OTTAWA -- The federal government says it can't measure how many people actually receive emergency-alert messages on their phones.
The Alert Ready system is designed to notify Canadians of potentially dangerous situations -- everything from terrorism and explosions to flash floods and tornadoes. It is also the system used to broadcast Amber Alerts when a child goes missing.
Public Safety Canada spokesman Tim Warmington said that during the most recent test of the system, conducted May 8, alerts "were successfully processed and distributed" without issue, but acknowledged there is no way to know how many people received them.
"Alert distributors do not have a mechanism to measure how many Canadians viewed or received the alert, but the confirmation in each jurisdiction indicates it was successfully distributed."
The system has been under scrutiny this week following a tornado in Ottawa's east end that hit, without warnings, around 6 p.m. Sunday.
The storm developed so quickly that it struck before most of the alerts were sent. Another problem was that Ottawa -- where the tornado touched down -- was never included in the areas where warnings were issued.
The Alert Ready system can be targeted to very small areas defined by just a few cell towers. On Sunday, the messages were sent to towers covering Gatineau, Que., other parts of western Quebec and a county south and east of Ottawa.
Radio and television stations have been required to broadcast the alerts since 2015, but wireless providers were only added in April 2018.
Public Safety Canada says people should receive the alerts if their phones are powered on and connected to an LTE network. On phones in silent mode, the alert will come in and be displayed on the screen, but the phone will not make a sound.
Erik de Groot, a meteorologist at Environment and Climate Change Canada, said Sunday's tornado was not typical and officials are still reviewing everything that happened.
"We are looking back to see what we can do to improve," he said.
De Groot said the main problem for warnings was the sudden onset of the storm. Most weather conditions that could lead to tornadoes can be predicted days in advance using radar and other forecasting tools, with advance warnings sent out in plenty of time.
The one that touched down in Ottawa Sunday evening wasn't foreseen at all, said de Groot.
Conditions were not conducive to the formation of a tornado and it was only when someone spotted a funnel cloud near the airport in Gatineau that alerts were issued. The decision was then made to expand the alert to other parts of western Quebec and the rural area outside Ottawa.
"Hindsight is always 20/20," he said. "In those first stages it's difficult to predict and the forecasters did the best they could."
Alert Ready only sends out the warnings to the areas the system is told. For extreme weather, those decisions are made by Environment Canada.
The tornado in Ottawa caused damage to buildings, but only one minor injury was reported.
Some residents in the west-Ottawa village of Dunrobin, where a tornado touched down last September, have credited the Alert Ready system for getting them to take cover before the EF3 tornado -- a rating for a tornado with wind speeds of more than 267 km/h --flattened their homes.
Liberal MP Will Amos said emergency alerts delivered over cellular networks might improve public safety, but it further highlights the digital divide between rural and urban Canada.
The House of Commons backed a motion Amos introduced earlier this year calling for improved cellphone coverage for rural communities. On Wednesday, Amos said that as emergency systems become more digital, officials "can't leave behind rural communities."
"They want to have the opportunity to get the alerts in the first place," he said.
-- with files from Christian Paas-Lang