The National Weather Service’s Kansas City/Pleasant Hill office is about to get an upgrade to its radar that is expected to lead to better information for the public it serves.
That office’s current WSR-88D Radar was installed in 1988. Since then its improvements have primarily consisted of the addition of faster and faster computer components. Beginning January 30, it will be upgraded to dual-polarization technology.
Warning Coordination Meteorologist Andy Bailey at Pleasant Hill explains that the current radar is called a “polarized doppler radar,” but it is only polarized in one direction; horizontal. That was chosen because it allows for better detect rain droplets, which flatten out as they fall.
Bailey says the new technology adds a vertical scan. “If they polarize the beam in two directions…first go out horizontal, then vertical…they can actually distinguish between raindrops which are kinda flat, and hailstones which are more round.” That will help to pinpoint where hail is falling and improve detection of differences between rain, sleet and snow. It could also help separate out other things in the atmosphere, like insects or dust.
Bailey, a self described “weather geek,” says he and his colleagues will also be able to see things in severe storms that they can’t now. “It’s gonna give us the capability to peer inside of those thunderstorms with a detail level giving us structure of, for instance, where the hail is being generated at, where the hail core is descending and how that evolves over time.”
Another phenomenon that should show up better after the upgrade is the “debris ball,” which was reported by meteorologists tracking the May 22 Joplin tornado. That is the image that appears when a tornado is close enough to the radar that debris being thrown up into the thunderstorm can be detected. That is one more criteria that can confirm the presence of a tornado.
The work will cost about $225,000 and could take between ten days and two weeks. During that time the Pleasant Hill office’s radar will be down. Bailey says during that time his staff will rely on imagery from adjacent offices, such as St. Louis and Springfield.
Because the radar will be down for so long, Bailey says it is no accident that the work will take place in the first part of February. “While it’s not impossible to get severe weather that time of year, (it’s) pretty unlikely. We’re pretty fortunate that we got placed in the rotation of installs when we did. It’ll really be at our severe weather minimum.”
There will be some areas that will receive very little radar coverage during that time, but Bailey says the noticeable effect should be minimal. “The corridor from Columbia on up to Kirksville, for instance, or maybe even further west…those areas really didn’t see much in the way of coverage when it comes to winter-type precipitation anyway. Just the nature of snowfall and freezing precipitation doesn’t show up well on the radar at a very long distance anyway, so they probably won’t notice any difference.”
Another effect of the outage will be felt by many TV stations and internet services that offer radar imagery. Bailey says many in the general public may not realize that most of those entities get that imagery from the National Weather Service. “Almost all media outlets use our radar. It’s pretty much the only high-powered doppler radar in the region, and everybody uses it.”
The appearance of the radar unit itself will change little if any to the casual observer, however. Bailey says many of the components in the current radar will be employed in this new one. The large white dome visible at his office and much of what is inside it will carry over. “It’s down in some of the building beneath it that it really generates the microwave energy, where the energy is polarized that will change.”
The Pleasant Hill Office’s website has more information about the upgrade and what dual polarization radar is here.