A so-called Pineapple Express is raining down on Vancouver, threatening to shower the city with more rain over the next 48 hours than it has seen over the past 40 days.

Pineapple Express isn't a meteorological term, explains CBC meteorologist Johanna Wagstaffe. It refers to a weather system that originates near the Hawaiian Islands, where pineapples are from. The system transports warmth and moisture to the West coast.

On Thursday, a band of moisture extended from just north of the Hawaiian Islands to the B.C. coast. That stream of moisture is directing heavy rains and milder temperatures toward the province, she said.

The phenomenon is expected to intensify through Friday and into the weekend, when temperatures should rise into double digits before some sun breaks through on Sunday.

January and February have been unseasonably dry, Wagstaffe said. The next few days should bring rainfall totals closer to the 12 cm average mark for February.

"But we’ll still be well under, even with this Pineapple Express," she said.

'Typically a winter set-up'

A Pineapple Express is not unusual for B.C.

"We normally see a few of these during the winter months," said Wagstaffe. "This is typically a winter set-up." In the winter, a Pineapple Express can cause concern as warmer temperatures can cause rapid snowmelt, resulting in flooding.

Still, residents of low-lying areas are being warned to be vigilant for potential floods.

Rainfall warnings are in place for metro Vancouver, West Vancouver Island, Howe Sound, and the Sunshine Coast.

West Vancouver Island is expected to see up to 15 cm of rain by Saturday morning. Between six and 10 cm are expected across Howe Sound and the Sunshine Coast.

Across metro Vancouver and western sections of the Fraser Valley between four and eight cm of rain may fall.

Raingear stores pleased

In metro Vancouver, stores selling raingear are saying the Pineapple Express is a welcome weather system.

A Mark's Work Wearhouse employee told CBC News one customer, who works outdoors, came in today and purchased three pairs of pants so he wouldn't have to come in more than once during the heavy rainfall.