Updated: 11/21/2008 5:26 PM KSTP.com | Print Story
By: Dave Dahl

The ice isn't safe just yet!

This is the time of year when many of the season's accidental drownings happen thanks to thin ice.  Once the calendar changes from October to November, nighttime temperatures begin their big seasonal drop.  Overnight lows consistently drop below freezing and daytime highs seldom get much above the thawing point.  Lakes and ponds have already gone through their "turning over" process, which brings the coldest water to the top rather than keeping it at the bottom.  

Every morning most shallow lakes and ponds have a thin sheet of ice, which is very tempting for children of all ages to venture out on to see how far they can slide.  Unfortunately this usually has a tragic ending.  Many people contend that lake ice is never totally safe, but after growing up in this state and spending many of my younger years skating on lakes and ponds, I'd have to differ.  We just have to be patient.

The Department of Natural Resources has come up with a guideline to follow when considering skating, snowmobiling, or driving cars and trucks out on the ice this winter.  If the ice is 2 inches thick or less, stay off.  If the ice is at least 4 inches thick it should be safe for walking.  5 inches of ice thickness is usually enough for a snowmobile or ATV.  You need 8 to 12 inches of ice in order for it to support a car or small pickup and the ice should be over a foot thick to support a medium sized truck.

Remember these are just guidelines and every situation is unique.  We usually need at least a week of nighttime temperatures dropping into the single digits for ice to become thick enough to just walk on.  You should know something about the makeup of the lake before you venture out.  If the lake is spring fed, it may have many thin spots because of warmer water and circulation of the water.  Water movement around stream inlets and outlets results in thin ice as well.  Heavy snow on poorly developed ice can act like an insulating blanket, preventing safe ice from forming.  

The ice isn't safe yet so please warn your children to stay off all lakes and ponds.  We'll have plenty of time this winter to enjoy fun on the ice; we just have to wait a few more weeks.      

Have a great day!

Meteorologist Dave Dahl