With all the different weather news around the world over the last month or so, I thought that in this issue we should take a little time to look at some of these events.
The first item is the global temperatures for July. Depending on which data set you want to look at, the globe recorded either the second-or fifthwarmest July on record. According to the National Oceanic and Atmospheric Administration’s (NOAAs) National Climatic Data Center, July 2010 was the second warmest, behind 1998. Interestingly, July was the first month since February that was not the warmest on record, according to NOAA.
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Over at NASA’s Goddard Institute for Space Studies, they rated July 2010 as the fifthwarmest July on record. Land temperatures across the globe were the warmest on record during July, but cooler conditions across the Pacific led to lower overall global temperatures.
If you are a believer in satellite-derived global temperatures, which measure the temperature of the lowest eight km of the atmosphere, we’re having the second-warmest July on record, according to University of Alabama Huntsville (UAH), and the warmest on record, according to Remote Sensing Systems (RSS).
Tied into the look at global temperatures, Arctic sea ice in July was the second lowest on record, according to the National Snow and Ice Data Center. Weather over much of the Arctic during July was relatively cool, at least compared to 2007, when the record low was set. While the extent of sea ice was at its second lowest in July, ice volume was at a record low. By the middle of July, the fabled Northwest Passage was almost open and is expected to be open for navigation during most of late August and all of September. The northern part of the Northwest Passage is currently open, which is almost a month ahead of when it opened in 2007.
Hail record broken
For those of you who are into severe storms, and in particular hail (hello Alberta), a severe storm on July 23 dropped hundreds of massive hailstones on the small town of Vivian, South Dakota. One of the stones collected broke the U. S. record not only for the largest hailstone (in diameter) but also the heaviest. According to reports, the stone measured 20.3 cm in diameter, 47.0 cm in circumference, and weighed 0.89 kg (1.9375 lbs). Apparently the hailstone was originally much larger, but the freezer it was stored in lost power for about five to six hours and the person who collected it kept opening the freezer door to show friends and relatives!
The world record for the heaviest hailstone comes from Bangladesh, with a stone that weighed 1.02 kg (2.25 lb) collected in April 1986.
More recently, the Great Russian Heat Wave of 2010 has now officially come to an end. A large trough of low pressure crashed through the ridge of high pressure that has been “stuck” over eastern Asia, bringing much cooler conditions to the region, with high temperatures failing to break 20 C on Aug. 20. Along with the extreme heat this summer came record-dry conditions. Soil moisture over this region (European Russia) has dropped to levels so low that they would only be expected once in every 500 years. I guess we really shouldn’t complain about our weather over the past few years.
Going back to global temperatures, and in particular, temperatures across the Pacific Ocean, the equatorial Eastern Pacific Ocean is now experiencing what is considered a moderate La Nińa. Sea surface temperatures (SSTs) dropped to 1.1 C below average by the middle of August, according to NOAA. La Nińa conditions must be present for several months before this current cooling event will be officially classified as a La Nińa event, but it looks highly likely that a full-fledged La Nińa event has arrived.
So it appears that the overall atmospheric circulation pattern across the Northern Hemisphere is undergoing a major shift and exactly what new pattern will emerge is still up in the air (bad pun). It looks like it could be a couple of interesting months ahead as the atmosphere searches for a new stable pattern.
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Julywasthefirstmonth sinceFebruarythat wasnotthewarmest onrecord,accordingto NOAA.
