The Basics of How Storms Work

Learn the basics of how storms work in this section!

Want to Photograph Monsoon Season? | Five Tips to Photograph the Monsoons

Every summer in the desert southwest of the United States, a familiar pattern emerges and storms roam the desert landscapes. This pattern is known as the monsoon pattern. While this pattern isn’t as violent as the spring supercells on the Plains or as active as its namesake from India — the southwest monsoons are an…

What are updrafts and downdrafts?

From the NWS Glossary: Updraft – A small-scale current of rising air. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud or an individual tower of a towering cumulus or Cb. Downdraft – A small-scale column of air that rapidly sinks toward the ground, usually accompanied by precipitation as…

What is the rear flank downdraft?

The rear flank downdraft (RFD) is a key ingredient in tornado formation in supercell thunderstorms. The RFD is a region of air (usually dry) subsiding on the back side of a mesocyclone that then wraps around the mess. It is often visible as a clear slot wrapping around the wall cloud.

What is a wall cloud?

Check out this definition from the NWS Glossary: A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm. When seen from within several miles,…

What are shelf clouds?

Shelf clouds are usually associated with the leading edge of storm outflow — this is usually a sign of a line of storms or an HP supercell. Often, rising motion is seen at the front of the shelf, with the underbelly of the shelf being quite turbulent.

What are anvils?

Anvils are the flat, spreading top of a cumulonimbus cloud. Thunderstorm anvils may spread hundreds of miles downwind from the thunderstorm itself. Sometimes, they may even spread upwind.

A Primer on Tornado Formation…

How tornadoes form is one o the biggest questions facing atmospheric scientists today. However, we do know a lot of the ‘whys’ of tornado formation. Most tornadoes form from what we call supercell thunderstorms. These storms have a rotating updraft known as a mesocyclone, which creates the processes necessary for tornado formation.

What are landspouts?

Not all tornadoes originate from a mesocyclone or even a supercell. One type of non-supercell tornado is a land spout. Landspout tornadoes occur as the parent storm cloud is in its growth stage with the spin originating in the boundary layer of the storm.

Where do severe storms happen?

The answer: well basically everywhere but it depends on the time of year for the ‘normal’ peak of severe weather season.

The EF Scale

A look at the EF scale to measure tornado intensity.

The Basics of Lift: What Patterns Result in Storms?

Severe storms need three main ingredients: wind shear, instability, and atmospheric lift. Atmospheric lift is important to get air parcels in an unstable atmosphere to begin lifting upwards and eventually condensing into clouds. Lift is necessary to overcome a capping inversion on the most dynamic days as well. Usually, lift is associated with an upper…

How big can tornadoes get? Does the size matter?

Let’s answer the question: How big do tornadoes get? Tornadoes can be both very big, and quite small. Their sizes can range from a few yards across to a couple of miles! Thus, tornado size is certainly a variable topic. Interestingly, size doesn’t matter in terms of tornado strength. Bigger tornadoes do have a bigger…

Where, exactly, is tornado alley?

Depending on who is asking, the answer to where is tornado alley varies greatly. Who is asking? Why are they asking? Where are they asking from? Much of the United States lives under a near constant yearly threat from tornadoes spawned from supercells. The answer to where is tornado alley is actually quite complex. Air…

What are supercells?

A supercell is a thunderstorm with a deep, persistently rotating updraft. Supercells are the least common form of thunderstorm yet they are potentially the most violent. Large hail of greater than baseball size, strong damaging winds, and tornadoes can accompany these storms. To storm chasers, Supercells are the grand catch — they are the bounty…

What is hail?

Hail is actually responsible for some big monetary loss disasters in the country. All too often during severe weather season, hail takes a back seat to tornadoes but many storms are notable just because of the gigantic hail they throw out. These big ice chunks from thunderstorms form and fall to the ground with intense…

What is wind shear? An Explainer on Speed Shear and Directional Shear…

We oftentimes talk about wind shear as if you already know what it is — but you may find yourself asking what is wind shear when you hear the term. Never fear, we’ve got a video about that very thing. Simply put, wind shear is the change of direction and speed with winds with heigh…

What is instability? What is CAPE? How do we measure it for storms?

Instability. We talk about it a lot. We talk about as if you know what it is. But you may not know, we may be assuming, and you may be lost. So let’s explain. First…a definition from the officially official experts: The tendency for air parcels to accelerate when they are displaced from their original…