WeatherWatcher: Thunder snow over Shoreline, Lake Forest Park
Sunday, March 18, 2012
Tonight, March 18, 2012 at about 8:40pm there was a bright flash of lightening, very quickly followed by a loud thunder. Due to the time between the lightening and the thunder I am estimating that the lightening was about half a mile away from Aurora Village (where I was during this time). It takes about 11 seconds for sound to travel one mile. There was about 5 seconds from the lightening before I was able to hear the thunder.
I looked at the radar as soon as I got to my weather station around 9pm and noticed that a convergence band has formed, which explains the thunderstorm development. The band has since drifted north to north Edmonds and Everett, and spans all the way to the Cascades. It is still active, so I can't rule out the possibility of more lightening and possible snow/hail for the remainder of the evening.
We currently have a cool moist northwest flow of air moving into the region which is what has caused this convergence to set up. Temperatures are hovering just barely above freezing in the areas that the convergence band has hit, everywhere else in the region appears to be running around 36-37ºF. By comparison we are at 34ºF.
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| Thunder snow - crunchy underfoot 11:17pm 3-18-2012 Photo by Diane Hettrick |
This band caused some spotty accumulations even on roads, some places have over an inch of snow mixed with snow pellets, and hail. Roads are very slick and as the low temperature is expected to drop below freezing tonight we will have some pretty tricky road conditions for the morning commute, so be careful out there. We're not out of the woods of winter just yet!
Twitter: @SWeatherWatcher
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4 comments:
The speed of sound is the distance traveled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 340.00 meters per second (1,115 ft/s). This is 1,236 kilometers per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds.
http://en.wikipedia.org/wiki/Speed_of_sound
I apologize. I was going out of memory on that one. Next time I'll check my facts. :)
That one clap of thunder that announced the storm was not only loud but seemed to last forever. Is there a correlation between how long it lasts and the length of the lightening strike?
It all depends on the characteristics of the lightening bolt. Lightning is still very mysterious, scientists still do not understand why it behaves the way it does, and like snow flakes, no two lightening bolts are the same. The length of rumble, texture of the rumble and all other variations in the sound of thunder are all dependent on the formation, length and complexity of the lightening bolt or bolts that generated the thunder.
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