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Negative NAO coming?


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snow 2-25-1972.pdfsnow 2-24-1972.pdf

actually it was the 23rd...

http://climate.usurf...ucts/output.php

The problem with citing to that storm is that it was a slushfest. From what I recall reading the New York Times the day after the storm (we flew in from Barbados that night) we had snow and rain. I tried to attach a copy of the articles.

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I suspect that we will see a SSW in January due to a number of factors. We have a descending QBO, increasing stratospheric ozone levels, feedback from end of October Siberian snow cover levels and increased Atlantic Ocean heat flux.

Does anyone here have experience on predicting wave breaking events into the stratosphere that we can use to predict a SSW.

Generally we will see wave breaking events into the stratosphere following strong mountain torque events. These can generally be predicted by following the GWO phases. So, is there anyone who has attempted to forecast SSW's in the US by using these techniques and if so how well have they done?

Cheers

c

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I suspect that we will see a SSW in January due to a number of factors. We have a descending QBO, increasing stratospheric ozone levels, feedback from end of October Siberian snow cover levels and increased Atlantic Ocean heat flux.

Does anyone here have experience on predicting wave breaking events into the stratosphere that we can use to predict a SSW.

Generally we will see wave breaking events into the stratosphere following strong mountain torque events. These can generally be predicted by following the GWO phases. So, is there anyone who has attempted to forecast SSW's in the US by using these techniques and if so how well have they done?

Cheers

c

I think HM may have. That's too sophisticated for me but I do think the strong positive ao should wane in Jan and think your reasonable sounds good.

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I think HM may have. That's too sophisticated for me but I do think the strong positive ao should wane in Jan and think your reasonable sounds good.

It will wane long before that... there already is a sub-minor SSW happening right now. Agreed that the big one won't be until at least mid-month though.

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Okie, look at the bottom panel and how the forecasts have been way too low since OCtober. That's partly due to the meaning out of all the solutions. I wouldn't be surprised if it weakend some but doubt that it will go negative that quickly but I guess we won't knwo for a couple of weeks.

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I don't think that looking at the 1hPa stratospheric charts are a reliable indicator of weather there is going to be a SSW. The top levels of the stratosphere show an increased response to all types of waves that reach the top of the stratosphere but from what I have observed very few will break through and propagate to lower levels. We can have minor warmings of stratosphere throughout the polar winter but we cannot have a minor SSW. We either have a SSW or we don't. The latest warming could hardly be classed as a minor minor warming even!

THere are two ways that waves can break into the stratosphere, either remotely by riding over the top of the 'surf zone' at the edge of the stratospheric vortex (where the greatest potential vorticity exists) or locally by breaking up through the central area of the tropospheric vortex. The start of last winter demonstrates a couple of local wave breaking events.

The rubber band analogy is interesting but if one looks at the Antarctic polar vortex we see that the stratosphere becomes a lot colder there with only ever snapping once. The difference between this and that Arctic polar vortex is the existence of the land masses that interact with the vortex allowing the waves to break upward into the stratosphere and therefore for the 'snap' to occur. So that brings me back to the original question in being able to predict the exact timing of a SSW.

Studies have shown that the stratospheric vortex is 'preconditioned' more often than not prior to a SSW occurring and that this preconditioning involves either a Pacific or Atlantic based upper blocking system (or both). However, there are far too many times when these types of block have occurred without a SSW so it is difficult to judge.

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Chiono,

I don't know the answer and you certainly do get blocking without a SSW event. I don't understand mountain torque events well enough to use them as a forecast tool. I have tried to use the GWO to try to anticipate blocking and it sure seems like when you get towards phases 7 and 8, the potential in the east is greater but I've had more success with that during el nino years like 2009-2010 than la nina ones.

As to those thinking the AO was gong to really tank. Look how badly it has underforecast the ao index and how even its forecasts show it rising again to astronomical levels towards the end of the period.

post-70-0-81996400-1322920275.gif

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I posted this comparison in the PHL subforum but think it fits well here. Here's a plot of what is currently happening at the higher latitudes.

post-70-0-73992000-1322924595.png

Note that as the blue shades get colder in the stratosphere the tropospheric pressures and heights also start to fall and that we really look to have started a cold vortex event in November.

Now look at the baldwin Dunkerton figure and note the similarities and how that the positive ao type conditions last for about two months.

post-70-0-82318900-1322924774.png

I'm sure using such a dumb guy approach is loaded with pitfalls but that's part of why I think the AO will stay positive into early Jan and then wane. What happens after that is anyone's guess. I've proved I'm not a seasonal guy.

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LOL, one member has it at +6, I'm not sure anything below or above -5 and +5 respectively is even possible.

FWIW, the following are the all-time records for the AO:

Highest: +5.911, February 26, 1990

Lowest: -7.433, January 15, 1977

The AO has reached or exceed +5.000 on 14 occasions since 1950. The AO has fallen to -5.000 or below on 47 occasions since 1950 and to or below -6.000 on 8 occasions since 1950.

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FWIW, the following are the all-time records for the AO:

Highest: +5.911, February 26, 1990

Lowest: -7.433, January 15, 1977

The AO has reached or exceed +5.000 on 14 occasions since 1950. The AO has fallen to -5.000 or below on 47 occasions since 1950 and to or below -6.000 on 8 occasions since 1950.

Interesting stats.

Jan 1977 was a beast of a month for cold, but no NESIS events. Perhaps the polar vortex was just too far south to allow anything to move up the coast.

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Interesting stats.

Jan 1977 was a beast of a month for cold, but no NESIS events. Perhaps the polar vortex was just too far south to allow anything to move up the coast.

there was one storm that tracked from the Gulf to the great lakes around January 10th or so...It brought snow changing to rain in NYC with another blast of cold air in its wake...

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Chiono,

I don't know the answer and you certainly do get blocking without a SSW event. I don't understand mountain torque events well enough to use them as a forecast tool. I have tried to use the GWO to try to anticipate blocking and it sure seems like when you get towards phases 7 and 8, the potential in the east is greater but I've had more success with that during el nino years like 2009-2010 than la nina ones.

As to those thinking the AO was gong to really tank. Look how badly it has underforecast the ao index and how even its forecasts show it rising again to astronomical levels towards the end of the period.

post-70-0-81996400-1322920275.gif

Tanked! lol

ao.sprd2.gif

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