Low Pressure Nov 16/17 - SRN ON

[Derecho]

A moderate low looks to develop in about 40 hours off the coast of Louisiana that will progress northeast across the Tennessee and Ohio Valley's. By about 7am on the 17th the GFS puts the low over southwest Ontario with pressure at 992mb. By 8pm on the 17th the centre of the low then exits Ontario and begins to dissipate over the St. Lawrence Valley.

Moist air from the Gulf of Mexico will be drawn northeastward with the low, so most of the precip will probably remain as rain, but some areas, especially early morning on the 17th, could see their first measurable snow. Daytime temps look to be within the range of 40F-50F so snow is definitely out of the question when the sun is up. Overnight temps for most areas look to be just above freezing, if not just below in some areas. Ripe temperature for snow showers!

Winds also look to be an issue with sustained winds forecast to be about 30kmh most of the day for inland areas of southern Ontario, and as high as 75kmh along the shorelines of Lake Erie and Lake Ontario. Extreme southwest Ontario looks to escape the worst of the winds, but the shores of Lake Huron could peak at 75kmh, too, around Goderich northward.

It may not be much, but it's something!



*EDIT: Forgot to mention snowsqualls look to develop on the 18th after the low passes through.