Capping off a week of suffocating humidity and frequent bouts of heavy rain, a menacing line of showers and storms cut through the Washington, D.C. metro region the evening of Friday the 13th.
While this activity – lined up along a cold front – took on a scary appearance, its passage was fairly anemic. It generated just some brief, spotty showers and a few gusts of wind. The atmosphere had been worked over by all the rain and storms from earlier in the day, and was zapped of energy.
Nevertheless, the sharp contrast between cooler, drier air moving in and the muggy air being kicked out made for turbulent and visually spectacular skies.
The shelf cloud
Along the leading edge of the line of storms – or gust front, a dramatic shelf cloud formed: the boundary between the warm, moist air rising into the storms and the rain-cooled air being dispensed. Here’s quite a collection of views from around the region:
Other scary clouds
In addition to the shelf clouds, some other ominous-looking clouds presented themselves. The low hanging dark clouds, which some mistook for a tornado, is actually a harmless cloud known as a scud which form as warm, moist air rises and condenses.
There’s an example of a scud and some other scary-looking clouds (mostly just cumulonimbus) from Friday the 13th below:
Beautiful clouds, too
The passage of the front near sunset cast a beautiful light on some of the clouds, as you can see here…