7:30pm Saturday...

The February 11th-13th 2021 snow/ice storm is going to be one for the record books. A few stats for you:

  1. PDX only made it to 30 degrees today; for the 2nd consecutive day. That's a rare event this late in the season. In fact only TWICE has PDX stayed at/below 30 degrees after the first week of February. In 1956 and 1960. We haven't seen such a cold day this late in the season during my lifetime...brrr!
  2. The Portland forecast office has picked up 8.0" snow so far, plus I wouldn't be surprised to see a bit more this next hour or two since it is snowing right now. That makes it the 4th snowiest February on record, or maybe it'll be #3 within a couple hours
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3. At the peak earlier today, Portland General Electric was reporting about 220,000 outages due to the catastrophic ice storm in the northern and central Willamette Valley. That is a similar percentage of customers we've seen during previous big ice storm events. But those have generally been central/east metro closer to the Gorge. This time everything went wrong. A thin subfreezing layer of air at the surface plus heavy precipitation overhead.

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Looking ahead...

KEY POINTS

Light mixed precipitation continues tonight through tomorrow morning throughout the region. In the Portland metro area it could be snow or freezing rain through sunrise. We are getting the typical showers between organized weather systems.

The entire metro area stays frozen tonight. Typically the showers putting down a fresh swath of light snow or a bit of freezing rain glazing would be a HUGE deal; but everything is covered in snow or ice already. Adding another inch or two of snow shouldn't change things much.

Another slug of steadier precipitation comes through midday/afternoon tomorrow. BUT, at this point it's warmed overhead so we're into liquid precipitation only. Temperatures rise into low-mid 30s metro area (away from Gorge) and that means we shouldn't see additional icing of roads tomorrow. In fact light rain showers will help melt things a bit. Tomorrow afternoon a southerly wind pushes up to the south edge of metro. Everyone in a line from Newberg to Wilsonville to Molalla and south should see temperatures jump into the 40s. We stay between 30-37 in the rest of metro.

Tomorrow night one last slug of steady rain comes inland. The last "holdout" of sub-freezing air will be east of I-205 and near the Columbia River from the airport to mouth of the Gorge. These areas (Troutdale, Gresham, East Portland) will see significant ice glazing tomorrow afternoon and night. Possibly up in the West Hills as well...maybe. I think the rest of the metro area will sit at 32-35 degrees tomorrow night which means no additional icing.

Finally, a mild southerly wind pushes through the ENTIRE metro area by sunrise Monday. We will immediately jump into the low-mid 40s at that point...MONDAY IS THE BIG MELT DAY. West wind pushes through the Gorge Monday as well, but midday/PM

TECHNICAL INFO

It was a somewhat poor choice to drive home last night; probably should have stayed at hotel one more night. 1-3 foot high snowdrifts...an experience like those Subaru commercials. I followed my son in his 4Runner through those drifts between Corbett and Vista House. That is the deepest snow I've driven through (separated by bare spots in the wind). Much better coming back to work today because Multnomah County and ODOT road crews have been working so hard. It was neat to be behind an ODOT plow blowing through those drifts today; an massive explosion of beautiful powdery white passing through each one.

This cold airmass is just about played out, we saw quite a bit of melting at 1,800' on our KPTV tower cam today. That means the cold layer is now that shallow overhead. Snow level from the Astoria profiler is around 2,300' or so right now, which means the cold air coming out of the Gorge is still thick enough to "fill the gap" and keep temps at/below freezing all the way down to the city. That's why we're seeing snow this evening.

That will change around sunrise tomorrow. WRF-GFS sounding for right now shows at/below freezing all the way down.

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But by 10am tomorrow, a warmer layer has moved in (temp above zero C) = all liquid rain in the metro area from this point forward. The red line is temperature, blue is dewpoint

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At 1pm tomorrow a weak front is moving onto the coastline, keeping easterly wind going through the Gorge. It's calm in the Willamette Valley.

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But then a 2nd/stronger system sweeps toward the coast tomorrow night. This time the surface low is headed north of us. At 1am tomorrow night, east wind is screaming through the Gorge again, although it's a thin layer of cold air compared to yesterday. Warm southerly wind has reached up to about Salem.

10pmMonday.PNG

Then at 7am the low is pushing across SW Washington. Gusty southerly wind has arrived in the metro area; temperatures suddenly pop into the mid 40s around sunrise...the melt is on.

7amMonday.PNG

Whatever falls from tomorrow morning through late tomorrow night will likely be freezing rain east of I-205 near and south of the Columbia River. Expect 1/4" to 3/4" glazing over there and into the western Gorge. Cold air will be deep enough for snow in the central and eastern Gorge until a warming west wind arrives Monday midday/PM. Seems unlikely that I-84 will reopen before Monday.

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I'll be on TV tonight at 10pm, and of course tomorrow night at 5/10/11pm. Chief Meteorologist Mark Nelsen

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