Warmer temperatures & snow pack could mean local flooding

Mid-Michigan is finally getting a break from the constant accumulating snowfall winter 2013-2014 has brought. As of Feb 11th, Flint has had 64.5â?? of snow. Saginaw has had 44.4â?? of snow. While this news has been great for snow lovers, it now has meteorologists, hydrologists, and home owners in flood zones a little concerned.

All of this snow eventually has to melt. What we would like to see is a slow, gradual melt of the snow over an extended period of time. If it happens too fast, or we see heavy rain, flooding is likely to occur. Here are the reasons why.

  • As of 2/11, the current snow depth across Mid-Michigan currently ranges from 12-22â??. If all that were to melt at one time, we are looking at an average of about 1-3â?? of liquid equivalent within the snow pack.

  • The ground is frozen solid due to the extreme cold weâ??ve been getting this winter. As the snow melts, the water canâ??t be absorbed by the ground, so it acts like pavement, allowing water to run off as it does on a driveway or in a parking lot.

  • If we see warm enough temperatures to allow for melting and rain to occur at the same time, the melted snow and rain water would not be absorbed by the frozen ground, and would run off into streams, creeks, and rivers, causing a rise in water level.

So, are we expecting this to happen any time soon? Yes and no. Weather models are showing a global pattern change beginning to take shape starting Monday. The brutally arctic air that has been over Lower Michigan for months, has been a result of pieces of the Polar Vortex swinging south. With the jetstream to our south, cold air from Canada had no problems funneling into the Great Lakes.

It now appears to be retrograding, or heading back west over Alaska and eastern Russia. This should allow the upper air pattern to be more â??zonalâ?? or flowing from west to east. A zonal flow across the US keeps the frigid, arctic air locked up to the north of the jetstream over Canada, and allows Pacific maritime air to overspread the country. With origins from the Pacific Ocean, this air mass is significantly warmer than the continental polar air weâ??ve been seeing from Canada. As a result, temperatures should warm into the low to mid 30s starting Monday, and may even exceed 40º later in the week. That would bring on some melting, and any storm system would be more of a rain maker than a snow maker.

With this pattern shift still days away, it is important to remember that things could change, but it is better to prepare now before it happens. Even if it doesnâ??t happen next week with the warm up, weâ??re going to warm up eventually, so we might as well get prepared as soon as possible.

Tomorrow, Iâ??ll discuss ways for you and your family to get prepared for the upcoming spring thaw and flooding that may occur as a result of our extremely cold and snowy winter.