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Wintry January 3rd-6th, 2018 Winter Storm The ARCC/Xtreme Weather Special

CAE is the airport code for Columbia, SC. So in these threads, if you see "CAE does well", it means Columbia. It's usually a good estimation of the precipitation shield, or how far South the cold air is getting.
 
Here’s to hoping Webber has to eat crow.... however i feel his explanation make too much sense to be wrong....being things currently modeled.... hoping we see some shifts.
 
metwannabe said:
Well Webb's post is thorough and hard to deny and I almost jumped (again) but I read the Rah NWS and believe I'll hold off just yet... still too much to figure out for us, especially the Central/Eastern Carolina's

As seems to have been the case the past few weeks, the
models can`t seem to agree on how this system will evolve and what
the resulting weather over Central NC will be. Even small variations
in the amplitude and southern extent of the aforementioned wave
could result in very different weather forecast for the area. The EC
has been wetter over NC but has been more consistent from run-to-
run. On the other hand, the GFS has been drier, but has trended
toward the EC with the latest (12Z) run. The feature in question at
the surface is the low that develops over the Atlantic. How strong
it is and it`s proximity to the east coast of the US will determine
if/what weather we will see here. Again, the EC solution has the low
much closer to the NC coast while the GFS is farther out over the
Atlantic. Given such large differences the precipitation forecast
for this period is low confidence and high uncertainty. Have kept
the forecast dry, with precipitation chances below slight for now,
but would not be surprised to see an introduction of some wintry
precip in the southeast in the coming days if current trends
continue.
Click to expand...

For areas south of the TN-KY and VA-NC border, the eastern Carolinas stand the best chance to come away with anything in this kind of pattern because their juxtaposition in the longwave pattern is most optimized for wintry weather (further east of the mean trough axis, closer to the large-scale southerly flow & WAA), but this doesn't mean our chances are really that great. We should certainly give this a few more days before getting worked up about another threat for wintry weather especially considering how many we've lost of late in the medium range
 
Webberweather53 said:
As a complimentary example to support the argument I'm putting forth here, look at the end of the GFS run, notice a big shortwave plows into south-central California and the Great Basin on January 8th. Not surprisingly a few days later, a big overrunning event breaks out east of the Rockies....
View attachment 2391
View attachment 2390

Right on its heels, another s/w crashes into southern California, and once again, a few days later, wintry precipitation begins to break out over the southern plains
View attachment 2393
View attachment 2392


Keep in mind, the point of this post is not to legitimize fantasyland GFS solutions, but rather provide a basis behind identifying a major ingredient we're currently missing and probably desperately need in this pattern that's necessary to catalyze a major overrunning event in the southern tier of the US. Equivalent to playing a competitive game of cards, while one move will work when you're dealt a particular hand to get you to win the game, when dealt a different set of cards, the same move/decision making may not work as effectively (or at all), and there's often another move or series of moves that will more likely lead you to win the game more quickly... Similarly, while shortwaves diving into the Pacific NW and Northern Rockies as well as California may have led to glory in the past when we were dealt w/ a pattern characterized by profound high-latitude North Atlantic blocking, the pattern we're currently dealt dictates that we have to rely more heavily on getting a wave into California and the four corners to produce the same result we want which is a lot of snow and ice...
Click to expand...
Glad to see this being talked about! I made mention in Banter that it appeared to me that on the 12z the flow had changed toward the end of the run. First half of the run had flow from the Northwest and toward the end of the run it was more from a Southwest orientation. Even though it’s a good ways out do you believe the GFS could potentially be picking up on a pattern change? I haven’t reviewed any prior runs to what was mentioned.
 
E16 for the win
98726922310f7cbfb443c472cfcf1a27.jpg



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There are no good signs here outside Coastal areas:

gefs_snow_ens_nc_29.png
 
Webberweather53 said:
For areas south of the TN-KY and VA-NC border, the eastern Carolinas stand the best chance to come away with anything in this kind of pattern because their juxtaposition in the longwave pattern is most optimized for wintry weather (further east of the mean trough axis, closer to the large-scale southerly flow & WAA), but this doesn't mean our chances are really that great. We should certainly give this a few more days before getting worked up about another threat for wintry weather especially considering how many we've lost of late in the medium range
Click to expand...

So Webb what would need to happen here in south Alabama for us to score?
 
Webberweather53 said:
The common denominator amongst every failed threat for wintry weather lately (& potentially this one too) is that aside from having a big vortex over SE Canada and New England, all of our potential events are associated with shortwaves that enter the contiguous US from the northern Rockies or Pacific Northwest and dive southeastward in the process, leading to a prolonged period of dry, west-northwest to northwesterly flow which leads to advection of cold, dry, descending air off the Rockies and Appalachians which suppresses the storm track and baroclinic zone well to the southeast. We can get the job done if we have a s/w that comes down the Rockies & Pacific NW, but we usually need to see shorter wavelengths and/or blocking upstream over the North Atlantic (-NAO) and/or north-central Canada to slow down the waves and give a chance for moist west-southwest to southwesterly flow to overrun the cold air that's obviously well entrenched atm. This doesn't mean the NAO is of upmost importance to get any wintry weather in general, but if we aren't receiving a steady supply of shortwaves in the southern stream, as we're often lacking in a NINA, we need a high-latitude blocking ridge there or else we're probably in trouble... If we can't get blocking in north-central Canada or Greenland, our only other primary option is we need a healthy shortwave to crash into California to really give us a chance for a board-wide overrunning event. You see, even with a big vortex over New England and SE Canada, plowing a healthy s/w into California and the four corners leads to moist west-southwest/southwesterly flow over the south-central plains anyway and allows deep tropical moisture from both the tropical east-central Pacific and Gulf of Mexico to overrun the low-level cold dome in the southern US, and gives us at least a legitimate fighting chance in a pattern like this. Huge upper level troughs plowing into California and the Four Corners regions often are associated with and herald a large-scale forthcoming pattern change and that may be what we need to trigger a storm here....

