ATL: LAURA - Models

[SouthFLTropics]

00z vs 18z

108 Hours

[AutoPenalti]

Looks like a center reformation of the HWRF at 24hrs? Jumps to the WSW.

[Blinhart]

Am I reading the model right? GFS now has a Cat 1 hurricane landfalling in the Northern Gulf? or maybe a Cat 2 even?

Low 970's is Cat 2 all day. It's still a little south of the state it looks like. So maybe going in between Cocodrie and Morgan City?
https://i.imgur.com/bJPwqcy.png

Just don't want it going up the Mermentau River in Grand Chenier.

[USTropics]

The CMC really hammers S Florida. Is there any info on what changes were made to improve this model? It was a joke a few short years ago and now is somehow worthy of discussion and consideration? SFL residents should be preparing anyway for what could be an epic 2nd half of the season regardless of where this ends up.

There were some big upgrades actually last year, the biggest was the change to one of its dynamic cores. It replaced an existing log-hydrostatic-pressure-type terrain-following vertical coordinate core (yea say that 5 times fast), instead adopting a height-based approach core. This was done to increase model stability (particularly over increasing heights/terrain) and to fulfill increases in demand for high resolution forecasting. Essentially the new core separates a three-dimensional elliptic boundary value problem into a set of two-dimensional independent Helmholtz problems (which gave the CMC a three-dimensional iterative solver).

TL;DR CMC replaced its pressure-based core with a height-based dynamical core.

[Shell Mound]

00z vs 18z

108 Hours

https://i.imgur.com/S0TUkBW.gif

Didn’t we see a similar evolution with the models for Matthew and Dorian? Several members initially showed a landfall in FL, but as a centre was better initialised and more upper-air data were ingested, a rather tight long-range cluster began to diverge, with the strongest members on the eastern side of the spread, and eventually both Matthew and Dorian ended up missing FL to the east. The current trend says “déjà vu.” Of course, no one should be complacent, even if it misses, but I’m just pointing out some similarities between past “near misses” and the current situation.

[lsuhurricane]

Pretty marked split between the stronger recurve solutions compared to the GOM solutions which feature a delayed strengthening.

[SouthFLTropics]

HMON will easily clear the Puerto Rico at 66 hours.

[Hurricaneman]

https://i.ibb.co/1Xw4B8q/Screen-Shot-2020-08-20-at-12-01-29-AM.png

Pretty marked split between the stronger recurve solutions compared to the GOM solutions which feature a delayed strengthening.

I will say this, no solution is off the table, the ensembles still put Florida in the crosshairs, we need sampling of the ridge north of td13

[WeatherEmperor]

Is it me or is the HWRF coming in way way weaker? Perhaps its starting to cave to the GFS??




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[SouthFLTropics]

HWRF is WAY off the pace from what it had at 18z. It's a big swing for it.

[SouthFLTropics]

Hour 81 to Hour 84, HMON really pours on the gas and starts cranking up. Looks like it will go big. HWRF looks like it finally is getting its act together North of Puerto Rico by hour 66.

[SouthFLTropics]

[Shell Mound]

https://i.imgur.com/mZ8iQ62.gif

Note that all the sub-990-mb members are on the eastern side of the guidance late on 24 August 2020:

These same members show 98L curving just east of or along the east coast of FL, à la Matthew/Dorian:


This is definitely an important trend. Given that 98L will likely be even stronger than these members indicate, it would curve even farther east.

[SouthFLTropics]

Key Largo, 948 MB, 105 knots/120MPH

[ConvergenceZone]

https://i.imgur.com/mZ8iQ62.gif

Note that all the sub-990-mb members are on the eastern side of the guidance late on 24 August 2020:
https://www.tropicaltidbits.com/analysis/models/gfs-ens/2020082000/gfs-ememb_lowlocs_watl_20.png
These same members show 98L curving just east of or along the east coast of FL, à la Matthew/Dorian:
https://www.tropicaltidbits.com/analysis/models/gfs-ens/2020082000/gfs-ememb_lowlocs_watl_22.png

This is definitely an important trend. Given that 98L will likely be even stronger than these members indicate, it would curve even farther east.

If that were the case, all it would mean is that the Carolina's and east could would be in the bulls eye...I don't think it's going to recurve. A brick wall is a brick wall, a hurricane can't just run through it. It might go "slightly more north, but not enough to miss anyone in my opinion.

[Shell Mound]

https://i.imgur.com/mZ8iQ62.gif

Note that all the sub-990-mb members are on the eastern side of the guidance late on 24 August 2020:
https://www.tropicaltidbits.com/analysis/models/gfs-ens/2020082000/gfs-ememb_lowlocs_watl_20.png
These same members show 98L curving just east of or along the east coast of FL, à la Matthew/Dorian:
https://www.tropicaltidbits.com/analysis/models/gfs-ens/2020082000/gfs-ememb_lowlocs_watl_22.png

This is definitely an important trend. Given that 98L will likely be even stronger than these members indicate, it would curve even farther east.

If that were the case, all it would mean is that the Carolina's and east could would be in the bulls eye...

If you look at the steering in the links I posted, you’ll notice that there is no ridging over the Northeastern U.S. Aside from the narrow ridge just east of the Southeastern U.S., there is a strong Hudson Bay vortex with northwesterly flow over the top of the ridge. Once 98L bypasses the ridge axis, the northwesterly flow would cause it to curve sharply NE and eventually ENE, which would certainly not favour a direct impact to the Carolinas or Mid-Atlantic, that is, a landfall, but could certainly portend very high surf. Again, I am reiterating that I am merely outlining a modelled scenario and interpreting the modelled meteorology ad verbatim. One would need strong blocking over the Northeast/eastern Canada to steer 98L into the East Coast. No model has shown this scenario even once for 98L. The ridge is narrow and farther south than is needed for a strong major hurricane to hit the East Coast.

[Fancy1001]

Hmon looks to be ending on a very ominous note, and hwrf looks like it wants to pull an Irma.

Nevermind, it looks like it learned from Irmas mistake.

[WeatherEmperor]

Horray the Euro shows something!!




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[Keldeo1997]

HWRF much futher South but still strengthing despite being very close to Cuba

[SFLcane]

HWRF misses FL through the straights that will probably pull the TCVN away from the peninsula. If trends continue we won’t be in the cone for to long. Big problem for the GOM