Big Weather Slowdown Heading into Mid-January

9:30pm Friday…

The big rain showed up as forecast. An atmospheric river of moisture, also known as a pineapple express, was aimed at southern Washington and extreme NW Oregon the past two days. Rain totals were not excessive from Portland south, but very heavy rain fell to our west, north, and east (Cascades/Gorge). The numbers from the past 3 days

Notice those numbers around 7″! Astoria saw its 2nd wettest day on record at the airport.

When records were kept in the city before that time, there were 2 wetter days in 1919 & 1904. Regardless, this was a high-end rain event on the far northern Oregon and southern Washington coastline. Check out the REALLY big numbers. Over 9″ in several spots, including the south Washington Cascades and Willapa Hills in SW Washington

I-5 in Chehalis just briefly closed today as Chehalis River water came up onto the edges of the freeway, but luckily it was 4 feet lower than during the huge 2007 flood. Just about all rivers are receding now and I think we dodged a bullet this time; no widespread heavy rain like in 1996. That year over 15″ rain fell all through the Cascades over a 4 day period, melting lots of the snowpack.

The good news is that the snowpack is still there in the Cascades, running well above normal


  • The next 7+ days feature a very quiet weather pattern; no big storms/weather systems moving through the region
  • Temperatures remain near normal through at least the 15th
  • There’s no sign of a cool/wet pattern OR low elevation snow/ice west of the Cascades
  • All models agree the next 10-14 days will feature mild weather with relatively weak weather systems
  • The “holy grail” of a cold/snowy January (for weather geeks like me) isn’t going to happen this year

It’s quite the pattern change coming up. We’ve had cool upper-level troughing near/over us most of the time since around the 10th of December. Now for the next two weeks it’ll be more like that mild weather that we started with in November and early December. Here’s the 500mb pattern on Monday

Warm upper level ridging overhead, but it’s a “dirty” ridge, meaning weather systems are brushing us early next week (red lines). We also don’t tend to get insanely strong east wind inversions with this setup. By NEXT Saturday, the 15th, it hasn’t changed much. Time for winter to arrive in the eastern USA! This is quite the flip from the past month.

Then even farther out, Friday the 21st. This is the ensemble average 500mb height anomaly, showing above and below normal heights. The same GENERAL pattern continues (Canadian ensembles shown)

Is winter over? Of course not, that would be ridiculous to proclaim on January 7th. But this is a big slowdown after the weather drama the past three weeks!

Looks like ONE ensemble member of the 30 GEFS members tries to bring snow down into the valley…in the next two weeks!

Seems like an excellent time to take my snow-blower in for repair. I did use it with that one snowfall of around 4″. I know…sad.

So…enjoy the much slower weather this upcoming week. Sunday WILL be spectacular with mainly sunny skies all day in much of the metro area. We’ve got strong offshore (easterly) flow, which should clear the fog out most areas west of the Cascades. Too windy in the western Gorge of course, but it’s January, it happens.

Chief Meteorologist Mark Nelsen

100 Responses to Big Weather Slowdown Heading into Mid-January

  1. Jessie says:

    Thanks Mark! Any Tualitonians on this blog? 😎

  2. boydo3 says:

    People are mowing their lawns down here on the south coast.

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