Record longest -NAO streak (going back to 1950) set today

[GaWx]

There hasn't been a single +NAO day since 6/5, meaning we're at 64 straight -NAO days. This ties the record longest -NAO streak (daily NAO records go back to 1950) that was first set 12/22/62-2/23/63! Based on the forecast, we will defintely set a new record tomorrow and we should at least get close to 70 days. I'm using this link for dailies:

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

For the 8/1/11-8/11/11 dailies, go here:

http://www.cpc.ncep....ily.index.ascii

If a solid -NAO were to continue into the heart of the hurricane season, it would increase the chance for a not so bad hurricane season for the states, especially vs. current expectations. However, here is the gfs ensemble mean based NAO forecast:

http://www.cpc.ncep....a/nao.sprd2.gif

This shows that there will likely be at least a close call to ending the -NAO streak next week. We'll see. If so, that should make the pattern more conducive for a threat(s) to the U.S. east coast just in time for the heart of the season.

Are there any implications for next winter's NAO? Any opinions?

[wxmx]

There hasn't been a single +NAO day since 6/5, meaning we're at 64 straight -NAO days. This ties the record longest -NAO streak (daily NAO records go back to 1950) that was first set 12/22/62-2/23/63! Based on the forecast, we will defintely set a new record tomorrow and we should at least get close to 70 days. I'm using this link for dailies:

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

For the 8/1/11-8/11/11 dailies, go here:

http://www.cpc.ncep....ily.index.ascii

If a solid -NAO this were to continue into the heart of the hurricane season, it would increase the chance for a not so bad hurricane season for the states, especially vs. current expectations. However, here is the gfs ensemble mean based NAO forecast:

http://www.cpc.ncep....a/nao.sprd2.gif

This shows that there will likely be at least a close call to ending the -NAO streak next week. We'll see. If so, that should make the pattern more conducive for a threat(s) to the east coast just in time for the heart of the season.

Are there any implications for next winter's NAO? Any opinions?

-NAO to continue for winter 2011-2012, same with the drought in the S, which will become critical (even moreso)... and probably a weak STJ. Mid west weenies jump in joy. My non-expert opinion, of course.

[rainstorm]

There hasn't been a single +NAO day since 6/5, meaning we're at 64 straight -NAO days. This ties the record longest -NAO streak (daily NAO records go back to 1950) that was first set 12/22/62-2/23/63! Based on the forecast, we will defintely set a new record tomorrow and we should at least get close to 70 days. I'm using this link for dailies:

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

For the 8/1/11-8/11/11 dailies, go here:

http://www.cpc.ncep....ily.index.ascii

If a solid -NAO this were to continue into the heart of the hurricane season, it would increase the chance for a not so bad hurricane season for the states, especially vs. current expectations. However, here is the gfs ensemble mean based NAO forecast:

http://www.cpc.ncep....a/nao.sprd2.gif

This shows that there will likely be at least a close call to ending the -NAO streak next week. We'll see. If so, that should make the pattern more conducive for a threat(s) to the east coast just in time for the heart of the season.

Are there any implications for next winter's NAO? Any opinions?

pretty amazing. hopefully it does indeed reverse very soon.

[Nikolai]

As Chuck's research has shown, summer -NAO is correlated well to a -NAO during the winter. I do think we see a continuation of the -NAO (respite in September-October/November, perhaps), and that the South will stay rather dry as well given the continuation of La Nina. Obviously, I think there's a good chance the STJ will be rather anemic this winter.

[matthewweatherwatcher]

In yet some people believe that we're going to have a crap load of big United states landfalls and that there is NO trough blocking the east coast. Blindness is all I've got to say. Do I believe we could get one if a favorable pattern sets up, YES. I think it is more likely this year with the trough axis being further westward then 2010 for that....I'd also watch Southern Texas through Sept and southern Florida for Caribbean systems making landfall there.

[OSUmetstud]

In yet some people believe that we're going to have a crap load of big United states landfalls and that there is NO trough blocking the east coast. Blindness is all I've got to say. Do I believe we could get one if a favorable pattern sets up, YES. I think it is more likely this year with the trough axis being further westward then 2010 for that....I'd also watch Southern Texas through Sept and southern Florida for Caribbean systems making landfall there.

