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Ontario Weather Review
PLEASE NOTE, THIS WILL BE THE FINAL ONTARIO MONTHLY WEATHER REVIEW TO BE POSTED ON THE ENVIRONMENT CANADA WEB SITE IN THE NEWS RELEASE SECTION. FUTURE ONTARIO WEATHER REVIEWS WILL ONLY BE AVAILABLE BY E-MAIL OR FAX.
IF YOU CURRENTLY RECEIVE THE REVIEW BY E-MAIL OR FAX, THEN NOTHING WILL CHANGE. IF YOU WOULD LIKE TO BEGIN TO RECEIVE THE REVIEWS, STARTING WITH THE JULY 2012 REVIEW, BY E-MAIL OR FAX, PLEASE CONTACT METEOROLOGIST GEOFF COULSON AT GEOFF.COULSON@EC.GC.CA.
This year, summer arrived early – with the temperature dial set to “High Heat”!
Throughout the province, mean temperatures were higher than the normal values by as much as 4.3 degrees Celsius. The largest variations were observed in the Far North, north of Superior, northeastern and eastern Ontario sections. For most locations, it was the warmest June since 2005 – particularly in Geraldton, north of Lake Superior, which set a mean temperature record.
Though it was no surprise to have days with temperatures exceeding 30 degrees in southern Ontario, this June the number of those days increased exponentially. For example, Windsor saw nine days of maximum temperatures above 30 degrees; normally, the expectation would be four to five such days for that location. Sarnia had nine such days, compared to three or four days in a typical June. London (7 versus 2), Kitchener-Waterloo (6 versus 1 or 2), Hamilton (7 versus 2), Toronto (6 versus 2) and Ottawa (5 versus 2 or 3) also saw significant increases. The same trend was observed in Petawawa, Muskoka and parts of northern Ontario, such as Earlton, Moosonee, Timmins and Kapuskasing.
Humidex advisories were issued for two heat episodes. The first was for southwestern Ontario, for an area extending from Windsor to Barrie-Orillia-Midland, for an event beginning June 19 and lasting through to June 21. Temperatures rose to the low to mid-thirties and, with the elevated humidity levels, combined to produce humidex values of 40 or higher. The area affected by the hot, humid and hazy conditions was extended to all of southern Ontario and the National Capital Region on June 20. A number of single-day temperature records were broken on June 20 and June 21 before the heat and humidity diminished on June 22 with the passage of a cold front.
The second heat episode that triggered the issue of humidex advisories was for June 28, when a very hot air mass over midwestern U.S. states moved into extreme southwestern Ontario. Humidex values reached 45 in the Windsor area and were forecasted to reach 40-41 in the London and Sarnia areas. On June 29 values lowered slightly, just reaching the warning criteria of 40 near Windsor, while slipping to the mid- to upper thirties in the London and Sarnia areas. For the long holiday weekend, afternoon temperatures were in the mid- to upper thirties.
As for precipitation, for southern Ontario the month started off on a rainy note. Significant rainfall associated with a major low-pressure area moved northward across the Great Lakes. Many locations began receiving rainfall overnight on June 1 and June 2, with several hours of heavy rainfall through the afternoon of June 2 and into the evening. This was often associated with gusty winds. Some locations received half of their monthly precipitation amounts from this event.
Southwestern and northwestern Ontario dominated the reports of severe weather during the month of June. Thunderstorms that produced significant rainfalls occurred in Kenora and Sioux Lookout on June 10. Two main bands of thunderstorm activity hit Kenora, one in the morning and one in the afternoon, resulting in 82.2 millimetres of rain. Sioux Lookout was hit with strong thunderstorms in the afternoon and evening hours of June 10, resulting in 62 millimetres of rain.
Northwestern Ontario was again in the headlines on June 17 as one of a number of strong thunderstorms produced a damaging gust of wind just to the east of Dryden. This powerful wind gust destroyed a shed in which a man was seeking shelter. Fortunately, he was uninjured.
Just a day later, on June 18, more severe thunderstorms popped up across the northwest, resulting in tornado warnings being issued for some areas. Aerial photos of tree damage in the Bread Lake area, about 30 kilometres to the east of Sioux Lookout, confirmed that one of these thunderstorms cells had produced the third tornado of Ontario’s season. The damage track was approximately 1.5 kilometres long and some 300 metres wide at its widest point. Other thunderstorm cells that day looked as strong as the one that produced the tornado near Bread Lake, and so investigations continue to see if any other tornadoes were spawned on June 18.
Ontario normally averages 13 tornadoes each year in a season that runs from late April until early October.
A series of strong thunderstorms rumbled through southwestern Ontario on June 21, resulting in a number of reports of possible cloud rotation, small hail and damaging winds that caused some trees to be uprooted. The most noteworthy damage occurred in the small community of Greenway, to the south of Grand Bend, where some of the fallen trees landed on a home in the area.
Another band of storms moved through the southwest on the evening of June 28, resulting in a report of ping pong ball-sized hail in the Chatham-Kent area.
|Record high mean temperature readings (in °C), ranked by variation from normal:|
|Location||Mean Temp||Normal||Difference||Previous record|
|Unusual mean temperature readings (in °C), ranked by variation from normal:|
|Location||Mean Temp||Normal||Difference||Warmest since|
|Sioux Lookout||17.8||15.7||2.1||1997 (tied)|
|Unusual precipitation readings (in mm), ranked by variation from normal:|
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