ATL: LAURA - Post-Tropical - Discussion

[SoupBone]

Laura is giving me Ike vibes (track-wise, anyhow; the actual synoptic pattern is quite different), in terms of initially being thought of as a threat to Florida (or possibly even a recurve east), but continuing relentlessly west into the Greater Antilles, and the forecast continuing to move west with it. Now the models are beginning to cluster around a Texas landfall, with Louisiana looking like the more easterly solution at this point.

It's one set of runs man. Go back two days worth of models. I think others made a great point that this is all fluff till Laura starts to emerge in the GoM. I'm starting to agree, watching single models runs like this will drive people crazy.

[Steve]

Safe travels Montegut and keep us updated on what you hear if the situation does get bad down there.

[Steve]

Laura is giving me Ike vibes (track-wise, anyhow; the actual synoptic pattern is quite different), in terms of initially being thought of as a threat to Florida (or possibly even a recurve east), but continuing relentlessly west into the Greater Antilles, and the forecast continuing to move west with it. Now the models are beginning to cluster around a Texas landfall, with Louisiana looking like the more easterly solution at this point.

It's one set of runs man. Go back two days worth of models. I think others made a great point that this is all fluff till Laura starts to emerge in the GoM. I'm starting to agree, watching single models runs like this will drive people crazy.

It definitely is as far as ultimate track. But just about every model worth looking at has a Cat 3 hit this week. Usually when you see that (with rare exceptions), they're keyed into the pattern.

[HurricaneEdouard]

Laura is giving me Ike vibes (track-wise, anyhow; the actual synoptic pattern is quite different), in terms of initially being thought of as a threat to Florida (or possibly even a recurve east), but continuing relentlessly west into the Greater Antilles, and the forecast continuing to move west with it. Now the models are beginning to cluster around a Texas landfall, with Louisiana looking like the more easterly solution at this point.

It's one set of runs man. Go back two days worth of models. I think others made a great point that this is all fluff till Laura starts to emerge in the GoM. I'm starting to agree, watching single models runs like this will drive people crazy.

Less about the latest runs, and more about the trends (which is what's actually important), both climatologically (Ivan, Ike, Irma etc) and with this storm itself (the model runs and forecast track have been steadily shifting significantly westward and southward since formation, if you ignore the windshield wiper effect). Not every model has a rightward bias in this kind of Cape Verde track, but those that do definitely weigh on the consensus aids and thus the NHC forecast, in my experience.

[SoupBone]

Laura is giving me Ike vibes (track-wise, anyhow; the actual synoptic pattern is quite different), in terms of initially being thought of as a threat to Florida (or possibly even a recurve east), but continuing relentlessly west into the Greater Antilles, and the forecast continuing to move west with it. Now the models are beginning to cluster around a Texas landfall, with Louisiana looking like the more easterly solution at this point.

It's one set of runs man. Go back two days worth of models. I think others made a great point that this is all fluff till Laura starts to emerge in the GoM. I'm starting to agree, watching single models runs like this will drive people crazy.

Less about the latest runs, and more about the trends (which is what's actually important), both climatologically (Ivan, Ike, Irma etc) and with this storm itself (the model runs and forecast track have been steadily shifting significantly westward and southward since formation, if you ignore the windshield wiper effect). Not every model has a rightward bias in this kind of Cape Verde track, but those that do definitely weigh on the consensus aids and thus the NHC forecast, in my experience.

If that's the criteria then the HWRF is the model we should be watching closely. It's nailed Laura for days now.

[SouthernBreeze]

NHC's projected tracks look pretty close to HWRF tracks

[MONTEGUT_LA]

Safe travels Montegut and keep us updated on what you hear if the situation does get bad down there.

I will ! My adult children plan on staying down here because you know they crazy. Im taking the grandkids and my mother out of the parish. But I will have view of the cameras and the kids plan to set it up to a battery if the electric goes out. Did I mention they crazy! I did make them promise me to leave if Laura bombs out.

[Kingarabian]

No in problem producing over-shooting cold cloud tops of -80C or more. Goes to show how high the OHC is in the area. And it looks like it will be a large system.

[dexterlabio]

The trusted models like GFS, EURO and HWRF show a major hurricane in the gulf in the coming days. I wonder why the official forecast does not reflect that yet.


I know this isn't even a hurricane yet, but what are the chances of "K-name" effect in the gulf from Laura? I bet a lot of things have already improved after 15 years?

[dexterlabio]

The WPAC has been quiet lately so let me just hang in here and watch things unfold in this side of the world

[Blinhart]

The trusted models like GFS, EURO and HWRF show a major hurricane in the gulf in the coming days. I wonder why the official forecast does not reflect that yet.


I know this isn't even a hurricane yet, but what are the chances of "K-name" effect in the gulf from Laura? I bet a lot of things have already improved after 15 years?

The NHC isn't 100% sold on the models yet, because they have been all over the place from run to run. They aren't sure what the system will be doing with Cuba, so they don't want to go to high and cause a major panic during a pandemic if nothing comes of it, however if these models continue showing this output I think they will slowly be increasing the numbers so by Monday they will be able to say a MAJOR is coming and do your best to get to safety.

[Kingarabian]

The trusted models like GFS, EURO and HWRF show a major hurricane in the gulf in the coming days. I wonder why the official forecast does not reflect that yet.