Who cares about east coast troughs if people are looking for landfalls in areas other than the east coast? There is too much troughing off the US east coast for a landfall...especially north of FL...how does that prevent other landfalls?

[OKpowdah]

AO/NAO show an intra-annual cycle ... the persistent -NAO this summer will transition into a +NAO bias for the fall, followed by a -NAO bias for the winter

[kab2791]

I guess GOM landfalls are underrated now?

Who cares about east coast troughs if people are looking for landfalls in areas other than the east coast? There is too much troughing off the US east coast for a landfall...especially north of FL...how does that prevent other landfalls?

[SoCoWx]

I feel it will reverse in a sense and be more varible during the fall with less negative days. But I feel that Winter will average a -NAO implying at least a colder winter on Average for the Mid-Atl, NE, and points north and westward...

[Isotherm]

AO/NAO show an intra-annual cycle ... the persistent -NAO this summer will transition into a +NAO bias for the fall, followed by a -NAO bias for the winter

And if we have a +NAO Sept/Oct, that will lend credence to a -NAO winter. There's solid statistics regarding that correlation (I believe it's about 65-70%).

[ORH_wxman]

The monthly NAO has been on an insane streak as well. We have had 32 out of the last 40 months with a -NAO.

Here's some posts back on eastern in 2008 that we made about the summer and autumn NAO as it pertains to winter. I found that deeply -NAO summers correlated well with a -NAO the following winter...but it had to be strong (i.e. value greater than -1.5 on the slp data)

http://www.easternuswx.com/bb/index.php?/topic/176022-summerautumn-nao/

[ORH_wxman]

It's bee

And if we have a +NAO Sept/Oct, that will lend credence to a -NAO winter. There's solid statistics regarding that correlation (I believe it's about 65-70%).

It's been useless the last 2 years however. We've just been -NAO almost the whole time. October comes in with these massive -NAO blocks and then it happens in winter again.

[rainstorm]

Who cares about east coast troughs if people are looking for landfalls in areas other than the east coast? There is too much troughing off the US east coast for a landfall...especially north of FL...how does that prevent other landfalls?

i think the theory would go that a persistent trough off the east coast translates to a blocking high over the south central states preventing gom landfalls except mexico. bonnie last year and don this year barely made it as the weakest possible ts's.

[matthewweatherwatcher]

Who cares about east coast troughs if people are looking for landfalls in areas other than the east coast? There is too much troughing off the US east coast for a landfall...especially north of FL...how does that prevent other landfalls?

Strong trough off east coast can mean strong ridge over Texas, La, Ms area with strong westerly flow. One of the reasons for many of the cyclones making landfall within Mexico last season. Don was only because the pattern shifted for a short time to allow for it to get north enough to hit Texas...As in the ridge weakening over Texas with a ridge developing off Ga for a few days, but overall the heat ridge at 500 mbs has been over Texas and the midwest for most of this year...2010 had this pattern in many ways and it prevent most cyclones from hitting the US. From time to time you get changes within this, but this is the way things have been since May.

[OSUmetstud]

i think the theory would go that a persistent trough off the east coast translates to a blocking high over the south central states preventing gom landfalls except mexico. bonnie last year and don this year barely made it as the weakest possible ts's.

You appear to be right on that level. I think the central US ridging and US East Coast troughing has been overwhelming strong. Once we get closer to a more neutral NAO state next week this shouldn't be the case.

[rainstorm]

You appear to be right on that level. I think the central US ridging and US East Coast troughing has been overwhelming strong. Once we get closer to a more neutral NAO state next week this shouldn't be the case.

your point is well taken and i agree.

[matthewweatherwatcher]

It's bee

It's been useless the last 2 years however. We've just been -NAO almost the whole time. October comes in with these massive -NAO blocks and then it happens in winter again.

That is what me and rainstorm is afraid of.

[OKpowdah]

It's bee

It's been useless the last 2 years however. We've just been -NAO almost the whole time. October comes in with these massive -NAO blocks and then it happens in winter again.

But the underlying mechanism for that correlation still works.

Here I've plotted daily NAO values (light blue), added a 15-day moving average (black), then the intra-seasonal cycle (red). The cycle moves with a period of about 188 days, or 94 days for each phase.

