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SE Mid-Long Range Discussion

CAD_Wedge_NC

By CAD_Wedge_NC,
in Southeastern States

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franklin NCwx

franklin NCwx

Posted
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Add the vortex moving into central/se Canada.

Is the only type of pattern change that everybody will accept as a legit pattern change a -AO and -NAO? Because if that's it, we should lock this thread down for a good while. It may be just me, but I thought there were other other ways to get cold and Winter weather events in the SE. When this thread was started, we had a massive PV in the GOA and a very nice -PNA. Since then, parts of the south and southeast have had snow and we now seem to be moving into more of a +PNA pattern, though it tends to wax and wane. I know we'd all love a big fat Greendland block, but surely there are other patterns or various atmospheric configurations that can lead to Winter weather, right?

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FallsLake

FallsLake

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A few years back Joe Bastardi (I know....don't take seriously) won a huge forecast battle by identifying a winter weather event for the east before the models could see it. Basically we were in a positive NAO with a strong SE ridge. Most models showed the ridge holding in the east. Joe kept insisting that the cold air (pushing down the plains) would under-cut the ridge and cause a huge over-running event. He was right. I hate to say it but I can't remember the exact event/date but do remember seeing the models finally catch on in the short range. So, if we can get some true arctic air in play it may not matter what the NAO is doing.

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Carvers Gap

Carvers Gap

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There has most definitely been a pattern shift. Looks to me like a +PNA which is far better than where we were. Blocking in the North Atlantic looks unlikelly for quite some time. DT stated it best when he said it's almost a miracle that it's getting cold in the SE at all. That get's us to the next point that many, many have stated over the past few years. We are in a new type of winter pattern. While I still think this winter will be warm against the norms, when DJF are averaged together, snow will still fall. The 90s were terrible for the central and southern TN Valley - absolutely abyssmal compared to 80s and 70s. I don't think it will get that bad. As a matter of fact this winter will probably still beat those winters on the whole and soundly at that. Now, until the NAO tanks and the AO moves negative, I'm not buying right now. Many on the main board are calling for a stratospheric warming event sometime in late December or January. If that happens, it will get cold during the coldest part of winter. That is good. If the storm track continues to stay active, someone in the SE will do well. I'm just never big on these patterns producing for E TN. Truly, NE TN needs a bombogenesis low moving northward through the Piedmont to hit the jackpot here. It's not the only way to get snow here, but it is one of the major ways we get big snows. Sometimes if the jet sags south enough, we can catch an overrunning event and it will produce. Either way, that pattern is not on the map at the moment as they most often require high latitude blocking to get the low riding up the coast at the most optimum angle. Today's model runs have at least hinted at a stormy pattern in the interior East. If at the end of this winter I'm wrong on temps and below normal snowfall, I think two things will be the cause: 1.) We are in new winter weather pattern and the norm is no longer the norm(statistically, I would be excited to see that). 2.) -PDO. Also, I can't wait for the AMO to switch.

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GaWx

GaWx

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Posted

In a nutshell, having the little dots in 7,8, and 1 (good), everywhere else (bad).

Based on major (i.e. 3.5"+) KATL S/IP data since 1974, I wouldn't put too much emphasis on this for major snow/IP in ATL. For the eleven KATL major S/IP's since 1974, yes, there have been more during phase 8 (four) vs. any other one phase. However, the neighboring good phase 7 only had one and the other good phase 1 had zero. So, the total for phases 7, 8 and 1 was only five of the eleven total majors....i.e., not far from the four that would be expected had all phases been equal in terms of major chances. Interestingly, the second largest number was the three during phase 4. Two of the worst ATL winter storms since 1974, the 3/1993 blizzard and snowjam 1982, were actually during phase 4. The third highest number of majors was the two during phase 3. This included one of the two worst sleet storms in ATL history, 2/1979. The paralyzing S/IP storm of 1/2011 was during phases 5 and 6. Well, phases 3-6 are supposedly four of the "bad" phases, but they accounted for four of the five most paralyzing ATL S/IP's.

My point is that little emphasis should be placed on the MJO phase when talking about KATL major S/IP chances, especially of the paralyzing variety.

What about the five major ATL ZR's since 1974? Well, the most interesting that I found was that all five major ATL ZR's occurred when the MJO was inside the circle, i.e. of low intensity. Of the five, 2.5 were during phase 2, one was during phase 5, one was during phase 8, and one-half was during phase 1. So, the supposedly more favorable phases of 7, 8 and 1 accounted for only 1.5 of the five major KATL ZR's.

