Weathercatch: Our region’s least-liked clouds of wintertime are fading away as it gets warmer

For those of you familiar with our columns, you know we are fond of clouds and how they allow us to connect with nature without going anywhere. We often encourage readers to step outside and gaze up at clouds’ ever-changing shapes and sizes, ranging from puffy balls, swirls and wisps to discs and towering walls.

But what about clouds that have no shape?

Think back to last month and you may know what we’re talking about. Of January’s 31 days, 24 were entirely cloud-covered in the Spokane area, according to the National Weather Service. On most of those days, a layer of gray blanketed the sky. The damp bleakness may have created a pleasant environment for zombies, but not for the rest of us.

This persistent blanket of gray was caused by stratus clouds, the lowest cloud type in the atmosphere. Featureless and gloomy, they tend to give clouds a bad name.

Here in the Inland Northwest, stratus clouds are common in our winter skies. Not only do they blot out the sun, but they can hang around for days, as we saw last month. Stratus are thin and mostly generate small amounts of rain or snowfall, which is why we didn’t see a lot of precipitation in January. Because stratus form at such low altitudes – below 6,500 feet compared with cirrus clouds that form above 18,000 feet – they can drape over hillsides and tall buildings, resembling fog that doesn’t reach the ground.

Why did they hang around so much last month, particularly during its second half? An upper atmospheric ridge locked in stagnant conditions and warmer temperatures aloft. This, combined with plenty of moisture from melting and evaporating snow on the ground helped fuel the clouds’ formation. It’s interesting to note that, in summer, sinking air associated with an upper-level ridge typically produces hot weather. In wintertime, however, the resulting lid of warmer temperatures can overspread a cooler air mass and cause a temperature inversion. Hence, stratus clouds and fog are likely to form.

Another high-pressure ridge moved in on Monday of this week, contributing to temperatures in the mid-40s – the warmest we’ve seen so far this year – transient lower-level clouds and patches of morning fog. Even so, we’ve had ample sunshine. Now that it’s February, the strengthening warmth of the sun weakens inversions and helps burn off low clouds and fog. This means it’s highly unlikely we’ll see a repeat of January’s long-term gloom.

Instead, look for more sunshine and mild temperatures during the next week, with periodic intervals of morning fog or low clouds that should mostly burn off in the afternoon.