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Possible Change In Weather Pattern

I’m going to start off this week’s article with a quick look at global weather records and patterns so far this year. According to the National Oceanic and Atmospheric Administration (NOAA), the first nine months of 2010 have been the warmest ever recorded. If this pattern keeps up, 2010 will go down as the warmest year, as a globe, on record. For those of you who question or don’t trust land records of temperature, according to global satellite-measured temperature data for the lowest eight kilometres of the atmosphere, as measured by both NASA’s Goddard Institute for Space Studies’ remote sensing systems and by University of Alabama Huntsville, the year-to-date January-to-September period is the first-and second-warmest such period as well.

Interestingly, this global temperature record will have occurred at a period when the sun’s sunspot activity is just coming out of a record-low period. Research seems to indicate that when we experience low numbers of sunspots, the Earth tends to cool down. This makes sense as the amount of energy coming out of the sun decreases and increases slightly in accordance with sunspot activity. Since we didn’t see any global cool-down during this latest sunspot minimum, it will be interesting to see what happens

with global temperature over the next five years as sunspot activity increases toward the next maximum expected to occur around 2012 or 2014.

Another area of interest, weather-wise, is the current La Nińa event occurring over the Pacific Ocean. During September, this cool ocean phase intensified from what is considered a moderate La Nińa to a strong La Nińa. These conditions are forecast to last right through the winter and into the spring, which means there is a fairly good chance we will see a La Nińa winter across Western Canada.

Our final area of global interest is the Arctic sea ice extent. The Arctic sea ice reached a minimum coverage of 4.6 million square km on Sept. 19, which was 2.44 million square km below the 1979-2000 average.

This made 2010 the third-lowest amount of sea ice on record. During September, for the third time in the last five years, and the third time ever recorded, both the Northeast and Northwest Passage were open and ice free at the same time. This made it possible to circumnavigate around the Arct ic by boat dur ing September.

Also of extreme interest was the total Arctic ice volume this year. The ice volume takes into account not only the surface extent of the sea ice but also the thickness of the ice. During 2010 the Arctic ice volume fell to an all-time record low of 4,000 cubic km. This is 70 per cent below the 1979-2000 average of 13,400 cubic km. This value really shows just how dramatic the loss of Arctic sea ice has been over the last 10 years.

TREATS AND TRICKS

Looking at the weather locally, October 2010 has brought some of the nicest October weather seen on the Prairies in a number of years. After a cool and wet spring, a very slightly warmer-than-average but fairly wet summer, and then a cool September across much of Western Canada, this October’s mild and dry start has not only been welcomed, but in some areas has been a real lifesaver.

Whi le it doesn’t look as though we’ll break any weather records for the month of October, it does look like the warm, dry weather will continue, at least for the next week. The medium-to long-range models are keeping most of Western Canada under a ridge of high pressure right through to around Oct. 25. At that time the models are pointing toward a dramatic change in the weather across the Prairies. With this change in weather we’ll see wetter weather move in – and along with it, cooler conditions.

While it looks like October will end on a cool, wet note, I am not 100 per cent sure whether we will get through the month of October without seeing any major snow events. Each model run over the last few days has been showing colder and colder conditions moving in by the middle of next week.

For those of you looking for an early Halloween forecast, the models currently bounce back and forth between cold and mild conditions. One model run has Western Canada fairly warm and the next run it shows us cold and possibly snowy. When the models do this, all I know is that we are likely going to have a significant change in our weather pattern; the big question is, when will it occur? It would be nice if we could see a mild Halloween for all the trick-or-treaters out there.

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Itwillbeinterestingtoseewhathappens withglobaltemperatureoverthenext fiveyearsassunspotactivityincreases.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.

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