[tacoman25]

As Chuck's research has shown, summer -NAO is correlated well to a -NAO during the winter. I do think we see a continuation of the -NAO (respite in September-October/November, perhaps), and that the South will stay rather dry as well given the continuation of La Nina. Obviously, I think there's a good chance the STJ will be rather anemic this winter.

Yup, and the same with -PDO. We will likely see big-time blocking on both sides of the continent this coming winter...yet again.

[GaWx]

Since 1950, I found five July's that weren't (pre) Nino, that were during a +AMO, and had a sub -1 NAO: 1950, 58, 62, 00, and 08.

Regarding the NAO, the respective August's that followed averaged -0.6, Sep. averaged +0.1, and Oct. averaged +0.5. Avg. # of storms forming Aug. and later: 11; Avg. # of U.S. hits August and later: 2.4. Avg. # of east coast hits: 0.2 (all from one hit, Hanna of 2008).

[ORH_wxman]

Since 1950, I found five July's that weren't (pre) Nino, that were during a +AMO, and had a sub -1 NAO: 1950, 58, 62, 00, and 08.

Regarding the NAO, the respective August's that followed averaged -0.6, Sep. averaged +0.1, and Oct. averaged +0.5. Avg. # of storms forming Aug. and later: 11; Avg. # of U.S. hits August and later: 2.4. Avg. # of east coast hits: 0.2 (all from one hit, Hanna of 2008).

All 5 years had the following winter NAO in negative territory.

[GaWx]

All 5 years had the following winter NAO in negative territory.

Yep, an excellent sign for winter fans!

[uncle W]

I found a few summer -nao streaks...

7/21-8/28 1954

1957 missed by one day having a two month streak...

7/12-9/9 1958

7/27-9/6 1966

6/20-8/9 2009

[GaWx]

I found a few summer -nao streaks...

7/21-8/28 1954

1957 missed by one day having a two month streak...

7/12-9/9 1958

7/27-9/6 1966

6/20-8/9 2009

Thanks, Unc. Do you mean 6/26-8/10/09?

[A-L-E-X]

Yup, and the same with -PDO. We will likely see big-time blocking on both sides of the continent this coming winter...yet again.

This is starting to make up for the abysmal 80s and early 90s.

[A-L-E-X]

I found a few summer -nao streaks...

7/21-8/28 1954

1957 missed by one day having a two month streak...

7/12-9/9 1958

7/27-9/6 1966

6/20-8/9 2009

Did we have a long -NAO streak last summer also? It's interesting that the one in 1966 was correlated to a very hot and dry summer here, but none of the others in that list were. We've had -NAO for the last four summers, but the first two were cooler and the last two (including this one), have been hot.

[A-L-E-X]

It's bee

It's been useless the last 2 years however. We've just been -NAO almost the whole time. October comes in with these massive -NAO blocks and then it happens in winter again.

Will, I've noticed isotherm's pattern of milder than normal Novembers resulting from a +NAO correlates well with snowy winters here.... but the last couple of years, it seems like -1 has almost become the base NAO state. I remember reading that this also happened during earlier solar minima.

[A-L-E-X]

You appear to be right on that level. I think the central US ridging and US East Coast troughing has been overwhelming strong. Once we get closer to a more neutral NAO state next week this shouldn't be the case.

I believe this also happened in 1995-- and you needed a late season reversal (Opal, October 1995) to get a major landfall.... perhaps this is the kind of pattern that favors late season landfalls, when the NAO temporarily switches back to positive, before really going in the tank for winter. I have been telling Matt for awhile now (he lives in Florida) not to look for any landfalling hurricanes before September lol.

[A-L-E-X]

Yup, and the same with -PDO. We will likely see big-time blocking on both sides of the continent this coming winter...yet again.

Omega Block

[SnowGoose69]

As Chuck's research has shown, summer -NAO is correlated well to a -NAO during the winter. I do think we see a continuation of the -NAO (respite in September-October/November, perhaps), and that the South will stay rather dry as well given the continuation of La Nina. Obviously, I think there's a good chance the STJ will be rather anemic this winter.

Cue weenie suicides in the southern Plains and Southeast as well as a few farmers in OK and TX.