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Wintry January 3rd-6th, 2018 Winter Storm The ARCC/Xtreme Weather Special

Meteorologist1999 said:
How does the 18z CMC Look?
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You ask how every model looks. The European model’s best graphics are through pay sites, but every other model can be found freely. Your question should be “can someone post the link to the 18z Canadian?” Then you play around with all of the features. I’ve spent the last 15 years or so doing it. It’s very fun and educational.
 
Rain Cold said:
Yeah, I guess. That keeps getting thrown out there. But in my experience, at least with Gulf systems, the models usually show plenty of qpf and we end up getting shafted at the last minute, when none of them showed a minimum of precip due to convection robbing. In this case, nobody but the 3k NAM is showing appreciable precip making it back to the Triangle. Either the models do a great job picking up convection robbing in the Atlantic or there's something else going on.
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I hope you guys get hammered with snow. Just let us have a little bit of that back this way.
 
1300m said:
It could be, but none of the models that are dry have the resolution to resolve convection. Many of the ones that do, like the 3km NAM and the WRF-ARW2 pound us. I was also reading a WPC event summary from December 2017 for Texas and they mentioned those two models handling that event best for their area. Totally, and I do mean totally, different situation here but further adds some credibility to them. I know I tout the RGEM, and it may well end up being correct, but it actually has worse resolution that the ECMWF I believe, and it definitely doesn't have the resolution of the NAM so perhaps it is struggling with this extremely convective system also. I'm not trying to wish cast, I'm going to look like a moron at work where I put out my forecast to 7 offices across the state this afternoon if I'm wrong. This one is going to be a lot of fun to look back on and learn, hopefully after several days of playing in the snow ;)
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That is crazy. Sounds like we really have no explanation why the models are so different. I guess the local TV mets just go with which ever one shows the least. That doesn't sound like the models are reliable either way, though.
 
You can see the clear difference on the 3k vs the gfs below. The gfs continues to pin the 700mb convergence to the coast and a westerly flow inland. You don't get much snow that way. The 3k nam develops a weak 700mb circulation over NE SC and a deep SE flow into nc
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Mr. Grinch said:
You can see the clear difference on the 3k vs the gfs below. The gfs continues to pin the 700mb convergence to the coast and a westerly flow inland. You don't get much snow that way. The 3k nam develops a weak 700mb circulation over NE SC and a deep SE flow into nc
a9a247916dd9b8be31220151f5e4c5ee.jpg
a93c5cd53d8dcb6f289c92c8774ff6a7.jpg


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So, when will we be able to tell which one is right? And how do the mets figure out which one to go with for a forecast?
 
Cad Wedge NC said:
Now-casting, radar trend and current up-stream obvs
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But how do they decide which one to go with right now? From all I read 1300 and Webber think the NAM is more correct, with the setup we have, but seems like all the local mets are going with the globals.
 
Less than 24 hrs from go time, our best bet is just to nowcast it seems there still a lot of questions. How many times have these forecasts happen exactly like it was forecasted 12-24 hrs before? Very rare.

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Mr. Grinch said:
You can see the clear difference on the 3k vs the gfs below. The gfs continues to pin the 700mb convergence to the coast and a westerly flow inland. You don't get much snow that way. The 3k nam develops a weak 700mb circulation over NE SC and a deep SE flow into nc
a9a247916dd9b8be31220151f5e4c5ee.jpg
a93c5cd53d8dcb6f289c92c8774ff6a7.jpg


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Isn't this that the reason we so often deal with a warm nose that cuts precip amounts, especially in marginal temp profile setups? The NAM usually nails that, I think Webb said earlier we actually need some waa to get moisture return like the NAM is showing...

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Good luck to folks in the eastern parts of our area but the amount of IMBY posts are really increasing!
 
Brick Tamland said:
So, when will we be able to tell which one is right? And how do the mets figure out which one to go with for a forecast?
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I would really look at the 18z rgem it splits the difference and seems like a viable solution.

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ForsythSnow said:
Wow the HRRR has the low 30 miles north of last run.
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Still having issues finding out where to place the low pressure on various modeling. Jumping all around with the various vorticity off the SE coast. Precip shield about the same in SE GA regardless of placement of the "L"
 
metwannabe said:
Isn't this that the reason we so often deal with a warm nose that cuts precip amounts, especially in marginal temp profile setups? The NAM usually nails that, I think Webb said earlier we actually need some waa to get moisture return like the NAM is showing...

