December 8-10, 2018 Winter Storm

[superjames1992]

34 minutes ago, Poimen said:

By 18Z Sunday the NAM has a sleet sounding over the Triad with a pronounced warm nose above 850. 

The NAM is good at spotting those and I've noticed a lot of our storms have warm noses in the 700-800 mb range that you won't pick up on the "normal" 850 mb 0C charts (or on the clown maps).  Soundings are important.

I think my call for the Triad at this point would be for 6-8" snow/sleet with freezing rain on top.  A lot of storms end up in that range in the area.

[sarcean]

...WINTER STORM WATCH IN EFFECT FROM SUNDAY MORNING THROUGH
MONDAY EVENING...

* WHAT...Significant accumulations of snow combined with sleet and
  freezing rain is expected. Total snow accumulations of 4 to 8
  inches combined with ice accumulations of up to one tenth of an
  inch are possible. The greatest snow amounts are likely to be in
  the Triad, where amounts could approach 10 inches.

[Nraleigh]

Just now, FallsLake said:

Anything greater that .5" can get real bad. Again it only take .25" to warrant a Winter Storm criteria.  

.5" of freezing rain would be major outages. .25" is the level when outages usually begin.  If this is the case, it needs to be getting more attention.  Snow is nice, that amount of freezing rain is dangerous.

[magpiemaniac]

I’ve been wondering.  If you were to piece together the various call maps from adjacent NWS field offices, would the accumulation projections along their border counties match up fairly well?  Has anyone ever seen a 10” call for one county and then 2” in a neighboring county forecasted by another NWS office?

[SnowGoose69]

4 minutes ago, superjames1992 said:

The NAM is good at spotting those and I've noticed a lot of our storms have warm noses in the 700-800 mb range that you won't pick up on the "normal" 850 mb 0C charts (or on the clown maps).  Soundings are important.

I think my call for the Triad at this point would be for 6-8" snow/sleet with freezing rain on top.  A lot of storms end up in that range in the area.

You usually can tell on soundings before models pick it up.  If you have WSW or SW flow over 30kts in the 700-850 layer anywhere and aren’t at least -2C or colder it’s generally verifying above 0 in the end 

[Blue_Ridge_Escarpment]

18 minutes ago, wncsnow said:

Blacksburgs version 

Looks like two offices aren’t doing much collaborative work. Smh. 

[BullCityWx]

[BullCityWx]

The percentage chance of seeing a foot of snow increased fairly significantly on 12z EPS. 

[MJO812]

Enjoy guys

[Poimen]

FWIW, and it may be totally unrelated, but it's interesting that it appears as if the NAM totally busted on the high side out in Oklahoma. Just brutal for some of those areas. Maybe it will bust here equally bad on the low side.

[PGAWx]

1 minute ago, Poimen said:

FWIW, and it may be totally unrelated, but it's interesting that it appears as if the NAM totally busted on the high side out in Oklahoma. Just brutal for some of those areas. Maybe it will bust here equally bad on the low side.

To clarify - you mean there was more accumulation than the NAM modeled?

[griteater]

29 minutes ago, rduwx said:

Once that warm nose makes an appearance for the RDU area, I've learned to count on it.  It's usually worse than modeled.  I'm not saying that's the case for this storm but I've found that mostly true for past storms.

I just looked thru the NAM, Euro, GFS, and FV3 with the 850 low track and temps, and it's not pretty.  The FV3 is the coldest of the 4 even though its track is comparatively pretty far north....but it maintains the cold aloft the best on the front side of the storm in NC...it's the model to root for with the CLT To RDU crowd.  The other thing to root for is for continued suppression of the southern wave...either via it taking a little bit more of a southerly track or the NE confluence coming in a little stronger.  Anything that tracks the wave just a little farther south will want to make the 850mb low track a little farther south as well.  It's probably a tall task, but that's what is needed.  Here's the 850mb evolution on the FV3 on the front side of the storm:

 

 

[Shane]

9 minutes ago, magpiemaniac said:

I’ve been wondering.  If you were to piece together the various call maps from adjacent NWS field offices, would the accumulation projections along their border counties match up fairly well?  Has anyone ever seen a 10” call for one county and then 2” in a neighboring county forecasted by another NWS office?

Blacksburg NWS has good discussion text

 

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM EST Thursday...

Cold high pressure will continue to move east across the Ohio
Valley to the Mid Atlantic region Saturday evening. Overnight
Saturday into Sunday morning, cold dry air will wedge south into
the Carolinas and southern Appalachian Mountains. Meanwhile
across the south, an upper level low over the Mid West will push
a surface low east across the Gulf States. Bulk of Gulf and
Atlantic moisture with the surface low will stay south of the
area through Saturday evening. Snow will edge northward Saturday
night, starting across the High Country of North Carolina then
spreading across the entire area Sunday morning.

Sunday morning the upper level low tracks over Tennessee and
Kentucky increasing moisture transport over the wedge. The
combination of upslope flow, strong warm air advection and
isentropic lift will bring moderate to heavy snow to areas along
and south of highway 460. With an easterly flow, the higher
accumulations will be across counties along and adjacent to the
Blue Ridge. Going into the afternoon, the surface low tracks off
the Southeast Coast, taking majority of the moisture and lift
with it. However, the area will sit in the deformation zone
between the surface low and upper level trough into Monday
morning. Even though snowfall rates will decrease Sunday night,
persistent light snow will continue to fall into Monday morning.
There is a possibility snow will continue through the day
Monday as the deformation zones hangs over the area, waiting on
a stronger upper level low over the northern Plains to kick
everything to the east on Tuesday.

