A storm dropped a record 126 mm of rain on Toronto on Monday, July 8, 2013, primarily during the evening commute. There wasn’t much advance warning.
More bad weather was forecast for Wednesday night but nothing happened.
On Thursday, Environment Canada issued a Severe Thunderstorm Watch (the capitalization is theirs):
POTENTIAL FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ALONG A COLD FRONT. THIS IS AN ALERT TO THE POTENTIAL DEVELOPMENT OF SEVERE THUNDERSTORMS WITH LARGE HAIL, DAMAGING WINDS OR HEAVY RAINFALL.I was hosting a 7 PM meeting for the executive of six Toastmaster clubs (I’m the Area Governor). Based on the 4 PM forecasts, I cancelled the meeting. The weather didn’t cooperate. By that I mean the weather was wonderful. No storm. What happened to the 100 km/h winds and the hail pellets of 2-4 cm? The weather warning was cancelled shortly after 7 PM, which was way too late to reinstate the meeting.
Aren’t weather forecasts wonderful?
The Weather ChannelIf you’re expecting rain and get sun instead, you’re probably happier than if you expected sun and got rain.
The Weather Channel has a “wet bias” at the extremes. When precipitation is unlikely, the forecast exaggerates the chance of rain. When the likelihood is moderate, the forecast is honest. When precipitation is virtually certain, the forecast rounds up from 90% to 100% more often than it should. — Dan Allan (Oct 2012) [includes links to research by the American Meteorological Society]Did you know of these biases?
Bad Weather Is Good NewsStations like 680 News have weather reports every 10 minutes. They are quick to report on potential bad weather, which has the effect of creating anxiety and encouraging you to keep listening for more updates … after the commercials.
AccuracySkill is difficult to measure. Do you pay more attention to the scientific equipment or your uncle whose ears get hot before a storm?
Attempts to predict earthquakes have continued to envisage disasters that never happened and failed to prepare us for those, like the 2011 disaster in Japan, that did. — New York Times (Sep 2012)Weather forecasts are meant to be accurate but are not accurate enough.
The accuracy gets worse the farther away the event. If you want to know whether it’s better to hold your picnic next Saturday vs Sunday, you won’t get much guidance. The forecast for tomorrow will be more accurate but that’s not enough time to plan a group event.
“… the 2013 ‘Report Card for America’s Infrastructure’ gave the US a D on its maintenance of dams. There are 13,991 dams in the US that are classified as high-hazard, the report said. A high-hazard dam is defined as one whose failure would cause loss of life.” — Wired (June 2013)Since we can’t predict the weather, maybe we can prepare better?
- Weather predicting: do it yourself (Old Farmers Almanac)
- How valid are TV weather forecasts? (Freakonomics, April 2008)
- The weatherman is not a moron (New York Times, Sep 2012)
- Why everyone hates the weatherman (Washington Post, Sep 2012)
- Why we should lie about the weather (and maybe more) (Brett Keller, Sep 2012)
- Meet the woman whose legs illustrated Toronto’s flood frustration (Canada.com, Jul 10, 2013)
- Toronto Storm 2013 (Huffington Post, Jul 8, 2013)
- Of rainstorms, blackouts and memories
- 9/13: prepare your disaster recovery plan now
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PS Today looks a great day for a picnic. I’m taking my umbrella.