A severe thunderstorm raced from Mecklenburg County through Rowan County on Sunday just before 10 a.m., sounding sirens and knocking down trees and power lines.

One Cleveland resident, Matthew Ronald Steeple, 70, was killed when a tree fell on his pickup truck as he travelled on N.C. Hwy. 152 near Brumley Road in Iredell County, just over the line from Rowan. State police have said the accident happened during a period of heavy rain about 10:10 a.m.

During that same period, towns around Rowan County were receiving numerous reports of trees down, many on power lines.

A tornado warning was issued for Rowan County just after 9:45 a.m., and at 9:50, fire departments throughout Rowan simultaneously sounded siren alarms for the warning. There is a marked difference between a tornado watch and a warning. A watch is a prediction of where a tornado may occur and typically covers a fairly wide area. A warning means a tornado has either been physically sighted or indicated by weather radar and the area it covers is typically much smaller, a city or small county.

The National Weather Service does have one higher level of alert, a tornado emergency, which it issues “when a violent tornado has touched down in the watch area,” according to the organization’s website. “There is a severe threat to human life and property, with catastrophic damage confirmed.”

Spencer Fire Chief Michael Lanning explained that the fire departments will sound the department’s siren when a tornado warning is received and residents can recognize the difference because the siren will “wind up” and not come back down like it does for calls. Before the age of pagers and application-based notification systems, local volunteers would be called by the siren on the firehouse. Some departments, he said, still use the sirens for calls, but not all do because they are no longer needed with technology. However, the sirens are still used for tornado warnings.

Trees came down across the area, from China Grove to Kannapolis to Cleveland, in several spots in Salisbury and in Spencer. Some came down across power wires and caused spots of power outages. At one point, Duke reported there were more than 1,600 outages throughout the county but in isolated spots rather than wide swaths. Duke was so busy they were unable to give estimated time of arrival for calls, and some had to be prioritized because of the hazard.

For instance, one line that was pulled down by a tree on Neelytown Road was sparking, and though the leaves were wet from the heavy rain, a resident called firefighters who had been on the scene removing a separate tree from the road because the tree on the wire had begun to smoke. Firefighters closed the dead-end road at Corriher Gravel Road for a time until the danger passed. A second tree in the same section of road came down across the roadway, and China Grove firefighters worked to clear the street. It was an all-hands-on-deck effort, including firefighters, employees from city and town street departments, and homeowners to clear fallen limbs and trees.

Fortunately, there were no reports of actual fires from downed wires.

The worst of the storm passed through within about 30 to 45 minutes, and the sun began to try to break through the clouds from time to time.

In fact, the NWS reports that the storms were moving so fast they were actually outrunning a lot of the warning times. The NWS has confirmed three tornadoes in S.C. and is now working to assess damage in Mecklenburg and Rowan counties to see if damage was caused by straight line winds or if in fact there was a tornado. The organization is expected to release the findings Monday night.

According to an explanation from the NWS, the line of storms that blew threw Sunday morning is called a Quasi-Linear Convective System or QLCS. Storms in these move fast, reaching speeds of 40 to 60 mph, because winds inside the storm are pushing it to move faster. This type of line of thunderstorm forms ahead of or along a cold front. They can begin as individual storms that then merge into a line or “family” of storms, and can produce heavy rain, damaging straight-line winds, hail and tornadoes. A “kink” or notch in the QLCS line can lead to the spin that develops into a tornado. The line of storms in a QLCS is not a straight line, but is more often called a “squall” line and can be wrapped in such heavy rain it can be hard to see a possible tornado’s velocity.

About 20 percent of all tornadoes are associated with a QLCS, and most of the tornadoes that happen in N.C., especially in the western part of the state, occur along a QLCS. QLCS tornadoes have a reputation for producing quick, damaging tornadoes that, because of the speed of the storms and the rain produced, can have little or no warning.