pcbjr
Member
Larry,
Absolutely! And a -AO can be quite useful down our way ... NAO be "torpedoed" ...
How do I know? I'm posting back to the fellow who helped me figure that out a year or two ago ... Best!
The Curmudgeon
-
Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!
Absolutely! And a -AO can be quite useful down our way ... NAO be "torpedoed" ...
How do I know? I'm posting back to the fellow who helped me figure that out a year or two ago ... Best!
The Curmudgeon
Storm5
Member
Not sure and someone else could probably chime in say @1300m but if I'm not mistaken a -NAO is preferred for significant winter threats in parts of the SE, especially NC as I've read that on the NC Climate website somewhere before. Anyway it seems the more we learn the less we know..... we've all seen winter storms during +/-NAO, +/-PNA, "bad" phases of the MJO, +/-SOI, +/-AO, etc. What we really need is cold air to collide with rising moisture to produce frozen precip, I don't care what acronym influences it
I’m not 1300 but my understanding most great minds prefer a -NAO for your area
Sent from my iPhone using Tapatalk
Yeah your no @1300m Lol but I believe you are correct and actually @Webberweather53 or @SD shoot probably even that @Rain Cold guy could confirm this for me.
Larry,
Absolutely! And a -AO can be quite useful down our way ... NAO be "torpedoed" ...
Best!
The Curmudgeon
Now I’m not saying -NAO dominated winters aren’t decently correlated with colder SE winters because they are. And colder winters do generate more snow on average. But when looking at individual major SE snows and comparing the NAO for the day of as well as preceding days, there really hasn’t been much of a correlation. Any correlation is pretty small. The list of storms during and just preceding a period of +NAO is pretty impressive.
GeorgiaGirl
Member
No, it's not NECESSARY, but it's more needed in some areas of the southeast. I'm often speaking for the whole southeast, but in some areas like central GA, SC, and some areas of eastern NC, no they do need a -NAO to have a much better chance at a major snow.
I might be way off and 2/12/10 came during a +NAO (while I don't remember with 1/28/14, I do think 2/12/10 was a -NAO), along with other storms that affected areas that were more south and east of Atlanta and Upstate SC.
pcbjr
Member
As we've seen since 2011, there are a lot of other ways we can score winter storms in the south without a sustained -NAO. However, I think what is most telling is this composite that I've shared ad nauseam of the RDU composite of 6" + snowstorm evolution from 5 days out, which clearly shows a negative west-based NAO in the mean. It's also important to point out that often the NAO is receding as the event occurs, so essentially the -NAO is setting the stage with cold and suppression before often lifting as the storm develops. I believe we looked at some cases of winter storms and this scenario last winter and while I don't remember the exact numbers, I think the NAO may have been present in roughly half of the cases? It's certainly not a requirement, but it also is something that opens up the window of opportunity and backs up the jet stream - often in a very favorable way.Not sure and someone else could probably chime in say @1300m but if I'm not mistaken a -NAO is preferred for significant winter threats in parts of the SE, especially NC as I've read that on the NC Climate website somewhere before. Anyway it seems the more we learn the less we know..... we've all seen winter storms during +/-NAO, +/-PNA, "bad" phases of the MJO, +/-SOI, +/-AO, etc. What we really need is cold air to collide with rising moisture to produce frozen precip, I don't care what acronym influences it
It isn't a requirement, but if I could choose I would opt to have it every single time. I mean who wouldn't want that look on this forum right now lol?!
And the numbers for NC speak for themselves. A negative NAO in an El Nino year substantially increases the odds of snow days exceeding 1".
GG,
No, none of the areas you listed are anywhere close to “needing” -NAO. Central GA and SC needing one? If that were true, how do you explain the biggest central GA/SC snowstorm by far (2/1973) being during a long period of solid +NAO?
GeorgiaGirl
Member
You got me lol. Then I don't fully understand why when I've looked at the retrospective maps, the low pressure just sat off shore and stalled. There was some blocking that kept it from leaving quicker. I might have read about it and it just slipped my mind.
I am not trying to call you out, but one of NC's biggest snowstorms (1/25/2000) also occurred during a positive NAO, yet the numbers clearly show an increase in the overall frequency of snow days with a negative NAO, so that is a bit of flawed logic.
Tarheel1
I TOLD YALL IT WASN’T GOING TO SNOW
Member
2024 Supporter
2017-2023 Supporter
2025 Supporter
Seems like we’ve been seeing positive trends in modeling for like 4 weeks, and here we are , still looking longingly for a great pattern!
