Outflow winds are not your usual steady wind pattern that comes from one direction. These are more sporadic.
"When winds are erratic it's a little harder to predict what's going to happen,” said Charlie Moore of Truckee Meadows Fire Protection District.
Thunderstorms produce outflow winds as the storm collapses. Warm air rises and eventually turns into a storm cloud. As the cloud grows the moisture in the middle of the storm eventually cools down from evaporation. Eventually the cool air becomes so dense that it sinks to the ground as a fast moving of rush air, spreading out in a variety of directions.
"It’s like a fireplace. It gives oxygen to the fire and propels the fire a lot faster than we might be able to get around it,” said Moore.
When it comes to fire safety even 20 miles an hour is strong enough to be dangerous. Especially if the direction of the wind is variable. Outflow winds can exceed 40 miles per hour.
"The lightning causes the fire and the outflow winds fans the fire,” said Moore.
Acting as a mini cold front outflow winds can also cause the air to rise and create new thunderstorms. They might even seem like they are popping up out of nowhere. With the sudden formation of new storms and the variety of wind directions, outflow winds makes fires more unpredictable. Since they form below the radar beam they can also be hard to detect in our area.
