Big -NAO Numbers In For November 2010

[bluewave]

The monthly number is -1.62 just behind -1.66 for November 1965.

http://www.cpc.noaa....ent.ascii.table

The 11/30/10 -2.696 daily number looks like the it could be the lowest daily for November

with 11/09/63 coming in with -2.471.

ftp://ftp.cpc.ncep.n...1.current.ascii

A very impressive positive 500 mb height anomaly from 11/25/10-11/30/10

NOV 2010

[NJwinter23]

Did real well for dumping the cold into Europe. The amazing streak of -nao continues

[AfewUniversesBelowNormal]

It's interesting that despite this most of the East coast finished the month with near normal temperatures.

This is the usual result of a -NAO November:

The Pacific RNA pattern in both composites (2010 vs historical -NAO November's) shows that the anomaly is largely Pacific-driven.

[tacoman25]

Most of the East Coast was also near normal in 1965 (though northern New England was quite cold). I don't think the NAO has as high a correlation with East Coast temps in Nov as it does DJF...exact placement of blocking and wavelength are definitely factors here.

[tacoman25]

Did real well for dumping the cold into Europe. The amazing streak of -nao continues

Looking like December will probably be very -NAO as well. So much for the Nina overwhelming this tendency.

[AfewUniversesBelowNormal]

Most of the East Coast was also near normal in 1965 (though northern New England was quite cold). I don't think the NAO has as high a correlation with East Coast temps in Nov as it does DJF...exact placement of blocking and wavelength are definitely factors here.

Along the East Coast the general correlation is about the same

[Nikolai]

Along the East Coast the general correlation is about the same

Are you not releasing a winter forecast this year?

[AfewUniversesBelowNormal]

Looking like December will probably be very -NAO as well. So much for the Nina overwhelming this tendency.

The NAO is negative in large part due to the Tropical Pacific. This won't continue all Winter.

[tacoman25]

Along the East Coast the general correlation is about the same

Eh, that doesn't fit what happened in the west Nov 2010, either. Plenty of exceptions, I guess.

[tacoman25]

The NAO is negative in large part due to the Tropical Pacific. This won't continue all Winter.

No doubt. We'd have record level 2009-10 type numbers again if it did. We aren't just looking at a -NAO, we are looking at a very impressive -NAO.

There is no way to get around the fact that the NAO has been much more negative so far than occurs with most Ninas. If those that were predicting the Nina would overpower the blocking tendency aren't scratching their heads just a little bit at this point, they should be.

[ORH_wxman]

Along the East Coast the general correlation is about the same

What are you using to define "-NAO periods" for November...any November that was below 0 for NAO?

When you run the correlation program, it shows significantly less influence in November than the DJF period. But given its robust strength, its still a bit surprising we didn't see it slightly colder in the east. Looks like our low heights ended up mostly off the east coast.

[AfewUniversesBelowNormal]

Are you not releasing a winter forecast this year?

I've been very busy. Here are Temps:

Dec 15 - Jan 5: Well above average in the Upper Midwest.. Above average in the Lower Midwest and Northeast.. Near average in West and Southeast.

Jan 5 - Jan 25: Below average in the Upper Midwest and Northeast... Near average in the Northwest.. Above average in the Southwest, Lower Midwest, and Southeast. Sharp warm/cold cutoff somewhere in the Mid Atlantic

Jan 25 - Feb 20: Well above average in the Eastern 1/2 of the US.. Near average in the Southwest and Rockies... Below average in the Northwest.

Best chance for snow in the Northeast.. Jan 10-25 and March

Best chance for snow in the Great Lakes.. Late January/early February

Best chance for snow in the Midwest.. Feb 1-25.. maybe historic amounts in some areas.

That's the quick summary. Sorry I didn't do a full discussion this year.

[AfewUniversesBelowNormal]

What are you using to define "-NAO periods" for November...any November that was below 0 for NAO?

I manually went through each day on the CDC Daily climates page since 1948 and created my own index based on Greenland 500mb height anomalies. The same is true for just about every important Northern Hemispheric region. The CDC and CPC datasets are both very flawed, this works a lot better.

The data also allows to me to go forward or back 48 days to check basically anything that led or preceded these periods. So far this research has proven to be very productive as a predictor.

[tacoman25]

I manually went through each day on the CDC Daily climates page since 1948 and created my own index based on Greenland 500mb height anomalies. The same is true for just about every important Northern Hemispheric region. The CDC and CPC datasets are both very flawed.

Well then you are talking apples to oranges, then, since the orginal post was about the CPC number for November...

[AfewUniversesBelowNormal]

Well then you are talking apples to oranges, then, since the orginal post was about the CPC number for November...

No. 500mb heights also show November as a significant anomaly, second only to 1965.

[ORH_wxman]

Well then you are talking apples to oranges, then, since the orginal post was about the CPC number for November...

Yeah it did mention the CPC number...but in this case, the CPC number is actually decent when you look at the 5h anomalies. They were over the classic NAO region and not offset.

I like to look at the actual anomalies too more so than the numbers. The numbers though help for a quick guide, but as discussed many times in the past, I don't agree with their method od calculating it...at least in terms of sensible wx to the Eastern US. Chuck's region 6 on his map is basically the meat of the NAO region that is probably the most important.

[tacoman25]

No. 500mb heights also show November as a significant anomaly, second only to 1965.

Still, you were making your argument that it should have been colder based on a correlation map of your own creation, when that correlation does not apply directly to the CPC number.

