Dozens of tornadoes hit the southern US

The damage was complete from a Sunday tornado in Mayflower, Arkansas. The three day onslaught of severe weather has left 29 dead. (CNN)

A slow moving low pressure area with a nasty trailing cold front along with all the right ingredients of wind, temperature and moisture continues to produce a multi-day severe weather outbreak across the southern US. On Monday it was Mississippi and Alabama that bore the brunt of severe thunderstorms and massive tornadoes. Nearly 3 dozen tornadoes were reported across the region and into northern Georgia and western Tennessee. Hardest hit yesterday were the communities of Louisville and Tupelo, MS where a mid afternoon tornado destroyed dozens of homes and businesses. A dozen fatalities were reported on Monday across the south bringing the death toll up to 29 since Friday night.

A Twitter photo showing the power of a tornado to throw debris into the air. This storm was in Baxter Springs, Kansas on Sunday afternoon.

I have a modest understanding of the mechanics and power of these deadly storms and even I have been astonished by the level of destruction. Entire downtown cores have been leveled and cars tossed into piles in fields. The storm that is causing all this severe weather is a slow moving low pressure area centered over the Great Lakes. The system has a trailing cold front slicing through unstable air across the southern US. Combine that with low level moisture blowing in from the Gulf of Mexico and you have all the ingredients necessary for a big outbreak. It will continue today with more tornadoes forecast from Mississippi east to the Atlantic Coast and severe thunderstorms as far north as the Great Lake states.

This system will control the weather in Montreal for the entire week with cool northeast winds and lots of moisture beginning tonight. Montreal and the entire region could see up to 40mm of rain by Friday. It will be cool with highs up to 13C and lows around 7C. Any thunderstorm activity at this time locally will be confined to southwest Ontario particularly London to Windsor.