We just experienced the stormiest weather we've seen so far this very benign winter. It was quite a triumph of weather forecast models too. They nailed the rain totals plus end time of that heavy rain.

Rain Record 2.png

A few points:

  1. Portland broke a record for daily rain yesterday
  2. Tuesday's rain was the most we've seen in one day in over 3 years!
  3. Over a 100,000 power customers lost power in the metro area as a cold front moved through early today

Surprisingly uniform rain totals at the official reporting locations

Rain Metro Jan11-13 60hrs.png

Of course hills pick up more precipitation; there were some spots in the metro area that saw up to 4" of rain. But the big totals were in the mountains; look at all those 8"+ spots!

big rain

By the way, the south wind and warm airmass pushed Portland to 61 degrees right after midnight, tying a record high for the date. That's when things turned wild. The one surprise was last night's cold front; it was stronger than expected. Strong WEST wind came in behind it between midnight and 1am. Peak metro gusts...

Wind Metro Peak Gusts Jan 13th.png

Of course you are probably wondering how we ended up with 94,000 PGE customers out of power with gusts only up around 35-50 mph? Two thoughts on that:

  1. Two days of soaking rain saturated the ground, loosening roots and allowing trees fall over easier than if ground was dry
  2. I haven't seen a strong west wind like this since March 2011. That month we saw a rare westerly gust to 55mph at PDX. Strong wind from an "unusual" direction can easily give us more damage than expected

What's Ahead?

We've got a lot of SLOW weather the next 7 days. Upper-level ridging sticks around now through the middle of next week. Only very weak systems slide through Friday, Sunday, and maybe next Tuesday. First, you can see the 500mb map for Saturday...ridging over the western USA

ecm_saturday.png

Then Wednesday

ecm_wed20th.png

But a change late next week; ridging moves farther west and weakens. Looks like we're heading into a cooler flow of air from the northwest.

ecmwf_fri_22nd.png

That was the ECMWF for Friday the 22nd. Beyond this point is where models diverge. Will a much sharper upper-level ridge build over the Gulf of Alaska and allow a cold trough to dig south over us? Or will westerly flow dominate? Regardless, it's obvious we're headed into a cooler pattern starting around the 20th. We've been seeing this pattern change for almost a week! Look at the ECMWF ensemble chart for 850mb temps over the next two weeks (the rest of January). You see the sudden change on the 20th.

tseries_850t_000-360_Portland.png

The "0" line means snow down to about Government Camp; notice that for about 10 days starting the 20th the sticking snow level should be near/below the passes. We haven't seen that yet this season. Could be a great snow pattern for the Cascades and the foothills will finally start seeing some snow!

Summary

  • The Pacific Northwest will likely enter the first cool weather pattern of winter; starting late next week
  • It's too early to know how low snow could fall, the change is still 8-9 days away
  • No, we don't know if it's going to snow in the lowlands the 2nd half of January. But for the first time this winter, yes, I'm saying..."there's a chance". It's bizarre that I haven't mentioned that phrase; we're 3/4 of the way through winter west of the Cascades!
  • If something fun (snow and/or cold) is on the way, it would be the last full week of the month (23rd-31st), not next week

Notice 20 of the 51 ECMWF ensembles forecast some sort of real snow in Portland sometime in the next two weeks.

ecmwf-ensemble-KPDX-indiv_snow_24-0539200.png

That's it for this evening. I'm off the next three days and will have plenty of time for a fresh post Sunday evening.

Chief Meteorologist Mark Nelsen

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