Daily Archives: September 21, 2012

Watch a microburst make a building almost disappear

I came across an incredible video yesterday that demonstrated one of the most exciting, yet common weather events in the Midwest called a microburst. In fact, these weather events are so rare in the Seattle area that I found only one news article highlighting that we’ve ever seen one in this region, and it was dated in the year 2000.

So what are these strange weather events we call “microbursts”? Don’t let the prefix “micro” fool you into thinking this is a small deal. In fact, as you’ll see in a moment, it’s quite a BIG deal. Remember when we were going through that long series of thunderstorms in July?  The most basic ingredients for thunderstorms are: moisture, unstable air and lift. This “lift” can usually form from fronts, ocean breezes or mountains. In our case, we had a lot of lift from the Cascades, as that is where these storms originated.

Now, a microburst is one of the many demon children of thunderstorms (the others being hail, tornadoes, etc). One of the most prominent meteorologists of all time, Ted Fujita, coined the term “microburst”, which is a downpour that can affect an area within a 2.5 mile diameter or less. (Ever heard of an “F-1” or “F5” tornado? The Fujita scale for measuring tornadoes came from him too!) A macroburst is anything larger than 2.5 miles.

These microbursts can be described as rapidly sinking air in a thunderstorm that is, as previously mentioned, less than 2.5 miles in diameter.

Weak updrafts followed by strong downdrafts are a perfect recipe for a severe, albeit short, burst of rain, hail and/or damaging winds. In fact, there are “dry microbursts” which usually contain strong gusty winds, but no rain. Conversely, the stronger the updraft is, the weaker the downdraft, yet as you can see flash floods and hail are not uncommon in these situations.

So, with this knowledge in mind, let’s take a look at an incredible microburst near New Berlin, Wisconsin that made the visibility go to zero. If you don’t want to watch the whole thing, skip to the 2:00 mark and watch from there. Posted by Steve Paluch:

Just amazing how Mother Nature works, huh? For those of you who were hoping this post would lead to an eventual confession that we could be experiencing a microburst soon, I hate to disappoint. So, let me assuage your mind by pointing out that the National Weather Service has discussed the potential of some wandering thunderstorms tonight into tomorrow. Again, the “lift” we talked about will be provided by the Cascades, so that’s the biggest threat, but you never know which ones could trickle our way.

The rest of the forecast? Well…it looks like I’ve been too liberal with the temperatures and sunshine, so you’ll probably notice the forecast doesn’t look nearly as warm or sunny as it did a few days ago, but I’m sure many of you are OK with that 🙂

Make it a great weekend!

Matthew Leach

Forecasting Kitsap