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      Beam Blockage: Why we can't see snow in the Keweenaw Peninsula

      You hear it from us almost every day in the wintertime. We could have white out conditions with heavy snow in the Keweenaw Peninsula and radar simply does not show it.

      So what's the deal with this phenomenon known as beam blockage? The simple answer is that the hills of northwestern Marquette County block the radar beam from reaching portions of western Upper Michigan.

      But why can we see radar activity just fine in the spring and summer? That's because thunderstorm cloud tops in the spring and summer can typically reach 40-50 thousand feet into the atmosphere. The radar beam shoots right over the terrain and hits its intended target, clouds and precipitation! But lake effect snow clouds are much lower, 7-8 thousand feet high. So by the time that radar beam arrives over places like Houghton, it overshoots the clouds and keeps on going.

      Unfortunately, there's not much we can do about this beam blockage problem. The radar tower, which is located on government property near the TV6 station on US-41 in Negaunee, is already as high as it can safely be. It sits about 1550 feet above sea level.

      You might ask why was this particular site chosen in the first place? And why not move the radar tower or perhaps add another one? Mike Dutter is the Science and Operations Officer at the National Weather Service. He said, â??The Radar is close by so we can easily maintain it. And it also gives us very good coverage across the eastern U.P. If we put this radar tower somewhere else, we then lose the radar coverage across the eastern Upper Michigan or other places. It was chosen in the mid '90s when the radar was first put in for the best coverage possible for the forecast area.â??

      How do we get around this blind spot?

      Mike Dutter explained that through the magic of visible satellite imagery, we can get an idea of whatâ??s going on. He said, â??Even though our radar doesn't see lake effect snow in the Keweenaw, we can get an idea that there are some bands of snow in the Keweenaw from the satellite. But that doesn't always guarantee that there's lake effect snow. And so if we do see some signatures on satellite, that's when we go and investigate further.â??

      So even though our radar tower struggles with depicting lake effect snow activity through the Copper Country and Keweenaw Peninsula, we get by with a little help from our friends. That means you!

      Mike Dutterâ??s face glowed when he described the use of webcams in the Keweenaw. He said, â??We use webcams extensively up there. Webcams are huge! There are various webcams, not only from MDOT but also from local businesses and private residences that are extremely helpful!â?? According to Mike, those webcams are dispersed relatively evenly from Copper Harbor, all through the Keweenaw Peninsula.

      Not only are webcams extremely helpful, surface observations from the Houghton County airport, co-op observers and civilian storm spotters are crucial. Thatâ??s were you can help us out! We're always looking for snow and weather reports all across the Upper Peninsula, even in places where the radar works well. For more information on how to share your latest weather observation, follow the links below!