For the past year and a half, the National Weather Service has been doing upgrades to their network of Doppler radars across the country.
The upgrade is called dual polarization, and has already proven very beneficial for those using it. Among those receiving upgrades, is Indiana’s National Weather Service. And while the impact of the improved Doppler upgrades will not be seen in Michiana, meteorologists everywhere will see great improvements in how they look at storms.
“It's gonna allow us to see more of a two to three dimensional view of hydrometeors, or snowflakes, raindrops, those kind of particles in clouds. And it's gonna allow us to improve our precipitation algorithms so we'll know how much rainfall is occurring,” says Sam Lashley, the Science and Operations Officer of the National Weather Service.
So, how does it work? The current Doppler radar sends out a single, a horizontal pulse of energy, which only gives a horizontal view of its target. With the upgrade, the radar will send out both a horizontal and a vertical pulse, which will provide better information about the size, shape and type of precipitation.
"There are several factors that are gonna help us,” says Lashley, “The main difference is gonna be in the wintertime distinguishing that rain from snow. We'll be able to tell if it's a dry, fluffy snow or a wet, heavy snow, which is gonna impact accumulations. So we'll be able to improve our forecast in the short term, update the forecast for improved snow amounts in certain areas.”
Lashley adds that the benefits will be very apparent when the temperatures warm up, "In the summertime, we're gonna be able to distinguish the large hail from the small hail in thunderstorms.That might actually help us improve our warning lead time in a hail situation."
The interesting feature of the new Doppler is identifying the debris ball signature from tornadoes, “It's been tested in the plains with large tornadoes, but we don't have a lot of cases of smaller type tornadoes that we here in Indiana. So it will be interesting to see if we can detect that on radar up here."
Radar images are from a tornado that hit Hattiesburg, Mississippi on Sunday, Feb. 10 show the debris balls thanks to the dual-polarization images.
Comparing Chicago radar to Indiana’s radar images, it is harder to distinguish what exactly is going on with the old system. But with the new enhancements, meteorologists are able to see the type of precipitation across the images.
According to Lashley, “When we look at the atmosphere and know it's cold enough for snow, that easily confirms to us that this is an area of light snow that's moving in and then we can easily track that across the area. Now, if we were seeing some mixed precipitation and some rain along with the snow we'd see more of some greens and yellows that would show up in there that would indicate that there's different sized particles in the clouds and we might need to look at this area a lot more closely to determine precipitation type.”
The meteorologists at the National Weather Service are excited for their "new toy". But this is a toy that will bring better forecasts and better warnings to Michiana.
Although the average person going to the internet to look at a radar image won't really see a difference with the new upgrade, meteorologists working behind the scenes will benefit from a great new tool to help monitor and forecast.