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The Big One - Forecast & Discussion


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Verbatim, that was a great NAM run for the NC mountains (for snow).  Strengthening closed 850mb low tracks from N MS, to extreme NW SC, to just east of Asheville.  For a 850mb low of that strength, it's pretty much a must to be NW of its track to get all snow (12z Euro and Euro Ensemble tracked the 850mb low more through central NC).  For the mtns, the NAM has strong warm advection lift combined with upslope flow out of the SE.  Also, a nice 500mb vort max track from central AL to central NC.  Heavy snow for the mtns on this NAM run.

 

By comparison, the GFS 850mb low track runs from central AL, to just north of Columbia, to Cape Hatteras.  Big difference between it and the more amped up NAM.  GFS looks good for GSP to CLT corridor for snow, whereas NAM had too much warming aloft.

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By comparison, the GFS 850mb low track runs from central AL, to just north of Columbia, to Cape Hatteras. Big difference between it and the more amped up NAM. GFS looks good for GSP to CLT corridor for snow, whereas NAM had too much warming aloft.

the gfs has a problem with storms like this. Do you think its right or in its bias with stringing out the max vorticity?
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Gfs phases just a tad later than the nam. Trend so far at 0z is an earlier phase. Hope the cmc, ukie and euro follow.

Only the nam phases earlier, so the trend you are speaking of doesn't involve other guidance. In fact euro op phased latter at 12 z compared to 0 z last night. This is the first time I've see the GFS phase , unless it did at 18z I wasn't paying attn. I know you need an earlier phase solution like the nam solutions .

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Gfs looks realistic at least, the nam is just bonkers. it's extremely rare to get a coastal plain runner in early february like the nam and euro from last night show. the nam past 48 hours is essentially like throwing darts. the higher resolution seems to magnify the potential errors as you go further out in time.

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Gfs looks realistic at least, the nam is just bonkers. it's extremely rare to get a coastal plain runner in early february like the nam and euro from last night show. the nam past 48 hours is essentially like throwing darts. the higher resolution it has seems to magnify the potential errors as you go further out in time.

We've certainly had coastal plain runners. There's no good blocking for this storm, so any track is reasonable at this point.
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Only the nam phases earlier, so the trend you are speaking of doesn't involve other guidance. In fact euro op phased latter at 12 z compared to 0 z last night. This is the first time I've see the GFS phase , unless it did at 18z I wasn't paying attn. I know you need an earlier phase solution like the nam solutions .

you are right about the euro. I was only comparing the nam and gfs runs which are the only 0z runs in. I still think the gfs is playing catch up and will be more amped in future runs.
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gfs continues to have what looks like feedback issues with that blob of convection. It's a little concerning that it's had this for several runs so it might not be all convective feedback but a real cluster..in which case areas further north would be hurt with totals. Will be interesting to see if the canadian or euro show it because up until now they haven't.

 

gfs has my 850mb temp at around 33...nam is around 40 lol.

 

Gfs looks like a lot of sleet or snow/sleet mix here but it's very close to being all snow. Any heavier precip it probably would be. Looks like all snow in gainesville to anderson

I must say, this run is def. colder than the NAM (throw that out cuz its too far north and strong) but it increases my ZR amounts this run by a lot.  W/O looking at bufkit yet, I estimate its showing .30 ZR so this run is def colder.  

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At 72hrs, the Ukmet has a nice consolidated sub 1010 surface low sitting just south of Tallahasee, Florida.  The Nam has our low in Southern, GA at the same time.

 

I imagine when the better Ukmet maps come out they are going to look yummy.

IMO, again...the NAM is an outlier and should be tossed at this point.  *for the most part*  UKmet sounds like its even better than the GFS?

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I must say, this run is def. colder than the NAM (throw that out cuz its too far north and strong) but it increases my ZR amounts this run by a lot.  W/O looking at bufkit yet, I estimate its showing .30 ZR so this run is def colder.  

I know it's absurd and not right and I actually really hate model snow fall total maps..but since I normally take a glance at those from twister I had to post this just for fun because I've never seen it show totals even close to this high here. Just eye candy though.

