Portland’s ‘Winter Of Fog’

Some people were photographing the fog this January weekend.

Raymond sent this awesome shot of dense fog over the Columbia River (and cities on both sides) while Mount St. Helens sparkled in the bright sunshine.

Some people were talking about it. When I went out to eat I was asked about ‘all the fog.’

Some people were tweeting about it. And when I checked twitter over the weekend–it was the hot topic as you see in this series of tweets on the #pdxtst hashtag — it’s the pdx twitter storm team.

And what’s craziest of all? It’ll probably be the most talked about weather topic of the coming week because the weather setup is just right for more areas of dense fog!

Portland’s Winter Of Fog

Check out what’s happened so far. Let’s look at Dense Fog which reduces visibility to 1/4 mile or less. I’m comparing the number of days with dense fog this rainy season — versus what’s average:

• November – average 6 days of dense fog / November 2011 – we had 7 days
• December – average 5 days of dense fog / December 2011 – we had 12 days
• January – average 4 days of dense fog / January 2012 – 3 days during the first week…with more to come!
• Total 3 month average = 15
• Actual 3 months this time = 22

We also had one of our longest streaks on record when it comes to the number of days in a row with dense fog. December 5-10, 2011, we had a 6 day stretch of this for the first time since 1999!

But how many days have we had with any kind of fog, even if it’s not dense? Well, that’s trickier to answer. The automated weather stations used by the National Weather Service specifically track dense fog. But for some reason, they do not track non-dense fog exclusively–instead, reporting it as fog/mist. So, technically, drizzle looks like fog on the report and vice-versa. But for what it’s worth…at PDX…fog or mist (mainly fog, I think) was recorded 25 days in November, 29 days in December, and 6 of the first 7 days in January.

What’s causing all our fog this winter? Having only occasional storm systems. That leaves us with unusual amounts on clearing and calm weather in-between those systems and put that with long winter nights and it’s a great recipe for fog. Normally, this is something we see at the start of the rainy season. This year, that pattern has continued all the way into January!

Could we look back on this as Portland’s Winter of Fog? It’s an interesting prediction made by @dampscribbler