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Tropical Cyclone Forecast from Global Models Discussion


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This is crap. I have worked for NOAA/NWS since the late '80s, and we have never been "encouraged" to use ANY one model, and I have never heard of such a thing.

And I also want to agree with MS Weather about the model depicition of Ernesto. In spite of comments to the contrary at the time, the models did not dissipate that system. In fact, the ECMWF correctly showed better organization and intensification of the low level vorticity center as it approached the Yucatan. Did it forecast a 975 mb hurricane? Of course not. Did it get the trend right? Yes. And it did much better on the trend than the LGEM/SHIPS which consistently showed intensification way too early.

Perhaps it was different in different regions. I can't name names, all I can tell you is that I am NOT making this up, and heard from a few reputable people "in the know" that until at least 1994-95 or so, in this region, NWS was discouraged from looking at anything other than the AVN/MRF, ETA, and NGM.

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Perhaps it was different in different regions. I can't name names, all I can tell you is that I am NOT making this up, and heard from a few reputable people "in the know" that until at least 1994-95 or so, in this region, NWS was discouraged from looking at anything other than the AVN/MRF, ETA, and NGM.

My vague understanding is that it wasn't a problem of looking at things, what was discouraged was specifically citing the ECMWF in AFDs.

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Perhaps it was different in different regions. I can't name names, all I can tell you is that I am NOT making this up, and heard from a few reputable people "in the know" that until at least 1994-95 or so, in this region, NWS was discouraged from looking at anything other than the AVN/MRF, ETA, and NGM.

I don't want to belabor this issue, but the fact of the matter is up until around 1995 the only product we had to look at from the ECMWF or UKMET was the 120 hour 500 mb heights and MSLP - and I mean the 120 hour ONLY, not out to 120 hours. For all intents and purposes there wasn't anything to look at but the AVN, ETA and NGM (and LFM). So it wasn't a matter of discouraging the ECMWF - it was a matter of the American models were essentially the only game in town in an NWS office 20 years ago.

NMC had access to more of the ECMWF, but at that time from what I understand there were a lot more restrictions (from the EC themselves because of commercial interests, not from the NWS) as far as what could be directly disseminated or discussed by NMC - but they certainly used it extensively.

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Serious question about the lower resolution of the global ensembles, and whether it would manifest itself in stronger or weaker storms. The ensembles run on reduced resolution, so initially I might think if four ensemble members are showing 1000 mb or below storms offshore SETX in a week, with two showing sub 996, than maybe four perturbations are suggesting probable hurricanes.

But then I got to thinking, a discussion I had once with a red tagger about an entire grouping of the SREFs showing what I thought were supercells, and which he described as grid scale convective feedback, along with a link about recognizing QPF bombs on low res models.

So, what is the greater likelihood of happening (I suspect it could go either way), a reduced resolution global ensemble member under-estimating storm strength because TCs tend to be fairly compact, or a reduced resolution ensemble over-doing intensity due to grid scale convective feedback.

I do know, simply because of the nature of ensemble means, they will tend to show weaker systems because of the smoothing between ensemble members with different storm locations.

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Good post, Phil.

As I always say, I'm no forecaster-- not even on the hobbyist level-- but the Euro and the GFS have very little credibility this year, as far as I'm concerned. They both bombed with Ernie-- simple as that. The GFS did score that semi-win with Debby, but the Euro bombed on that one, tool

So I'm not exactly gonna write this one off because these two models do. Not after Ernie.

:huh:

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My vague understanding is that it wasn't a problem of looking at things, what was discouraged was specifically citing the ECMWF in AFDs.

I worked at HPC and I don't remember ever being told not to look at the other models though I tended not to put much credence in the canadian as back then it wasn't as good as the GFS. I did give credence to the euro but way back when we didn't get model guidance of the qpf. Once we started getting it in gridded form we started using it.

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