Tarheel1
I TOLD YALL IT WASN’T GOING TO SNOW
Member
2024 Supporter
2017-2023 Supporter
2025 Supporter
Pretty sure Jan 88 was a +NAO
olhausen
Member
Anyone who claims to know for sure one way or the other at this point is jumping the gun imo. Seeing as we are only 8 days in to this current winter one could not possibly know for sure weather it’s a go or no go on a good winter. Sure the long range hasn’t looked like what we were hoping for so far but I do believe I’ve herd many say December was expected to be warm followed by a cold January and even colder February. If in about 15-17 days nothing has changed and models don’t show the future goods then I will definitely start worrying.
Webberweather53
Meteorologist
To bring back a point I've mentioned many times on this forum the past year or two, I think the NAO actually has a bigger role to play in the type of winter storm you can get out of a pattern, and yes there's some signaling for -NAO being favored overall for more frequent winter storms especially in NC where our climo is good enough for where one or a few storms are less likely to bias the teleconnection relationship.
Patterns loaded with North Pacific blocking (-EPO/WPO) and little no-north Atlantic blocking are often accompanied by a deep SE Canada/Lakes vortex which yields large surface highs over SE Canada & the NE US, and southern stream disturbances getting stuck underneath the blocking high over Alaska, the Bering Sea, & eastern Siberia.
This pattern will usually give you Miller B/CAD &/or overrunning events in the Carolinas which is what we've seen in most cases over & over again the past several years.
(no better examples than earlier this past month or February 12-13 2014).
Those with stout -NAOs and a deep GOA low usually favor large coastal cyclones/Miller As in NC with the inherent risk of said storm turning up the coast into the mid-Atlantic & NE US, although it won't actually explicitly tell you where most of the snow will fall (Carolina crusher, mid-Atlantic centric hit, New England, etc.)
I’m not calling you out either, 1300, but since you mentioned it, 1/25/00 was actually during a -NAO period. Furthermore, these major SE winter storms were during a +NAO dominated period:
1/1973, 3/1980, 3/1983, 1/1988 (Mack is correct), 3/1993, 3/2009, Snowjam of 1/2014, 2/2014, the very rare coastal SE major snow of early 1/2018, and the big Carolina snow of mid 1/2018.
Daily NAO data: ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii
So, I’m not just cherry picking out a rare +NAO storm. There were a good number of them that included several historic storms.
Last edited:
Tarheel1
I TOLD YALL IT WASN’T GOING TO SNOW
Member
2024 Supporter
2017-2023 Supporter
2025 Supporter
Cold is a key ingredient, that’s what we’re missing for the next 10-15 days, depending on what model you look at!
Webberweather53
Meteorologist
On a somewhat unrelated note, I also now realized thanks to the government shutdown that I can't do quick back-of-the-envelope composite analyses on ESRL or continue building my archive of winter storms & seasonal maps in NC while I have some legitimate free time before the next semester begins. Ugh. I swear if it's not one thing it's another.
Kylo
Member
88 was probably a neutral NAO but did have a form of an atlantic block with big 50/50 low.
Storm5
Member
12z euro control and eps
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Webberweather53
Meteorologist
Sort of on topic given this was one of the most infamous SSW events on record and in a weak-moderate 1st year NINO event, it snowed TEN separate times in Lexington, NC (just SW of Greensboro) from late Dec 1939 thru early Feb 1940. Wtf lol.
RDU also got a nice little storm on Christmas Eve that winter.
RDU also got a nice little storm on Christmas Eve that winter.
Regardless, 1/1988 was during a very solid +NAO per this daily NAO record:
ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii
January 2000 as a whole was a positive NAO month. Yes, the NAO was negative preceding the storm, just as I mentioned was often the case. So you can also put that when in the bin for NC snowstorms following a negative NAO.
You can cherry pick a few storms but that doesn't change the overall trends, nor the fact that when you say there is no correlation between the NAO and southeastern snow that that is a completely inaccurate assessment, unless NC is not part of your southeast. It's really as simple as looking at what a negative NAO is from a pattern perspective. You can't tell me that doesn't increase the odds of wintry weather.
By your logic, since a negative NAO is no more favorable for a southeastern snowstorm than a positive one, then you are saying that this (a negative, west-based NAO):
is no more favorable for a winter storm as this (a positive NAO):
You and I are both smart enough to know one of those patterns is far more conducive to southern U.S. winter storms than the other, and to say otherwise is simply misleading and I can't let you keep spreading that false information on here uncontested. It's really not even debatable as far as I'm concerned.