Before we get to the first guess storm totals, there are
several questions yet to be answered with this event. At the top
of the list is the track of the surface low. A wobble north or
south will dramatically change amounts. Second, is the effect of
the dry air with the wedge. Does this dry air hold off
precipitation or does it contribute to higher totals early due
to fluffiness. Late in the event, snow is expected to be wetter
and heavier, compressing the drier fluffy snow already on the
ground. With all that said, our first guess totals through
Sunday night will range from 12-18 inches across the North
Carolina High Country and Grayson Highlands to 5-10 inches
across the Mountain Empire, New River and Roanoke Valleys to
Southside Virginia. North of highway 460, 2 to 6 inches are
possible. Again these are first guess estimates on a storm that
is 2-3 days away.

Temperatures will drop into the 20s Friday and may warm into
the upper 30s to lower 40s Saturday. Temperatures will again
drop into the 20s Saturday night, but may not get above freezing
Sunday. Clouds and possibly snow will hang around Monday with
temperatures warming above freezing but not making it out of the
30s.

[Poimen]

1 minute ago, PGAWx said:

To clarify - you mean there was more accumulation than the NAM modeled?

No---sorry if I worded that incorrectly. It's the oppsite. It was going bonkers with precip (1.5" qpf)/snow 24 hours ago and some areas are going to end up with zilch. 

[McDowell_Weather]

39 minutes ago, griteater said:

I'd like to revisit this...I will not get more snow than Newland or Lenoir or Hickory

Its all Cantores fault......he should have never went to asheville smdh. sorry i know its banter if the nam keeps it up its guna be a sleetfest.....

[DopplerWx]

3k nam at hr 60.

[PGAWx]

Just now, Poimen said:

No---sorry if I worded that incorrectly. It's the oppsite. It was going bonkers with precip (1.5" qpf)/snow 24 hours ago and some areas are going to end up with zilch. 

Ahh, gotcha.  Misconstrued "brutal". 

[Poimen]

It looks like another solid run from the Canadian at 18Z. A good snow for the western/Northern Piedmont from about 6Z-18Z Sunday, followed by a transition to sleet/Freezing rain for some...then back to snow with a good deform band Monday. 

[Poimen]

[SnowDawg]

1 minute ago, Poimen said:

No---sorry if I worded that incorrectly. It's the oppsite. It was going bonkers with precip (1.5" qpf)/snow 24 hours ago and some areas are going to end up with zilch. 

From what I've read from mets out there this has been due to a weaker system over all and not the temps which is gonna be our problem.

[Poimen]

[ryan1234]

4 minutes ago, Poimen said:

FWIW, and it may be totally unrelated, but it's interesting that it appears as if the NAM totally busted on the high side out in Oklahoma. Just brutal for some of those areas. Maybe it will bust here equally bad on the low side.

So, I am curious about something. I've always noticed on some of our bigger storms that places like OK and AR seem to get snow as well. Sometimes extending to TN. Is what happens with their snowfall amounts worth noting and getting an idea for what we will receive? Like overperformance or snowfall farther south? 

[Poimen]

One last frame from the Canadian for Monday morning:

[SnowDeac]

How can GSP possibly have 8 inches as the "low end" (90% likely for more) for CLT? That makes no sense to me, at all, especially given the high end is 13 and "predicted" is 12. AVL, for example, is 3 on low, 4 on predicted, and 13 on high.

It seems they're completely discounting the NAM and assuming the profile will support snow for the vast majority of the storm. That doesn't seem likely at all, let alone 90% likely.

[SnowNiner]

13 minutes ago, griteater said:

I just looked thru the NAM, Euro, GFS, and FV3 with the 850 low track and temps, and it's not pretty.  The FV3 is the coldest of the 4 even though its track is comparatively pretty far north....but it maintains the cold aloft the best on the front side of the storm in NC...it's the model to root for with the CLT To RDU crowd.  The other thing to root for is for continued suppression of the southern wave...either via it taking a little bit more of a southerly track or the NE confluence coming in a little stronger.  Anything that tracks the wave just a little farther south will want to make the 850mb low track a little farther south as well.  It's probably a tall task, but that's what is needed.  Here's the 850mb evolution on the FV3 on the front side of the storm:

 

 

Well dang.  

NWS is still full blast on Miller A synoptics I think with snow/rain mainly.  It looks like it's going to just be a big mess/mixed bag south of 40.  

[DopplerWx]

yikes, at 45 the snow line looks even farther north 

[BullCityWx]

5 minutes ago, SnowDeac said:

How can GSP possibly have 8 inches as the "low end" (90% likely for more) for CLT? That makes no sense to me, at all, especially given the high end is 13 and "predicted" is 12. AVL, for example, is 3 on low, 4 on predicted, and 13 on high.

It seems they're completely discounting the NAM and assuming the profile will support snow for the vast majority of the storm. That doesn't seem likely at all, let alone 90% likely.

They said as much in their disco, as I recall. Might want to fact check me. 

[Nraleigh]

1 minute ago, DopplerWx said:

yikes, at 45 the snow line looks even farther north 

When does the FV3  run next?

[WxJordan]

Usually I do not disagree with the NWS, but the map by GSP is a little confusing. While the general idea of sleet mixing in and lowering snow totals seems possible, it would be area wide and not just limited to the far western portion of NC.

I am going to issue my first call map later this evening, and no, it does not match what GSP put out.

[HKY1894]

NAM has been garbage in the Midwest at 60 hour leads for now I think it should be discounted. I believe the warm nose will affect clt but the way it drives it all the way to the escapement basically I’m not buying right now.


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