Radar Coverage in Vermont

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Created on Tuesday, 06 April 2021 21:00
Written by Nate Rubin

Vermont - In late March, Vermont was hit by a rare tornado that destroyed several homes and injured two people. Radar coverage in the western half of the state is not a problem but as you get over the green mountains, radar coverage starts to get blocked. This posed a question if it is necessary to implement a new radar tower to improve the coverage in the eastern half of the state since storms happen all throughout the state. 

 

 

Trying to put out warnings for the eastern half of the state can be quite tricky as the signal gets blocked by the mountains. The only radar tower in the state currently stands at the Burlington International Airport where the National Weather Office is located. Radars have five different tilt elevations used to look at storms. It starts at 0.5° which is what the beam antenna is angled at above the ground. The beam itself is 1° wide. So, with that in mind it starts scanning at 1.5° and continues through 2.4°, 3.4°, and 4.3°. Once you start getting to the higher elevations, you're able to see further but, now you are looking at a storm from higher up not knowing what could be happening at the surface. "Although we have beam blockage at 0.5° and 0.9°, our warning forecasters rely on the higher elevation scans to effectively issue convective warnings across central and eastern Vermont. We also use adjacent radars, such as KGYX (Portland, Maine), to help with coverage" said Pete Banacos, Science and Operations Officer at NWS Burlington. This can be difficult because if you have a severe thunderstorms, it will have rotation associated with it but, that rotation may not reach the surface, so warning these storms can be tough.

Currently, the NWS doesn't have any plans to build additional radar sites. But, It would definitely benefit Vermont to add an additional radar site. According to Pete Banacos, "The original cost of the WSR-88D (radar) network was approximately $3.1 Billion to build 122 radars". That comes out to be a little over $25 million per radar. In comparison, President Biden's stimulus package was $1.9 trillion dollars. That would pay for about 75,000 radar towers. 

Radar coverage did not play a role in the March 26th tornado in Middlebury. Middlebury has unobstructed view in radar coverage so seeing the storm coming was not a problem. What caused this tornado to be missed by warning is how fast this tornado spinned up and how short-lived it was. According to Pete, the National Weather Service estimates that the tornado was on the ground for 60 seconds and a total path length of 0.6 miles. Radar's receives a new scan every 3 minutes and this tornado happened between radar scans so, it wasn't visible on the radar. In that short amount of time, the tornado destroyed 4 houses and injured 2 people. The tornado was officially rated an EF1 tornado with max wind speeds of 110 mph.