Are the 6z/18z model runs less accurate than the 0z/12z?

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Are the 6z/18z model runs less accurate than the 0z/12z?

#1 Postby South Texas Storms » Wed Jul 20, 2011 11:30 pm

Is there any truth to this rumor? Is it true that the 6z and 18z model runs have much less data put into them (soundings, etc.) than the 0z and 12z model runs?
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#2 Postby South Texas Storms » Tue Oct 11, 2011 12:31 pm

Can anyone answer this?
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#3 Postby cycloneye » Tue Oct 11, 2011 12:35 pm

The 12z and 00z runs have much more data than the 18z and 06z runs as one of the factors is the ballons that go up to look how are the soundings for the 12z and 00z runs.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#4 Postby South Texas Storms » Wed Oct 12, 2011 2:31 pm

Thanks cycloneye, that is what I was thinking.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#5 Postby Laplacian » Thu Jun 14, 2012 5:24 am

Hello everyone,

I just joined the forum as my retirement looms in July. A few of my ex-students told me about Storm2K and I decided to give it a try. Please forgive my irrepressible urge to teach, but I saw this thread from 2011 and couldn't resist.

The answer given here is incorrect (I'm hoping that its not representative of the discussion here). The 06Z and 18Z model runs are just as accurate as the 00Z and 12Z runs.

The sondes are a small part of the obs for model initial conditions these days. There are also satellite data and ACARS aircraft data among other data going into the model (VAD winds, NOAA profilers, buoys, ships, GOES cloud winds, GOES cloud-top pressures, GPS precipitable water, radar reflectivity and lightning, the list goes on and on). The model background also carries information from previous obs.

The 06z and 18z runs are just as accurate as 12z and 00z. Sondes are still important, but not like the old days when I was a young meteorologist.

I hope you folks don't mind me chiming in. The truth always matters.

Looking forward to great discussions in my retirement,

Laplacian
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#6 Postby Laplacian » Thu Jun 14, 2012 7:53 am

P.S. I should add that a large fraction of the models' initialization is a forecast from the previous run.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#7 Postby wxman57 » Thu Jun 14, 2012 7:56 am

Welcome to the forum, Laplacian.

You are correct in that it's not a question of accuracy of the 6Z/18Z runs. While balloon data is important, it's not thrown out for the 6Z/18Z runs. And there are some additional data that go into the 6Z and 18Z runs.

Are you retiring from teaching meteorology? What school?
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#8 Postby Laplacian » Thu Jun 14, 2012 10:26 am

Many thanks for your warm welcome.

Yes. 31 years of teaching meteorology.

I understand why you're asking about additional data for the 06Z and 18Z model runs. Keep in mind that there are other sources for upper-air data, and that, although sondes are nice to have, we are not totally dependent on them. Indeed, models can incorporate data from literally thousands of aircraft observations each hour. And that's only one available source of upper-air data.

For folks who live for a single aircraft reconnaissance into a tropical cyclone, I would think that thousands of aircraft observations each hour, aided by satellite-inferred winds, VAD winds, NOAA profilers, etc., would be enough to convince them that 06Z and 18Z model runs are just as accurate as the 00Z and 12Z runs. Also keep in mind that our data assimilation methods carry forward observations from the 00Z and 12Z sondes and all other data, even after the sonde times.

The bottom line for the folks who believe that the model runs at 06Z and 18Z are not as accurate as the 00Z and 12Z run is pretty compelling: If the runs initialized at times different than the sonde times (at 06Z and 18Z, or hourly in the case of Rapid Refresh or other such models) were really not as accurate, do they really think that NCEP would be spending so much computer time on them (as opposed to making the model resolutions higher for the two sonde-time runs)?

Thanks again for the welcome. I look forward to the tropical discussions!
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#9 Postby Laplacian » Thu Jun 14, 2012 3:18 pm

P.S.

A fellow Storm2K member and an ex-student of mine pointed out to me that I didn't answer your question about where I taught. Sorry. I was a senior lecturer at Penn State, teaching for 26 years and two years prior as a PhD student.

For the last 12 years, I've been the lead faculty for our online program:

http://www.worldcampus.psu.edu/degrees- ... e/overview

Again, thanks for the warm welcome.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#10 Postby ozonepete » Thu Jun 14, 2012 7:28 pm

Welcome! You will love the discussions on active tropical systems and can probably contribute a lot of sound science there. Looking forward to your participation.
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#11 Postby Cyclenall » Fri Jun 15, 2012 4:18 am

Welcome Laplacian! Are you a meteorologist with a PhD? You mentioned two years prior as a PhD student teaching so I guess so? Feel free to answer any of these questions no matter how old or new (I have some unanswered! :) ) and I look forward to your insight.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#12 Postby Laplacian » Fri Jun 15, 2012 5:39 am

I got sidetracked from my PhD by teaching, the New York Times daily weather page and on-air forecasting stints. So my experience is more operational and synoptic meteorology. But I find tropical and mesoscale meteorology very stimulating, which is why I joined Storm2K.
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Re: Are the 6z/18z model runs less accurate than the 0z/12z?

#13 Postby South Texas Storms » Tue Sep 24, 2013 12:43 am

Thanks for answering my question!
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