Great Lakes Snow Squall Risk Late Next Week

There are some meteorological indicators that hint at the risk of snow squalls moving into the Great Lakes region in just over a week from now.

Current Setup

The end of this week and the start of this weekend will see an upper-level ridge bring temperatures 10-15 degree Celcius above normal values for late October.   This ridge will break down by this Sunday and an adjustment will come by the middle of next week to the overall flow pattern.

So far all of Ontario has experienced above normal temperatures for the first eighteen days of the month by several degrees.  That will come to an end by next Wednesday as we move towards a cooler scenario heading into the final week of October.

Next Week

The implications of this change will be dramatic.  Many locations could see daily high temperatures drop nearly 20 degrees over the next 7-10 days.  One area that will see a big impact is the locations near the Great Lakes.  See the map to the left for the upper-level trough (and a complete reversal from this week) that will bring a change to colder conditions.

Warmer than normal water temperatures now exist across the lakes. This combined with this blast of colder than normal air will be the perfect combination of lake effect snow squalls to the lee of the Great Lakes.

Where

Specifically, I will be watching the eastern Superior region near Sault Ste. Marie and the Georgian Bay area near Muskoka.  Some current long range forecast models are already pointing towards the perfect combination of wind direction and over-lake instability to all for the first significant snowfall event.

When

The exact dates of this event appear to be late on Thursday, October 26 to Saturday, October 28th. Luckily the ground temperatures are so warm that any snow is likely to melt within hours, if not immediately.

Monthly Outlook

My long-range forecast for November is about to be released.  Stay tuned for the month that could be very active and see a big change from what we’ve experienced the last couple months in Ontario.