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.
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)
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.”
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.
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.