ATL: INVEST 99L - Models

[BobHarlem]

Looking at the icon/euro ensembles it seems if the system "overachieves" and develops, it's more likely to head up into the Gulf and maybe keep going or bend back to Florida as a labor day surprise. (icon/Euro Ensembles) If the graveyard does its thing it'll creep more westerly (GFS/GEFS). Gotta watch this one close, glad recon is heading in tomorrow.

[skillz305]

18Z ICON currently in progress

[TomballEd]

Unless I am mistaken, SHIPS is not a track forecast model. 'The forecast is based on the TAB model, which is input with wind fields from the GFS.

SHIPS uses statistical methods to estimate intensity of a system based on where the TAB model using GFS forecasts says the storm will be. SHIPS doesn't forecast track. The TAB which simply calculates mean steering entirely based on GFS forecasts does.

The Trajectory and Beta model (TAB), another trajectory track model,
applies a gridpoint spatial filter to smooth winds from the National Centers for Environmental Prediction (NCEP) Global
Forecast System (GFS) model. TAB model errors were 10%–15% lower than those of the Beta and Advection model (BAM),
the model it replaced in 2017. Optimizing TAB’s vertical weights shows that the lower troposphere’s environmental flow
provides a better match to observed tropical cyclone motion than does the upper troposphere’s, and that the optimal steering layer is shallower for higher-latitude and weaker tropical cyclones.

[Pelicane]

18Z ICON currently in progress

Weaker and South

[Stratton23]

yep, but it still ends up near the NW yucatan, it still probably develops this if it went out beyone 120 hours, regardless the ICON has fluctuated greatly from run to run in terms of intensity

[Pelicane]

18z GFS strings it out in the Carribean. Something I've noticed over these past few runs is that the upper-level vorticity at the 700 and 500 mb levels seems to get sucked north while the 850 mb races west with the trades. At 12z, that upper-level vorticity even formed a storm on the GFS. That would indicate that'd unless it's vertically stacked and deep, the storm will get sliced in half at its upper levels, which is not uncommon for waves like this in the Eastern Carribean. Can't discount development down the line though. 6z did get something going in the BOC and 12z tried to before it got buried in CA. Plenty of moisture and the waters are warm.

[AJC3]

Gang,

We're all for occasional strolls down 'Model Performance During <Storm X> Memory Lane', but please let's not let these sidebar discussions take over whole pages of threads (e.g. model performance for Erin and Oscar). Those posts have their place, but in the future, try not to get into at length discussions. And yes, those posts have been cleaned out.

Thanks,
The Admin team

[LAF92]

18z GEFS a tad more aggressive

[Hypercane_Kyle]

Pretty clear trend that the models are underestimating the short-term organization of this system. My guess is this one may develop in the Western Caribbean.

[Kingarabian]

Check the past initializations in the runs of the Euro and GFS. Really underestimating the organization of this system.

[Travorum]

00z SHIPS initializes at the 35kts that ATCF best track has it at right now and keeps increasing the intensity from there, it doesn't really show any degradation in the ECAR despite the strong trades and shear. It continues the trend of developing into a hurricane in the WCAR:

[LAF92]

[imgur] [/imgur]
18z EPS still aggressive

[floridasun]

let see models show next few days remember eastern Caribbean can destroy systems let see if can make it past eastern Caribbean into western Caribbean

[BobHarlem]

The 0z Icon has backed off on development of 99L in the west Caribbean, shifted left from 12z, and gets it into the Yucatan peninsula pretty weak, last frame is just off the north coast.

[Weathertracker96]

The 0z Icon has backed off on development of 99L in the west Caribbean, shifted left from 12z, and gets it into the Yucatan peninsula pretty weak, last frame is just off the north coast.

It’s off the coast at 1006Mb. Could be TD or weak TS. Depending on conditions in gulf, this could develop more if it makes it there.

[Stratton23]

ICON didnt back off from development, in fact this run compared to 18z has more organized but weak low around the yucatan penninsula, 18z was just an open wave

[Stratton23]

ICON intensity wise backed off compared to 12z run but shows a more developed system compared to the 18z run, weak TD around the yucatan penninsula, 18z was just an open wave

[Woofde]

ICON didnt back off from development, in fact this run compared to 18z has more organized but weak low around the yucatan penninsula, 18z was just an open wave

Certainly has enough organization to be dangerous in the Gulf if this run continued.

[Woofde]

The ICON is still trending South over the past few runs though, not much wiggle room till it buries into CA. It probably depends on how it evolves in the short term (next day or 2). It will be interesting to see how it looks in the morning.

[Jr0d]

I haven't been watching this closely but it does seem like the Ensembles(EURO, GFS, and Canadian) are showing a much stronger signal when this makes it to the NW Caribbean and the GoM versus earlier this week.

I will be monitoring this trend closer now. Regardless it seems to be outperforming the models except the ICON.