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Yes it's one if the reasons I've stayed optimistic about getting more snow than what the globals show. How many times have we been in a jackpot at even 24 hrs only to end up 50 miles in the warm nose. If we were to shift the gfs and euro 50 miles NW we have a respectable snowfall

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Makes me wonder if the 3k NAM is the one that is best at resolving convection, then what would make it is off in this case if it is off?
 
I've literally been on the edge of virtually every single model that's been out there tonight. The NWS is calling for around an inch here, but I have my doubts that anything will fall from the sky and places to my SE are going to get obliterated. The new snow shield in the entire region resides over the area just SE of Macon, GA.
 
quite the ice storm potential in a narrow stripe; some folks way down there could get quite an unpleasant surprise.
 
Doesn't look too far off from what is likely; maybe a little more around SE GA, Coastal SC, OBX:

18z GEFS Precipitation Mean:
gefs_qpf_mean_nc_11.png
 
Shawn said:
Doesn't look too far off from what is likely; maybe a little more around SE GA, Coastal SC, OBX:

18z GEFS Precipitation Mean:
gefs_qpf_mean_nc_11.png
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Like SD said, the heaviest precip usually ends up more NW than the globals show, so I feel good with that and with what the NAM keeps showing, and with the globals shifting west today.
 
I don't think a widespread 1-3 inches in the Columbia area is out of the question with more to the SE and less to the NW.
metwannabe said:
Isn't this that the reason we so often deal with a warm nose that cuts precip amounts, especially in marginal temp profile setups? The NAM usually nails that, I think Webb said earlier we actually need some waa to get moisture return like the NAM is showing...

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Where the convergence zone at the 850mb level sets up is where the heaviest snows will fall. Typically where 850s are between -3C and -5C are is where the heaviest snow axis is. It's going to depend heavily on where the 850mb low tracks. You want to be about 150-200 miles northwest of the 850 mb low. Any closer and you're probably getting sleet or freezing rain from too much warm air getting into the lower/mid-levels and too far and drier/colder air is limiting lift.

So yeah, pay a lot of attention to where the winds circulate at the 850mb level tomorrow along with the general movement of the center of circulation. That will determine where people get crushed by this thing.
 
Fishel actually was completely honest on air just now and said he doesn't know which way to lean. He thinks it's going to come down to watching satellite imagery as it develops and go from there. He doesn't trust any specific model right now. He's usually the first to tell you that it ain't happening, so it see him waiver is different
 
Cary_Snow95 said:
Fishel actually was completely honest on air just now and said he doesn't know which way to lean. He thinks it's going to come down to watching satellite imagery as it develops and go from there. He doesn't trust any specific model right now
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Nice to hear he's being honest instead of just trying to say he nailed the forecast. Sounds like Jan 2000 with them having to forecast and make changes as the storm started to unfold. Except then everyone said beforehand nothing would happen until it started to unfold.
 
Cary_Snow95 said:
Fishel actually was completely honest on air just now and said he doesn't know which way to lean. He thinks it's going to come down to watching satellite imagery as it develops and go from there. He doesn't trust any specific model right now. He's usually the first to tell you that it ain't happening, so it see him waiver is different
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To go with his statement here is a interview with him about the Jan 2000 snow: http://www.wral.com/weather/story/6871964/

Quote from it:
I can't sit here and honestly tell you that it wasn't until late that evening that I had an idea it was going to turn out to be the epic storm.

Ten years of advancement in technology have made predicting big storms easier, Fishel said, but he fears that the same mistakes could be made again.
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EPS qpf SAV
0Z : 0.25"
12Z; 0.50"

GEFS qpf SAV:
0Z: 0.25'
6Z: 0.30"
12Z: 0.55"
18Z: 0.65"

GEPS:
0Z: 0.45"
12Z: 0.50"

Has the slow but steady NW qpf trend ceased? If not, the 0.75" qpf line is right on our doorstep!
 
Shawn said:
Still having issues finding out where to place the low pressure on various modeling. Jumping all around with the various vorticity off the SE coast. Precip shield about the same in SE GA regardless of placement of the "L"
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The HRR throwing some snow in runners away from the storm, is interesting, in lieu of the jumping low, lol. I wouldn't mind a flurry patch going by :)
 
This probably belongs in banter but just for fun the new Canadian HRDPS that was just added the other day on TT (it only covers the northern areas you see so please don't ask about other areas) but fun to look at and a good test run for it in our area.
hrdps_asnow_neus_45.png
 
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