Early Spring Deluge
The major low pressure system that has been affecting Southern Ontario in the past three days finally exited the area but it left copious amounts of rain. The system was much stronger when it hit the American Midwest resulting in about 82 tornado & 217 severe wind reports and 457 severe t-storm warnings.
The climax reached Toronto at 1700 EDT where a line of heavy rain pounded the area. The continental water vapour content map shows that the moisture extends from the Gulf of Mexico all the way up to James Bay in northern Ontario/Quebec.
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Based on radar estimate, the rainfall intensity peaked around 45-50 dBZ as the line moved in a northeasterly direction. In the radar map below, storm “C8″ located in Markham had a cloud top of approximately 10,000 feet, Vertical Integrated Liquid (VIL) of 7kg/m2 and it’s moving to the NE at 38 knots.
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When the line hit the east side of the city at 1715 EDT, it brought heavy rain and strong winds. Here is a snapshot of the radar image as it pounded the Toronto East York Weather Station (look at the station in the East York area with a temp reading of 54 F).
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In fact the passage of the storm line resulted in rapid temperature dropped and rise in barometric pressure as indicated in the graph below from the Toronto East York weather station. The pressure rose from 1003.6 mb to 1005.1 mb in just one minute (17:13 to 17:14 EDT).
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Closer analysis indicated that the temperature dropped 2.3 deg. C from 15.0 deg. C to 12.7 deg. C in a matter of ten minutes (17:12 to 17:22 EDT). For five minutes, the rainfall rate was more than 100 mm/hr until it reached the peak at 160 mm/hr at 17:20 EDT.
In the end, the 24-hour rainfall accumulation was 16.8 mm and the total storm accumulation from May 1-3 is 25.8 mm. For more weather information and live weather readings, visit www.TorontoForecast.com.
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