Mentioning a possibility is not an "all clear". it is a mention of one of many options at this early juncture.

[Shell Mound]

Personally, I think there is a good chance that this ends up missing FL to the east, given that models are underestimating short-term as well as long-term organisation. The key is that the ridge to its north is going to be narrow. Any changes in either the size/intensity of 98L and/or the orientation of the ridge axis relative to the numerous shortwave impulses will make a tremendous difference, since 98L will be nearing the Bahamas and FL at an angle, heading WNW or even NW. This puts us in yet another Matthew-, Irma-, or Dorian-type scenario, with potentially large ramifications. Note that the global models show persistent northwesterly flow over the Northeastern U.S. This kind of pattern normally would favour a sharp curve at some point, especially if one is contending with a powerful major hurricane. Of course, uncertainty is still high at this stage, but climatology and the upcoming setup combined would normally favour a track missing FL, especially if we are dealing with a major hurricane.

CMC
ECMWF
EPS

If that were the case, I would think that the NHC would be picking up on it. They don't mention "recurve" in any part of their discussion, and they usually don't shy away from that word if they think it's a possibility...

Continuing with the latest (00Z) GEFS output, two clearly modelled camps are seemingly emerging:

1. Weaker 98L (strong TS or weaker): tracks over Greater Antilles and/or the Florida Keys, enters the Gulf of Mexico (GoM)
2. Stronger 98L (Cat-1 or stronger): curves NW just offshore of or along/over the east coast of FL, à la Matthew/Dorian

The strongest members on the GEFS, for instance, are no stronger than a high-end Category 2, yet show the latter scenario.

If the projected upper-air pattern remains the same but 98L is even stronger than these projections, it would curve even sooner.

I am merely outlining a very plausible possibility. At the moment it seems to becoming increasingly likely vs. yesterday.

[WeatherEmperor]

2:00 AM AST Thu Aug 20
Location: 15.1°N 49.0°W
Moving: WNW at 20 mph
Min pressure: 1008 mb
Max sustained: 35 mph


Sent from my iPhone using Tapatalk

[Sanibel]

Models are putting a worst case scenario bomber track right up the west coast and over us...Pretty grooved-in too...Tight consensus...Gulp...

[Bocadude85]

If that were the case, I would think that the NHC would be picking up on it. They don't mention "recurve" in any part of their discussion, and they usually don't shy away from that word if they think it's a possibility...

Continuing with the latest (00Z) GEFS output, two clearly modelled camps are seemingly emerging:

1. Weaker 98L (strong TS or weaker): tracks over Greater Antilles and/or the Florida Keys, enters the Gulf of Mexico (GoM)
2. Stronger 98L (Cat-1 or stronger): curves NW just offshore of or along/over the east coast of FL, à la Matthew/Dorian

The strongest members on the GEFS, for instance, are no stronger than a high-end Category 2, yet show the latter scenario.

If the projected upper-air pattern remains the same but 98L is even stronger than these projections, it would curve even sooner.

I am merely outlining a very plausible possibility. At the moment it seems to becoming increasingly likely vs. yesterday.

Other then about 50% of the 0z GEFS what models are showing the scenario you are describing? HWRF and HMON both are showing a major hurricane tracking south of or over extreme S. Fla. CMC is into S.Fla and the UKMET misses Florida to the south...not sure where a trend is emerging for a recurve east of Florida?

[hurricaneCW]

Mentioning a possibility is not an "all clear". it is a mention of one of many options at this early juncture.

A near 0% chance of that happening given the ridge building over this. I'd say it has a 15% chance at getting shredded over land.

Impacts to the SE coast are extremely likely and gulf state impacts are possible as well.

[fci]

Here’s my forecast and those between Palm Beach to the Key West May need to prepare for a major hurricane

Here is the forecast intensity

Now. TD. 35mph
12hrs. TS. 40mph
24hrs. TS. 45mph
36hrs. TS. 50mph
48hrs. TS 60mph
72hrs. C1. 80mph
96hrs. C2. 100mph
108hrs C2. 110mph over Miami
120hrs C1 85mph Over Lakeland
144hrs. C1. 80mph near Cedar Key

Feeling safeish for now up here in southern Martin county.

Depending on the size, Martin and PBC would be in the NE quadrant or just north of it which is not where we like to be.

[Cyclenall]

That discussion does not mention any other inhibitors to development besides land interaction...

That's the part that strikes me as interesting, zero mention about conditions in 5 days if the track holds. The forecast intensity error has high potential to be enormous in 120 hours. Basically from dissipation to a category 5 hurricane.

[AxaltaRacing24]

That discussion does not mention any other inhibitors to development besides land interaction...

That's the part that strikes me as interesting, zero mention about conditions in 5 days if the track holds. The forecast intensity error has high potential to be enormous in 120 hours. Basically from dissipation to a category 5 hurricane.

that's because if it clears the islands, not much is stopping it from becoming at least a cat 1 for the time being. it's sorta like dorian and Hispaniola last year.

[SouthFLTropics]

Here’s my forecast and those between Palm Beach to the Key West May need to prepare for a major hurricane

Here is the forecast intensity

Now. TD. 35mph
12hrs. TS. 40mph
24hrs. TS. 45mph
36hrs. TS. 50mph
48hrs. TS 60mph
72hrs. C1. 80mph
96hrs. C2. 100mph
108hrs C2. 110mph over Miami
120hrs C1 85mph Over Lakeland
144hrs. C1. 80mph near Cedar Key

Feeling safeish for now up here in southern Martin county.

