The snowpack has pretty much disappeared across farmland on the Prairies, and, as is typical with spring, the snow has come and gone a few times now!
That said, for the most part, it was a fairly early year for snow cover loss. With rising temperatures our thoughts slowly begin to shift towards more summer-like weather, and in particular, thunderstorms. So far it’s been a very quiet start to the thunderstorm season across the U.S., with the period of January to March only seeing 38 tornadoes, compared to an average of 163, as reported by the Weather Underground.
Across our region there have been a few lightning strikes so far this year, making some of us wonder if this might be a more active year for our part of the world. Usually by this time of the year, I like to re-explore the topic of thunderstorms and severe weather, but I think I’ll leave that for another couple of weeks and allow the weather to warm up a bit more.
For this issue we’ll take a look at a few interesting weather stories that have come up around the world.
Let’s start off at the bottom of our planet — Antarctica. According to Christopher C. Burt, the continent may have broken an all-time heat record. On March 24, Base Esperanza, located near the northern tip of the Antarctic Peninsula, recorded a temperature of 17.5 C. The reason for the “may have” broken a record is kind of complicated, and basically has to do with the remoteness of the region and what is officially considered Antarctica and what is not. Should the record only count if it comes from the continent proper and not one of the islands? If you include the islands, then how far off of the coast do you go? If you are interested in looking into this further, I suggest you read Christopher’s full article located at the Weather Underground.
Jumping to the top of the world, it appears Arctic winter sea ice will set a record for the lowest maximum extent. Ice coverage reached what looked to be a maximum on February 25 at 14.54 million square kilometres. The 1981 to 2010 average is 15.64 million square kilometres. The ice continued to decline into early March before growing slightly during the rest of the month, but it doesn’t appear that it increased beyond the February 25 level and has started to decline once again. With ice coverage already two standard deviations below average at the beginning of the melt season, it could be an interesting summer over Arctic waters.
Going back south, heavy rain fell in the driest place on Earth, the Atacama Desert in Chile. This region typically only sees about 1.7 millimetres of rain a year. You read that right — 1.7 millimetres of rain per year! There are parts of this desert that have never seen rain.
The reason this region is so incredibly dry is that it has a triple whammy of conditions that prevent rainfall. First of all, it is located around 20 degrees south, which puts it in the zone where high pressure usually resides due to subsiding air. Second, it is located on the rain shadow side of the Andes Mountains. As the easterly trades rise up over the Andes they cool and the moisture falls. This air then descends across the Atacama Desert, warming and drying as it does.
Either of these two processes would keep the region dry, but to make it even worse is the fact that there is a cold current of water flowing along the coast, which prevents any significant amount of moisture from coming in off of the Pacific. In fact, most of the rainfall in this region comes in the form of mist or drizzle.
So, how much rain did it get? Well, on March 25-26, 24.4 millimetres of rain fell in a 24-hour period, or more than 14 years’ worth of rain. While this doesn’t sound like much, for an area that does not get rain, it has caused some severe flooding with at least 107 people either dead or missing.
Finally, our last piece of weather news comes out of California, and yes you probably guessed it — drought. Modest winter rains brought water reservoir levels up a little, but a recent spring-winter snowpack survey brought some devastating news. The survey found that the snowpack, which is a major contributor to filling California’s reservoirs over the summer, held only five per cent of the usual amount of water it should have at this time of the year. This means there will be virtually no spring run-off and thus almost no water making it into the reservoirs. So while the reservoirs might seem to be doing a bit better, any water that is in them right now will be quickly depleted over the summer. California has now introduced mandatory water restrictions, and with a large part of California’s agricultural industry relying on water, this will be a very interesting summer to watch and see what happens.