Boldmethod
What looks like a harmless cumulus cloud can quickly become a thunderstorm in the right conditions.
Thunderstorm Formation
As you lift air from the surface, it cools. The temperature keeps dropping and approaching the air's dew point. Once it hits the dew point, moisture starts to condense out of the air, forming clouds. This altitude is the convective condensation level. It's the lowest altitude that condensation occurs because of convection from surface heating.
As moisture condenses out of the air, it releases energy. (It takes energy to turn water into a gas, and that energy releases as heat as the gas condenses back into water.) Now that moisture is condensing out of the lifted air, it's much warmer than the surrounding air. As it rises, that temperature gap grows, and the air continues to accelerate upward, forming a strong updraft. This creates a towering cumulus cloud, or TCU. And with that, you have the developing stage of a thunderstorm.
Boldmethod
From the spring through early fall, you'll find pop-up thunderstorms all over the United States. It's usually completely clear under the cloud base layer right before precipitation begins. And even after light precip has started, the bottom of the cloud base doesn't always look that bad.
But, you should never fly underneath a build-up that could become a thunderstorm, or one that already is. Here's a good example of why...
NTSB Report: Pilot Flies 172 Under Thunderstorm
The pilot did not receive a weather briefing before beginning the cross-country flight. After takeoff,the pilot requested from air traffic control to fly below 500 ft above ground level along the oceanshoreline. The controller approved the request but advised of heavy precipitation (a thunderstorm) atthe airplane's 12-o'clock position and 4 miles ahead. The controller further advised that the pilotshould turn left and fly offshore 3 miles to avoid the thunderstorm. Although the pilot acknowledgedthe instructions, a review of radar and GPS data for the flight revealed that he continued on course.
About 3 minutes later, the pilot reported he was reversing direction, and no furthercommunications were received from the pilot. Review of the airplane's GPS track overlaid on weatherradar plots revealed that the airplane flew into an area of extreme intensity precipitation and thenentered a rapid descent and impacted the ocean. Examination of the wreckage did not reveal anyevidence of preimpact mechanical malfunctions. It is likely that the pilot lost control of the airplanewhen it encountered strong downdrafts and heavy rain associated with the thunderstorm.
Mature Stage = Mixed Updrafts and Downdrafts
During the second stage of thunderstorm growth, cool falling raindrops pull air down, creating cold downdrafts. This causes a mixing of updrafts and downdrafts, creating extremely turbulent air within and beneath a thunderstorm. Eventually, rain will begin to fall. And when it does, you can experience downdrafts exceeding 2,500 FPM, even when you're under the cloud base.
Boldmethod
Dissipating Stage = Strong Downdrafts
If you get caught under a thunderstorm as it reaches the dissipating stage, you could encounter severe downdrafts exceeding 6,000 FPM. As rain becomes heavy, more air is pulled down with it. At this point, the thunderstorm will begin to die quickly, but it's also the most dangerous time to be caught underneath it.
Boldmethod
With the right conditions, it only takes a few minutes for a seemingly benign cloud to become a full-blown thunderstorm. So what's the best advice to stay safe? If the cloud looks like something you wouldn't want to fly through, you shouldn't fly under it either.
Keep Your Distance
The FAA recommends you stay at least 5 miles from any visible storm cloud, but they strongly recommend increasing the distance to 20 miles or more if you can. Hail, violent turbulence, and strong downdrafts can extend miles away from a thunderstorm.
Use the same logic when flying underneath clouds, and you'll keep yourself out of harm's way.
These rules-of-thumb are even more important in hilly and mountainous terrain, where rising ground elevation gives you fewer outs to escape developing weather.
Feel more comfortable flying around the mountains this spring.
It's easy to think that mountain weather only happens in places like the Rockies. But the hills of Eastern Ohio can produce the same types of weather year-round. If you've ever flown near the Appalachians, you probably experienced mountain weather, even if you didn't realize it was happening.
Whether you're flying on the East Coast, the Coastal Ranges of California, or any of the rough terrain in between, Boldmethod's Mountain Weather course makes you confident and comfortable flying around the mountains.
You'll learn how to evaluate mountain weather during your planning and while you're in flight. You'll also learn how terrain generates updrafts, downdrafts, turbulence, and storms, and changes the direction of the wind throughout the day.
Plus, for less than the cost of a cross-country flight, you get lifetime access to tools that increase your confidence and make your flights more fun.
Ready to get started? Click here to purchase Mountain Weather now.
$299.99
Add To Cart Learn More
