NELLIS AIR FORCE BASE, Nev. — I just got home after a long day of work Sept. 8, 2011, when the phone rang. It was Senior Master Sgt. Lee Smith, the 99th Civil Engineer Squadron Emergency Management superintendent. He said I needed to return to base, the base had been hit by a microburst causing a base-wide power outage.
I have been the Nellis AFB emergency manager since February, 2004, and I have never witnessed anything like a microburst.
A microburst occurred at approximately 4:48 p.m. which affected several facilities, aircraft revetment and the substation which provides power to the entire base. As a direct result of the substation failure, commercial power to the entire installation was temporarily lost with some areas experiencing extended power loss.
The aircraft revetment located on the southeast side of the flightline sustained catastrophic structural failure, and it collapsed on 11 F-16 Fighting Falcons and two A-10 Thunderbolts resulting in one F-16 sustaining a fuel leak. Eight military members received minor injuries and were treated at the Mike O’Callaghan Federal Medical Center and later released.
So what is a microburst? According to Dan Berc, from the National Weather Service Las Vegas Office, it is a strong, localized downburst. A microburst can cause damaging winds up to 120 mph and can last from five to 15 minutes according to the weather service.
When rain falls directly from the base of a cloud or is mixed with dry air, it begins to evaporate, and this evaporation process cools the air. The cool air descends and accelerates as it approaches the ground. When the cool air approaches the ground, it spreads out in all directions, and this divergence of the wind is the signature of the microburst. High winds spreading out in this type of pattern showing little or no curvature are known as straight-line winds.
It is possible that the microburst that hit Nellis AFB that day produced wind gusts of up to 67 mph.
Master Sgt. Robert Ross, 57th Operations Support Squadron Weather Flight, said during the summer months thunderstorms can develop in this area with the potential for microbursts occurring.
Ross advises when people receive Severe Weather Warnings from the 99th Air Base Wing Command Post take the necessary precautionary measures, check all outside areas to be sure items that could become projectiles in storm winds are secured and critical pieces of equipment don’t become damaged.
Winds over 30 mph can cause lighter objects to become airborne and should be considered dangerous.
Weather can take an unexpected turn very quickly. The best way to stay safe is to be prepared and educated on the possible risks and the steps to take in order to decrease their danger.