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2011-2012 Winter Outlook

weatherwiz

By weatherwiz,
in New England

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weatherwiz

weatherwiz

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I'm not really happy with how I wrote it, been typing it up for several hours but w/e. Been going absolutely insane mentally working on composing this. From now on I'm doing much more work with long-range forecasting and understanding all the variables involved.

Disclaimer: If reading this outlook keep in mind I am not a meteorologist nor do I have any skill in long-range forecasting. The aspect of long-range (seasonal) forecasting is very challenging and this is a relatively new science. Major progress has been made though over the past decade as research on past weather patterns and data has improved vastly. Long-range forecasting is something I have become highly interested in over the past few years and I would like to one day forecast for energy companies. In order to do this and be successful it takes a great deal of practice and study, which is why I compose outlooks. With this said it's probably a safe bet not to take this forecast to heart and not something you want to rely on. I am still in the early stages of learning and understanding all the process involved in long-range forecast. With this cleared up it's time to go into my 2011-2012 Winter Outlook.

When composing a seasonal outlook one of the most important things to consider is the current ENSO state, where ENSO may be headed over the next several months and what the ENSO state was the previous season. The winter of 2011-2012 is on the heels of what was a borderline moderate/strong La Nina winter. By early summer the Nina faded, however, was still present but in a lesser form. Over the past few months we have seen ocean temperatures in the equatorial Pacific gradually cool and it appears as if we will be headed towards yet another La Nina winter, although this one is not forecasted to be as strong as last winter's Nina.

Once you have answered the above questions the next thing to do is find analog years. Analogs are when you look back at past years and compare them to the current pattern in place and how the pattern has unfolded the past several months. One thing to do is look at trimonthly ONI (Oceanic-Nino Index) data and compare it to past ONI data for the same period.

2011 ONI data for MAM (March-April-May) was -0.6C, AMJ (April-May-June) was -0.2C, MJJ (May-June-July) was 0.0C, JJA (June-July-August) was 0.0C and JAS (July-August-September) was -0.2C. From here I went back and looked at all MAM, AMJ, MJJ, JJA, and JAS data between 1950-2010. If any other period had values which were within +/- 0.3C of the period being looked at I wrote down that year. For example, since the 2011 MAM number was -0.6C I looked back at all MAM's from 1950-2011 and anyone that was between -0.3C and -0.9C I wrote that year down. When all this was completed and a list of years was compiled I looked for which years appeared the most. The following years are; 1967-1968; 1996-1997; 1962-1963; 1968-1969; 1976-1977; 1984-1985; 1951-1952; and 1989-1990. The next step was too look at the ENSO state for each of those years. If any of these years featured a Nina of some sort or ENSO neutral the years were kept, if they featured an EL Nino they were discarded. Going by this method the following years were kept; 1967-1968; 1996-1997; 1962-1963; and 1984-1985. With these four years in mind next it was time to dissect the past following months even further and gauge how quickly La Nina conditions in the equatorial Pacific may be developing and take a look at sea-surface temperature anomaly (SSTA) readings over the past several weeks then take a look at what long-range computer model forecasts are showing in terms of ENSO state for the upcoming winter.

Beloware animations from the Climate Prediction Center (CPC) showing sea-surface temperatures (SST'a) (top image) and sea-surface temperature anomaly trends (bottom image) across the eastern equatorial Pacific from August 3rd, 2011 through October 19th, 2011. Blue/purple shadings represent colder than normal sea-surface temperatures (SST's) while yellows/oranges/reds represent warmer than normal sea-surface temperatures. As you can see since the beginning of August we have seen some cooling of the sea-surface temperatures just off the coast of South American with this cooling beginning to develop further east out into the Pacific as well.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml

After a visual look was taken at the SSTA's across the equatorial Pacific the next thing I did was to look at actual raw numbers for each of the Nino regions; Nino 1+2, Nino 3, Nino 3.4, and Nino 4. Here is a graphic showing where each region is defined:

ninoareas_c.jpg

Below is a chart showing SSTA anomalies in each of the four Nino regions dating back to the first week of August. As you can see since the first week of August we have seen some gradual and steady cooling occur in all Nino regions:

ENSOweeklies.jpg

The final process here was to take a look at what some long-range computer models are showing for the ENSO states this upcoming winter. Will we continue to develop a La Nina and if so, how strong would it become? The following image is from the CPC and shows a list of several different long-term computer models and what they project will happen. In this graphic the consensus seems to be that we will indeed continue heading into La Nina territory and the Nina may peak at a high end weak La Nina or perhaps a low-end moderate La Nina:

sstaa.gif

With all of this information compiled I feel that we will indeed see a La Nina continue to develop and strengthen and end up around moderate strength category. With this idea in mind I went back to the analog years I had compiled and looked at how strong the Nina's were that developed. 1967-1968 featured a weak La Nina, 1996-1997 was neutral, 1962-1963 was a weak La Nina, and 1984-1985. Due to the fact that 1996-1997 winter was a neutral ENSO winter and this winter will be more of a Nina 1996-1997 was discarded and I was left with the following years as my analogs; 1962-1963, 1967-1968, and 1984-1985. It is these three years that will influence what I believe will happen this winter.

