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.

[Derecho]

18z GFS has decreased temperatures to just above freezing for most of the day on Wednesday. Mixed precip looks likely this run. If it's going to snow then it'd be nice if it would accumulate

Pressure remains at 992mb, and speed remains relatively the same. The centre of the low and the area of the lowest pressure looks poised to traverse over a line from Cleveland to Hamilton to Kingston to Montreal.

The wind fields over the lakes have decreased to about 60km, but Lake Ontario remains at 75kmh out on the water. Over land, the wind field has increased and many areas are now in a 50-60kmh area. Could be a decent wind event for some of us, especially east of Stratford, and for much of the GTA.

Also, judging by forecast parameters, isolated thundershowers, possibly even thundersnow, look possible!!

[Derecho]

Well, looks like it'll be mainly a rain and wind event. Hopefully someone will see some flakes today/tonight! Or even a crack of thunder...

Beautiful...

[davefootball123]

This is a very potent low pressure. The center of circulation is very defined. Lots of rain and mabye some thunder for us. who knows

[Derecho]

Originally Posted by davefootball123

This is a very potent low pressure. The center of circulation is very defined. Lots of rain and mabye some thunder for us. who knows

It's deepening as pressure has dropped from 997mb to 995mb. I'm sad I have to work... I'll probably miss any thunder that we may have.

[obwan]

pressure down to 993 now

[davefootball123]

Last i checked it was 992

[Derecho]

I ended up with 22mm of rain here. The wind was really strong this morning, but it has since tapered off. Next...

[davefootball123]

I got 34mm here on the mountain. Winds were strong from about 830 until 3