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About dtk

  • Birthday August 30

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    Alexandria, VA

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  1. To this and the other question regarding next steps for HiRes guidance... 1) NAM (including nests) are frozen. They will be replaced in the coming years. 2) SREF is also frozen (and now coarse resolution). Effort is being re-oriented toward true high resolution ensembles. 3) HRRR will include ensembles in the DA in 2020, but we cannot afford a true HRRR-ensemble. The HREF fills some of this void in the interim. 4) All of the above are going to be part of some sort of FV3-based, (truly) high resolution convection allowing ensemble. We are still several years away as there is still science to explore for defining the configuration. There's also serious lack of HPC for a large-domain, convection allowing ensemble.
  2. I'm gone from the threads for a really long time....only to come back and see references to "sampling" and "suffering from convective feedback". The more things change, the more they stay the same...
  3. Yes, the cool/low height bias with increasing forecast time is already well known and documented. In fact, I am pretty sure there is already a fix for this particular issue, though it is too late to include in the Jan. 2019 implementation.
  4. It's all part of our plan to get people to pay attention. In reality, it is going to be dead wrong. This is a pretty solid implementation, considering that we haven't had a chance to put a ton of new science into the package (outside of the model dynamics and MP scheme, a few DA enhancements, etc.). For things like extratropical 500 hpa AC, it has gained us about a point (about what we'd expect/want from a biannual upgrade). Improvements are statistically significant. I should caution, our model evaluation group has noted that there are times where the FV3-based GFS appears to be too progressive at longer ranges. It's not clear how general this is and for what types of cases this has been noted.
  5. FV3-based GEFS will not be implemented until early FY 2020 (probably Q2...e.g. about Jan 2020). Some of this is driven by human and compute resources as there is a requirement for a 30 year reforecast for calibration before implementation. Definitely 2017. All official retrospectives and real-time experiment use the Lin-type GFDL MP scheme.
  6. Sref as we know it is in the process of being phased out with something radically different. It's going to take a couple of years, but folks are working in the direction of a convection allowing ensemble (think hrrr, nam3k, ncar ensemble).
  7. Great post. I'm pretty sure the global models have set monthly records for day 5/6 skill in the NH yet again over the past couple of months.
  8. I can't wait until we start running a global rapid update cycle. So many off hours to go wacky!
  9. OK, I'll recommend that NCEP just has someone run the old single-layer barotropic model on their phone and we can get rid of our supercomputers.
  10. No apology necessary and there was no disrespect.
  11. Fair enough and I appreciate the response. One of the things I have observed over the years is just how much expectations have grown, which is a testament to our successes. Wes is right in pointing out just how good the models really are and how much we continue to improve. I am really fascinated by the conversation about the Euro being bouncy and inconsistent, as I/we dealt with hearing that about the GFS for so long. I am a little worried that our new model (the FV3-based core) will have more of this characteristic given that it is a gridpoint model and we'll be using the non-hydrostatic version.
  12. We continue to gain about about one day of lead time per decade of research and development. We are getting pretty close to having some breakthroughs in data assimilation to better handle nonlinearity and non-Gaussianity. While AI (maching learning, neural nets) has gained some footing in model post-processing, I think this is going to be an area of active development within the models themselves. More/better computing will continue to be a driving force, as we can get higher and higher resolution, more complex physics, coupled components, etc. The problem is, there are fundamental predictability limits that we are going to run up against.
  13. Yeah, I'm not disputing people's perception of model behavior. In fact, I'm fascinated by some of what has been observed and want to understand it better. There is some follow up to this in the banter. Now, back to our sNOw....
  14. Yeah, it's a huge problem with the GEFS and we get complaints from the regions all the time. There is lots of work ongoing to address this in the next GEFS upgrade (v12). Interesting that it's being observed in the EPS for certain events.
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