With the ENSO state looked at and reviewed and analogs found to match how things have unfolded the past several months the next step was to look into the major teleconnection indices which are known to have a significant impact on the overall weather pattern during the winter months. Some of the global teleconnection indices looked at were the North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Quasi-Biennial Oscillation (QBO), Madden-Julien Oscillation (MJO) and the current state of solar activity going on with the sun.

North Atlantic Oscillation (NAO)

The NAO is measured by the difference in sea-level pressure (SLP) between the Icelandic Low (Polar Low) and the Azores High (Subtropical High). The NAO oscillates between positive and negative phases (with the positive phase of the NAO occurring when the Polar Low is deeper than normal and the Subtropical High is stronger than normal and the negative phase occurring when both the Polar Low and Subtropical High are both weaker than normal) which can occur on a monthly to even weekly basis. However, the NAO can also tend to stay in one phase for periods lasting as long as several years to decades. The NAO plays an extremely important role in the North American pattern during the winter months.

When taking the NAO into consideration here the biggest factor to consider was how has the NAO behaved lately? As mentioned above while the NAO can fluctuate between positive and negative phases on a monthly or even weekly basis it does have a tendency to be in one phase more commonly for periods lasting as long as several years or even decades. For example, from about 1950 through the late 1970's the NAO was commonly more negative, while from about 1980 through early 2000's the positive phase of the NAO seemed to be a more common occurrence. Since the early 2000's we have seen more variability in the NAO phase, however, since about 2008 the NAO has been predominately negative, especially in the winter months. This was noted and taken into strong consideration when dealing with predicting what the NAO will be this winter.

The next thing to do was look at the winter months for my analog years and see which phase the NAO was in for those winters. It just turned out to happen that all years with the exception of December of 1984 featured a NAO that was negative.

When dealing with forecasting the phase of the NAO long-term there is not a great deal of success with this quite yet, although there are some that have done excellent work with this. It is still not entirely understood how the NAO works or what exactly influences it's changes, although through research conducted by several people it appears as if the Quasi-Biennial Oscillation as well as solar activity do have an influence on the NAO. With this said I have zero knowledge of forecasting the NAO nor have I ever tried doing so. When coming up with my thoughts for the NAO this upcoming winter I just looked at what some long-range computer models are forecasting. While they don't go out very far they are showing a potential positive NAO for much of the first part of November. With this said, December of 1984 is the only month of my analog years which featured a positive NAO. When composing my temperature outlook for the month of December I decided to influence a potential positive NAO into the forecast. I do think we will see a negative NAO for much of January and February, however.

Arctic Oscillation (AO)

The AO has a close relationship with the NAO and it's believed that the NAO/AO sort of work together or at least influence one another. Like the NAO, the AO also oscillates between positive and negative phases and each phase can last for months, for weeks, and like the NAO this AO has a tendency to be in one phase for several years or even decades. I'm thinking with a potential positive NAO in December we will see a positive AO as well with a negative AO the rest of winter.

The combination of a positive NAO/AO for December I think will help lead to a warmer than average December across much of the east coast.

Quasi-Biennial Oscillation (QBO)/solar activity

The QBO is an oscillation of the zonal winds in the stratosphere (westerlies and easterlies) which propagate downward through the stratosphere and then dissipate at the tropopause in the tropics. When positive the winds are westerly and when negative the winds are easterly. The entire oscillation from the stratosphere to tropical tropopause is a little less than 30 months. The QBO is best measured between about 30-50mb. Through research it's thought that the phase of the QBO along with solar activity can have an influence on the phase of the NAO. Currently the 30mb QBO winds are now in the beginning stages of the negative (easterly winds) stage but don't look to become that strong during the winter if current pace holds true. On the other hand the 50mb QBO winds have been positive (westerly) for several months and these westerlies continue to grow stronger. With the QBO signal not very strong now and not really looking to be so right now the QBO may not play a major role this winter.

As far as solar activity goes we have finally seen an explosion of solar activity the past several months and look to be entering a period of increased solar activity. This may help lead to some good blocking patterns come mid winter on (help lead to a solid negative NAO). This could mean a colder than normal winter overall.