Combining major KATL S/IP and major ZR storms (16 total), phases 7, 8 and 1 accounted for 6.5 of the 16, or 41% of the 16. If each phase had had equal numbers (i.e., 12.5%), the total for those three phases would have been 37.5%. So, this emphasizes that based on the last 37 years of data, little emphasis should be placed on the MJO phase when talking about KATL major winter storm chances. Although it would be nice to see more data (more storms), there appears to be enough data out there (16 major storms) to at least say that there is no evidence of a sig. correlation between phases 7,8 and 1 as a group and higher major winter storm chances at KATL. One might argue that there may be enough data to say there may be a somewhat enhanced chance during phase 8, alone, since 5 of the 16 majors were during phase 8, alone. Then again, why did the neighboring good phases of 7 and 1 have so little activity (only 1.5 for those two phases, combined)? That makes me a bit skeptical about the actual favorability of phase 8.

Perhaps, the most interesting conclusion is that the chances for a major ATL ZR may be enhanced when the MJO intensity is weak (i.e. within the circle or under 1.0).

Now, the above doesn't say anything about the correlation or lack thereof of cold and MJO phase. However, since most here seem to care more about winter storms than cold, itself, it probably isn't quite as important to analyze.

***EDIT: OTOH, I've also done analyses of major KATL S/IP with NAO and PDO and have concluded that there likely is SOME correlation of the chance for a major KATL S/IP with a -NAO and with a +PDO. Therefore, I believe that the NAO/PDO states have a good bit more predictive power than the MJO phase with regard to major KATL S/IP chances..

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tnweathernut

tnweathernut

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Based on major KATL S/IP data since 1974, I wouldn't put too much emphasis on this for major snow/IP in ATL. For the eleven KATL major S/IP's since 1974, yes, there have been more during phase 8 (four) vs. any other one phase. However, the neighboring good phase 7 only had one and the other good phase 1 had zero. So, the total for phases 7, 8 and 1 was only five of the eleven total majors....i.e., not far from the four that would expected had all phases been equal in terms of major chances. Interestingly, the second largest number was the three during phase 4. Two of the worst ATL winter storms since 1974, the 3/1993 blizzard and snowjam 1982, were actually during phase 4. The third highest number of majors was the two during phase 3. This included one of the two worst sleet storms in ATL history, 2/1979. The paralyzing S/IP storm of 1/2011 was during phases 5 and 6. Well, phases 3-6 are supposedly four of the "bad" phases, but they accounted for four of the five most paralyzing ATL S/IP's.

My point is that little emphasis should be placed on the MJO phase when talking about KATL major S/IP chances, especially of the paralyzing variety.

What about the five major ATL ZR's since 1974? Well, the most interesting that I found was that all five major ATL ZR's occurred when the MJO was inside the circle, i.e. of low intensity. Of the five, 2.5 were during phase 2, one was during phase 5, one was during phase 8, and one-half was during phase 1. So, the supposedly more favorable phases of 7, 8 and 1 accounted for only 1.5 of the five major KATL ZR's.

Combining major KATL S/IP and major ZR storms (16 total), phases 7, 8 and 1 accounted for 6.5 of the 16, or 41% of the 16. If each phase had had equal numbers (i.e., 12.5%), the total for those three phases would have been 37.5%. So, this emphasizes that based on the last 37 years of data, little emphasis should be placed on the MJO phase when talking about KATL major winter storm chances. Although it would be nice to see more data (more storms), there appears to be enough data out there (16 major storms) to at least say that there is no evidence of a sig. correlation between phases 7,8 and 1 as a group and higher major winter storm chances at KATL. One might argue that there may be enough data to say there may be a somewhat enhanced chance during phase 8, alone, since 5 of the 16 majors were during phase 8, alone. Then again, why did the neighboring good phases of 7 and 1 have so little activity (only 1.5 for those two phases, combined)? That makes me a bit skeptical about the actual favorability of phase 8.

Perhaps, the most interesting conclusion is that the chances for a major ATL ZR may be enhanced when the MJO intensity is weak (i.e. within the circle or under 1.0).

Now, the above doesn't say anything about the correlation or lack thereof of cold and MJO phase. However, since most here seem to care more about winter storms than cold, itself, it probably isn't quite as important to analyze.

Interesting statistics. Thank you for taking the time to go through this. Very helpful!

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FoothillsNC

FoothillsNC

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My point is that little emphasis should be placed on the MJO phase when talking about KATL major S/IP chances, especially of the paralyzing variety.

Excellent post Larry. I think most folks think weather will follow a certain formula all the time, and in some years it does. Maybe even most years. But certain patterns do evolve over time that trump the larger indicies, and something as big and vast as weather can't be summed up into a nice , neat package of this +this= that. Some seasons follow the norm and x +y =Z but some patterns don't...it's just we don't have the last few years of patterns that often too look back at, and hence the big snows and cold for example in the South. This season it looks like we're in a pattern that is way overamplfied and way overactive. That combo might be what trumps the normal indicies, and so far it's been pretty interesting and full of changeups. It also makes it hard to forecast into the longer range with any usefulness, unless you rely heavily on persistence. Looks like the Fall pattern is continuing, i.e., very active and turning colder. I actually prefer this type of global flow of lots of action, versus just a couple years ago when El Nino was a lot more predictable.

