Mackerel sky. Taken near Corcoran, MN, February 19, 2012. Laura Betker.
GOLDEN VALLEY, Minn. - The old wives tale, "Mackerel sky, not three days dry" or "Mackerel sky, not 24 hours dry" does hold truth. Monday is a great example of these clouds that resemble fish scales and signal impending rain or snow.
We see these high clouds forming ahead of a storm system where the atmosphere is beginning to destabilize and moisture is moving in. Weak upward motion develops these altocumulus or cirrocumulus clouds, as they are officially named. But they don't necessarily mean it's time to stock up on canned goods and head for the basement.
Another similar phrase says, "Mackerel sky, Never long wet, Never long dry," which is a great description for the trend that storm systems following a mackerel sky usually aren't deep, well-developed lows that bring an abundance of moisture, but rather quick moving and weaker frontal systems.
Tonight, look for about 2" of slushy snow in the Metro with larger accumulations north and west, up to 5".
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