Southwest Virginia weather radar down for two weeks. Here’s what that means for forecasting.

From March 27 through April 10, the National Weather Service radar, Southwest Virginia’s main weather radar, will be out of service for an important upgrade.

The Doppler radar in Floyd county was installed in the mid 1990s and has been serving the region ever since as the primary radar for southwest and central Virginia as well as parts of West Virginia and North Carolina. It’s the only local radar source for local media as well as the public.

The system outage is all related to a planned life extension project with the goal of keeping the radar operational through the 2030s. When complete, the radar will sit on a brand new pedestal.

WHAT DOES THE RADAR DO?

Radar can be an exceptional tool in a meteorologist’s arsenal for helping to protect life and property. Inside the golf ball-like dome is the radar itself which sends pulses of electromagnetic energy into the atmosphere. This allows WDBJ7 meteorologists to find precipitation, determine its motion and intensity, and identify the precipitation type such as rain, snow or hail.

It also allows our team to identify any potential severe risk including damaging storms, tornadoes, and if rain is heavy enough to cause flooding.

WHAT AN OUTAGE MEANS FOR COVERAGE?

The good news is there are several surrounding radars that we will be using during the extended outage. We always have direct feeds into WDBJ7 weather system from surrounding radars across the country, including:

Charleston, WV
Morristown, TN
Raleigh, NC
Sterling and Wakefield, VA

However, there are some restrictions using weather radar outside of our area.

Limited Range: The surrounding radars aren’t able to see target objects at a long-distant range with complete confidence. Anything that is outside the normal radar range is unclear, often either underdone or overblown.

The Earth is Round: Since the Earth curves with distance, the radar is shooting the beam higher and higher the greater distance away from the pedestal. This means it’s going to often underdo precipitation that is lower in altitude and farther from the nearby radar. This could mean a few things.

Light precipitation from low-topped clouds may go undetected if the radar beam is shooting too high. This means it might be raining but not showing on the radar image.
Surrounding radar may be “seeing” precipitation in the clouds but it’s not reaching the ground due to evaporation. This means your pocket doppler radar (WDBJ7 weather app) may show rain but it’s not raining.
The radar beam may be shooting too high into a storm to detect low-level rotation. We’ll be extra cautious in alerting you for severe weather.

We have Mountains: The mountains can sometimes block the radar beam from surrounding sites. This could prevent seeing the full picture.

These types of outages occur from time-to-time, but an extended outage during what is often a severe weather season is why we wanted to be upfront on the limitations.

We’ll continue to keep you updated as we always do, but wanted to be transparent on what’s happening behind the scenes.

Here’s to clear skies and smooth weather the next few weeks. We’ll keep you updated on the progress.

-Chief meteorologist Brent Watts