The storm that hit Calgary Saturday was just supposed to be a moderate one, according to the city’s emergency management chief.
It was anything but.
And there was little notice it would be that severe.
Mayor Naheed Nenshi said he would be surprised if it wasn’t one of the top five insured storms in Canadian history. Hundreds of cars were totaled and there was massive damage to hundreds more homes.
In council, questions were raised about why there was no cell phone notification for the storm on Saturday.
A severe thunderstorm warning appeared at 6:37 p.m. Saturday. The warning ended at 7:46 p.m.
“I think that the greatest challenge here is that the storm actually intensified over the city,” said Calgary Emergency Management Agency Chief Tom Sampson.
He said their capacity to do that is limited, in terms of real-time information because there’s a delay in transmitting and receiving it.
“Environment Canada, on their notification system, wouldn’t know that we have hail as large as 61 millimetres until someone actually sent them the photo. They wouldn’t catch that on their radar.”
Environment Canada, however, doesn’t control cell phone alerts. They send data to Pelmorex, an aggregation service that sends alerts to the national system, including Alberta Emergency Alert.
Pelmorex is in charge of issuing cell phone alerts. Currently, Environment Canada doesn’t do cell phone, or “broadcast intrusive” alerts for hailstorms, only tornadoes.
Why the delay in providing information?
Environment Canada’s Strathmore radar station is unmanned, and there’s a radar that transmits data 24 hours a day. The data comes in 10 minutes after the scan.
“That’s just the way radars work, it’s not a fault of the system,” said Environment Canada meteorologist Dan Kulak.
He gave the example that if it’s 4 p.m., the scan begins at 3:55 p.m. and ends at 4:05 p.m. The center of the scan is at the top of the hour, and so it takes nearly 10 minutes to receive the results from that scan.
A radar is at many different elevations, it rotates round at 360 rotations, and there’s a number of different scans at different heights above the horizon. That scan cycle takes between five and 10 minutes depending on what it’s looking for and the data that has to be processed.
He said there is no real 15-minute delay, as it the problem of the system.
“It’s just how the radar has to be monitored and how the data gets transferred to the forecasters,” he said.
Like anything, it takes time to do a radar scan. There are technological, mechanical, processing and transmission limitations. It’s a matter of how the technology functions.
“It’s a question of, ‘how fast can you go?’,” said Kulak.
“That’s just the reality. You can’t go the speed of light on an aircraft, it takes time time to get to wherever you’re going.”