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Pattern The Great December Dump

Webber, i heard before winter started with the IOD being so positive that it would allow the mjo to focus in the 8-2 phases, so what do we need to have happen? Standing wave is an interesting term.?
 
Do we really think that, based on the current maps, without snowfall that the surface temps will be cold enough to support zr?
 
@BirdManDoomW You can't really hate the LR pattern at all on the 18z GFS or the GEFS, especially compared to the last several Decembers. Cold, active, big EPO ridge, PV on our side of the globe. Looks favorable for at least a couple winter storm threats.
 
Rain Cold said:
The effort you put into this post and analysis is commendable. I can't say I'm not disappointed that your not expecting a mostly heavy snow event anymore. Looks like about half snow and half ice now.

I disagree with the ptype distribution you have, based on the track and storm type you have. If the cold is in place that you expect, and the storm takes that track (which would represent a Miller A cyclone), there would be little zr. It would be mostly snow, quickly transitioning to rain. The pattern, however, strongly suggests a Miller B, which would favor more of the ptype scheme you have shown in your map, east of the mountains.

Good luck on your forecast!
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This storm system could turn out to be a complex storm system. And a complex storm system can bring various of frozen p-types due to multiple above freezing layers in the thermal profiles. Due to this, this is why I'm now predicting ice over a certain area. This is all going to depend on the physical process. On tonight's 18z run of the GFS, it shows an inland ULL developing, (which may not verify, and the GFS is off with this feature) but if it does verify, it could become associated with the main low. This is what could generate this system to become a complex storm system.

gfs_mslp_pcpn_frzn_seus_38.png
 
WxWatch said:
This storm system could turn out to be a complex storm system. And a complex storm system can bring various of frozen p-types due to multiple above freezing layers in the thermal profiles. Due to this, this is why I'm now predicting ice over a certain area. This is all going to depend on the physical process. On tonight's 18z run of the GFS, it shows an inland ULL developing, (which may not verify, and the GFS is off with this feature) but if it does verify, it could become associated with the main low. This is what could generate this system to become a complex storm system.

View attachment 27187
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This is why I (personal preference) don't try and get too specific about ptypes and timing more than 4-5 days out. There are too many variables that we just don't know yet. I like to look at the big picture pattern being modeled, seeing if there is consistency across model suites, seeing how much variability there is with it from run to run, and seeing how it evolves as we get closer.

If you can accurately nail the pattern, then you can get close to identifying the storm type potential. Paying too much attention to specific short waves, intensity of high pressure, interaction of energy, things like that will lead you to a lot of false solutions.

The pattern being modeled here is consistent with a Miller B, a cutter, or a frontal passage. You can never say never, but it's not really the best pattern for a consolidated, slowly strengthening Miller A, taking a great track from the Gulf, off the coast of SC.
 
I forgot to share this with you all this evening, graphic explanation below. I only did GSO, but if we get closer, I wouldn't mind adding RDU or CLT, GSP or even ATL
GSO png.PNG

Data: 12z EPS and GFS ensemble members, reflected from Weatherbell Meteograms
Region: KGSO (Greensboro) Most Triad regions apply, even triangle regions wouldn't be too far off
Note: Data in explanation is an example

Section 1. Mean
What I did with this set was as I created my excel spreadsheet, I set up the members and found their averages separately. The second thing I did was, weigh the members seperately. The GEFS was weighed 40% of the total; 1.1(mean) was multiplied by .40 and I got .44 The EPS was weighed 60%, I multiplied .29(mean) times .60 and got 0.171. I then added the total and got my average in which see below which is 61". Nothing Incredible

Section 2. % of members show snow
A bit more self-explanatory, I turned the members that showed snow into a percentage.

Section 3. Consistency.
What is did here was to use the mathematical formula, Mean Absolute Deviation, or for short MAD. Essentially It's the average distance the ensemble members are away from the mean. The process would be finding the original average, subtract the average from each member and find the average of that product. It is helpful because it lets you know whether a model is much more or less likely to verify. So essentially the smaller the number, the more likely that model set will verify and vise virsa, you could have a mean with 100 inches of snow, but will a low number, that would most likely verify, a high number and that means that 100 mean probably has a couple 50" members and a few 200" members.
 
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It’s getting suppressed that cold push is strong.


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accu35 said:
The icon has temps in the low mid 30s with moisture.
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Yeah, that's very close to a pretty good ZR storm for portions of the deep South.

Edit: FWIW, the second wave is close to another storm. A sharper ridge out west and it dives toward TX. That along with the ULL over the Baha and strong high over the east coast and that may be another icy setup.
 
Myfrotho704_ said:
Still trending towards euro View attachment 27192
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Was gonna post exact same thing, baby steps GFS baby steps....
a541316289633507d992a17d101d8d01.gif


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