The NWS radar is moving. Here’s what you need to know

BATON ROUGE, La. (WAFB) - The National Weather Service (NWS) radar in Slidell will be relocated to Hammond in the months ahead. The radar was officially taken offline on Monday, November 27, and is expected to remain offline into March 2024. The move approximately 45 miles to the west is designed to improve radar coverage in parts of south Louisiana and southwest Mississippi without causing any significant degradation in coverage elsewhere.

Why, specifically, is the radar moving?

The relocation is largely designed to improve radar coverage and severe weather detection for western parts of the NWS New Orleans/Baton Rouge County Warning Area (CWA), including metro Baton Rouge. Prior to the move, the radar beam emanating from Slidell was typically scanning more than a mile above the ground in the Capital Region. At that elevation, it could be challenging for radar operators to get a good look at the lowest levels of storms. Lauren Nash, Warning Coordination Meteorologist with the NWS office in Slidell, explained the significance of that change.

“Right now, over Baton Rouge, we can only see storms around 6,000-7,000 feet. Once we move the radar and lower the tilt of the radar, we’ll be able to see storms around 1000-3000 feet in Baton Rouge. While we need to see all heights for a full storm analysis, this should help us see tornado formation a little easier.”

The beam from the National Weather Service radar in Slidell was approximately 5,600-7,200 feet... — The beam from the National Weather Service radar in Slidell was approximately 5,600-7,200 feet above ground by the time it reached Baton Rouge. Once the radar is moved to Hammond and a lower tilt is used, the beam will scan approximately 1,800-2,800 feet above the Capital City.(WAFB)

Tornado detection is the key benefit to the relocation. I have been outspoken about this radar coverage gap for years, demonstrating how it may have been an issue during a record-setting tornado outbreak in February 2016 and again less than 6 months later. A Louisiana congressman even proposed legislation to close the gap after reading my commentary about the February 2016 event.

Where and by how much will coverage improve?

As Nash points out, it’s not only that the radar is moving closer to the Capital Region, but it will also be operating at a lower tilt than ever before. Prior to the move, the lowest tilt was 0.5° above horizontal. Once online in Hammond, the radar will be allowed to operate at a tilt of 0.3°, aiding in a lower scan and better detection of high winds and areas of potential rotation in the lowest levels of storms. The map below shows where low-level radar coverage will be improved. Note that the greatest improvement, indicated by the darkest shades of green, extends from southwest Mississippi through metro Baton Rouge to St. Mary Parish along the coast.

Graphic showing how much lower the radar beam will scan once the radar is relocated from... — Graphic showing how much lower the radar beam will scan once the radar is relocated from Slidell to Hammond a lower tilt is used. The greatest improvement in low-level radar coverage is indicated by shaded of dark green.(NWS New Orleans/Baton Rouge)

How will we track storms until the move is complete?

There is no sugar coating the fact that losing a key radar for 4 months or more is a concern in a part of the world that doesn’t really have a dry season. In fact, as I shared in a previous post, an ongoing El Niño event could very well lead to a wetter, more active winter locally.

Nash notes that NWS forecasters will have to rely on surrounding radars and other technology to track storms.

“We luckily have many surrounding radars in Lake Charles, Fort Johnson, Jackson and Mobile and a radar at MSY airport. We also have many satellite and lightning tools. But we will need reports from the public.”

Map showing nearby radars that NWS New Orleans/Baton Rouge will rely on while the radar in... — Map showing nearby radars that NWS New Orleans/Baton Rouge will rely on while the radar in Slidell is relocated to Hammond. The terminal Doppler near MSY is a lower power radar that doesn't really reach Baton Rouge.(WAFB)

WAFB viewers will have the added benefit of our exclusive First Alert Radar Network. Radars located in West Feliciana Parish and western St. Mary Parish are in prime position to fill the coverage gap left by the NWS radar relocation. While these radars operate with less power than those of the NWS, they provide more frequent scans and greater detail of storms in the region. Not only can you catch these on air, but they are also available on our website and in our free First Alert Weather App.