December 8-10, 2018 Winter Storm

[bargainmusic]

It's snowing on Stratford Road in Winston-Salem, NC.

[Brick Tamland]

2 minutes ago, Solak said:

RAH:

Sat through Mon night: A significant wintertime storm for NC is 
growing more likely with every model run. Differences among the 
models regarding timing, track, precip amounts, and the vertical 
thermal structure and advection patterns persist, which makes any 
details still difficult to pin down. But the chance of at least some 
wintry precip over the central NC forecast area with this event is 
growing. 

-Synopsis: A potent mid-upper trough/low will cross the S Plains, 
Gulf States, and Southeast during this period, as a surface low 
tracks along the Gulf coast/S GA/FL Panhandle, likely evolving into 
a Miller B configuration as this energy transfers to a deepening low 
just off the Carolinas late Sun. This low should then intensify as 
it tracks NE just off the NC coast through Mon. A second, strong 
polar stream wave will dive through the Midwest Sat night through 
Sun night and into the southern stream wave, prolonging the lift 
over central NC as the column cools further. 

-Timing: Following the slower ECMWF/Canadian/NAM solution over the 
faster GFS, the heaviest precip is expected to fall from early 
morning to late afternoon on Sun, in conjunction with strong upper 
divergence and mid level DPVA. After this time, drying aloft and 
waning forcing for ascent should mean a trend to lower precip rates. 

-Ptype: Still appears to be mostly a rain event through Sun in areas 
from the Triangle to the S and E, albeit with a little wintry precip 
early in the event. For areas N and W of the Triangle, including the 
Triad and most VA border counties, a wintry mix with some 
accumulation is expected for most of the event through Sun, although 
we may see a trend to mostly cold rain Sun afternoon. Some low level 
drying is expected by Mon, but decent moisture and lift in the -12C 
to -18C depth should result in a secondary chance of some light snow 
or a wintry mix associated with the polar wave. It's too early for 
specific amounts, but an inch or two is not out of the question in 
the Triad region, with a non-zero chance of greater amounts. This 
could change, however, especially given the sensitivity of precip 
types to small changes in thermal structure and lift, so stay tuned.

-Temps: Expect highs in the upper 30s to mid 40s Sat and Mon, with 
low 30s to upper 40s on Sun. Again, this is all predicated on 
getting enough warm air into central NC to allow surface temps to 
trend above freezing over the forecast area. Lows in the 30s.

An inch or two in the triad?  Okay...

[BIG FROSTY]

That hole from MT Airy to GSO up to Roanoke seems to set up when a low transfers to the coast

Yup, seen it too many times!! I’m right smack in it also.


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[jjwxman]

2 minutes ago, Solak said:

RAH:

Sat through Mon night: A significant wintertime storm for NC is 
growing more likely with every model run. Differences among the 
models regarding timing, track, precip amounts, and the vertical 
thermal structure and advection patterns persist, which makes any 
details still difficult to pin down. But the chance of at least some 
wintry precip over the central NC forecast area with this event is 
growing. 

-Synopsis: A potent mid-upper trough/low will cross the S Plains, 
Gulf States, and Southeast during this period, as a surface low 
tracks along the Gulf coast/S GA/FL Panhandle, likely evolving into 
a Miller B configuration as this energy transfers to a deepening low 
just off the Carolinas late Sun. This low should then intensify as 
it tracks NE just off the NC coast through Mon. A second, strong 
polar stream wave will dive through the Midwest Sat night through 
Sun night and into the southern stream wave, prolonging the lift 
over central NC as the column cools further. 

-Timing: Following the slower ECMWF/Canadian/NAM solution over the 
faster GFS, the heaviest precip is expected to fall from early 
morning to late afternoon on Sun, in conjunction with strong upper 
divergence and mid level DPVA. After this time, drying aloft and 
waning forcing for ascent should mean a trend to lower precip rates. 