Madden-Juilien Oscillation MJO:

The final process looked at was MJO activity. The MJO is a cluster of showers/t'storms that develops in the Indian Ocean and works eastward through the tropical Pacific. Since the MJO is associated with tropical moisture and convection during moderate and strong La Nina episodes the MJO can be almost nonexistent as the cooler waters lead to less in the way of instability. The MJO goes through a cycle of 8 phases with each phase having an impact on the pattern across the United States. Currently the MJO is in phase 2 and should work between phases 3-6 or 7 as we move through the winter. These phases are usually associated with warmer weather throughout much of the US. The MJO could play a bigger role during the month of December with warmth, especially if the positive NAO does develop. How much of an impact will the MJO have later on in winter? All depends on how strong the MJO wave(s) is/are working through the Pacific and how strong the Nina gets.

With all of this put together here are my temperature/precipitation forecasts for each winter month as well as an average for the winter period. Enjoy...

winteroutlook.jpg

winteroutlookprecipanomalies.jpg

When composing the temperature maps for the month of December I weighed December of 1967 and 1984 more heavily. Both Decembers featured more of a ridge in the east with a trough in the west. While the NAO was not positive in December of 1967 like it was in December of 1984 the NAO signal was not quite strong and the negative Pacific-North American (PNA) teleconnection pattern helped to dig a trough deeper into the west which in turn helped to pump up the ridge across the eastern United States.

As for January/February all 3 analog years pretty much had similar January and February conditions across the United States with just about the entire country below average both months with only the west coast featuring above-average temps in February thanks to a developing positive PNA.

As far as precipitation goes all years also featured mainly below-average precipitation throughout a large chunk of the country at times, however, it was only slightly below-average and nothing really too extreme. When composing these maps one of the things taken into account were the 250mb zonal wind anomalies for the winter months of my analog years as well as the 250mb zonal wind anomalies across the globe currently and what they look to do over the following months.

Last but not least, what seems to be everyone's favorite...snowfall! Snowfall can be somewhat related to precipitation departures although the correlation is not always perfect and it does seem to be stronger across the northeast. When composing my thoughts on the snowfall outlook I just used the precip anomaly departure maps and looked at seasonal snowfall totals for the analog years. When doing that this is what I came up with as far as snowfall potential goes.

Snowfall across New England should run average to slightly-below average across the region with snowfall down across the mid-Atlantic region running average to slightly above average.

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weatherwiz

weatherwiz

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Good luck Wiz. What data did you use to determine the AO state for Nov.

Thanks, Steve.

I just looked at the ENS AO outlook

ao.sprd2.gif

I know this is a really poor method to use, especially considering I'm basing a December forecast off this but I know very little about forecasting NAO/AO long-term. Been reading alot of papers though lately on influences from QBO and solar and such and tried doing some work but I couldn't find anything that stood out but I really hope to do more.

Normally in the past when I've made outlooks I never continued to learn more and read when finished, I'd just wait until it's time to compose another outlook.

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Ginx snewx

Ginx snewx

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Thanks, Steve.

I just looked at the ENS AO outlook

ao.sprd2.gif

I know this is a really poor method to use, especially considering I'm basing a December forecast off this but I know very little about forecasting NAO/AO long-term. Been reading alot of papers though lately on influences from QBO and solar and such and tried doing some work but I couldn't find anything that stood out but I really hope to do more.

Normally in the past when I've made outlooks I never continued to learn more and read when finished, I'd just wait until it's time to compose another outlook.

Did you see NOAA mention in this years winter outlook that AO state is a much bigger player in the Northeast than Nina?

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weatherwiz

weatherwiz

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Did you see NOAA mention in this years winter outlook that AO state is a much bigger player in the Northeast than Nina?

I did not see that, interesting. I could see this as certainly being true. Last year I was doing something with the AO and Nina's and noticed that the AO seemed to have a pretty significant impact across the Northeast but didn't take much out of it.

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weatherwiz

weatherwiz

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It happens. The increase in flares is not tied to a increase in magnetism. Also check out Coastals thread I posted a great paper that explains a lot.

I did see the thread and I'm glad Scott made that thread. I will definitely have to read that paper.

This is what I was looking at when determining solar activity:

http://www.esrl.noaa.gov/psd/data/correlation/solar.data

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MegaMike

MegaMike

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A little snippet from Pete Bouchard's blog (11/3).

"Are we ready to read the tea leaves on winter yet? Nope. Still too early. But I will say this: ready the snowblowers, short sleeves and generators. If this year's been any indication, we're in for a doozy of a season. One that may see more records set (snow, high temps) more towns buried in snow or ice, and a busy pattern through the spring."

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