OTTAWA — They predicted rain. It snowed.
They called for temperatures above freezing. It was below freezing.
They forecast barely five millimetres of precipitation. It was almost five times more.
Environment Canada’s botched forecast in Nova Scotia in the fall of 2008 left 1,500 motorists stranded on the Trans-Canada Highway for nearly 24 hours.
And a draft report on the “Cobequid Pass Snowfall Event,” dated last month, blames bad software and a “blind spot” in Canada’s network of weather stations.
Forecasters were reduced to huddling around webcast images from a traffic camera operated by the province of Nova Scotia to find out what was going on.
“Sporadically available Webcam images ... were the only source of direct information available to the weather office as to what was happening over the Cobequid Pass,” says the internal report.
A copy of the document, dated Feb. 1, was obtained by The Canadian Press under the Access to Information Act.
The analysis, by meteorologist Darin Borgel of the Atlantic Storm Prediction Centre in Dartmouth, N.S., notes that the storm on the afternoon of Nov. 19, 2008, “was not a particularly remarkable meteorological event.”
Even so, forecasters had inadequate tools for predicting or monitoring the late-fall storm.
“Meteorologists were left to issue updated bulletins and warnings based mainly on second-hand information trickling into the office as the event was unfolding,” says the report.
“This resulted in little or no lead time of the heavy snow event to the travelling public.”
The lack of reliable weather data made reconstruction of the storm so difficult that the post-mortem report had to draw on a newspaper’s account to determine when it hit.
Environment Canada has no weather stations along the four-lane Cobequid Pass highway between Truro and Amherst, N.S., which opened in 1997.
The busy 45-kilometre tolled stretch of Trans-Canada Highway is a vital transportation link between Nova Scotia and News Brunswick, attracting about 8,000 vehicles daily.
Federal forecasters issued no storm warnings that day, and motorists were caught unaware. Trucks jack-knifed, cars skidded into ditches, and all lanes became blocked.
About 1,500 vehicles were stranded overnight in freezing temperatures without food or water. No one was injured.
“The rapid evolution of this snowfall event ... could not have come at a worse time of day,” says the report, noting that the workload at the weather office is already extremely heavy in the afternoon.
“It is not surprising that the initial onset of this event slipped through the cracks.”
The report is also critical of a regional forecasting computer model that erroneously forecast light rain and warm temperatures.
Borgel recommends establishing a weather station along the Cobequid Pass; more study of the unique weather patterns of the area; and more systematic use of existing webcam information.
A spokeswoman for Environment Canada said the recommendations are only preliminary and must still be reviewed by senior staff.
“Until this is done, we cannot comment on what may or may not be done in terms of the installation of a Meteorological Service of Canada weather station along the Cobequid Pass,” Brigitte Lemay said in an email.
She added the service is working to improve the accessibility of the province’s webcam information.
Lemay defended the forecasting software, saying it remains useful and is always being improved.
“The storm that closed the Cobequid Pass in November 2008 was very much influenced by local effects over a small area,” she said.
“These systems are a challenge from a forecasting perspective and will continue to be.”
Nova Scotia’s Transportation and Infrastructure Renewal Department installed a second traffic webcam along the route, at Lornevale Station, in December. Like the first, at Westchester, the installation also provides some basic weather data.
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On the web — highway webcams operated by Nova Scotia: http://www.gov.ns.ca/tran/cameras/