Rainfall far below average, says City of Nanaimo and Environment Canada
Chris Bush Apr. 2, 2019 1:35 p.m.LOCAL NEWSNEWS
Anyone wondering if March seemed particularly dry had their suspicions confirmed by precipitation statistics recorded for the month.
According to Environment Canada, March 2019 was Nanaimo’s sixth driest since record-keeping started in 1892.
“This is the lowest March we’ve seen in about 12 years in our drinking watershed,” said Bill Sims, city director of engineering and public works. “Up in the watershed we get significantly more rain than we do in town. We almost had nothing in town.”
Nanaimo initiated water conservation measures Monday, limiting lawn and garden water to nights and early mornings between 7 p.m. and 7 a.m.
Sims said in March, Nanaimo received just a fraction of normal precipitation.
“It was, like, five millimetres for the month, but we had 42 up in the watershed, which is something like 10 to 20 per cent of our normal March rainfall,” Sims said.
The snowpack is much less too, about 50 per cent of the normal average.
“We would typically see it continuing to build well into April, but it’s been declining now for about two or three weeks,” Sims said.
But, he said, the region has received near average precipitation overall throughout the wet season that starts in October.
The city started storing water in the Jump Lake Reservoir, now at about 87 per cent of full storage, in March to prepare for the dry season. Water is being saved up slowly to have full storage by June. Sims said water storage now starts earlier in response to the pattern of winter droughts in recent years.
“I think the major concern for us is how dry everything is right now,” Sims said. “People will start watering early and the local forests are very dry. The risk of wildfire is pretty significant.”
Armel Castellan, Environment Canada meteorologist, said March dry conditions spread across all of B.C. and much of the Yukon.
“We started off where February left off, which was cold,” Castellan said.
The high pressure ridge that helped maintain cold clear air over B.C. helped prevent precipitation from the Pacific Ocean from reaching the B.C. coast until the middle of March when it started to warm up.
“Just to give you an example, Nanaimo only saw 17.8 per cent of normal precipitation, so 20 millimetres versus the 113 they normally would see, so that ranks them sixth driest and that takes them back to 1892 records,” he said.
Castellan said this is the time of year when meteorologists become concerned about the snow pack in the mountains, which becomes a source of water that replenishes city water reservoirs through the summer, and people working in emergency management and atmospheric science are “doing a rain dance” in hopes there will be “June-uary” conditions in late spring, early summer that will provide steady rains.
“Because we know come July and August there’s going to be a honking big [high-pressure] ridge that’s going to probably give us almost no precipitation, maybe a few little dry cold fronts that spark some wildfires and then you’ve got yourself a problem again,” Castellan said.
Rain patterns are changing too. Castellan and Sims said the majority of the region’s annual precipitation is now compressed into fewer days of the year.
“One thing that has become more and more clear over the last decade is we’re expecting precipitation to go up in total, but we’re actually expecting it to be concentrated during our active storm months,” Castellan said. “The November, December, Januaries of the year are going to be wetter still … We used to see 12 days of the year amount to half the annual total of rain or precipitation and we’re expecting that to shift to only six.”
Rain is on the way over the coming week and into mid April, bringing a close to the March dry spell.
The five coldest Marches on record occurred in 1912, 1926, 1924, 1911 and 1965, according to Environment Canada records.https://www.nanaimobulletin.com/news/nanaimo-watershed-sees-driest-march-in-more-than-a-decade/