 

NAM_221_2014021000_F84_SNOWIN_SURFACE.pn

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Agree completely, I can't buy that Greenwood will get triple what Asheville gets. I am quite amazed by the models today, actually too much so. I just can't buy into the solutions they are showing. My head won't let my heart buy into the idea of 6-10 inches or more for the upstate (some showing 12 inches plus). I would love it of course, but to be realistic, I think the smaller amounts the TV mets are showing may be closer to reality, even if they are being conservative. A couple of things to remember here, the solutions we are seeing is based on a phase. If that doesn't happen (and it may not) then this is a totally different game. The Jan 88 analog mentioned is fine, but surface temps were much colder for many areas in that storm. Also, someone mentioned ground temps - I think that could be a real problem, as temps have soared into the 60s all weekend over much of the area, and will be pushing 50 or more tomorrow. Cold surface temps or not, it will take a while (and lots of frozen precip) to get the ground cold enough for accums. And I am still concerned about surface temps. Virtually all local mets have highs Tues and Wed in the mid 30's, even for many mtn locations. I look to March 09 and Christmas 2010 to show how temps a couple degrees above freezing can destroy accums. We'll see, I hope it truly is epic!  :snowing: 

One thing to remember though. In all the really big snowstorms I've ever seen, the mets NEVER say, before the storm begins, the accumulations will be what they turn out to be. They always give a conservative estimate before the storm begins to unfold. I know just a few minutes ago on Fox 21 the met showed the new projected snow totals map and it showed a little over 7 inches here in the Greenville area and he said he didn't buy it, that he would cut that in half. But from what I've been seeing you guys on the forums say about the total liquid content during this event, I don't see how 7 inches would be out of the question.

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I am going with a blend of the GFS and NAM model tonight. The NAM is too far inland, in my opinion; however, the GFS is too weak with the storm.

 

The NAM's QPF is also too high, but the GFS is also too low. So I am going with a blend of both tonight. The storm will track right up the eastern seaboard with snow from roughly I-85 northward, with 6+ inch accumulations there. Elseware, it gets tricky due to ice.

 

The NAM is a clear outlier at the moment, but we need to continue to watch the trends. The NAM may be closer to right than the GFS, but I do believe the NAM is also too warm. We shall see as we move forward, it will be interesting to see what the EURO says.

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rgem is similar to the gfs showing a 2 to 4 inch snow fall for north ga and south carolina. Hard to tell but it could have about close to 0.50 liquid here but ratios are probably going to be less than 10:1.

Something to keep in the back of your minds if you are in the jackpot all snow zone. Lookout made a good point ratios are gonna be 10:1at best. This will be a heavy wet snow. You start getting above 10 -12 inches and it can go to town on tree limbs and power lines.. I haven't even sweated power issues because pretty confident of all snow or sleet and no much freezing rain. I spent 6 days in the dark in jan 2000 from heavy wet snow and 6 days in the dark from December 2002 1.5 freezing rain., hope no one on here has to endure those scenarios (power outages).

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I am going with a blend of the GFS and NAM model tonight. The NAM is too far inland, in my opinion; however, the GFS is too weak with the storm.

 

The NAM's QPF is also too high, but the GFS is also too low. So I am going with a blend of both tonight. The storm will track right up the eastern seaboard with snow from roughly I-85 northward, with 6+ inch accumulations there. Elseware, it gets tricky due to ice.

 

The NAM is a clear outlier at the moment, but we need to continue to watch the trends. The NAM may be closer to right than the GFS, but I do believe the NAM is also too warm. We shall see as we move forward, it will be interesting to see what the EURO says.

 

Good luck with that. Seems strange to blend such an outlier like the NAM and not blend maybe GFS/EURO. It's your call though so good luck.

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I know this is extremely crappy but this is south of prior runs. I wish the canadians would join this century and update their crappy graphics.

 

Much better graphics for the Canadian here - http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html

 

RGEM goes to hour 48, then GGEM picks up after hour 48 (not out yet)...make sure you have the correct model run entered

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Good luck with that. Seems strange to blend such an outlier like the NAM and not blend maybe GFS/EURO. It's your call though so good luck.

 

Well, the 12z EURO and 0z NAM are relatively close in my opinion. The storm, in my opinion, is going to wrap itself up and move up the eastern seaboard. The GFS is continuing to trend that way. The NAM is too far inland with the storm which causes the QPF to be too high, but the GFS is too far eastward, in my opinion leading to lower precipitation totals. Still yet, this is going to be a big storm for a lot of people regardless. The questions now become about where does the snow/ice/rain lines set-up and how much moisture will be pulled northward.

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Much better graphics for the Canadian here - http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html

 

RGEM goes to hour 48, then GGEM picks up after hour 48 (not out yet)...make sure you have the correct model run entered

Yeah I keep forgetting about that site

 

This was RGEM snow through 48 hours.

Actually has a fair bit of it as rain.

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