Question: Which Forecasting Models Did the Best in 2004?

[gatorcane]

Ivan stood out the most last year as far as forecasting models. The models did well when it formed (at very low lattitudes) off of Africa. They generally agreed it would move west into the eastern Caribbean and strengthen rapidly. But then, the NHC's cone basically ended up spanning the entire Caribbean from Puerto Rico to the north central Gulf coast by the time everything was all done. I remember they had it going over Hispanolia early on, then off the East coast of FL, then the FL Keys, then the West coast of FL, and finally it hit the northern Gulf coast....

Why were some of the models having such a hard time taking the Bermuda High strength into account?

[StormChasr]

Why were some of the models having such a hard time taking the Bermuda High strength into account?

Because that was NOT what caused the storms to track the way they did.

[gatorcane]

so I'm curious, what do you think caused them to track so far west instead of their usual curvature into the northern atlantic?

[mobilebay]

so I'm curious, what do you think caused them to track so far west instead of their usual curvature into the northern atlantic?

because the models where initializing the BERMUDA High a lot weaker than it actually was. Also, some bad dropsonde data was used from several of the NOAA missions.

[mobilebay]

Ivan stood out the most last year as far as forecasting models. The models did well when it formed (at very low lattitudes) off of Africa. They generally agreed it would move west into the eastern Caribbean and strengthen rapidly. But then, the NHC's cone basically ended up spanning the entire Caribbean from Puerto Rico to the north central Gulf coast by the time everything was all done. I remember they had it going over Hispanolia early on, then off the East coast of FL, then the FL Keys, then the West coast of FL, and finally it hit the northern Gulf coast....

Why were some of the models having such a hard time taking the Bermuda High strength into account?

One of two reasons.
1. Bad data was used.
2. Not enough data available.
Remember, all areas of the Atlantic basin are not data rich like our area.

[MWatkins]

I'm not sure what all of this model bashing is about...I suppose it comes down to what you expect from the models. If you want a perfect model that is going to predict every storm 100% accurately...well...the atmosphere is WAY too dynamic. It's not going to happen. And NOGAPS? It had Frances recurving in front of 50W...then 60W...then 70W then going into the Gulf on subsequent runs.

If the GFS was bad, every other model was far worse. The verification statistics don't lie.

The models are just another tool...they aren't perfect and they are all useful as guidance. It's funny we all remember the handfull of really bad runs (especially when storms are starting to develop) but forget about the 17 ot 18 straight runs that nailed Ivan's track from the western Caribbean on.

he GFS and any other models are only as good as the observations going into them. For example...with Ivan...once the models had a hold of Ivan in a relatively data-rich environment they performed quite well. The dropwindsondes...as we know...caused many of the problems we saw with the models jumping hurricanes into ridges etc when we had less data to resolve north of the storms. If someone can figure a way to collect more and better data...perhaps the forecast models will provide something closer to what you may expect. But for now...the models are just another tool...but as long as you understand the limitations they can be useful tools.

MW

Mike. I don't intend any disrespect here but the following is a direct quote from you when Ivan was in the Caribbean. "Is the GFS on crack". also, "note to GFS- Ivan is not a NOREASTER". You was in there with the bashing yourself. People on this board remember what you type. You are one of the very best Forecasters on this board but please do not accuse others of things you've done. Thanks.

Fair enough. Please consider the context....

At the time...I had no idea the dropwindsondes were corrupting the model...but retrospectivelly...they did more harm than good in the face of conventional wisdom.

We know far more now than we did then. Actually...I was wrong to blast the model for a single run or even a small series of runs. The point was that something was wrong...and we know now what it is. We should hammer away when something is clearly wrong (see Charley dropsonde). But hammering the model that performed the best right after a significant resolution upgrade...I think is not the way to go.

All I am saying is that the GFS model...once Ivan hit the western Caribbean...did really well.

MW

[mobilebay]

I agree 100% that it did very well once it was in the Northwest Caribbean Sea. In fact, most of the others (models) was steadily going further west and the GFS stayed at home.

[MWatkins]

I agree 100% that it did very well once it was in the Northwest Caribbean Sea. In fact, most of the others (models) was steadily going further west and the GFS stayed at home.

Cool...not trying to be a hypocrite...if something looks wrong I'll be the first to hollar...but the categorical dismissal of the GFS model is what drew out that reply you referenced. Dismissing a paticular set of runs is OK...categorical blasting of the model...I'm against.

Plus...I've learned a little bit since last season

MW

[mobilebay]

Sorry I called you out like that. I respect your opinion more than alot of the NWS opinions. I have been following your forecasts since GOPBI, and you will forget more than I will ever know about the tropics.

[Wthrman13]

However, the GUNA performed almost as well and all the components of it are avaliable to the public (and Stomtrakker can calculate it automatically for you.)

One thing that PDF has ALMOST totally cleared up for me is the nature of the GUNA; I always asssumed it was as straight average, but I chatted with a met student who said a prof of his insisted GUNA was a complex weighted average which would mean the GUNA that Stormtrakker caculates wasn't the "real" GUNA; but from the way GUNA is listed in the PDF and talked about it seems it is in fact a plain average.

The GUNA is, in fact, a straight average of the lats and lons of its component members. The professor is misinformed, or someone confused GUNA with the FSU superensemble.

I think that that was me (not the professor, but the student). Thanks for clearing this up for me as well. I can't remember which professor told me this, but it is possible he was confusing it with the FSU superensemble. It's been a while, and I can't remember for sure.[/quote]