January 2000 as a whole was a positive NAO month. Yes, the NAO was negative preceding the storm, just as I mentioned was often the case. So you can also put that when in the bin for NC snowstorms following a negative NAO.
You can cherry pick a few storms but that doesn't change the overall trends, nor the fact that when you say there is no correlation between the NAO and southeastern snow that that is a completely inaccurate assessment, unless NC is not part of your southeast. It's really as simple as looking at what a negative NAO is from a pattern perspective. You can't tell me that doesn't increase the odds of wintry weather.
By your logic, since a negative NAO is no more favorable for a southeastern snowstorm than a positive one, then you are saying that this (a negative, west-based NAO):
is no more favorable for a winter storm as this (a positive NAO):
You and I are both smart enough to know one of those patterns is far more conducive to soutern U.S. winter storms than the other, and to say otherwise is simply misleading and I can't let you keep spreading that false information on here uncontested.
1300,
I’m not cherry picking when I list 10 big SE storms since 1973 that were during +NAO dominated periods. The +NAO storms are based on hard data. So, there’s nothing being falsified. I’m using facts.
Again, here’s the daily data:
ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii
No one is saying you can't have a snowstorm during a +NAO. Where you and I are having a disagreement is when you say there is no correlation between a negative NAO and southeastern snowstorms.
I’m not saying there’s no correlation at all but am saying any correlation is small based for the SE as a whole on actual hard data. How else can you explain that 10 major SE winter storms, including big historic ones like 2/1973, 3/1980, 3/1983, 1/1988, 3/1993, and the 2 from 1/2018 were included in the +NAO group?
If I were just looking at Raleigh major storms, the correlation might be a little higher but for the SE as a whole I don’t see how one can conclude the correlation is more than small when the actual daily storm and NAO data says otherwise.
Last edited:
Also just to take this a step further, many of these storms are effectively neutral NAOs (which I loosely define as anything between +/- 1), not raging positive in the ten days preceding the storms. In other words, the NAO was not really influencing the pattern. I went through about half, but it's pretty obvious the pattern here. None of the ones listed here are strong positive NAOs. Sometimes just doing hard data analysis does not tell the full story.
1/3/2018 storm
2017 12 24 0.778
2017 12 25 0.553
2017 12 26 0.023
2017 12 27 -0.038
2017 12 28 0.171
2017 12 29 0.310
2017 12 30 0.502
2017 12 31 0.694
2018 1 1 0.502
2018 1 2 0.743
1/17/2018 storm
2018 1 6 0.023
2018 1 7 0.233
2018 1 8 0.288
2018 1 9 0.199
2018 1 10 -0.004
2018 1 11 0.073
2018 1 12 0.569
2018 1 13 1.103
2018 1 14 1.582
2018 1 15 1.667
2018 1 16 1.430
1/29/2014 storm
2014 1 19 -0.081
2014 1 20 0.052
2014 1 21 0.137
2014 1 22 0.167
2014 1 23 0.357
2014 1 24 0.995
2014 1 25 1.298
2014 1 26 0.955
2014 1 27 0.381
2014 1 28 0.246
2014 1 29 0.628
3/3/2009 storm
2009 2 21 0.709
2009 2 22 0.867
2009 2 23 0.873
2009 2 24 0.638
2009 2 25 0.619
2009 2 26 0.669
2009 2 27 0.646
2009 2 28 0.689
2009 3 1 1.006
2009 3 2 1.025
3/12/1993 storm
1993 3 1 0.140
1993 3 2 -0.030
1993 3 3 -0.112
1993 3 4 -0.145
1993 3 5 -0.075
1993 3 6 -0.089
1993 3 7 0.142
1993 3 8 0.165
1993 3 9 -0.073
1993 3 10 -0.197
1993 3 11 -0.108
1/7-8/1988 storm
1987 12 28 0.502
1987 12 29 0.585
1987 12 30 0.516
1987 12 31 0.166
1988 1 1 0.615
1988 1 2 0.953
1988 1 3 0.754
1988 1 4 0.392
1988 1 5 0.103
1988 1 6 0.171
1300,
Now you’re changing the goalposts. Now it has to be a raging +NAO dominated by NAO of +1+. I never said “raging NAO”.
No, it has to be a functional NAO. You're too caught up in a number, the atmosphere does not work that way. A -.000001 NAO has no influence on the pattern, just like a .000001 doesn't. I'm not changing anything, you just don't seem to understand how teleconnection indices actually relate to the real atmosphere. You are simplifying things way too much and it does not work that way.
