Part 2 Major weather events included Hurricane Isaac, hot rain in Mecca and Greenland’s major melt
It has been a fairly active start to 2013 across much of Canada. With heavy snows over parts of Alberta and Saskatchewan, blizzard conditions over southern Manitoba, record-shattering heat over southern Ontario, and the season’s first big snowstorm in Newfoundland. If this keeps up, 2013 just might be one of those weather years for the record books — much like 2012!
In this issue we’re not going to look ahead to see what 2013 might hold in store for us; that will be in a few weeks. Instead, we are going to continue our look at what I think were the top weather stories around the world in 2012. Instead of ranking them like most lists, I chose to look at the weather on a month-by-month basis, picking out the biggest weather stories for each.
In our last article I finished up with April, a surprisingly quiet month globally. May continued this quiet trend, although there were a few notable weather events. The two most prominent of those were tied together: record heat over Europe and extreme record heat over Greenland. A persistent area of low pressure allowed warm Saharan air to invade much of central Europe during the last few days of April and the first week or so of May. Temperatures soared into the low 30s in Austria, Poland and Germany during this early-season heat wave. Later in the month, climate records were rewritten over the southern coast of Greenland when the temperature at Narsarsuaq reached 24.8 C. This was the hottest temperature ever recorded in May for Greenland and was just 0.7 C below its all-time record high.
Warmest. Temperatures. Ever
There were, I think, two weather stories in June worthy of discussion. The first occurred June 5 in the city of Mecca, when sea breeze from the Red Sea pushed inland creating thunderstorms with some light rain. What’s astounding was that rain fell when the temperature in Mecca was 43 C, making it the hottest rain ever recorded! The other big event was the record-warm temperatures over much of the central U.S. During the last week of June nearly five per cent of the main long-term weather reporting stations in the region broke all-time record highs. These were not just June all-time records, but rather, records for the warmest temperatures ever recorded! This was definitely a heat wave that would rival the 1930s-era dust bowl.
The big story of July was not the continuation of the heat over much of the central U.S and southern Canada, but the extreme heat over Greenland. On July 12, satellites observed that 97 per cent of Greenland had experienced melting, something that only appears to occur naturally every 150 years or so. At the top of Greenland a weather station that has only reported four days above freezing over the last 12 years experienced five days during June with above-freezing temperatures. These warm temperatures and melting resulted in record flooding and may have contributed to a massive 119-square-kilometre iceberg breaking off the Petermann Glacier. I think I also have to note Death Valley, California broke the world record for the warmest overnight low on July 12, when the thermometer only dropped down to 41.7 C (107 F).
The big weather story for August was probably Hurricane Isaac, which formed in the tropical Atlantic on June 21, hit the Dominican Republic and Haiti on the 25th, and finally made landfall in the U.S. near New Orleans on Aug. 30. While Isaac wasn’t an exceptionally strong hurricane it was very slow moving. This resulted in rainfall totals exceeding 400 to 500 mm (15 to 20 inches). The reason for Isaac’s slow motion was the continued drought over the central and northern U.S., which helped to intensify a ridge of high pressure over this region, preventing Isaac from moving northward.
I think unquestionably the biggest weather story of September was the record-low Arctic ice. After ice levels over the Arctic Ocean reached near-average levels in April, the ice began to quickly melt from May through into August. This melt was mostly due to the fact that previous years’ melts have greatly reduced the amount of multi-year ice, leaving mostly thin one- or two-year-old ice that is susceptible to quick melting. Weather conditions over the Arctic were warmer than average, but overall, they were not conducive to extreme melting. By the time Sept. 16 rolled around, sea ice extent had fallen to 3.41 million square km, beating the previous record set in 2007 by 18 per cent. This past year was also the fifth in a row (and also the fifth time in recorded history) in which ice-free navigation was possible in both the Northwest Passage and the Russian Passage.
Once again that’s all the room I have for this issue. Next I’ll finish my roundup of 2012 world weather events, then take a quick look at Canada’s top 10 weather stories from 2012.