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Southeast February Mid/Long Range Discussion II


Marion_NC_WX

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Gotcha. Makes sense. As a general rule, I try to avoid looking at surface temps on any model outside of a couple/few days. I focus more on the H500 look and see where the players are first and then look at H850 temps. If the H5 looks good, I worry about the surface temps later.

Im looking at the accumulation maps on the euro though.... Wants to paint accums in middle Tennessee, but it's spotty bc it's elevation dependent. That leads me to believe we're getting a snow sounding but the surface is too warm for the model to paint accumulations. Which could mean the warm bias at the surface could be affecting that. I wish I could see the soundings or the skew t

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Nogaps is a fairly good model. I remember a discussion about it having similarities to the euro, but can't recall exactly what I heard. It was from a met though, maybe DT.

It's certainly gotten better. DT did mention that they changed something in the software recently that caused it to be so inferior.

However - its got a ways to go. Its generally worse than the gfs, especially outside of about 72 hours.

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Not sure if it lends credibility to, or away from the euro, but the 12z no gaps has a colder, wetter version of the storm midweek. Assuming the whole column is good below 850, would be a solid 3-6 inch event for middle and eastern tn, with the exception of maybe eastern valley.

NOGAPS would be a Miller "B",probably a nice hit NE

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From the PSU e-wall site:

One of the main model biases with the ECMWF model is that it tends to overdevelop mid-level and upper-level cyclones across the southwestern United States. The reason for this is that the model is not fast enough to move a system out from the desert southwest and actually slows the system down and further develops it in place. The model also seems to have a warm bias when it comes to forecasting mid-level and upper-level tropospheric heights, and the resulting thickness calculations. The model also has a tendency to “bomb-out” extratropical cyclones along the east coast of the United States too prematurely.

On the reverse side, out of all of the medium range forecast models, the ECMWF generally performs the best with driving arctic fronts down the east slopes of the Rocky Mountains.

http://www.personal.psu.edu/adb241/eWallTutorial/models/ecmwf.htm

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Im looking at the accumulation maps on the euro though.... Wants to paint accums in middle Tennessee, but it's spotty bc it's elevation dependent. That leads me to believe we're getting a snow sounding but the surface is too warm for the model to paint accumulations. Which could mean the warm bias at the surface could be affecting that. I wish I could see the soundings or the skew t

Partials for mid-Ten on the 12z euro at 132 are around 1310 to 1320/ 1540 to 1550. On the nomogram this is really close between the indeterminate zone, rain, and measurable snow with rain categories. Looking at the sounding for mid-Ten, I would venture to guess if that exact scenario verified that it would depend on precip rates and that probably a little snow would fall, but I imagine it would be difficult to get much accumulation.

Nomogram for reference: http://www4.ncsu.edu/~nwsfo/storage/nomogram/nomogram.categories.html

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That's interesting and a good find. I wonder if that is research results or just their opinion though? I certainly believe the first part and the last part, but I don't have an opinion either way regarding the warm bias section.

Credit goes to Math/Met who linked that during a discussion about the warm bias earlier this week. ;)

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This is probably one of the better things we have going for us right now. AO is solidly negative and it is forecast to continue...and the actual AO values are coming in lower than the forecasts over the last 10-12 days...but even with that, there are no guarantees that the cold gets displaced down into the conus.

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That's interesting and a good find. I wonder if that is research results or just their opinion though? I certainly believe the first part and the last part, but I don't have an opinion either way regarding the warm bias section.

The warm bias has always been there with the EC, along with the hanging back in the sw lp's as long as I can remember. A couple of degrees; not great but enough to make a difference in precip outcomes sometimes as we all know.

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This is probably one of the better things we have going for us right now. AO is solidly negative and it is forecast to continue...and the actual AO values are coming in lower than the forecasts over the last 10-12 days...but even with that, there are no guarantees that the cold gets displaced down into the conus.

Month late and $5.00 short ....

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One thing I seem to be noticing during the long range is along with the building western ridge the GFS just keeps progressively nosing the other ridge further into Greenland so that's a good sign on that part, and we can see how the colder airmass sinks further southward as it happens with the vortex's behavior. Calling it a good run this go around with the overall 5H look.

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Folks been waiting on atleast fantasy maps, the GFS delivers. It has beautiful blocking, practically double blocking in the perfect spots on the last few panels. It's something to see if it holds on to it, but obviously so far out chances are it's not exact. I will say the overall evolution of the hemispheric flow makes a lot of sense. Usually an extreme solution in Alaska, then Europe, is followed by a Major High Plains event, a Northeast coast event, then a deep south event. Most of the evolutions of big snows I've studied that had blocking in Winters in Alaska, followed that pattern. So we'll see.

post-38-0-70234100-1328331644.gif

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Folks been waiting on atleast fantasy maps, the GFS delivers. It has beautiful blocking, practically double blocking in the perfect spots on the last few panels. It's something to see if it holds on to it, but obviously so far out chances are it's not exact. I will say the overall evolution of the hemispheric flow makes a lot of sense. Usually an extreme solution in Alaska, then Europe, is followed by a Major High Plains event, a Northeast coast event, then a deep south event. Most of the evolutions of big snows I've studied that had blocking in Winters in Alaska, followed that pattern. So we'll see.

post-38-0-70234100-1328331644.gif

Great to see you pop by Foothills. I have been following you on you website. Hope all is going well for getting that completly up and runing.

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