It's hard to pick out here (a testament to how pitiful this s/w was) but the shortwave that was associated with the December 28-29th threat (which ended up being a huge bust) entered the US thru the Pacific NW and Northern Rockies.
View attachment 2389

Shortwave associated with the New Years Day threat (which ended up busting), entered the US through the Pacific NW and Northern Rockies
View attachment 2388


Shortwave for the potential January 2-4 event enters the US thru the Northern Rockies in a few days. See the pattern here?
View attachment 2387
Click to expand...

Contrarily, if we were in an El Nino base state, with a juicy subtropical jet, these northern stream injections from the northern Rockies and Pacific NW can work out because our shortwaves on the whole are generally stronger, more frequent & not total pieces of crap, so even if they start to get sheared apart, they're so strong to begin with you still have more than enough energy left over to get a storm...
 
So I guess we are riding the GFS/GEFS off the cliff for next week. I’m still interested to see how these next few runs evolve before I completely write this one off.


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This specific “threat” is extremely similar to the threat we tracked in Feb of 2016. There was a low that kept appearing too far offshore for about 7 days and we waited for it to come NW and it just never budged. I think the coastal and sand hill areas recieved some token flakes but that was it. I think a similar solution is likely IMHO
 
Storm5 said:
Except for the members that show otherwise . All in e16 e6 e1 e4 e2
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I just can't get on board without a couple big hits (at least) on the GEFS. We had many big hits for the Thurs/Fri deal on the GEFS for days, and it didn't even work out then.
 
Shawn said:
I just can't get on board without a couple big hits (at least) on the GEFS. We had many big hits for the Thurs/Fri deal on the GEFS for days, and it didn't even work out then.
Click to expand...
Why does it matter if they have big hits or not if the outcome is still nothing? I remember all the big dogs the GEFS had for the 28th and 29th, like half of them, and that still turned to crap. Wrong is wrong either way.
 
Webberweather53 said:
As a complimentary example to support the argument I'm putting forth here, look at the end of the GFS run, notice a big shortwave plows into south-central California and the Great Basin on January 8th. Not surprisingly a few days later, a big overrunning event breaks out east of the Rockies....
View attachment 2391
View attachment 2390

Right on its heels, another s/w crashes into southern California, and once again, a few days later, wintry precipitation begins to break out over the southern plains
View attachment 2393
View attachment 2392


Keep in mind, the point of this post is not to legitimize fantasyland GFS solutions, but rather provide a basis behind identifying a major ingredient we're currently missing and probably desperately need in this pattern that's necessary to catalyze a major overrunning event in the southern tier of the US. Equivalent to playing a competitive game of cards, while one move will work when you're dealt a particular hand to get you to win the game, when dealt a different set of cards, the same move/decision making may not work as effectively (or at all), and there's often another move or series of moves that will more likely lead you to win the game more quickly... Similarly, while shortwaves diving into the Pacific NW and Northern Rockies as well as California may have led to glory in the past when we were dealt w/ a pattern characterized by profound high-latitude North Atlantic blocking, the pattern we're currently dealt dictates that we have to rely more heavily on getting a wave into California and the four corners to produce the same result we want which is a lot of snow and ice...
Click to expand...

To just solidify my point even more, the last time a healthy shortwave crashed into California was earlier this month on December 5th.
We all know what happened a few days later...
So again, in this kind of pattern, to get a big, board-wide event, we need a healthy wave to smack into California to kick off a large area of intense, moist southwesterly-WSWly flow and that's what we've been lacking since that storm on the 8th-9th, but our fortunes could change in another 2 weeks or so as the tropical forcing shifts around a little bit to the Maritime Continent and the ridge over Alaska builds and begins to retrograde towards the Bering Sea & NE Eurasia.
Here's the z500 analysis from the high resolution DWD-ICON model for 0z December 5, 2017. This is a model analysis which takes real-time observations and merges them with a first guess very short term forecast from the model, so it's going to be practically the same for most models anyway and it's really hard to screw that up in general, so I decided to go with the highest resolution global model that was available in the Meteocentre's archive in spite of its recent forecast busts.

QQ_GZ_UU_VV_000_0500.gif
 
DT is not " bullish" or " excited " about the 3/4th event.
 
The only problem with that is by the time we get a healthy shortwave the cold air will be long gone.
We will be back at square one again.
 
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