-Ptype: Still appears to be mostly a rain event through Sun in areas 
from the Triangle to the S and E, albeit with a little wintry precip 
early in the event. For areas N and W of the Triangle, including the 
Triad and most VA border counties, a wintry mix with some 
accumulation is expected for most of the event through Sun, although 
we may see a trend to mostly cold rain Sun afternoon. Some low level 
drying is expected by Mon, but decent moisture and lift in the -12C 
to -18C depth should result in a secondary chance of some light snow 
or a wintry mix associated with the polar wave. It's too early for 
specific amounts, but an inch or two is not out of the question in 
the Triad region, with a non-zero chance of greater amounts. This 
could change, however, especially given the sensitivity of precip 
types to small changes in thermal structure and lift, so stay tuned.

-Temps: Expect highs in the upper 30s to mid 40s Sat and Mon, with 
low 30s to upper 40s on Sun. Again, this is all predicated on 
getting enough warm air into central NC to allow surface temps to 
trend above freezing over the forecast area. Lows in the 30s.

They favored the GFS on the 3am discussion. Lol. 

[burgertime]

9 minutes ago, GunBlade said:

Kind of reminds me of the Feb 2014 storm we got.  We got nailed with snow from the get go, had wonderful rates and quickly accumulated maybe 4-6”.  But the WAA turned the last few hours into a sleet fest. Really killed the totals we could’ve had here.  Good thing is having lots of snow then sleet didn’t cause the issues like sleet alone would or had it been freezing rain on top of everything.

But like most have said, the transition line almost always sets up around this area, especially with strong systems like this one as the WAA is rarely modeled correctly.  From past storms, the models seem to get a decent idea around 1-2 days out (especially the NAM) of the WAA and transition area but the subsequent runs seem to slowly erode away the WAA and increase QPF and give back hope of big totals.  Only to be smashed once the storms over.  By the time we get close enough to the HRRR etc...being used and they start showing the WAA, ppl then want to assume those models aren’t correct based on the prior global runs not showing it  

I would not disregard any model(s) that start to push that snow line west over the next cpl days, if it happens, as much as I want to bury my head and pretend I don’t see it on the models either. 

I know the info above isn’t very technical in nature, just experience from seeing these storms and models year after year. 

That storm also dropped a few more inches after an ULL passed by us. IIRC there was a colder airmass to our north but might be mistaken. 

[PGAWx]

Seriously RAH?  I get you want to be conservative but 1 inch for the triad looks absurd right now.  

[CentralNC]

3 minutes ago, Brick Tamland said:

An inch or two in the triad?  Okay...

I guess they love playing catch-up.  They are right about the amount of uncertainty though.

[SnowNiner]

5 minutes ago, Solak said:

RAH:

Sat through Mon night: A significant wintertime storm for NC is 
growing more likely with every model run. Differences among the 
models regarding timing, track, precip amounts, and the vertical 
thermal structure and advection patterns persist, which makes any 
details still difficult to pin down. But the chance of at least some 
wintry precip over the central NC forecast area with this event is 
growing. 

-Synopsis: A potent mid-upper trough/low will cross the S Plains, 
Gulf States, and Southeast during this period, as a surface low 
tracks along the Gulf coast/S GA/FL Panhandle, likely evolving into 
a Miller B configuration as this energy transfers to a deepening low 
just off the Carolinas late Sun. This low should then intensify as 
it tracks NE just off the NC coast through Mon. A second, strong 
polar stream wave will dive through the Midwest Sat night through 
Sun night and into the southern stream wave, prolonging the lift 
over central NC as the column cools further. 

-Timing: Following the slower ECMWF/Canadian/NAM solution over the 
faster GFS, the heaviest precip is expected to fall from early 
morning to late afternoon on Sun, in conjunction with strong upper 
divergence and mid level DPVA. After this time, drying aloft and 
waning forcing for ascent should mean a trend to lower precip rates. 

-Ptype: Still appears to be mostly a rain event through Sun in areas 
from the Triangle to the S and E, albeit with a little wintry precip 
early in the event. For areas N and W of the Triangle, including the 
Triad and most VA border counties, a wintry mix with some 
accumulation is expected for most of the event through Sun, although 
we may see a trend to mostly cold rain Sun afternoon. Some low level 
drying is expected by Mon, but decent moisture and lift in the -12C 
to -18C depth should result in a secondary chance of some light snow 
or a wintry mix associated with the polar wave. It's too early for 
specific amounts, but an inch or two is not out of the question in 
the Triad region, with a non-zero chance of greater amounts. This 
could change, however, especially given the sensitivity of precip 
types to small changes in thermal structure and lift, so stay tuned.

