The Clouds Predict

Sunrise in Pittsburgh, 15 January 2021, 7:26am (photo by Kate St. John)

16 January 2021

Red sky at morn, sailors forewarn.

Sunrise on Friday 15 January was a deep crimson red. Though it was sunny for a couple of hours yesterday, gusty wind arrived at 9:30a and rain followed five hours later.

Mackerel sky without rain.

Sky over Frick Park, 9 Jan 2021, 2:30pm

A mackerel sky can predict rain 6-8 hours later, but that wasn’t the case over Frick Park on Saturday 9 January 2021. The day was brilliantly sunny for two hours but became overcast by 5p. These clouds were the leading edge.

Are they a “mackerel sky” or not? What do you think?

Meanwhile, I’d say the bottom right corner is a Harbinger of Gloom.

p.s. See the comments below and this video for the definition of a mackerel sky. Indeed this is an altocumulus one.

(photos by Kate St. John)

3 thoughts on “The Clouds Predict

  1. According to the book Clouds by Eric M. Wilcox, this is indeed a “mackerel sky,” made up of individual cells of altocumulus known as cloudlets.

    “Mackerel sky, mackerel sky; never long wet, never long dry.”

  2. I read a little further and Wilcox wrote that “when an extensive layer of these tufts appears on a humid summer’s morning, it is a good indication that thunderstorms will follow.” He didn’t mention if anything is indicated when they’re seen in winter.

    1. Thanks for looking that up. I took the picture because I thought it was a mackerel sky. Then I doubted because it didn’t rain.

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