2017 Global Model Runs Discussion (Out to day 16)

[toad strangler]

There is not much to go on with the GFS. Each run is predictably vastly different in what is fantasy range. None of these phantom systems have moved up in time so for now, that's what they are. Phantoms.

[SFLcane]

GFS not showing much last few runs more then likely another phantom tc from this model.

[otowntiger]

There is not much to go on with the GFS. Each run is predictably vastly different in what is fantasy range. None of these phantom systems have moved up in time so for now, that's what they are. Phantoms.

. So Euro also a no go?

[Alyono]

These are NOT phantoms. The differences in development have to do regarding the monsoon trough position.

[TheStormExpert]

12z Euro still shows slow and gradual development in 9-10 days over the Western Caribbean.

[toad strangler]

These are NOT phantoms. The differences in development have to do regarding the monsoon trough position.

Well at 290 plus hours a couple of those could certainly be phantoms Also, don't the models have some climo bias built into them at this range?

[Alyono]

These are NOT phantoms. The differences in development have to do regarding the monsoon trough position.

Well at 290 plus hours a couple of those could certainly be phantoms Also, don't the models have some climo bias built into them at this range?

these are full physics models that simply solve the Navier-Stokes equations numerically

No climo in the Navier-Stokes equations

[Hurricaneman]

The Euro should show development by tomorrow's model runs or Monday's runs imo

[LarryWx]

There hasn't been another GEFS run nearly so active as the last 2 18Zs. However, the 12Z EPS still has moderate support for a W. Car. genesis in early Oct with 20% of members having a sub 1000 mb.

[Frank2]

No doubt some of it is climotology - October development always active in the Western Caribbean.

I'm hoping for an early end - many seasons have ended after early October...

[LarryWx]

Strongest signal yet from GEFS:

I'm quoting this to show that there seems to be a weird pattern of high levels of W Caribbean in early Oct showing up only on the 18Z GEFS! This post was about the Thursday 18Z GEFS. I'm about to quote a post referring to a very similar Fri 18Z GEFS. And now the Saturday 18Z GEFS is AT LEAST the 3rd GEFS run in a row with a very strong western Caribbean genesis signal for early October with no GEFS runs in between showing anywhere near the same very strong signal!

[WeatherEmperor]

The 18z GFS Ensembles show deep low pressure around 240hrs and keeps it near the Yucatan channel through the supet long range. Slowly but surely the signal of some type of low pressure system organizing in the WC is increasing...


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[LarryWx]

[quote="WeatherEmperor"
The 18z GFS Ensembles show deep low pressure around 240hrs and keeps it near the Yucatan channel through the supet long range. Slowly but surely the signal of some type of low pressure system organizing in the WC is increasing...
[/quote]

It is amazing that you posted this essentially at the same time as I made my post just before yours. Read mine and you'll see that there may be a glitch with the 18Z GEFS programming.

[LarryWx]

The GEFS is a little too playful this run

I'm now quoting the post about the Friday 18Z GEFS being another 18Z GEFS run with a very active W Caribbean in early October. And as just posted by WeatherEmporer, this evening's 18Z GEFS is doing it all over again!! None of the other GEFS runs between these 18Z GEFS runs has had nearly the very strong genesis signal. I'm now getting very suspicious that there's something off about the 18Z GEFS programming.

[otowntiger]

The GEFS is a little too playful this run

I'm now quoting the post about the Friday 18Z GEFS being another 18Z GEFS run with a very active W Caribbean in early October. And as just posted by WeatherEmporer, this evening's 18Z GEFS is doing it all over again!! None of the other GEFS runs between these 18Z GEFS runs has had nearly the very strong genesis signal. I'm now getting very suspicious that there's something off about the 18Z GEFS programming.

Is that possible? Why would the programming be different for different times a model is run??