Kylo
Member
We are arguing two different things here. The correlation is Raleigh see's more snow days when the NAO is negative. That's a fairly easy argument for Raleigh atleast....since the 80's we have been a +NAO dominated period and our seasonal snowfall average has been trending down. Also since the 80's we have been in primarily +PNA dominated patterns and yet Raleigh's seasonal snowfall average has been trending down. But, from the late 50's to about 1980 Raleigh's snowfall average was at an all time high and during that period it was dominated by -NAO/-PNA winters. Now I am not going to argue -PNA is better for Raleigh because it's not but the -NAO is clearly favorable for more consistent snowfall, atleast for Raleigh.
I see your point though, the past 30 years we have primarily +NAO and have had some great events. But, still not as consistent if we were to get -NAO dominated winters.
pcbjr
Member
Hey! An idea ... How 'bouts we wait until there is actually a -NAO, or for that matter a real SE snowstorm ... {I know ... it'll be 2021} ... and look then to see what's up ... and in the meantime, let's live and learn ...
Last edited:
It's pretty cut and dry.
Average snowfall departure from five NC Stations (yellow) and NAO index departure (shaded)
Kylo
Member
It's pretty cut and dry.
Average snowfall departure from five NC Stations (yellow) and NAO index departure (shaded)
Yep. The argument should be that Raleigh, and I would lump in the SE, gets more consistent snowy winters with -NAO. We just haven't had many NAO periods in recent decades
It's pretty cut and dry.
Average snowfall departure from five NC Stations (yellow) and NAO index departure (shaded)
Another important thing to take away from this chart is that the larger the NAO signal, the more substantial the departure. Like I was trying to explain to GaWx, weak NAO's (positive or negative) don't exert much influence over the large scale pattern and there is likely something else driving the pattern. However, a strong NAO is the number one driver of the eastern U.S. pattern when in place IMO, and I think this chart helps demonstrate that.
Webberweather53
Meteorologist
"....since the 80's we have been a +NAO dominated period and our seasonal snowfall average has been trending down. "
From what I can tell, areas like Winston-Salem and the far western piedmont actually have seen little-no discernible decrease in snowfall over the past century or so (obviously the 1990s still sucked), and in fact in some cases the snowfall means appear to be increasing slightly in these regions. After accounting for missing & bad data, the snowfall averages are surprisingly virtually the same at Greensboro & Raleigh for nearly half a century from the mid 1890s to World War 2, you don't really see the Triangle & Triad begin to significantly diverge until the 1940s.
Fayetteville & other areas of the eastern piedmont & coastal plain are suffering from the same long-term decline in snowfall as RDU that's been ongoing well before the NAO underwent a multidecadal shift in the 1970s-80s.
It's been a really long time since Fayetteville has picked up a 1 foot event (Dec 11-12 1958) or > 15" of snow in a single season (1979-80), they certainly used to be rare events but they did occur with some legitimate non-zero frequency in the early 20th & late 19th centuries.
When’s the last time we had a +NAO stretch of winter months like this?
ATLwxfan
Member
12z euro control and eps
Sent from my iPhone using Tapatalk
So close to a flizzard.
Sent from my iPhone using Tapatalk
Webberweather53
Meteorologist
You have to go back to the early-mid 1990s to find something similar to this, the Pinatubo Eruption made the early 90s NAO even more positive than it probably should have been all else considered. We've been fortunate to not observe a major tropical volcanic eruption, have persistent North Pacific blocking the last several years and more ozone to work with, or else we'd find ourselves in an analogous set of circumstances.
Heightened +NAO frequency in the very late holocone has been a hallmark of a warmer climate w/ expanded, poleward Hadley Cells and mid-latitude jet. It's only during winters like the one we're currently in where we have a fighting chance to crank out a sustained -NAO via semi-persistent central Pacific tropical forcing and contracted Hadley Cells like we used to see more frequently in the mid-late 20th century & probably the Little Ice Age (LIA). The LIA is noted in proxy records to have both more narrow Hadley Cells and more frequent El Ninos.
Fortunately for us, I think we stand a pretty good chance to see another El Nino next winter especially if the MJO is strong & persistent in the Pacific in the coming weeks. Subseasonal tropical forcing from the MJO during northern winter is important to keep an eye on for ENSO next year because the e-folding scales of the Kelvin Waves that are generated from said forcing provide significant input into the initial state of the Eq Pacific during the spring predictability barrier, where future ENSO evolution is highly sensitive to initial boundary layer conditions, even more so than at other times of the year.
Latest gfs wants to say a 1030 hp in the northeast, hmm still watching that storm next week
sigwx
Member
Maybe?