-Temps: Expect highs in the upper 30s to mid 40s Sat and Mon, with 
low 30s to upper 40s on Sun. Again, this is all predicated on 
getting enough warm air into central NC to allow surface temps to 
trend above freezing over the forecast area. Lows in the 30s.

Wow, they poo poo'd the whole thing, didn't they? Even for the Triad.  Cold rain trend for the Triad? I'm lost on that one. 

[Shane]

2 minutes ago, BIG FROSTY said:

Yup, seen it too many times!! I’m right smack in it also.


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That's why I'm rooting for the slider with some English on it versus the miller B hybrid. Boo coastal low transfer

[burgertime]

NAM out to 54...looks a tad bit colder with more artic air coming south in the NE...if that continues over the next few runs that's a good sign. 

[Dunkman]

3 minutes ago, PGAWx said:

Seriously RAH?  I get you want to be conservative but 1 inch for the triad looks absurd right now.  

I'm not going to pretend to have a better feel for this than RAH does but I did find it kind of interesting that they opened saying it looked like a significant winter storm and then proceeded to forecast conditions that are very much not significant for the region.

[Solak]

It's almost like they don't want snow in the forecast

Again, this is all predicated on 
getting enough warm air into central NC to allow surface temps to 
trend above freezing over the forecast area.

[Cold Rain]

Here's my final call.  Ignore areas outside of NC.  Just drew a continuous area for symmetry, such that it is.

[lilj4425]

2 minutes ago, SnowNiner said:

Wow, they poo poo'd the whole thing, didn't they? Even for the Triad.  Cold rain trend for the Triad? I'm lost on that one. 

Maybe we’re being punk’d. Lol. 

[burgertime]

Strong CAD on this run but not by much. More widespread precip out in TX compared to 12z NAM as well. 

[SnowNiner]

Here's my forecast in Mooresville.  What warm nose? lol.  I don't know I'm sure I'll probably switch over too, but it's nice at this point that NWS says I may not.  We'll see what tomorrow holds....

 

[Regan]

RAH isn’t really buying any of it. 

[burgertime]

Just now, Cold Rain said:

Here's my final call.  Ignore areas outside of NC.  Just drew a continuous area for symmetry, such that it is.

 

 

But it's still a few days away? 

[lilj4425]

Just now, Regan said:

RAH isn’t really buying any of it. 

Curious to see what GSP says. 

[burgertime]

I'm betting this NAM run is gonna look good at the end. It also isn't looking to far off from the other models as well which is a good sign. 

[Brick Tamland]

Well, if we are within 24 hours and the models are about the same as they are now, and it ends up like RAH says, then the technology really needs to be improved with regards to the models. 

[burgertime]

@66 our energy in TX is close to closing off. CAD looks stronger compared to 12z. 

[packfan98]

Thanks for the pbp today Burger!  It's like old times.  We miss you around here.

[burgertime]

Scratch that SFC temps are cooler this run but 850's are a little warmer across NC. Let's see where it goes. 

[burgertime]

@75 nice cold air in NC with moisture starting to head towards SC/NC. 

[Brick Tamland]

7 inches from Wake westward in NC. 

[Cold Rain]

7 minutes ago, burgertime said:

But it's still a few days away? 

I've lived here a long time!

We'll check back in on Tuesday and see how I did.

[beanskip]

The 18z 12k NAM at 63 hours is yummy. The CAD actually doesn't press quite as far SW as in the 12z run, but if you look closely in N.C. the depth of the cold air is more impressive. Would be a terrific run if extrapolated, I bet.  

EDIT: Yikes, but at 69 hours, pretty serious retreat of the 850 0C line -- was over much of I-85 corridor for 12z run, now doesn't even touch S.C. 

[burgertime]

Well NAM is doing it's NAM thing when it's getting far out. Has an ULL in the panhandle of TX. 

[burgertime]

Just now, beanskip said:

The 18z 12k NAM at 63 hours is yummy. The CAD actually doesn't press quite as far SW as in the 12z run, but if you look closely in N.C. the depth of the cold air is more impressive. Would be a terrific run if extrapolated, I bet.  

Wait till you get to hour 75.