You can predict a rainstorm days in advance, if you know the pattern. Storm clouds follow a pattern. The clouds form and progress across the sky in a predictable order. Some clouds bring simple rain showers. Other clouds bring thunderstorms with flashes of lightening.
The rainstorm pattern I am about to describe happens between 30° to 60° north latitude which would include North America and Europe and parts of Asia and from 30° to 60° south latitude.
How Clouds Change as Rain Draws Near
The clouds increase in number, size and density as rain draws near. This change in the clouds is a show that plays out in the blue sky above us.
Stage One: Wispy Clouds
A few wispy cirrus clouds appear in the western sky. Cirrus clouds are thin, high latitude clouds that look like thin strands of cotton candy. They whirl and curl in the sky (higher than 35,000 feet).
Stage Two: Cirrus Clouds Thicken
The cirrus clouds thicken and bunch together and become lower in the sky. The cirrus clouds become cirrostratus clouds, layers of cirrus clouds that don’t have a definite top or bottom, but spread out over a sizeable area. (20,000 feet altitude). I call these clouds, ‘a thick wet blanket’. I know when I see these clouds rain is near.
Stage Three: Altostratus Clouds Appear
The cirrostratus clouds are hidden or replaced by altostratus clouds which are flat, gray clouds that lie in stripes or ridges across the sky. These clouds are dark and lower in the sky. (8,000 feet altitude)
Stage Four: Nimbostratus Clouds Are Dark and Shapeless
Nimbostratus clouds move in. These clouds are low, dark, thick and shapeless. Their ragged edges produce a steady, heavy rain or snow. (about 6,000 feet)
Stage Five: Massive Cumulonimbus Clouds Bring Thunderstorms
Cumulonimbus clouds, massive and with broad bases may form in the spring and summer. These are the powerful “thunder clouds” which bring hail, lightning, and thunder. Heavy rain may pour down to the ground below. (base about 3,000 feet towering up to 16,000 and even up to 65,000 feet high)
As the storm passes, the sky may stay overcast with gray stratocumulus clouds. Once these clouds pass through fair weather returns.
Now We Can Predict the Coming Rainstorm
Now we know the progression of rainstorm clouds. I have often watched as distinct types of clouds roll across the sky. The wind kicks up. The birds quiet down. The squirrels seek shelter, and a stillness fills the air. And then there is the smell of rain.