Monday, December 07, 2009

BIG storm this week

The mainstream media is finally picking up on what we have been talking about on this blog for a week, the first big winter storm for southern Quebec. While many parts of the country are already having mid winter weather, such as the Prairies and the region around the snowbelts of Lake Huron, we have been relatively mild and snow free. A burst of flurrie activity overnight put down 1-2cm of snow across our area. Another weak area of low pressure will move across the valley this afternoon with another 1-3cm of very light fluffy snow. This is just a warm up for what lies ahead. Tuesday will be the calm before the storm as high pressure dominates with clear and cool weather.

975mb Low
Low pressure will emerge from the southern Rockies and move to near Chicago on Wednesday and just north of Montreal on Thursday. This low is expected to intensify rapidly to a 975mb low. The intense storm will produce heavy precipitation north and east of the system. It appears that snow will start across Ontario late Tuesday and spread into Montreal by Wednesday morning. The onset will be all heavy snow with 10-20cm expected before a push of warmer air and a transition to freezing rain and sleet from Montreal south. From Montreal north it should remain all snow with 25cm plus expected. There may even be some rain along the US border. There is still some question as to the track of the system, but the described scenario above is becoming more clear with each computer model run.

Another component of this storm will be fierce winds. Winds will be northeast from 30-60km/h and then backing Thursday to the northwest 50-70km/h and gusty. These winds will cause blowing snow and reduced visibility. Air and road travel will be impacted all over the Northeast, New England, Ontario, Quebec, the Midwest and eventually the Maratimes. Plan your week accordingly.
The next update will be no later than 7pm this evening.

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