Safety risk? What the local National Weather Service radar outage means to you
BLACKSBURG, Va. (WSET) - It's a change you probably haven't noticed - but one that could impact your ability to know exactly where rain and wind are located.
George Flickinger went to Blacksburg to investigate what's going on with the local National Weather Service's radar.
The National Weather Service discovered problems with the Floyd county Nexrad Doppler radar during an upgrade, so we asked Phil Hysell what happened. Phil is the warning coordination meteorologist at the Blacksburg office.
Hysell says engineers found a small crack in the radar's hardware, and the radar is shut down to prevent further damage.
With our local weather radar off-line, we're forced to use other radars farther away.
Our closest working radar is in North Carolina, over 100 miles away in Raleigh.
Here are two things that will most affect you:
- Rain on the radar can differ from what's actually reaching the ground.
- Wind near the ground is not detected because the radar beam is too high off the ground
This means the wet weather you see on a radar app might not match what you're actually getting.
This affects every television station and nearly all weather apps.
When rain is measured from farther away, some storms will look more intense and larger than they actually are.
Rain can be overestimated when the radar beam is too high.
From the Raleigh radar, rain and wind are being measured at 14,000 feet above the ground in Lynchburg.
The Floyd county radar detects rain/wind near 7,000 feet overhead in Lynchburg.
The higher in elevation the sampling, the more the data doesn't match up with what's occurring at ground level.
I noticed last week there was a shower with moderate rain indicated over Lynchburg, but little to no rain was falling. If you were watching my weathercast or using weather app, it would appear to you that the rain was overestimated.
Over the weekend I also noticed moderate rain (yellow on the radar) detected over our house, yet we received zero rain-- air was too dry near the ground. This rain evaporated below the radar beam.
If light rain or drizzle are occurring, the precipitation near the ground could be underestimated, or might not even show up at all because the rain is forming too low to the ground.
If you use the radar to find subtle wind shifts near the surface, you're out of luck until the Floyd county radar is repaired.
So, what happens if we are expecting strong wind and severe weather, like a derecho or tornado?
The NWS tells us we're actually okay. The other nearby radars can fill in the gaps to track the location and movement of the storms. Warnings will NOT be missed, though the actual conditions near the ground are uncertain.
If the weather is severe enough, and conditions near the ground need to be measured, the Floyd county radar could briefly be turned on for an emergency.
However, there is a risk of causing more damage to the radar.
The Floyd county radar is expected to be down for the month of August.
Once repairs and upgrades are complete, we will all benefit from faster processors, better data and longer reliability.
Until then, rain and wind data near the ground is a bit of a mystery!