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February 8-12 model discussion


Rankin5150

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Oh OK for some reason I thought it used the GFS.

The DGEX is a downscaled GFS with NAM extension. It is run at the NAM resolution using GFS boundary conditions from the previous run. So this 18z run was using the 12z GFS boundary layer conditions. It is considered a hybrid model in that it takes the NAM at 84 hrs and runs it using GFS physics, at-least how I understand it. If one had to pick though between the NAM or DGEX at 84 hrs, the DGEX is preferred. Like all other models, it is a tool, and you have to look at available guidance and determine whether it fits within the possible envelope. This run does and save a couple mb, it looks very similar to the 12z Euro ens mean with respect to position off the SE coast at 156 hrs.

18z DGEX

eta.pptslp156.gif

12z Euro ens mean

12zecmwfenstropical500mbSLP168.gif

Granted, the model is known for producing epic SN maps this time of year that almost never verify, however, I do remember several runs leading up to the Christmas event that actually verified pretty well considering it was in the 5-7 day range.

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The DGEX is a downscaled GFS with NAM extension. It is run at the NAM resolution using GFS boundary conditions from the previous run. So this 18z run was using the 12z GFS boundary layer conditions. It is considered a hybrid model in that it takes the NAM at 84 hrs and runs it using GFS physics, at-least how I understand it. If one had to pick though between the NAM or DGEX at 84 hrs, the DGEX is preferred. Like all other models, it is a tool, and you have to look at available guidance and determine whether it fits within the possible envelope. This run does and save a couple mb, it looks very similar to the 12z Euro ens mean with respect to position off the SE coast at 156 hrs.

18z DGEX

Granted, the model is known for producing epic SN maps this time of year that almost never verify, however, I do remember several runs leading up to the Christmas event that actually verified pretty well considering it was in the 5-7 day range.

Cool thanks for the info! We need for the DGEX to win one time.

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While the HPC did mention in their afternoon discussion that the trend NW may continue to match a La Nina track, they are currently sticking with a gulf coast solution which matches the global ensembles and, by a snowball's chance, the DGEX. :snowman:

http://www.hpc.ncep....bgfnl_conus.gif

Good enough for me, thanks for posting....I almost always forget to look at hpc graphics.

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Cool thanks for the info! We need for the DGEX to win one time.

This is from DGEX snowfall map from Dec 18th, while not perfect it is not all that far off what happened Dec 25-26th. In fact its actually pretty good given it was 7 days out from the event. That said 90% of the time the snowfall maps are great porn but thats about it as a forecasting tool lol.

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Here is why DGEX is a terrible model. Take the 84 hour 'off hour runs' of the nam; which has issues at that time range. Then input that into the GFS physic system and run that data out to 192. Treat it as just one more member of the 18z/6z ensemble packages imo.

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This is from DGEX snowfall map from Dec 18th, while not perfect it is not all that far off what happened Dec 25-26th. In fact its actually pretty good given it was 7 days out from the event. That said 90% of the time the snowfall maps are great porn but thats about it as a forecasting tool lol.

It was spot-on for my area. However, we did see the axis of heavier snow move NW from that map.

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Maybe the Christmas storm was that blind squirrel but to be fair it has missed almost every storm this year (I'm talking about these crazy snow maps). Believe me I would love to have the 15 or so inches it's showing for me but I have a hard time believing the dgex is remotely close w/ that snow map. I will agree however w/ WeatherNC that it could possibly be right w/ the track of the storm since it is close to the 12z euro ensemble mean track.

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This is from DGEX snowfall map from Dec 18th, while not perfect it is not all that far off what happened Dec 25-26th. In fact its actually pretty good given it was 7 days out from the event. That said 90% of the time the snowfall maps are great porn but thats about it as a forecasting tool lol.

Ahh...DGEX porn...crayola style bay-B!! :snowman::lightning:

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This run is much, much colder than the 18z run.

Well it's running up I-95, so it will hit I-77 and points west pretty good. I-85 and points east might get some wraparound, but that never works out. Between 77 and 85 would be iffy. But, one thing I take from this run is how much it changed from 12z at 5H, athough it didn't help us. We need that big axx Canadian vortex to sag further south and then we would be sitting pretty, I would assume.

Also, just to clarify, the foothills, mountains and TN should love this run so they won't want anything to change. If this shifted S/E then RDU and points east would love and then the mountains/foothills/TN might not be so happy. So don't let us RDU folks rain on your parade, I just hope this doesn't turn in to be a OH runner.

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Already some big changes this run compared to 12z... @ 96 hrs, it is much deeper with the trough coming through the Carolinas and vortmax, looks nothing like 12z in that regard. At 138, and just basing this on the H5 setup compared to 12z, it should be east of that run with respect to our low track, since the trough is more positively tilted, and looks slower in making the turn towards neutral. Will see, but this should be a better run than 12z.

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Already some big changes this run compared to 12z... @ 96 hrs, it is much deeper with the trough coming through the Carolinas and vortmax, looks nothing like 12z in that regard. At 138, and just basing this on the H5 setup compared to 12z, it should be east of that run with respect to our low track, since the trough is more positively tilted, and looks slower in making the turn towards neutral. Will see, but this should be a better run than 12z.

It's pretty night and day just considering what it showed at 18z.

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Already some big changes this run compared to 12z... @ 96 hrs, it is much deeper with the trough coming through the Carolinas and vortmax, looks nothing like 12z in that regard. At 138, and just basing this on the H5 setup compared to 12z, it should be east of that run with respect to our low track, since the trough is more positively tilted, and looks slower in making the turn towards neutral. Will see, but this should be a better run than 12z.

What do us folks in central/eastern NC want to happen? Do we simply just want the Canadian vortex to sag further south and be further east?

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