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Wintry Dec 8-10th Winter Storm

Webberweather53 said:
The large-scale setup & QPF look impressive enough in general to even go insofar as to say that if the main precipitation type were to be sleet for the duration of the event (as we've seen many times before) there actually could be enough of it to trigger winter storm warnings based on IP alone and little-no snow accum, but I'd still like to get a few days closer to the event before delving into specifics, this is just where my head is on that atm.
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The 6z EPS track is pretty classic for big NC hits that we've seen with the surface low sliding up the coast like that. Just assuming that track were to verify I would expect this to be a bit colder aloft and at the surface compared with what the models are actually showing. I'm not sure they're really handling the thermal profiles very well yet either. The GFS was awful with several events last winter not catching on until we were 24 hours or less out to the cold air and the FV3 we haven't seen in an event like this so it remains to be seen how it performs. It's interesting to me that the Euro is taking the 850 low well to the south while the GFS has it in TN before a transfer occurs and the FV3 has it all the way up into Kentucky... I'm just not buying the 850 low tracking that far north like the GFS is indicating.
 
Rain Cold said:
We'll get some sleet pellets at the onset probably. And if you squint real hard, you might see one or two of those fast falling wet snowflakes that make you wonder whether it was really a snowflake at all or just a really big raindrop. The writing's on the wall with this one. There's still a needle to be threaded, but it's getting smaller and smaller with the eroding eastern edge of each new clown map.
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If we can't do better than some sleet pellets with this than we suck.

ecmwf-ens_mslpaNorm_us_fh120_trend (1).gif
 
snowlover91 said:
The 6z EPS track is pretty classic for big NC hits that we've seen with the surface low sliding up the coast like that. Just assuming that track were to verify I would expect this to be a big colder aloft and at the surface compared with what the models are showing. I'm not sure they're really handling the thermal profiles very well yet. The GFS was awful with several events last winter not catching on until we were 24 hours or less out to the cold air and the FV3 we haven't seen in an event like this so it remains to be seen how it performs. It's interesting to me that the Euro is taking the 850 low well to the south while the GFS has it in TN before a transfer occurs and the FV3 has it all the way up into Kentucky... I'm just not buying the 850 low tracking that far north like the GFS is indicating.
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If the 850s were to be south then what the globles modles are showing, than the wrap around would be all snow. I don't understand why north Bama and South central TN isn't getting any snow?
 
nam_mslp_pcpn_frzn_us_28.png
Once again someone beat me to it, but look how far south this is. DANG
 
Jessy89 said:
Isn’t the nam the most accurate come Thursday?
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NAM and accurate, should never be in the same sentence together! But you look at it for its temp profiles!!
 
Sub freezing 850’s were also tucked further south at hour 84..I love getting NAM’d
 
Webberweather53 said:
Yeah you can easily have a winter storm analog but the outcome sensibly is much different, I expect this event to be a lot warmer overall, no way we're getting into the 10s during this storm here lol.
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Based on accumulation amounts at temperatures like that though, this may be a much wetter system, which might help out. What were QPF values like in Jan 88? There must've been some incredible ratios!
 
FFC:
LONG TERM /Wednesday Night through Monday/...
The main concern for the long term period is the potential
for a winter mix of precipitation across portions of the
forecast area this coming weekend into Monday, most so
across portions of the ne Mountains.
The GFS and European are similar in developing surface low pressure
along the Gulf Coast states and moving it to the Atlanta coast
through Monday. Deep moisture is forecast to move over the area
Friday night with a rather strong surface ridge of high pressure
nosing down the eastern Appalachians providing a strong overrunning
flow. The question will be is how cold the airmass will be through
this period over the far ne especially the mountains. For the most
part, a cold rain can be expected. However a period of a winter mix
is possible of sleet and/or snow and this will depend greatly on
how cold the airmass is over the NE counties. Confidence is low
for any significant accumulations of sleet and snow and it will
be a watch and monitor of future model runs to see how this system
might develop. As a side note, the Canadian model is still the warmest
and all rain.

The associated upper system moves to the area late Sunday and Sunday
night giving some potential for a Rain/Snow mix Sunday night into
Monday. Any amounts with the upper system are expected to be light.
 
Those basing any hope with the NAM at this range as to track or strength are doing it at their own peril. Thursday night I will start paying attention to its Thermal Profiles which is does excellent on inside 48 hours
 
Again this is the very long range Nam, it Has to be taken with a grain of salt for sure, so the “noise” at this range Has to be watched but that’s all it is right now. “NOISE”
As you all no I’m not a huge fan of models trying to figure out temperatures especially dealing with CAD events. The. NAM is not to be really trusted, at this range, however it’s thermal profiles usually do the best out of most if not all models (in cad events). Now at this range the long range, we have plenty of time to see how we are just as we get closer however look at how much different and better in my opinion it’s handling the dewpoints and the wedge with the high-pressure already building in with precipitation not even close to us yet. Noticed how high pressure is starting to push down lower TD and even more importantly than that it’s doing it well before we even remotely have a chance to see any precipitation, and to me that is absolutely crucial in CAD events. FDE98461-8E8A-48EF-8D27-B81B1D175455.pngD0DCE7F0-C465-4758-8AD2-E50B519D4414.png7EE5A77A-DB8F-425F-A8B8-548D40475F0D.pngD8880164-DD1C-43AA-8F21-BF10D117C6CA.png
 
The NAM gets a bad reputation outside of 60 hours because it is prone to large errors at times but it's also worth noting that it can be useful in picking up on trends that the future global suite's may also show. IMO the NAM temp profiles match more with what you would expect to see from a Gulf Coast track like the globals depict... but we have plenty of time to track it and see once it gets in range.
 
deltadog03 said:
Again this is the very long range Nam, it Has to be taken with a grain of salt for sure, so the “noise” at this range Has to be watched but that’s all it is right now.
As you all no I’m not a huge fan of models trying to figure out temperatures especially dealing with CAD events. The. NAM is not to be really trusted however it’s thermal profiles usually do the best out of most if not all models. Now at this being the long range, we have plenty of time to see how we are just as we get closer however look at how much different and better in my opinion it’s handling the dewpoints and the wedge with the high-pressure already building in with precipitation not even close to us yet. Noticed how high pressure is starting to push down lower TD and even more importantly than that it’s doing it well before we even remotely have a chance to see any precipitation, and to me that is absolutely crucial in CAD events. View attachment 8245View attachment 8246View attachment 8247View attachment 8248
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Chris Ik is that good or bad thing? Don’t we need high to move with low pressure?
 
Snowflowxxl said:
NAM was spot on last year for the early December storm. Two very different things but it does hit occasionally
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This is a much more dynamic and larger storm. Last year was an overrunning event with a moist southwest flow. I'd at least wait until the NAM 3km is online before taking the NAM seriously.
 
14F6AE73-2D93-4087-A21A-2CF07CD986AA.jpeg Here is GFS, notice how it takes much longer for the “feed” to get established. Doesn’t do it until sometime Saturday when precip is arriving. Again noise for now, but something to watch.
 
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