Some thoughts on Potential Carolina Winter Storm...

[Stormsfury]

Anyone wanna bet which way the 18Z ETA trends? I'm guessing 50 miles N.

Back and forth, she goes, where she stops, no one knows ...

I put up that dry nose to show just what has to be overcome (and significant moisture would do to cool the atmosphere significantly ... IMHO, the model guidance, except the ETA and maybe the RGEM are picking up on the degree of cold air damming) ... the GFS is wretchedly losing it too prematurely ... it's quite possible with the multiple s/w's, that the models are keying in on the wrong one ...

SF

[yoda]

Hmmm... that would be interesting if it did. The 12z run at 48 hours shows the main low back in the Gulf of Mex., with its heaviest precip off shore... unless you are in GA/FL... where .25-.50 liquid could fall. Even at 60 hrs... the low is off the coast and there IS ABSOLUTELY NO PRECIP in NC. Northern SC may get some good snows if the 12z ETA at 60 hrs. is correct, but again there appears to be a sharp cutoff to the northern extent of the precip. But I doubt this will happen. We shall see at 4PM...

[yoda]

I agree there SF. The GFS always seems to lose CAD prematurely. It will be interesting though to see what the models do. It is interesting that the 12z ETA at 60 hrs places Northern and NE SC for 1 inch liquid and 850 temps are at -1 or -2.... but with that much dry air in place... it would probably only give you 2-4 inches of snow at most...

[Stormsfury]

MM5 very bullish with CAD and brings 925mb temperatures at 0ºC all the way down into the South Carolina coast as the first low departs, but slightly warms as the second low takes shape and a little farther south (offshore towards the FL/GA border)...

http://cheget.msrc.sunysb.edu/loop/36km.slp.html

The 12z NOGAPS pulls the FRZ line into Central GA/SC with a large are of moisture in GA ... but begins to weaken it afterwards and slightly warms the 850mb temperatures afterward ...

https://www.fnmoc.navy.mil/products/WXM ... .namer.gif

SF

[yoda]

I would throw out the MM5.... for now. The model seems to even have trouble with the low itself. It takes the first low SE for a bit, then back NW.... that is an interesting track for a low -- NW, SE, NW, NE. That is the track of the first low off the SC/GA coast. The second low appears to come in a little too late for anyone to get snow.... but the CAD is still strong just east of the Apps in SC.

[Stormsfury]

What I like about the MM5 is the fact that how it shows the strong wedging configuration ... I'm still hesitant to say that the cold air leaves so suddenly as being depicted, especially on the GFS, and to some degree, the ETA ... part of it MIGHT be the less QPF's being depicted and thus, less cooling occurring, but again, considering the 950mb air with TD's in the minus teens below zero ... yes, that will modify and the TD's will come up with the moisture return and temperatures subsequently fall due to this.

Again, the question remains, how aggressively the moisture returns (and this is an active southern stream series of s/w's ... and also if the models are keying off the wrong one ... this definitely is a very complex scenario and will not be easy to gauge ... in fact, it'll likely come down to radar trends and WV imagery once again.

SF

[ColdFront77]

I would throw out the MM5.... for now. The model seems to even have trouble with the low itself. It takes the first low SE for a bit, then back NW.... that is an interesting track for a low -- NW, SE, NW, NE. That is the track of the first low off the SC/GA coast.

Sort of sounds like what a tropical low does.

[QCWx]

ETA jogged back to the north this run.

[Stormsfury]

ETA jogged back to the north this run.

As generally expected with the 18z runs ... good call, QC.