iWeather Online contributor Damien Kelly compares the freezing conditions of the 1962-63 and 2009-2010 winters, and assesses our chances of experiencing another severe winter this year.
Before assessing the potential for a sustained period of cold weather during the coming winter, I will first focus on the long harsh winter of 62/63.
By using Teleconnections of the atmosphere during this record breaking cold winter as well as the same set of criteria for last winter's sustained cold, I will outline what makes the perfect combination to enjoy the once abundant past cold winters.
The term "teleconnection pattern" refers to a recurring and persistent, large-scale pattern of pressure and circulation anomalies that spans vast geographical areas. Teleconnection patterns are also referred to as preferred modes of low-frequency (or long time scale) variability. Although these patterns typically last for several weeks to several months, they can sometimes be prominent for several consecutive years, thus reflecting an important part of both the interannual and interdecadal variability of the atmospheric circulation.
Many of the teleconnection patterns are also planetary-scale in nature, and span entire ocean basins and continents. For example, some patterns span the entire North Pacific basin, while others extend from eastern North America to central Europe. Still others cover nearly all of Eurasia (MORE).
This link recalls an excellent day-to-day summary of the winter that many have failed to live up to.
Now let me analyse that period with regards to teleconnections.
The QBO was very much negative during that bitterly harsh winter.
WINTER 1962/63
NOV DEC
1962 -15.40 -15.16
JAN FEB MAR
1963 -17.35 -16.68 -19.93
WINTER 2009/10
NOV DEC
2009 -13.83 -15.57
JAN FEB MAR
2010 -16.02 -16.98 -19.68
OCT 2010
10.83 (Now in positive state)
So looking at the state of the QBO last winter we can see that it gave 62/63 a great run for it's money, in fact not too far off a match.
OCTOBER 2010 - 10.83 (in a positive state which does not favour sustained cold).
WINTER 1962/63
NOV DEC
1962 -0.23 -1.32
JAN FEB MAR
1963 -2.12 -0.96 -0.43
WINTER 2009/10
NOV DEC
2009 -0.02 -1.93
JAN FEB MAR
2010 -1.11 -1.98 -0.88
Reviewing one of the most crucial atmospheric states for our region, we see that the beginning of the big freeze in November 1962 was a little below neutral (slighty negative) where as November 2009 was relatively neutral.
Our big switch came in December 2009 with the NAO going into a strong negative state.
December 1962 almost on a par but we won that one.
Apart from Janurary 1963 being more negative we had the perfect NAO state to open the siberian door.
WINTER 1962/63
NOV DEC
1962 0.57 -0.08
JAN FEB MAR
1963 0.58 0.81 -1.79
WINTER 2009/10
NOV DEC
2009 0.21 0.34
JAN FEB MAR
2010 1.25 0.58 2.02
I am uncertain about what bearing, if any, this has on Ireland. However it appears that anything slightly positive delivers cold because the PNA went strongly negative in March 63 and the big frreeze ended after the first week of this month.
I could be wrong, just an observation.
Now this is another interesting one.
WINTER 1962/63
NOV DEC
1962 -1.59 0.03
JAN FEB MAR
1963 -0.15 -0.74 1.49
WINTER 2009/10
NOV DEC
2009 -0.25 -0.79
JAN FEB MAR
2010 -0.63 -0.69 0.75
Again we see the change to strong positive in March 63, which also is in line with the end of the freeze. So anything below neutral seems to favour cold conditions here.
(AO - ARCTIC OSCILLATION. Click on image to enlarge)
This chart indicates that the winter of 62/63 was strongly negative peaking at -3.311.
WINTER 1962/63
NOV DEC
1962 -1.112 -0.711
JAN FEB MAR
1963 -3.311 -1.721 0.724
Note there wasa return to positive in March (the end of the big freeze)
A negative AO indicates height rises over the Arctic and it displaces the cold polar air further south. This is precisely waht happened during last winter.
WINTER 2009/10
NOV DEC
2009 0.459 -3.413
JAN FEB MAR
2010 -2.587 -4.266 -0.432
The below chart documents the last 30 days of 500mb height anomalies over the northern hemisphere.
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| Click image for a larger view |
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| CURRENT NAO CONDITIONS |
So what does it all mean for this upcoming Irish winter?
This summarised comparison of Teleconnections states during the winters of 1962/63 and 2009/10 provides an insight into the types of conditions required for a sustained outbreak of cold weather in Ireland this coming winter.
However, it is not as clear cut as this because these are just pieces of a huge jigsaw that hopefully someday will be completed to finally be able to stand back and eventually see the bigger picture.
This summarised comparison of Teleconnections states during the winters of 1962/63 and 2009/10 provides an insight into the types of conditions required for a sustained outbreak of cold weather in Ireland this coming winter.
However, it is not as clear cut as this because these are just pieces of a huge jigsaw that hopefully someday will be completed to finally be able to stand back and eventually see the bigger picture.