It’s Raining at My House…Why Is It Not Showing on Radar?

WOAY-TV (Oak Hill, WV): While there are still shortcomings with the tools meteorologist use to forecast the weather, solutions are available to help fill the voids, especially when referencing critical radar data.

Chief Meteorologist Chad Merrill has the story:

Simply put, Radar is an acronym for RAdio Detection And Ranging. Each weather radar in the country sends out pulses every hour and then listens for returns. These return echoes are the result of the radar beam bouncing off precipitation in the atmosphere, which you see at home on our televised weather reports or the StormWatch 4 Weather App.

The signal is transmitted from a Radar Dome and the pulses are sent from a dish inside the dome that scans around and up and down.

While keeping the radar running properly is a daily task, National Weather Service in Charleston, W.Va., Radar Technician David Cunningham says, “Then, in addition to the daily maintenance, we have our periodic checks to where we do the calibrations to make sure it’s accurate to where we do. We do check with the Sun to make sure that the positioning is correct on it.”

Despite the upkeep, radars do have their limitations.

The Charleston Radar is a 120-foot tower that captures 80-percent of the precipitation that impacts our 10-county area. It sits at 1,100 feet, but a ridge to the southeast is 1,200 feet. Why does this matter? The lowest tilt of the radar scan (which often detects precipitation closest to the ground) always hits this ridge and the pulse can’t go through the terrain, so any precipitation east of the ridge goes undetected. This beam blockage creates a triangle of silence whereas the radar shows no rain or snow even though it’s likely actually occurring.

Fortunately, radar sends pulses out at higher tilts, which do clear the 1,200-foot ridgeline southeast of the Charleston radar. These higher tilts (0.9 degrees and up) help us analyze severe storms that push into our 10-county region.

The pulses sent out by the radar follow a linear path up and away from the dome. The farther you live from the radar (such as our 10-county region), even the lowest level scan of the radar beam has a difficult time identifying precipitation occurring from a low cloud base like drizzle and occasionally snow showers. That’s why Dual Polar Radar products are supplemented on the air to identify precipitation and high winds aloft that could surface in storms.

These more recent and advanced radar products help, but what truly is needed to clearly see the atmosphere above us are supplemental radars.

As Climavision CEO President Chris Goode explains, the company’s priority of increasing radar coverage across the country has been met with much support in the community.

Goode said in an interview, “We’ve seen a lot of enthusiasm, Chad. This is a long-standing problem, as you know, not only in your area. There are several gaps and they’re all not created equal. You’ve got real issues with distance between existing radars in the western part of the country. Really, that exacerbates the problem where you have beam heights in excess of 10,000 feet in many areas. So, we’re missing a lot of low-level information. That is critical both to real-time monitoring during breaking weather, but also in the downstream ability to assimilate new observations at these low levels into models that can help us better predict what will happen.”

In response, Chief Meteorologist Chad Merrill referenced the radar gap between the Blacksburg, Va., Jackson, Ky., and Charleston, W.Va., radars in southwestern Virginia.

Goode said, “And as you can see there (in the video), we’re planning to deploy in this area as well. In near proximity, we’ve already deployed two radars in central Kentucky, one up in Dry Ridge in the northern part of the state, and another one on down in the southern part of the state that covers a major recreational area around Lake Cumberland. So, again, similar problems that we’re solving in that part of the state and nearby to your particular issue here in West Virginia.”

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