By Ian Holmes

October downpour shatters Nanaimo rainfall record

Nov 2, 2016 | 12:55 PM

NANAIMO — Eye-popping rainfall statistics are being reported on mid-Vancouver Island following an extremely wet month.

Environment Canada meteorologist Armel Castellan says 315.6 mm of rain fell in October at Nanaimo Airport, crushing the previous record set in 1975, when 289 mm of rain was recorded. He says all but three days saw measurable rainfall at Nanaimo Airport last month.

“We were seeing at least four days with 25 mm of rain or more and that’s easily more than the 0.7 days that you usually see in any given October,” said Castellan.

An average of about 100 mm of rain falls during the month of October, according to Castellan, who adds that October is the sixth wettest month of the year on average. He says about 110 mm of rain poured down while the remnants of a typhoon swept over the south coast during a three day stretch (Oct. 12-14).

Castellan notes that the systems that pounded the coast aren’t unusual, but says several powerful storms at the same time entered with the absence of a ridge to redirect the storms.

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“That would help for some of these storms to migrate up to the Gulf of Alaska which we traditionally see this time of year,” said Castellan. “That really wasn’t happening. They basically just had an open entry into the province all the way into the south coast.”

He notes that the average temperature last month locally was 10.3 degrees, slightly warmer than the average of 9.9 degrees. Other areas in the mid-island were pounded with much more rain. The city of Nanaimo’s manager of water resources Bill Sims reports that an incredible 980 mm of rain poured down on the city’s Jump Lake Reservoir, located south of the Nanaimo Lakes.

“Almost 1,000 mm a month is a mind-boggling amount,” Sims said. “Typically we will see 600 to 700 mm in the winter rain period. To see 1,000 in October is really, really high.”

He said October’s rainfall recorded at the Jump Lake Reservoir is the highest in any month in recent memory. Sims points out that the 16.5 million cubic metre reservoir sees more than its fair share of rain given the fact it’s located inland and at a higher elevation.

The Regional District of Nanaimo’s drinking water and watershed protection program coordinator Julie Pisani stated in an email that the October downpour would have a positive impact.

“This fall precipitation provides a welcome recharge for our groundwater aquifers and gets our rivers running at higher levels which is good for salmon returning to spawn,” stated Pisani in the email.

“Our drinking water supplies are dependent on our watersheds receiving fall, winter and spring rainfall. Hopefully we also get some snowpack this winter as another means of storing the winter precipitation,” she added.

As for those hoping for a break from steady rain, Castellan doesn’t have the answer you’re looking for.

“We will definitely see a continuation of the pattern in October which looked a lot like what we see in November,” Castellan said.