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

Well the RGEM, looks like something tainted the data at 500mb vort. So I would wait for the 12z. Its MESSY! whole damn map shows vorticity.

EDIT: NVM.
 
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example (junk run):

example.png
 
@Shawn, can you explain the two lows on this map. It seems like many of the models get really wonky when that surface low starts moving north. One piece hugs the coast more and moves due north, and then the other piece takes over and takes a right turn. If the piece closer to the coast becomes the dominant piece, it's game on for many more folks.
refcmp_ptype.us_ma.png
 
Looks like the 6z GEFS was the best run yet. Here are the ensemble lows. Still room to correct west I believe.
gfs-ememb_lowlocs_eus_13.png
 
National Weather Services are starting to update their beta Winter Weather Pages. Raleigh says that there's a 10% chance of getting this much snow or more. As I see things, I would give this a 20-25% of verifying.
SnowAmt90Prcntl.png
 
packfan98 said:
@Shawn, can you explain the two lows on this map. It seems like many of the models get really wonky when that surface low starts moving north. One piece hugs the coast more and moves due north, and then the other piece takes over and takes a right turn. If the piece closer to the coast becomes the dominant piece, it's game on for many more folks.
refcmp_ptype.us_ma.png
Click to expand...

The NAM has a rapid occlusion phase, although that look surprises me some.
 
packfan98 said:
National Weather Services are starting to update their beta Winter Weather Pages. Raleigh says that there's a 10% chance of getting this much snow or more. As I see things, I would give this a 20-25% of verifying.
SnowAmt90Prcntl.png
Click to expand...
It has 6-8" on high side, hope it happens!!
 
packfan98 said:
The look where a main low takes a right turn after phasing and doesn't go up the coastline looks so strange to me.
Click to expand...

It's related to the same problem I alluded to yesterday the Bets-Miller-Janic convective parameterization scheme in the 12km NAM is notorious for creating fictitious diabatically-generated low pressure centers. What's going to end up happening in all likelihood, one will takeover and as a result, this will only serve to aid w/ inland moisture transport, so we end up with an even bigger storm further west...
 
Webberweather53 said:
It's related to the same problem I alluded to yesterday the Bets-Miller-Janic convective parameterization scheme in the 12km NAM is notorious for creating fictitious diabatically-generated low pressure centers. What's going to end up happening in all likelihood, one will takeover and as a result, this will only serve to aid w/ inland moisture transport, so we end up with an even bigger storm further west...
Click to expand...
Thanks. That was what I was thinking. I was using anecdotal data and wishcasting. It's good to know there is some science to support it!
 
Webberweather53 said:
It's related to the same problem I alluded to yesterday the Bets-Miller-Janic convective parameterization scheme in the 12km NAM is notorious for creating fictitious diabatically-generated low pressure centers. What's going to end up happening in all likelihood, one will takeover and as a result, this will only serve to aid w/ inland moisture transport, so we end up with an even bigger storm further west...
Click to expand...
When do you think models will do better, 12z?
 
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