[RL3AO]

The GEFS is a little too playful this run

[img]https://i.imgur.com/bPe4EjL.png[/g]

I'm now quoting the post about the Friday 18Z GEFS being another 18Z GEFS run with a very active W Caribbean in early October. And as just posted by WeatherEmporer, this evening's 18Z GEFS is doing it all over again!! None of the other GEFS runs between these 18Z GEFS runs has had nearly the very strong genesis signal. I'm now getting very suspicious that there's something off about the 18Z GEFS programming.

Is that possible? Why would the programming be different for different times a model is run??

I've heard that there might be an actual bias in the 18z run relating to how the model is initializing during near-peak solar radiation in this part of the world. I can't remember the exact details or if it's been shown to occur in other parts of the world during other model runs.

Whatever is causing it, there has seemed to be a bias in over-forecasting TCs in the long range of the 18z GFS/GEFS. The programming doesn't change, but how the model initializes millions of data points each run is critical. If there is even a small bias in how the GFS starts the 18z run, it could grow into large errors over time.

[floridasun78]

:eek:

 https://twitter.com/nwscpc/status/911306527121854464

so no good or good could see area form after sep 27or you think wont happen?

[LarryWx]

I'm now quoting the post about the Friday 18Z GEFS being another 18Z GEFS run with a very active W Caribbean in early October. And as just posted by WeatherEmporer, this evening's 18Z GEFS is doing it all over again!! None of the other GEFS runs between these 18Z GEFS runs has had nearly the very strong genesis signal. I'm now getting very suspicious that there's something off about the 18Z GEFS programming.

Is that possible? Why would the programming be different for different times a model is run??

I've heard that there might be an actual bias in the 18z run relating to how the model is initializing during near-peak solar radiation in this part of the world. I can't remember the exact details or if it's been shown to occur in other parts of the world during other model runs.

Whatever is causing it, there has seemed to be a bias in over-forecasting TCs in the long range of the 18z GFS/GEFS. The programming doesn't change, but how the model initializes millions of data points each run is critical. If there is even a small bias in how the GFS starts the 18z run, it could grow into large errors over time.

OMG that is fascinating to know! My bad in thinking the 18Z programming might have been the culprit as opposed to the 18Z initialization being near peak insolation in the western
basin.

I just went back to Tropical Tidbits and see that they still have GEFS runs going back to 18Z of 9/16. If one first chooses the 384 hour map for the 9/16 GEFS run (which is the map for 18Z of 10/2) and then repeatedly clicked on "next run", one can clearly see a strong tendency for the 18Z GEFS mean having lower pressures in/near the W Caribbean as of 18Z on 10/2 pretty much every run as compared to the nearby 0Z, 6Z, and 12Z runs! I'll never think of the 18Z GFS suite the same way again when it is on its own with a strong TC genesis signal in the western basin...well until if/when this apparent bias due to peak insolation is fixed.

[LarryWx]

Taking the above further, would the 6Z tend to underdo TC genesis chances due to
it being in the middle of the night/zero solar insolation? Also, would the 12Z runs tend to show less activity than the 0Z runs due to it being a cooler time of day than 0Z in the western basin even though solar insolation is similar? Finally, do other models show these same biases?

[otowntiger]

I'm now quoting the post about the Friday 18Z GEFS being another 18Z GEFS run with a very active W Caribbean in early October. And as just posted by WeatherEmporer, this evening's 18Z GEFS is doing it all over again!! None of the other GEFS runs between these 18Z GEFS runs has had nearly the very strong genesis signal. I'm now getting very suspicious that there's something off about the 18Z GEFS programming.

Is that possible? Why would the programming be different for different times a model is run??

I've heard that there might be an actual bias in the 18z run relating to how the model is initializing during near-peak solar radiation in this part of the world. I can't remember the exact details or if it's been shown to occur in other parts of the world during other model runs.

Whatever is causing it, there has seemed to be a bias in over-forecasting TCs in the long range of the 18z GFS/GEFS. The programming doesn't change, but how the model initializes millions of data points each run is critical. If there is even a small bias in how the GFS starts the 18z run, it could grow into large errors over time.

Sounds like a real problem then.