McRidge – The End Is Near

McRidge – The End Is Near

It’s been five days since my initial post, which, despite describing the most boring weather feature in existence, actually became my most-viewed post ever with over 1,000 views this week! That’s because Scott Sistek, a University of Washington meteorology grad who works for KOMO as a content writer/off-air meteorologist, was generous enough to share my blog on his Facebook Page. Scott is a huge reason why KOMO’s forecast team is so darn good, as he is able to explain pretty darn complicated atmospheric phenomena with ease in his weather blog while remaining true to the science. And he’s a captivating writer too! Check his blog and be sure to follow him on Facebook and Twitter for his latest weather updates. You wouldn’t believe how fast Scott can tweet during a snowstorm!

McRidge hasn’t done too much since initially setting up shop over the area. In fact, he’s still centered over the area, and he’ll continue to have a strong grip on us for the next 5 days.

Infrared satellite and overlaid 500 mb heights (green lines) and temperatures (red lines) per 12Z 12/9/2017 GFS
Infrared satellite and overlaid 500 mb heights (green lines) and temperatures (red lines) per 12Z 12/9/2017 GFS
Credit: David Ovens/University of Washington Atmospheric Sciences

One thing we haven’t seen much of over the past week is fog in the lowlands west of the Cascades. We’ve seen a little fog in spots across the more sheltered locations like the southern Willamette Valley and some lower-elevation areas near Puget Sound, but as today’s image from NASA’s TERRA satellite shows, we can’t hold a candle to the low stratus and fog over the Columbia Basin.

Fog over the Columbia Basin. The smoke off the coast is from the California wildfires due to southerly flow aloft on the western side of McRidge
Fog over the Columbia Basin. The smoke off the coast is from the California wildfires due to southerly flow aloft on the western side of McRidge
Credit: NASA

The reason why the Columbia Basin is so much cloudier/foggier is because they are so much colder. The bowl shape of the basin allows cold air to settle at the bottom, and this air is cold enough that it cools the temperature to the dewpoint and forms low clouds/fog. With such cold air at the surface, we get an über-strong inversion that ensures that these clouds will be here to stay.

Current conditions over Washington/Northern Oregon. Notice how much colder Eastern Washington is than Western Washington.
Credit: NWS

The reason why many places around Western Washington/Oregon have remained fog-free is because the ground was not terribly wet when this ridge first settled over the area. If we were wet, we wouldn’t have to cool as much to reach the dewpoint at night. Additionally, Portland and areas along the Gorge have been spared of fog due to the intrusion of strong easterlies through the Gorge, which helps mix the airmass and prevents an inversion from forming in the first place. You can see gust to 36 at Troutdale above, and Crown Point is still gusting between 60 and 70 mph. It has been doing this since Wednesday.

Wind Speeds/Gusts at Crown Point, OR
Wind Speeds/Gusts at Crown Point, OR
Credit: Mesowest/NWS

The profiler at the NWS office at Sand Point in Seattle, Washington is a fantastic tool for gauging the strength of these inversions. The temperature increased from 3.5 degrees C (38 degrees F) at the surface to approximately 20 degrees C (68 degrees F) by 700 meters (2300 feet). That’s an incredibly strong inversion!

Sand Point Profiler showing temperature (X axis) and height (Y axis). Note how the temperature lines are skewed - this chart is called a "Skew-T."
Sand Point Profiler showing temperature (X axis) and height (Y axis). Note how the temperature lines are skewed – this chart is called a “Skew-T.”
Credit: University of Washington Atmospheric Sciences Department

The highest temperature in Oregon today was a 72-degree reading at Flynn Prairie (1,543 feet) near the Southern Oregon Coast, but Yellowstone Mountain (3,080 feet) and Emigrant (3,840 feet) both deserve respect for hitting 67 degrees and being higher in both elevation and latitude. The highest temperature I found in Washington was 65 at Gold Hill (3,350 feet). These are astonishingly high numbers considering we are less than two weeks away from the winter solstice.

The Death of the Death Ridge

Models now finally show McRidge breaking down sometime around December 14/15 (which, coincidentally, is the 11th anniversary of the Hanukkah Eve Storm) as a storm traveling north into BC drags a weak atmospheric river across the area. This may usher in a period of zonal, westerly flow, which would mark a return to more unsettled weather.

Precipitable water and 500 hPa geopotential heights over the NE Pacific. Valid 4 pm PST Thursday, 12/14/2017

Though there is plenty of uncertainty with the location and strength of this westerly flow, confidence really begins to die off after 12/17 or 12/18. We are always grasping at straws that far out, but it appears as though this westerly flow may die off and a blocking pattern may once again set up . Still, models are unsure whether the block, if there is one, would once again be located over the West Coast (McRidge #2) or further offshore. A block further offshore would be a better setup for a modified arctic airmass to plunge southward into the region, so that’s what all of us weather geeks are hoping for.

We are confident that we’ll finally get rid of our ridge on December 14th/15th. We may have a couple days of zonal flow off the Pacific after that, but confidence once again deteriorates after December 17th/18th.

I hope you can make the best of our remaining days with McRidge overhead! I think we’ll at least be able to get rid of some of the fog/low clouds in Eastern Washington over the next few days as a system brushes by the coast on Monday evening and helps mix the atmosphere a bit.

Before I go, I’ll leave you with one shot of Mt. Rainier from Paradise (5,130 feet), which hit 57 degrees today. Our current pattern is actually pretty darn splendid if you can get above the inversion. 🙂

Looking at Mt. Rainier from Paradise Ranger Station
Credit: National Park Service

Thanks for reading,
Charlie

2 thoughts on “McRidge – The End Is Near

  1. Another awesome write-up of our strange weather, Charlie! I’ve been able to get yard work done with the dry streak, though my hands were starting to feel like fake ones with the cold, windy air. Never thought that I’d be able to schedule December yard work 5 days in advance (I took the day off from work knowing that this was coming).
    Now, if we can just get this next potential ridge to set up further offshore.

  2. Charlie what to you is not normal that is an all to familiar pattern here in the North. You just need to come up for an few years and you will see what I mean. Every time during the deep cold I drive thru the inversion layer that fills the bowl in the Tanana valley in which Fairbanks is in.

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