I know this isn't even a hurricane yet, but what are the chances of "K-name" effect in the gulf from Laura? I bet a lot of things have already improved after 15 years?

The NHC isn't 100% sold on the models yet, because they have been all over the place from run to run. They aren't sure what the system will be doing with Cuba, so they don't want to go to high and cause a major panic during a pandemic if nothing comes of it, however if these models continue showing this output I think they will slowly be increasing the numbers so by Monday they will be able to say a MAJOR is coming and do your best to get to safety.

Great points. Yeah let's see how it does after Cuba. I think they have Erika 2015 fresh in their memories.

[Kingarabian]

[Chemmers]

Looking very healthy this morning

[Blinhart]

https://i.imgur.com/kCRzX5k.jpg

Looks like Hispaniola did exactly what a lot of us expected (unfortunately) helped make Laura a much larger system but without a well defined LLC, which will allow it to survive Cuba.

[Keldeo1997]

Laura's UL divergence is just going crazy right now. Meanwhile Marco is just sad

[Hammy]

Weather Underground map with surface obs--hard to tell clearly because of the mountains but one of three places the center might be--either way pretty close to the heaviest convection.

[Kingarabian]

Tropical Storm Laura Discussion Number 14
NWS National Hurricane Center Miami FL AL132020
500 AM EDT Sun Aug 23 2020

Laura has maintained an impressive convective pattern despite the
center being located over extreme south-central Dominican Republic.
Numerous cloud tops of -85C to -90C have been noted over the
Barahona peninsula, an indication that extremely heavy rainfall has
been occurring there. The center of Laura passed over or very near
Santo Domingo around 0430Z based on a noticeable wind shift that
was measured at the international airport. Laura's outflow pattern
has also continue to improve in all quadrants. The initial intensity
of 40 kt is based on earlier scatterometer and aircraft data, along
with surface observations along the north coast of the Dominican
Republic.

Laura has continued to move west-northwestward and the initial
motion estimate is now 285/16 kt. There has been a significant
westward shift in the latest NHC model guidance, which appears to be
due to most of the global models taking the center of Laura farther
south over central or southern Hispaniola rather than emerging it
off the north coast of Haiti like the GFS is and has been
forecasting. Given that the most intense convection has persisted
along the southern coast of Hispaniola, that is where the most
likely area that a low-level and/or mid-level circulation is most
probable to develop or persist. As a result, the new NHC track
forecast favors a more southerly and westerly track solution
similar to the preponderance of the track guidance. However, the
new forecast track has not been shifted as far to the left as the
consensus models in the event that the models shift back to the
north. However, the latter scenario is appearing less likely based
observed satellite trends since the previous advisory.

Little if any significant change in strength is expected due to
Laura moving pretty much down the spine of Hispaniola and Cuba
during the the next 36 hours, with the strongest wind likely
remaining over water in the northeast quadrant where the pressure
gradient will be the tightest between the cyclone and the Bermuda
High. By 48 hours and continuing until landfall, Laura is forecast
to remain in a low shear and very favorable upper-level outflow
environment while passing of extremely warm SSTs near 31C. This
should allow for significant strengthening to occur once the cyclone
regains a decent inner core after exiting Cuba. The new NHC
intensity forecast is a blend of the intensity forecasts by the GFS
and ECMWF global models and the corrected consensus models HCCA and
FSSE.

Key Messages:

1. Tropical storm conditions are expected across portions of the
Dominican Republic and Haiti, the Turks and Caicos, the
southeastern Bahamas, and Cuba through Monday. Heavy rainfall is
likely across these areas and could cause mudslides and flash and
urban flooding.

2. Tropical storm conditions are possible the central Bahamas and
Andros Island tonight and Monday, and in the Florida Keys on
Monday.

3. The details of the long-range track and intensity forecasts
remain uncertain since Laura is forecast to move near or over
portions of the Greater Antilles through Monday. However, Laura is
forecast to strengthen over the Gulf of Mexico and could bring storm
surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast
by the middle of next week. This could result in a prolonged period
of hazardous weather for areas that are likely to be affected by
Tropical Storm Marco earlier in the week. Interests there should
monitor the progress of Laura and Marco and updates to the forecast
during the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT 23/0900Z 18.8N 70.9W 40 KT 45 MPH
12H 23/1800Z 19.8N 73.7W 40 KT 45 MPH...OVER WATER
24H 24/0600Z 20.9N 77.5W 40 KT 45 MPH...INLAND
36H 24/1800Z 22.2N 81.1W 40 KT 45 MPH...INLAND
48H 25/0600Z 23.5N 84.2W 45 KT 50 MPH...OVER WATER
60H 25/1800Z 24.9N 87.0W 60 KT 70 MPH
72H 26/0600Z 26.4N 89.4W 75 KT 85 MPH
96H 27/0600Z 29.9N 92.5W 85 KT 100 MPH
120H 28/0600Z 35.0N 91.4W 30 KT 35 MPH...INLAND

$$
Forecaster Stewart

[Kingarabian]

[MGC]

Laura has a impressive IR sat presentation this morning. I'm not so sure how it's surface circulation looks considering the terrain the storm is currently traversing. Should see a brief opportunity to intensify as Laura crosses the Windward Passage later today. Chances are increasing that Laura becomes a major in the Gulf IMO.....MGC