Doppler radar upgrade

RICHMOND, VA (WWBT) – The National Weather Service Office in Wakefield has recently upgraded their Doppler radar to dual polarization. This is a new technology that promises to change the way we look at storms.

Doppler radar works by sending out a pulse of energy that travels until it encounters something in the air, say a raindrop. That raindrop reflects part of that pulse back, which tells us something's out there. But those pulses are only sent in one direction-horizontally. With the dual polarization upgrade, a vertical pulse will be included, painting a 3-D picture of what a storm looks like.

It will also be easier to see the difference between hail versus rain. More importantly, "We have the ability with dual polarization to potentially be able to assess whether or not a tornado is actually on the ground," said Bill Sammler with NWS in Wakefield.

Storms will still be analyzed to see if they have the potential to produce a tornado.

"But because we are now looking at precipitation or debris in the air in three dimensions, we actually have the ability for close in tornadoes to see whether or not it might be on the ground because of what is called a tornado debris signature," Sammler said.

The tornado debris signature tells us that debris from the ground is being picked up and tossed into the air by powerful winds. Right now we can track it in some of the strongest tornadoes. But the dual polarization will allow us to see the debris in some of the weaker ones- the types of tornadoes that are more common here in Virginia.

"The tornado debris signature will first of all give us 2 clues, one is whether or not the tornado may actually be on the ground and then secondly give us a better assessment of what the track would be, you know within a half mile or so either way, which is really quite good," added Sammler.

This will go a long way in helping to more accurately warn those communities who are in the direct path of these dangerous storms.

There is still much to learn as the entire nation of radars upgrade to dual polarization in the coming years. Along with improved tornado tracking, rainfall estimates should become more precise. This will allow us to identify areas at risk for flash flooding, which is the leading cause of weather related deaths ahead of both lightning and tornadoes. 

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