UBC ATSC 113 - Basic Thunderstorms

Learning Goal 4a (continuation):
Describe thunderstorm cells and the different types of thunderstorms. (This portion is on basic thunderstorms.)

Basic storm types:
a. single cell (airmass)
b. multicell
c. orographic

BASIC STORMS
a. Single-cell (airmass) Thunderstorm
These are short-lived (15 to 30 minutes) and often not as violent as other types of thunderstorms. At right, in the vertical cross section: white dashes indicate ice crystals, asterisks indicate snow flakes, white dots are supercooled (unfrozen) liquid water raindrops, black dots indicate raindrops. Gray background indicates clouds. Arrows indicate winds.
b. Multicell Thunderstorm
Two or more cells. Each cell can be in a different stage of its life cycle. Below, in the vertical cross section: the oldest cell, cell 1, is already dissipating; cell 2 is mature; and the youngest cells, cells 3 and 4, are in the cumulus stage. So each cell has different hazards, even though they are all in the same large cloud mass. Light gray indicates clouds. Black arrows indicate up- and down-drafts. Colors indicate intensity of rain as might be seen on weather radar. Note that only the rain portions are visible on radar.	Multicell thunderstorm as viewed from the cockpit.
Horizontal (map) radar image. Red colors indicate the centers of the cells. The thin blue arc is a gust front.
c. Orographic Thunderstorm
These form over mountains. When the wind blows warm humid air toward hills and mountains, the air hits the mountain and is forced to rise. If it rises far enough, a cloud can form, and could develop into a thunderstorm if conditions are right. If an orographic storm is stationary, then all the rain falls in the same watershed, causing flash floods.
A line of orographic thunderstorms over the Vancouver Island mountains, as viewed from UBC. Photo 24 March 2018 by Shawn Nigam, used with permission.

BASIC STORMS

a. Single-cell (airmass) Thunderstorm

These are short-lived (15 to 30 minutes) and often not as violent as other types of thunderstorms.

At right, in the vertical cross section: white dashes indicate ice crystals, asterisks indicate snow flakes, white dots are supercooled (unfrozen) liquid water raindrops, black dots indicate raindrops. Gray background indicates clouds. Arrows indicate winds.

b. Multicell Thunderstorm

Two or more cells. Each cell can be in a different stage of its life cycle. Below, in the vertical cross section:

the oldest cell, cell 1, is already dissipating;
cell 2 is mature;
and the youngest cells, cells 3 and 4, are in the cumulus stage.

So each cell has different hazards, even though they are all in the same large cloud mass.

multicell thunderstorm diagram

Light gray indicates clouds. Black arrows indicate up- and down-drafts. Colors indicate intensity of rain as might be seen on weather radar. Note that only the rain portions are visible on radar.

Multicell thunderstorm as viewed from the cockpit.

Horizontal (map) radar image. Red colors indicate the centers of the cells. The thin blue arc is a gust front.

c. Orographic Thunderstorm

These form over mountains. When the wind blows warm humid air toward hills and mountains, the air hits the mountain and is forced to rise. If it rises far enough, a cloud can form, and could develop into a thunderstorm if conditions are right. If an orographic storm is stationary, then all the rain falls in the same watershed, causing flash floods.

A line of orographic thunderstorms over the Vancouver Island mountains, as viewed from UBC.

Photo 24 March 2018 by Shawn Nigam, used with permission.

Orographic thunderstorms over Vancouver Island

Key words: multicell thunderstorm, orographic thunderstorm, single-cell (airmass) thunderstorm

Extra info for experts; not needed for this course.

Stull, 2017: Practical Meteorology. Chapter 14. Thunderstorm Fundamentals.

Image credits. All figures by Roland Stull, except the following: Airmass thunderstorm photo, Single-cell cumulonimbus incus © User:sfortis / Wikimedia commons / CC BY-SA 3.0. Radar images courtesy of the US National Weather Service.

ATSC 113 Weather for Sailing, Flying & Snow Sports

Types of Thunderstorms > Basic Storms

Learning Goal 4a (continuation):
Describe thunderstorm cells and the different types of thunderstorms. (This portion is on basic thunderstorms.)

ATSC 113 Weather for Sailing, Flying & Snow Sports

Types of Thunderstorms > Basic Storms

Learning Goal 4a (continuation): Describe thunderstorm cells and the different types of thunderstorms. (This portion is on basic thunderstorms.)

Learning Goal 4a (continuation):
Describe thunderstorm cells and the different types of thunderstorms. (This portion is on basic thunderstorms.)