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Severe Weather Awareness Week: Wind as severe weather

Posted: 1:08 PM, Apr 20, 2018
Updated: 2018-04-20 15:08:48-04

Today wraps up our topics for severe weather for the week, and today’s topic is, wind.

Wind, is wind. Whether it comes from an outflow boundary, micro burst, or tornado. Once winds exceed 38 mph,they begin to do damage to property.

For southern Colorado, wind is a major player, in terms of frequency. It is one of the most frequent forms of severe weather here, and the mountains both increase the frequency…and increase the difficulty…because they interact with wind, in ways that lower elevations never would. Mountains, by very nature of being high, compact the atmosphere on one side, and then expand the atmosphere on the down-wind side, affecting outcomes. In addition that compacting and expanding of air, this process helps remove moisture and heats that air up. And finally, mountain passes create channels or dikes, allowing funneled air to pass through, whereas air elsewhere is forced to make the trek up…and then down the mountainsides.All of this creates a variability for the forecaster, as well as a variability as to what you will see where you live, relative to these winds.

In addition, all this variability for the same weather system, means that some storm cells will have opportunity to grow unfettered, others will be affected positively or negatively by the variability. Which means, in a warm-season T-storm, a place like Canon City may get a generic run-of-the-mill shower, but nearby at Penrose, it could turn severe (or vice versa).

We track wind through computer model simulations, which go forward in time, and cover surface winds, vertically, up to the top of the atmosphere, including the jet stream. But as said earlier, mountains make it particularly difficult to track well.

We are sometimes interested in wind-shear. Think of it like a highway with 3 lanes all going in the same direction…but traffic is traveling at different speeds in each lane, relative to the other lanes. That is the visual, for wind sheer, pockets of wind near each other, but traveling at very different speeds. That can affect individual T-storm development, and creates chaos even in clear air, for pilots. Outflow boundaries are the leading edges of thunderstorms that form a line. Every thunderstorm works a lot like a vacuum, sucking in wind in one area and bellowing it out, another. But when T-storms link up and form a line, you get one long straight-line "outflow boundary" of wind, combining all the individual storm cells’ strength. This is the most frequent storm-related wind issue.

The advice for all wind is the same. Get inside, away from windows, in as low or secure a room as possible. If caught outdoors, get low, in a ditch.

And as a reminder for all this week’s topics…it is crucial that you hold regular family meetings, to discuss and ensure everyone knows the plan of action now, not when the next type of severe weather strikes. That, is too late. Discussing and planning ahead of time with all family members, almost guarantees the best possible outcome.