Rainy and windy start to the weekend for Montreal

Periods of heavy showers and gusty winds are possible late Friday into the overnight hours in southern Quebec. Winds may gust to 80km/h in the St. Lawrence Valley.

Special Weather Statement issued for Montreal for gusty northeast winds between 50-80km/h this evening.

An unsettled weather pattern is with us for the next several days as an omega block in the atmosphere dominates our weather. An omega block, named after the Greek letter, is basically an atmospheric traffic jam allowing for a stagnant weather pattern. In our case, strong high pressure lies over the central portion of the continent, while deep upper levels lows sit near both coasts.

Here in Montreal, we can expect a rather cool, wet period of weather, with frequent troughs of low pressure pinwheeling around the aforementioned upper low over central Quebec. As the upper level low slowly slides to our southeast, west winds will veer to the northeast and increase Friday afternoon, gusting up to 80km/h at times into the overnight hours.

Rainfall may be briefly heavy at times Friday, with a few embedded thunderstorms possible late this afternoon and into the overnight hours. Amounts may reach 15-25mm for Montreal. Temperatures will be on the cool side in the middle teens to perhaps 20C (59F to 68F) for those who see some sunny breaks. Morning lows will be near 11C (52F) overnight Friday and again Saturday.

Partly cloudy skies will prevail most of the weekend, but with plenty of instability in the air. Therefore the risk for cloudy periods and showers remains all weekend and even into Monday. Some of the highest elevations across southeastern Quebec and northern New England may even see a snowflake or two.

Warmer and drier weather will return by the middle of next week, as the block begins to breakdown and the weather systems begin to move freely again from west to east.