Depending on the size, Martin and PBC would be in the NE quadrant or just north of it which is not where we like to be.

FCI is 100% correct here. A major storm coming in around Miami and moving up towards Lake Okeechobee is a worst case scenario and what keeps emergency planners up at night. Those are the ones that trigger evacs from the Keys northward. It's very difficult to move that many people out of harms way in a short period of time.

[Shell Mound]

Personally, I think there is a good chance that this ends up missing FL to the east, given that models are underestimating short-term as well as long-term organisation. The key is that the ridge to its north is going to be narrow. Any changes in either the size/intensity of 98L and/or the orientation of the ridge axis relative to the numerous shortwave impulses will make a tremendous difference, since 98L will be nearing the Bahamas and FL at an angle, heading WNW or even NW. This puts us in yet another Matthew-, Irma-, or Dorian-type scenario, with potentially large ramifications. Note that the global models show persistent northwesterly flow over the Northeastern U.S. This kind of pattern normally would favour a sharp curve at some point, especially if one is contending with a powerful major hurricane. Of course, uncertainty is still high at this stage, but climatology and the upcoming setup combined would normally favour a track missing FL, especially if we are dealing with a major hurricane.

CMC
ECMWF
EPS

If that were the case, I would think that the NHC would be picking up on it. They don't mention "recurve" in any part of their discussion, and they usually don't shy away from that word if they think it's a possibility...

Continuing with the latest (00Z) GEFS output, two clearly modelled camps are seemingly emerging:

1. Weaker 98L (strong TS or weaker): tracks over Greater Antilles and/or the Florida Keys, enters the Gulf of Mexico (GoM)
2. Stronger 98L (Cat-1 or stronger): curves NW just offshore of or along/over the east coast of FL, à la Matthew/Dorian

The strongest members on the GEFS, for instance, are no stronger than a high-end Category 2, yet show the latter scenario.

If the projected upper-air pattern remains the same but 98L is even stronger than these projections, it would curve even sooner.

I am merely outlining a very plausible possibility. At the moment it seems to becoming increasingly likely vs. yesterday.

To further elaborate, here is a comparison between the latest 00Z ECMWF and the 500-mb setup for Irma (2017).



The two setups are actually not very dissimilar from each other. However, unlike in 2017, we have a strong, west-based Greenland block (west-based -NAO) in place. Additionally, the overall NHEM pattern is a bit more progressive than in 2017, the ridge over the Rio Grande Valley and Llano Estacado (W TX/E NM) is instead centred farther NW, around the Four Corners, the orientation of that ridge’s primary axis is from SW-NE instead of SE-NW as in 2017, and northwesterly flow is more pronounced around the time that TD Thirteen begins to approach FL. In 2017 the trough axis was located to the west of Irma; in 2020 it will be to the east of TD Thirteen. This difference is critical: it allows energy from the trough to “cut off,” that is, enables vorticity to become elongated or “string out” as the Sonoran ridge “bridges” in the wake of the shortwave trough. Therefore, the mid-level flow—which a stronger TD Thirteen, being more likely at this point, is also more likely to sense—will not be out of the southwest, as in the case of Irma, but out of the northwest. A well-developed major hurricane then in or near the Bahamas would be more likely to curve sharply NW, NNW, and N, eventually being carried NE and ENE as it senses the lingering weakness and the next shortwave impulse approaches. Even the strongest 00Z GEFS members, which show TD Thirteen curving over or east of easternmost FL, only take the system to high-end Category-2 status. This means that if TD Thirteen becomes a major hurricane, that is, even stronger than modelled, it would be more likely to turn even earlier, all other factors remaining unchanged.

Short-term trends clearly favour a stronger TD Thirteen:

 https://twitter.com/pppapin/status/1296340014088028160



 https://twitter.com/pppapin/status/1296343407066066946



 https://twitter.com/WxPatel/status/1296343225289060354

[AtlanticWind]

This could be one of those fast moving storms like Andrew that rapidly intensifies in the last 24 /36 hours before hitting keys or south central florida.
One of those worst case scenarios.

Not predicting that at all ,but one with that potential.

Really hope its not.

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

[tiger_deF]

Convection is warming a little but obvious signs of banding are setting themselves up to the north and south, and you can easily see a cyclonic "wrap" in the convection

I cannot believe I am awake

[Jr0d]

While stronger storms moving poleward is generally true, the synoptic set up is more important. Andrew, Irma, and Katrina all took a WSW job before hitting Florida. Andrew and Irma did this as major hurricanes. The assumption that a stronger storm track further north is false.

Earlier I wrote my threat level in Key West was very low, now I will have to move the threat level to low...

The speed of this storm is potentially a problem, given that according to the NHC's wind arrival graphic we can have storm force winds as early as Sunday evening. This gives us much less time to prepare and possibly evacuate. If the forecast track remains the same(I expect the intensity forecast to go up), then evacuations will have to start Friday...tomorrow.

Today will be crucial in terms of data collection. Friday morning's model output will be crucial on an evacuation decision for my area. Obviously land interaction is going to be a major unknown, a little wobble can be the difference between a major hurricane or a shredded remnants of a tropical cyclone.

With that said, it does seem like I am in the cone very often with the first advisory of a system and the vast majority of the time the cone shifts and it misses me, so at least I have that going for me.