Weather Blog

Beware the 'June Gloom'?

Beware the 'June Gloom'?
Photo: Puget Sound Clean Air Agency

Late last week, the long range forecasters at NOAA's Climate Prediction Center released their new 30- and 90-day forecasts for the upcoming summer. And for the Pacific Northwest, it would appear that our sunny and summery mid-May was more of a tease than a sign of things to come -- at least in the short term.

The 30-day forecasts for June are showing an above average chance of cooler than normal temperatures across the Pacific Northwest (specifically, a 50 percent chance of cooler than normal June, a 33 percent chance of a normal June, and just a 17 percent chance of a warmer than normal June.)

But on the other hand, it's also showing a greater than average chance of a drier than normal June (same probability spread as the temperature above.)



A cool but dry June? That seems at least to me to point to a steady dose of what's known around here as the "June Gloom" -- where we get a steady marine flow that brings in the familiar ritual of morning clouds then afternoon sunshine.

But if the marine flow is stronger, the gray stays longer and the temperatures stay lower -- even though it's a dry pattern that, aside from perhaps some drizzle or mist in the thicker marine layers, doesn't really bring an accumulating rain.

This theory is supported in NOAA's text discussion which, despite confirming that cool waters tied to La Nina conditions are dead in the central Pacific tropics (Translation: "Don't blame La Nina!"), ocean temperatures do remain cooler than normal off the west coast of North America.

Those chilly waters (and we mean chillier than usual. It's not like you can go swimming in shorts into the Pacific even in the late summer) would help to enhance the low clouds and fog offshore.

Our marine layer is a staple of the late spring and early summer months because the cold waters will cool the warm air near the surface from the spring/summer daytime sun, creating an inversion.

That will trap the colder air near the surface, condensing it into low clouds or fog. The cooler the waters, the more enhanced this process can become, and the gloomier June can be.

However, before sun fans go making the movie "Missing Summer, Part 3 (How I pointed my GPS to Arizona)" the actual 90 day forecast for the summer is not as... gloomy.

It shows no signal on summer-time temperatures -- essentially placing even bets on a cooler, normal, or warmer than normal summer -- but is leaning a little drier than normal. And if you did point your GPS to Arizona, make sure the A/C is working too because models forecast a really scorching summer in the Desert Southwest -- even by their usual scorching standards.

In fact, perhaps they'll be pointing their GPS's north, looking for a little "June Gloom" for relief!