Seasonal winter 2013/2014 forecast based on OPI index

[Ginx snewx]

I confirm this news. We are very happy for this important collaboration. One of our main objectives will be to develop the themes related to the forecast of the winter subseasonal variations. At this regard we have already implemented on the software a specific algoritm which is able to calcolate (in October) the tropospheric wave activity development during the winter. The following figure shows this development about this winter (season 2013-2014):

As said, it shows the develompent of the wave activity during winter only at tropospheric level, so it shows directly the main winter phases at mid-latitudes (in particular North America and Europe).

By this graph we can see that there are two maximum tropospheric wave activity events: the first at the beginning of winter (end November-beginning of December) and the second almost at the end of winter (about 5-20 th of February).

About the first part of the winter already passed, we can note the high performance of our forecast. In fact we had predicted very strong advenctions of cold arctic air masses to the central-eastern areas of the North American continent due to a strong Aleutian anticyclone in elevation on the Gulf of Alaska at the end of november-first part of December. The following picture represents our forecast for this perid (end November-beginning of December) published at beginning of November:

Now we report the picture which shows the 500 hPa geopotential anomalies about the same period (end November-beginning of December):

After this first dynamic phase, we had predicted the start of the long zonal phase with a strong polar vortex. And this is the real development:

To conclude we can certainly note the good corrispondence between our forecast and the actual course of events about this first part of winter already passed.

About the future we believe that, after a very short stop (by first graph around end of December), the Tropospheric Polar Vortex (VPT) will reach again a new important compactness during January (especially the first half). In this way the mean quarterly AO would be very high and close to the value expected by the OPI (and also by the SAI).

The planetary tropospheric wave activity should resume in the second last part of Janary with restoring of winter season typical conditions. This new tropospheric wave activity should reach the best expession about at first half/central part of February (see again the graph), when they might occur other important cold arctic advenctions.

We wish you a marry Christmas

Riccardo Valente, Alessandro Pizzuti, Filippo Casciani and Andrea Zamboni member of the Center for Study on Climate and Teleconnections of "Centro Meteo Toscana"

fantastic theory, you may have a setback in your correlation numbers for the start of Jan. Also this upcoming Jan cold looks more impressive than the Dec cold.

[sebastiaan1973]

Due to Ginxy message, I reapeat myself here

 

Riccardo thanks for the update. I placed a link to the Dutch/ Belgium Website weerwoord.be as well. So the people from the Benelux can read it as well.

 

I have two questions. What does the vertical axis mean?

And secondly. This graph shows only troposferic wave-activity. Couldn't it be possible -hypothetically- that the maximum in february is forced by the stratosphere, i.e. by some sort of wave-induced event (either minor or major warming) in mid-january? So what is your opinion about warming of the stratosphere later on in januar and februar?

Thanks in advance!

[The_Global_Warmer]

The OPI calls for a 1.64 AO+ this year.  Barring a major period of negative AO.  It will probably be very close. 

 

 

 

 

 

It will be interesting to see how the guy making NAO predictions works out.  So far it doesn't look to hot.  If the NAO predictive index is legit(The Author won't tell anyone how he comes up with it) then we should expect long periods of the NAO being very negative sometime the next three months.

 

[donsutherland1]

IMO, it is too soon to call the proverbial horse race, just yet. The probability of a positive December-February AO has certainly been aided with December's values. The NAO figure, though, is for the larger December-March period.

 

Through 12/27, the AO has averaged +1.766. The NAO has averaged +0.481. If one takes the ensemble values for the rest of the month (assuming a -0.5 average AO, probably a "worst case" and 0.0) NAO, the monthly averages would come out to +1.474 for the AO and +0.354 for the NAO.

 

Here is where things get interesting. When it comes to the AO, a negative January-February (1950-2013) average has been twice as frequent as a positive one. In contrast, a positive NAO average for the January-March period has been just over 35% more common than a negative one. This means that if the AO comes out even reasonably close to the 1.64 OPI figure, the OPI will provide a lot of value, as the AO would have gone against the climatological probabilities for January-February.

 

As noted earlier, I am pulling for Ricardo and his team to be right, as accurate winter forecasts of the AO can improve overall seasonal forecasts. That Dr. Cohen is now collaborating with the OPI team indicates that at least some notable scientists find the work encouraging and it shows a willingness among the OPI team to share their work with the scientific community. This collaboration is a very good early assessment of the OPI's potential.  

 

With respect to the NAO, the proverbial degree of difficulty in overcoming climatology would not be as great. Nevertheless, there would be some challenge.

 

Below are tables showing the December-February AO average based on a range of January-February figures and the December-March NAO average based on a range of January-March figures. Both figures assume that the GFS ensembles will be correct. I have also included the climatological occurrence of each of the values (1950-2013) for greater perspective.

 

 

For now, near the end of December, the OPI is off to a very good start.

[Jonger]

The OPI seems to be working out for the AO index, just not the end all of winter forecasting. I should say that the AO isn't the end all of winter forecasting.

[donsutherland1]

The OPI seems to be working out for the AO index, just not the end all of winter forecasting. I should say that the AO isn't the end all of winter forecasting.

The AO has a larger influence on Europe, but is one important factor in shaping the North American winter. If the OPI proves reliable in forecasting the AO, it will be interesting to see if its methodology can be expanded to forecast the WPO/EPO. If so, there will be potential to markedly improve winter seasonal forecasts, though uncertainty will continue to exist as positions of ridges/troughs in the means can and do make a difference.

[Absolute Humidity]

FWIW, AO was negative for 11 consecutive days beginning Dec 28th. NAO was negative for 9 consecutive days as well.

[chionomaniac]

I confirm this news. We are very happy for this important collaboration. One of our main objectives will be to develop the themes related to the forecast of the winter subseasonal variations. At this regard we have already implemented on the software a specific algoritm which is able to calcolate (in October) the tropospheric wave activity development during the winter. The following figure shows this development about this winter (season 2013-2014):

 

As said, it shows the develompent of the wave activity during winter only at tropospheric level, so it shows directly the main winter phases at mid-latitudes (in particular North America and Europe).

By this graph we can see that there are two maximum tropospheric wave activity events: the first at the beginning of winter (end November-beginning of December) and the second almost at the end of winter (about 5-20 th of February).

 

About the first part of the winter already passed, we can note the high performance of our forecast. In fact we had predicted very strong advenctions of cold arctic air masses to the central-eastern areas of the North American continent due to a strong Aleutian anticyclone in elevation on the Gulf of Alaska at the end of november-first part of December. The following picture represents our forecast for this perid (end November-beginning of December) published at beginning of November:

 

 

 

 

 

 

Riccardo Valente, Alessandro Pizzuti, Filippo Casciani and Andrea Zamboni   member of the Center for Study on Climate and Teleconnections of "Centro Meteo Toscana" 

Hi Riccardo 

 

Looking at your tropospheric wave activity forecast, would you say that this has verified?  To my eye there has been a large amount of tropospheric wave activity rebounding into stratosphere since the start of the year - moreso than this graph would suggest. There are also hints that we are likley to see another increase in wave 2 activity coinciding with early February that would correlate well with your forecast - would you make any amendments at this point?

Thanks

 

c

 

Great work btw.

[Jonger]

So how did year end up correlating?

[easternsnowman]

It seems like the pacific has more to say this winter like 1993-94.