ORH showed a different November correlation than your composite did, so you can't have it both ways.

[AfewUniversesBelowNormal]

Still, you were making your argument that it should have been colder based on a correlation map of your own creation, when that correlation does not apply directly to the CPC number.

ORH showed a different November correlation than your composite did, so you can't have it both ways.

Why must you argue everything?

The problem with the CPC correlation map is that it includes both positive and negative periods, which don't always have the same effects. There is also a lot of noise in using the month as a whole versus specific NAO periods that happened in the given month, since certain Northern Hemispheric patterns do typically precede and follow an extreme NAO (Example: +PNA is usually followed by a huge -NAO so the CPC composite may have a large Pacific influence as well.. it is a 30-day map after all).

[tacoman25]

Yeah it did mention the CPC number...but in this case, the CPC number is actually decent when you look at the 5h anomalies. They were over the classic NAO region and not offset.

I like to look at the actual anomalies too more so than the numbers. The numbers though help for a quick guide, but as discussed many times in the past, I don't agree with their method od calculating it...at least in terms of sensible wx to the Eastern US. Chuck's region 6 on his map is basically the meat of the NAO region that is probably the most important.

Either way, the East was warmer and the West was colder than one would expect this Nov based purely on Chuck's NAO map...so what is the point? That the NAO isn't the be all end all for U.S. temps (especially in November)? I would agree.

[tacoman25]

Why must you argue everything?

You are the one that first challenged something that I said in this thread. See my first post, wasn't arguing anything you said. Check the facts, Chuck.

[weatherwiz]

Chuck,

Just wondering but how do you determine the regions? Is it broken up into latitude/longitude sections? I think this is real interesting...I've been trying to do something similar but since I don't know much about this stuff it's kind of hard for me.

[ORH_wxman]

Either way, the East was warmer and the West was colder than one would expect this Nov based purely on Chuck's NAO map...so what is the point? That the NAO isn't the be all end all for U.S. temps (especially in November)? I would agree.

Well I would agree that the NAO is less influential in Nov vs the rest of the winter. I've read some papers that showed this via wavelength differences, but I'm not an expert on that stuff. But obviously if it sets up in the right spot, it can still have a solid influence as Chuck showed on his map.

[tacoman25]

Well I would agree that the NAO is less influential in Nov vs the rest of the winter. I've read some papers that showed this via wavelength differences, but I'm not an expert on that stuff. But obviously if it sets up in the right spot, it can still have a solid influence as Chuck showed on his map.

Yup, pretty much exactly what I said in my first post. Placement and wavelengths play a role in how exactly the NAO effects the U.S. Regardless...major blocking going on up there. The past couple weeks it's been in a better position to deliver cold to Europe, which is of course why they've seen record cold lately there.

[AfewUniversesBelowNormal]

Chuck,

Just wondering but how do you determine the regions? Is it broken up into latitude/longitude sections? I think this is real interesting...I've been trying to do something similar but since I don't know much about this stuff it's kind of hard for me.

Yes, latitude/longitude grids. If you or anyone else need the data for something, PM me. It takes about 10 seconds to run these maps. I'll be on here more often going forward.

[skierinvermont]

I would definitely say correlations are more telling than composites, which argues for a lesser -NAO importance in Nov than DJF, I think this makes sense meteorologically as well.

[bluewave]

It's interesting that despite this most of the East coast finished the month with near normal temperatures.

This is the usual result of a -NAO November:

The Pacific RNA pattern in both composites (2010 vs historical -NAO November's) shows that the anomaly is largely Pacific-driven.

Chuck,

Great job at putting all those composites together.

Yeah,the warmer pattern has been really persistent since March with the extension of the ridging from the -NAO down toward the Eastern US.

[Amped]

Almost positve. A bit of a warm bias.

[NJwinter23]

I'm not sure what Wes Junker's method was for calculating, but he presented some composites in a recent thread showing how 1) The NAO has less of a correlation for eastern U.S. temperatures in November than DJF and 2) how eastern U.S. temperatures were notably more sensitive to the Pacific state than the north Atlantic pattern in November.

[A-L-E-X]

No doubt. We'd have record level 2009-10 type numbers again if it did. We aren't just looking at a -NAO, we are looking at a very impressive -NAO.

There is no way to get around the fact that the NAO has been much more negative so far than occurs with most Ninas. If those that were predicting the Nina would overpower the blocking tendency aren't scratching their heads just a little bit at this point, they should be.

This is probably why, when the NWS released their long range winter forecast, they had us as equal chances and said that the NAO influences our weather much more then ENSO does.

[michsnowfreak]

Yeah it did mention the CPC number...but in this case, the CPC number is actually decent when you look at the 5h anomalies. They were over the classic NAO region and not offset.

I like to look at the actual anomalies too more so than the numbers. The numbers though help for a quick guide, but as discussed many times in the past, I don't agree with their method od calculating it...at least in terms of sensible wx to the Eastern US. Chuck's region 6 on his map is basically the meat of the NAO region that is probably the most important.

I havent looked at other areas, but November's temp anamoly here is something you NEVER see today. The departure for DTW was +1.3F. It was a product of the high averaging +3.7F and the low averaging -1.0F. Honestly i dont ever recall seeing that. Usually the slightly warmer than normal months have highs averaging BELOW normal, with the above normal lows giving the month its slightly positive departure. And many of the colder than normal months often have a high averaging well below normal and a low averaging just slightly below normal. And I know this goes for most areas in these days of UHI.