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January 17th-18th Winter Storm Discussion


BullCityWx

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What does this mean?

 

At face value, it says the air closer to the ground would melt the wintry weather and make it liquid. but.. heavy rates.. could potentially cool the air closer to the surface down and allow it to regain the form of snow.  I wouldn't say it's a no go for CLT by any means on the last NAM run and that sounding.

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At face value, it says the air closer to the ground would melt the wintry weather and make it liquid. but.. heavy rates.. could potentially cool the air closer to the surface down and allow it to regain the form of snow.  I wouldn't say it's a no go for CLT by any means on the last NAM run and that sounding.

That was at the end of the event....after the dynamic cooling. 

 

it would be extremely difficult for ice crystals to survive that....

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This setup is very similar to the march 2009 storm. The lee warm trough was there on that one as well. It's essentially a situation where the mountains block the cold air advection and by the time the cold air aloft rushes in the heavier precip has focused further to the east. Leaving the escarpment in a snow hole. It happens sometimes. The setup is almost identical.

 

http://www.meteo.psu.edu/~fxg1/NARR/2009/us0301.php

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SW VA and S VA get a good thump of snow from 45-54hrs if taken verbatim. Soundings from those areas are below freezing all the way up.  Seems to be trending slightly north each run so far.

 

 

NAM_218_2013011600_F48_37.0000N_80.0000W

don't think the precip will get that far north.  maybe the nc. va border

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Just looked at the 00z NAM. Model definitely shows a 3-5 hour period or so of deformation band snow sweeping east across NC Thursday evening. The RDU sounding at 3z Friday is certainly snow with the column below freezing and saturation in the dendritic growth region. Taken literally and not the NAM snow accumulation algorithm, I would imagine a 1-3 inch type snow as the rain changes to snow.

 

Obvoiusly intriguing but woudl love for the GFS to show this as well.

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At face value, it says the air closer to the ground would melt the wintry weather and make it liquid. but.. heavy rates.. could potentially cool the air closer to the surface down and allow it to regain the form of snow.  I wouldn't say it's a no go for CLT by any means on the last NAM run and that sounding.

Thank you for your response!

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Love the lee side screw job in the foothills ! Great run for wnc...

 

I don't know about "great."  The 18Z was a bit better that this 00Z run for AVL downtown (and the airport).  Right now, the best snows are really along the TN/NC state line, a la the Appalachian Trail.  Meanwhile, the 18Z GFS continues to hold its ground with a further south run, but not nearly as wet.

 

So, take a blend of the two and you get a moister GFS with a southward displacement of the snow axis, from central Haywood over to central McDowell counties.  TN line gets snow, but not as much as the NAM shows.  East TN and Knoxville area get a dusting.

 

Let's see if the GFS can play this out..

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For the triangle I remain skeptical. I'd take the 16/00z NAM for sure right now, given the situation, if it were a perfect prog. I have been burned too many times by cold chasing moisture, and relying on dynamic cooling to result in a ptype change. As I see it, I'd prefer either a strengthening 850 hpa low (as opposed to weakening), and as always a good cold source HP to our north. I always mention it, because its always important for us here.

With this being said, I think some token flakes could definitely work out, and will consider anything else a bonus. Gonna come down to a nowcast and obs-fest for us here in the triangle. That being said, if I lived north of the triangle, I'd be encouraged by today's runs.

Great to have something to track if nothing else. Best of luck to everybody in the nc mountains!

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This setup is very similar to the march 2009 storm. The lee warm trough was there on that one as well. It's essentially a situation where the mountains block the cold air advection and by the time the cold air aloft rushes in the heavier precip has focused further to the east. Leaving the escarpment in a snow hole. It happens sometimes. The setup is almost identical.

 

http://www.meteo.psu.edu/~fxg1/NARR/2009/us0301.php

would be impressive if we have a 09 repeat!

accum.20090302.gif

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thunderstorm?

 

0z nam text extrat for charlotte

 

  33 01/17 09Z   57     57      68       3    0.07  0.00    560    571   10.5 -11.0 1013 100 RA    009OVC162    0.0    3.0  36 01/17 12Z   54     53      58       8    0.11  0.04    559    570    9.9 -11.9 1013 100 -TSRA 011OVC145    0.0   13.6  39 01/17 15Z   47     45      55      13    0.06  0.00    557    569    9.6 -13.1 1014 100 -RA   011OVC138    0.0   11.2  42 01/17 18Z   42     41      32      14    0.29  0.06    556    565   10.0 -14.3 1011 100 TSRA  010OVC339    0.0    3.3  45 01/17 21Z   41     39      10      17    0.66  0.02    552    561    4.7 -12.1 1011 100 -TSRA 015OVC233    0.0    2.4  48 01/18 00Z   38     36      17      19    0.38  0.00    543    553    0.3 -20.2 1013 100 -RA   013OVC138    0.0    8.4  51 01/18 03Z   35     32       2      13    0.23  0.01    540    557   -2.7 -19.5 1020  70       330BKN122    0.0   15.6
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