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December 8-10 Storm Discussion

Holston_River_Rambler

By Holston_River_Rambler,
in Tennessee Valley

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Holston_River_Rambler

Holston_River_Rambler

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I wonder if some of this waffling and models setting up shop in one camp or another has to do with the fact that the models rendering the storm are half filled with data supplemented by both satellites and real time obs. from the RAOB network and half fed with only satellite data? Half the wave is on shore, the other half not. Image attached.

Not trying to start a debate about whether satellite data means good input or not. There's no doubt that it is and vastly improved from the satellite data of yore. But if you have 3 sites in CA sending up balloons and observing the atmosphere in real time from the ground up, then satellites, satellites even as awesome as GOES 16 observing the atmosphere through several bandwidths from the top down (a Met for the NWS Louisville stated their data for model ingest was better above 500 mb), might that create an imbalance in data being ingested if the balloons only get to half the storm, the part on shore? That's big vortex, with little vorts embedded.  The model's algorithm/ program has real time data for half the system and has to extrapolate that same data for the other half.   And then individual microphysics/ algorithms of that model have to deal with that. And then those differences are compounded through time. Maybe this is taken into account in base programming, but I don't know.  Might explain why camps seem to be doubling down on their solutions.

I'm also not trying to say there will be one result or the other, but just wondering if the above has an impact. I would not base my hopes for snow on the above theory. But if there is something to it, when does the energy get fully under the RAOB network and how does that delay mess with how models deal with it? Looking at the NAM (just for the sake of example) the whole pocket of energy isn't entirely within the contiguous US and under the network until 00z Sunday, the time when precip. is projected to start in E. TN. 

Admittedly I could just be grasping at anything. I wholeheartedly admit I want me some snow! I guess we'll see if there are more changes in store. 

goes 17 12-6 evening.png

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Holston_River_Rambler

Holston_River_Rambler

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Also, a Met in the NC mts/ foothills section of the SE forum just gave a great write up (this same Met gave another amazing one last night as well)  about which models he or she thinks are doing the best (GFS is not so hot with this system, FV3/ Euro better). Worth a read and given model camps discussion above thought I'd link it: (Click on the "HurricanTracker replied to a topic" header)

 

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AndyHamachek

AndyHamachek

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So no weather worries for Friday night in pigeon forge my concern would be Saturday night Sunday am and basically no way to watch and try and run back home if it looks like it’s heading my way basically it will be raining and then boom freezing rain or snow all the sudden 

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PowellVolz

PowellVolz

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So no weather worries for Friday night in pigeon forge my concern would be Saturday night Sunday am and basically no way to watch and try and run back home if it looks like it’s heading my way basically it will be raining and then boom freezing rain or snow all the sudden 

I think it’s more late Saturday night, like after midnight before the changeover as of now. Still a lot of time.


.
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Blue Ridge

Blue Ridge

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So no weather worries for Friday night in pigeon forge my concern would be Saturday night Sunday am and basically no way to watch and try and run back home if it looks like it’s heading my way basically it will be raining and then boom freezing rain or snow all the sudden 

Hate to say it, but we just don’t have the answers right now. It’s going to be super close. Next 24 hrs of model runs are key, and then it’s basically nowcast time. Storms such as this in the Valley are so fluid.
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Math/Met

Math/Met

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43 minutes ago, John1122 said:

18z Euro was similar but less in SEKY for snow through 90 hours. That was the last map I was able to see. . Ratio'd I'd say 3-5 Plateau, 2-4 Central Eastern Valley and Southern Ky, 4-8 in NETN/SWVA.  That said, it's still snowing in most of East Tennessee at 90 on there.

I don’t have access to the 18z, but it looks like it increased precip along the eastern areas. Is that what you see? I haven’t seen snow maps or temperatures, so I’m not sure how that translates to snow accumulation.

Edit: Never mind, I found a snow map.

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nrgjeff

nrgjeff

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ECMWF has been a little south of American guidance (NAM/GFS Para) for a few runs. This happened in KCMO right after Thanksgiving. While I trust the Euro more 36+ hours out, at 30 hours they were still pretty different and I was leaning NAM. Finally at 24 hours the NAM caved to the Euro. ECMWF scored what I'd say was a significant coup.

I'm not saying it'll happen again, but I do like the discussion about the models. In fact this is likely the one of the best all-time threads. Lots of real-time data discussion has entered the mix which sweetens the deal even more. 

I'm still optimistic for northwest Tennessee, southern Kentucky, and northeast Tenn. Higher elevations look best. TRI looks better for snow than it did 24 hours ago.

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John1122

John1122

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39 minutes ago, Math/Met said:

I don’t have access to the 18z, but it looks like it increased precip along the eastern areas. Is that what you see? I haven’t seen snow maps or temperatures, so I’m not sure how that translates to snow accumulation.

Edit: Never mind, I found a snow map.

I am going with a 7:1 snow ratio, even though JKL said it may even be 5:1. A met in the SE Forum said 7:1 was good on the Euro. 10:1 maps put down 8-9 inches in my area, 4-5 in the Central Eastern Valley areas, and 10-13 or so in the NE all through 90. Snow was still falling through, I don't know how much, if any accumulation was added after. I'd also mention that my area and quite a bit of the TN/KY border areas see frozen that isn't snow as well as snow.

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Utvols235

Utvols235

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Great discussion guys. Only posted a few times and have very little knowledge. From Knoxville and live in Atlanta. Coming back home to the great state this weekend. Hoping that we get NAM’d like Atlanta did exactly one year ago. 6 inches in brookhaven. No one saw it coming other than the NAM of course.  

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tnweathernut

tnweathernut

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3 minutes ago, Bango said:

Nam is fast moving, heavy rates.  I wish we could get just a little more turn up the coast, would be epic for east tn/swva if that happened

It’s still pretty epic for a lot of east TN, especially considering it’s early December.  :-) I sure don’t want the .35 inches of ZR to go along with the 4-6 kuchera inches on the 0z NAM.  That could be very bad!

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Bango

Bango

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1 minute ago, tnweathernut said:

It’s still pretty epic for a lot of east TN, especially considering it’s early December.  :-) I sure don’t want the .35 inches of ZR to go along with the 4-6 kuchera inches on the 0z NAM.  That could be very bad!

Truer words never spoken.  It sure seems its trending toward a terrible freezing rain threat.

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