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CAD_Wedge_NC

CAD_Wedge_NC

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Thoughts and comments?

I don't like the looks of it.

Relax,,,,If I read the map correctly, it shows most of the SE US at +6 degrees for the winter. Going back through the records, there were only 2 years in Charlotte history where the entire winter average was that high and they were both more than 75 years ago. I would safely say that it will not happen this winter either. Besides, if you look at where that map places the highest anomolies, it would not seem possible to have a pattern that would yield a southeast ridge, a warm Alaska, and positive temps in the straits west of Greenland. Looks somewhat impossible if you ask me.

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FoothillsNC

FoothillsNC

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Relax,,,,If I read the map correctly, it shows most of the SE US at +6 degrees for the winter. Going back through the records, there were only 2 years in Charlotte history where the entire winter average was that high and they were both more than 75 years ago. I would safely say that it will not happen this winter either. Besides, if you look at where that map places the highest anomolies, it would not seem possible to have a pattern that would yield a southeast ridge, a warm Alaska, and positive temps in the straits west of Greenland. Looks somewhat impossible if you ask me.

For that map to be anywhere close to verifying, we'd have to have a strong Southeast ridge now. And it's not showing up, the pattern is progressive one, we keep repeating the process of a few days above normal, followed by a few below and lots of rain in interior regions. The CFS has no idea what kind of pattern we've been in and are in.

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LithiaWx

LithiaWx

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Thoughts and comments?

I don't like the looks of it.

The CFS is notoriously bad about overdoing La Nina strength. It would not surprise me to see this way overdone as well. I think we end up with a map that looks like that in general but I'm sure you can tone down some of those anomalies on the positive and negative side quite a bit. I think this is a case of the CFS having the right idea but just overdoing anomalies. That said current Teleconections are a train wreck and modeling shows them to be horrendous for the foreseeable future. The pattern is certainly not setup to deliver us any sustained cold or any GoM snowstorms, (Miller A) variety. I can't see a storm riding from the Northern GoM coast and hooking up the eastern seaboard with this pattern. Those imo are the best storms for folks living in the southern and eastern sections of the SEUS. I still think that KY and TN are the areas of what most people consider the SE to cash in. I've said it over and over again this year, the pattern this winter imo is going to be shifted north and west (comparative to the last couple seasons) delivering some decent storms for those folks and leaving the other parts of the SE looking in from the outside. I hope some of us farther south and east can cash in on something this season, maybe things will line up just right to give us something to have fun with. If we had the pattern of the last few years we would be talking about when a storm was coming not if like this season. Nobody can deny that we would be immensely better off with a pattern of locked in cold like the last couple years. Now we have to hope for a storm and cold to come together instead of just waiting for a storm to come plowing into cold air like we had in the past two seasons.

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LithiaWx

LithiaWx

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Most models show a pattern change right? I am ready for the white stuff here in northern Georgia! Love the website guys

If you looked in a textbook for the perfect pattern for snow in the deep south you would not see what we currently have right now. No, the models do not change what we currently have for the moment. Like some have said quite a few have "punted" to January. Perhaps by then things will be looking better.

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WxMidwest

WxMidwest

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There will be a SE ridge folks, but not of the magnitude the CFS is advertising, something like the 2007-2008 type of pattern is in the works, where you get decent +AO, but the SE ridge if shunted more East/rounded off and flat to the North then expected, and if those high above anomalies are in Alaska, that Cold Air isn't going to be just confined to West of the Mississippi, it will bleed 300-500 miles over to the East... Putting the Storm track in the middle of the country...

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WidreMann

WidreMann

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Information on today's near record levels of the +AO.

AO Discussion

The duration and results of Sutherland's corresponding +AO winters(post #20) are substantial. Pretty interesting to see today's date as the only December entry in the mix.

The analogs generally look terrible. We just have to hope that we can pull a 99/00, not specifically for the 1/25 storm, but just for the two to three week cold pattern that gave us some snow and ice. Honestly, that's probably preferable than a bunch of mediocre threats spread throughout the winter.

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LithiaWx

LithiaWx

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Thoughts and comments?

I don't like the looks of it.

Looks familiar?

The temporary warm shots are going to be pretty darn warm... While the cooler shots are going to bring us back to normal or slightly below normal. Even with a progressive look to the weather the warm is going to overpower the cold this month imo....

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