Garbage bags filled with soaked personal belonging line the back of homes on McRae Avenue in Mission after Saturday morning’s flash flood.

Intensity of rain factor in flood

Mission received 13.3 mm of rain between 5 and 6 a.m. on Saturday. That’s more than one-third of the total amount of precipitation that day.

A massive amount of rain in a short period of time contributed significantly to Mission’s flooding problem on Saturday morning.

More than 12 homes in the McRae Avenue area were damaged by flooding and residents continue to clean up and assess the damage caused by water overflowing a clogged culvert.

And while it may not seem to have been an overly large amount of precipitation, Environment Canada meteorologist Matt MacDonald said it wasn’t the total rainfall amount that was impressive, rather it was the intensity.

According to the Bradner Road weather station, the closest to Mission, 20.2 mm of rain fell on Friday and 35.1 mm on Saturday.

MacDonald called that a “reasonable amount” but nothing close to the March daily record of 73.6 mm

The significant factor, according to MacDonald, was the rainfall rate, which he said typically causes the most impact.

Mission received 13.3 mm of rain between 5 and 6 a.m. on Saturday. That’s more than one-third of the total amount of precipitation that day.

“‘That’s pretty significant. You’re getting close to tropical downpour type intensity.”

He said that high rate is a once in every five years occurrence.

“Culverts, streams and gutters only have a certain capacity and it just greatly exceeded that, I’m assuming,” said MacDonald regarding the flooding.

Mission Mayor Randy Hawes said he believes the culvert would have handled the water flow had it not been for a discarded Christmas tree and an old chair that were swept along and plugged the grate.

“It wasn’t a blockage because of negligence,” said Hawes, adding that all of the culverts were inspected in February.