Not seen this discussed.........

[Dean4Storms]

We've had two Tropical Cyclones form that were mostly not depicted even a couple days out beforehand by most global models, the exception being the CMC and NAM with Alberto. Whats up with the global models and their failings thus far with initiating cyclogenesis? Could this continue into the meat of the season?

[SouthFloridawx]

http://www.storm2k.org/phpbb2/viewtopic ... 77&start=0



Although I changed the title of the thread to the Low pressure near Nova Scotia it was primarily made to note that gfs was developing a warm core system off the coast of north carolina on the 18th.

[caneman]

We've had two Tropical Cyclones form that were mostly not depicted even a couple days out beforehand by most global models, the exception being the CMC and NAM with Alberto. Whats up with the global models and their failings thus far with initiating cyclogenesis? Could this continue into the meat of the season?

Glad you brought this up. I agree. And with the Globals not picking up much right now on anything else (which I highly doubt). I think I'll choose to just satellite watch.

[SouthFloridawx]

We've had two Tropical Cyclones form that were mostly not depicted even a couple days out beforehand by most global models, the exception being the CMC and NAM with Alberto. Whats up with the global models and their failings thus far with initiating cyclogenesis? Could this continue into the meat of the season?

Glad you brought this up. I agree. And with the Globals not picking up much right now on anything else (which I highly doubt). I think I'll choose to just satellite watch.

But GFS did pick this up ..

The number 18 where it has low pressure forming is a date.

[Thunder44]

yeah, in the medium range it did, but not in the short range

[SouthFloridawx]

yeah, in the medium range it did, but not in the short range

So you don't think that GFS picked up on this? What is the different whether it picked up on it 3 days ago or 24 hours ago. The point is that it verified.

[Dean4Storms]

yeah, in the medium range it did, but not in the short range

So you don't think that GFS picked up on this? What is the different whether it picked up on it 3 days ago or 24 hours ago. The point is that it verified.

Still SFwx, you need consistancy with verification with the models to be able to rely on them. If you have any given model developing a warm core low one day and not the next it does not make for a very trusted model for a weather forecaster, if anything it adds confusion.

[SouthFloridawx]

[caneman]

yeah, in the medium range it did, but not in the short range

So you don't think that GFS picked up on this? What is the different whether it picked up on it 3 days ago or 24 hours ago. The point is that it verified.

Still SFwx, you need consistancy with verification with the models to be able to rely on them. If you have any given model developing a warm core low one day and not the next it does not make for a very trusted model for a weather forecaster, if anything it adds confusion.

So true.......... They've been very confusing so far. No consistancy.

[SouthFloridawx]

They need something to be able to be consistent with. Give me a model that does well with a weak frontal boundary forming an area of low pressure at the southern end. Besides.. the GFS did forecast a warm core low in about the same position it is 3 days ago. There is no problem with the Forecast models just the people viewing them and forming conclusions about them. Just because GFS didn't pick up on Alberto doesn't mean there is anything wrong with it. Trust me when the time is here all the models will pick up on a system and they will be pretty much right about it and they will verify.

[caneman]

They need something to be able to be consistent with. Give me a model that does well with a weak frontal boundary forming an area of low pressure at the southern end. Besides.. the GFS did forecast a warm core low in about the same position it is 3 days ago. There is no problem with the Forecast models just the people viewing them and forming conclusions about them. Just because GFS didn't pick up on Alberto doesn't mean there is anything wrong with it. Trust me when the time is here all the models will pick up on a system and they will be pretty much right about it and they will verify.

Fact is they where not consistant with either. And further, one run a model would develop something then next one not, then next one or two would. I saw this happen a couple times with supposed BOC systems. In so far, they've not been reliable. I'm sure they will come around but for now I'm not model huggin, I'll stick to sat, wind shear, buoys, etc..

[boca]

Wasn't the bamm that picked up on Beryl.

[Wthrman13]

Wasn't the bamm that picked up on Beryl.

The BAMM is not a dynamical model, so it can't pick up on anything. The NHC runs it when it sees a system that is a possible development threat. It's a simple model that makes use of the large scale steering flow from the GFS model at different levels to forecast the movement of an abstract tropical cyclone vortex based on certain theoretical considerations.

Theoretically, if the dynamical models always had a consistent representation of a TC vortex on their own grids, they would be able to vastly outperform such simple models as the BAM family, but the fact is they often don't, so the NHC still gets some use out of the simpler models.

Regarding the discussion on why the models have not picked up on systems, I'll be the first to say that the dynamical models have many, many flaws. As I have stated numerous times on this board, it's a wonder our dynamical models do as well as they do, considering all the hurdles that need to be overcome. A severe lack of observations to initialize the model, pathetically inadequate representations of convection, cloud physics, turbulence, and other important atmospheric processes, and relatively coarse resolution of the global models in particular, are all contributors to this situation.

The problem is more with unreasonable expectations of flat-out miracles by many model end-users (not that that applies to anyone in this thread), than it is with the models themselves. Given the state of the science, we just don't have the capability of doing any better now, but things are continually improving, and the future looks bright. If we lost our dynamical models tomorrow, it would be akin to a person losing their eyesight. That's how important they are to our modern forecasting ability on many different space and timescales, and I'm not exaggerating.

I hope this helps put some things in perspective. One should definitely not "model-hug". A good meteorologist, amateur or professional, will always use a blend of current observational data and model guidance, and know when and where to emphasize one or the other, or neither. Just as you can't forecast with any semblance of accuracy where an upper level trough will be or how strong it will be in 5 days just by watching water vapor loops, so also is it misguided to be hugging a model solution of a low temperature of 35 degrees, when the temperature outside is already 32 and falling.

[clfenwi]

Regarding the discussion on why the models have not picked up on systems, I'll be the first to say that the dynamical models have many, many flaws. As I have stated numerous times on this board, it's a wonder our dynamical models do as well as they do, considering all the hurdles that need to be overcome. A severe lack of observations to initialize the model, pathetically inadequate representations of convection, cloud physics, turbulence, and other important atmospheric processes, and relatively coarse resolution of the global models in particular, are all contributors to this situation.

An important point, one that I didn't truly appreciate until working through the NWP distance learning course.

As for the question at the beginning of this thread... it's worth noting that the bulk of the globals were on top of the genesis of Bud and Carlotta in the EPAC, and the GFS was on top of the genesis of Daniel as well...those situations are more akin to what the meat of the season is in the Atlantic than what we've actually had in the Atlantic so far... because of that I don't foresee any "failures" during the August-October timeframe.

[Air Force Met]

They need something to be able to be consistent with. Give me a model that does well with a weak frontal boundary forming an area of low pressure at the southern end. Besides.. the GFS did forecast a warm core low in about the same position it is 3 days ago. There is no problem with the Forecast models just the people viewing them and forming conclusions about them. Just because GFS didn't pick up on Alberto doesn't mean there is anything wrong with it. Trust me when the time is here all the models will pick up on a system and they will be pretty much right about it and they will verify.

Sorry SFLWX...but you have to have consistancy in order to trust them. Otherwise you don't know if it is a case of a blind squirrel finding an acorn or what. If it doesn't pick up on a system and keep it...it is...in the grand scheme of things...overall worthless because you don't know when you should pay attention and when you should ignore it.

One of the very FIRST things they taught us in forecasters school was model consistancy. Trust in a particular model on a particular issue goes down as inconsitancy goes up. It is indirectly proportional...and I thnk that is the point being made...not that it was right in this case...but that it could be wrong in the next 9 cases.