Wetter Days Ahead, A Little Gorge Snow, & Lots of Mountain Powder

9pm Tuesday…

Christmas vacation so far has given us a mix of weather; from warm/mild rains to cool easterly wind. Some fog and freezing fog in spots too. In the central/eastern Gorge, you experienced the much desired “White Christmas”. 1-6″ fell from Cascade Locks to The Dalles and down into north-central Oregon. Now we’ve seen a few dry days. Portland is running near to a little below normal for rain this month. A good chunk of the region has been drier than average over the last two months; somewhat unexpected in a La Niña winter.

Most of the USA has been warmer than average this month; including the Pacific Northwest. This is our 3rd consecutive warm December.

We are approaching the “halfway point” of the Pacific Northwest storm season. That’s November-February. It’s been a disappointment so far if you’re looking for lots of active weather from this “La Niña” winter. No lowland snow, no significant windstorms, flooding, tornadoes etc… We are in the coldest time of the year (by the averages) right now. It’s always interesting to note the western USA is coolest when you would think it would be; lowest sun angle and shortest days. That’s right now. Yet the coldest of winter is more like February 1st once you get into the upper Midwest and Great Lakes regions. That’s due to the continuing cold Canadian airmasses moving south and thick snow cover reflecting much of that increasing solar insolation.

It appears weather action will be picking up again over the next week; these 12 Days of Christmas will be turning quite wet! A mid-winter Pacific jet stream will be ushering a series of wet weather systems into the PACNW starting tomorrow. We still have a little cool air stuck in the Gorge. The layer of cold air isn’t very thick and easterly gradient through the Gorge is weak. This may be just enough to bring very light snow (less than Christmas) tonight through midday tomorrow. A real “marginal” event though.

I see at least 6 separate cold/occluded fronts coming through the region tomorrow through Wednesday the 6th. You can see 4-5 of them moving quickly west to east in this loop of sea level pressure and precipitation type. That’s now through next Monday.

In general we seem to be headed toward slightly colder systems after Sunday as upper-level heights lower next week. You see the cool/lower height anomaly max out the middle of next week, before the ECMWF ensemble average pushes heights up again about two weeks from now.

At this point I don’t see any especially strong storms, although models have been waffling around each run with exact low placement and precipitation intensity. It’s quite the message here…no significant gaps in the 24 hour precipitation from any of the ECMWF ensembles

I see quite an increase in mountain snowpack the first week of January. The ECMWF model thinks 20-40″ is likely on Mt. Hood over the next week. Since snowpack is running a bit below average this is good news!

With almost constant onshore flow it’ll be tough to get snow down to sea level over the next 10+ days. Notice almost no members of the ECMWF ensembles produce significant snow over Portland the next two weeks.

That’s not to say we couldn’t have something happen like what Puget Sound saw last week. A low pressure area and dynamic cold front brought heavy post-frontal precipitation overhead for a few hours, dropping sticking snow all the way to sea level. It didn’t last long, and it warmed up in the hours following, but something quick/crazy like this could show up in the models just a few days ahead of time.

To wrap it up, my main points…

  • There’s NO sign of a widespread lowland snow/ice event in the next 10+ days…January begins mild
  • It’s also unlikely we’ll see an “arctic blast” in the first 15 days of January. That refers to a setup with cold arctic air drops south on north or east wind, keeping high temps in the 20s west of the Cascades and lows down in single digits or teens. I don’t see that in the cards.
  • Expect rain almost every day during the next week; some days will be wetter than others, but I can’t find a totally dry day.
  • Keep a close eye on the forecast during this time; a wind storm or river flooding could show up in the forecast maps just 3-4 days ahead of time.

Chief Meteorologist Mark Nelsen

119 Responses to Wetter Days Ahead, A Little Gorge Snow, & Lots of Mountain Powder

  1. Matt in Keizer says:

    I just looked at this evenings 00z models for 10 days out-Jan.14th and both the ECMWF and GFS are remarkably similar…both showing ridging pretty much right over us…..so if we can get some amplification and retrogression we should be in business by the last week of Jan. as Rob mentions below: 1st the ECMWF: http://img.meteocentre.com/models/ecmwf_amer_00/GZ_PN_240_0000.gif,….and 2nd the GFS:

  2. Evan -- Cedar Mill says:

    I swear it has been 47 degrees for like a 5 days straight. Boring…. Seems to be lots of 34 degree rain up at Govy.

  3. tim says:

    Mark said this winter will be more active then the last two has that happened yet?.

  4. The 18z GEFS continues the improvements with both timing moving ahead and sharper retrogression. The new EURO Weeklies look outstanding with persistent NPAC/Gulf of Alaska ridge/blocking for about a month. C’MON!!!!

    • Mountain Man says:

      Rob, Having background in climatology, nothing is looking that unusual. A lot of wet and mild, not that abnormal for the situation this year. Those who pay attention, know winter weather is supposed to be late anyway this year. That’s been said since October. Those who want to call it over, didn’t pay attention to the situation. It would be encouraging to see something really pop up in the models, but we have many weeks to go before we can say nothing winter like is going to happen. I’m glad you have been chiming in. I have been following this blog for it’s whole 15 years now. Sometimes the comments get annoying, but you are awesome! Thank you!

    • JohnD says:

      Fun getting “we heard it first” upstream “name drops” via our Buddy Rob. ‘Always enjoy your posts! Thanks much.

  5. Weatherdan says:

    Today’s weather in a word-bleeeeeeeep! Peace.

  6. More improvements on 12z Ensembles suite. A long ways to go of course, but the retrogression signal, retraction of NPAC/WPAC jet, Aleutian low dying, and timing is similar with GEFS, CMCE, EPS. Onto 00z! C’MON!!!!

  7. Chad says:

    Looking at all data available it is officially time to bring out the forks. Maybe next year😵😥

    • Tanis Leach says:

      Mark’s rule: The fork shall not be brought out until Valentines Day regardless of previous conditions as it can not be retracted.

    • saumcreek says:

      Are you bored of pretending to be abroad already?

      • W7ENK says:

        Glad to see I’m not the only one connecting the dots here…

        • Tanis Leach says:

          I’m pretty sure I have too (emoji use and messages are almost identical to ziggy). I do respect everyone’s right to talk, so I let it be, unless there is a personal attack or bad attack on someone else.

  8. tim says:

    Nws seattle mention possible ridgeing in west and trough in the east going into mid to late january today so maybe a early taste of spring on the way.

  9. Tanis Leach says:

    Been off for a few days, which was nice, but its also nice to get back into the swing. Quick question though: Does anyone know why I’m crazy enough to do my long run only during the wind advisory time? Because I don’t.

    Also, thank you for your compliments on my last detailed post. I should have another Portland statistical analysis post coming up soon.

  10. OLIVER WATSON says:

    Here are some of my thoughts on the rest of the winter. So far the models have done pretty bad this year even 4-5 days out and certainly over 8 days out. The models showed very consolidated systems rolling through for weeks with good snows forecasted for central oregon even. What happens is within 3-4 days it drys out some and warms up. Lots of southwest flow. Even with our systems our precip and snowfall for western oregon and mountains have been about normal to a hair below. In central oregon our precip and snow is about 75-85% of normal. Lots of rain shadowing with these systems. As far as looking ahead there’s no reason to trust the models 2 weeks out, especially when they show something good especially because of their poor performance this year. If we have a big pattern change that will deliver cold air to the lower 48 the very very likely chance is it will dump east of the rockies. I’m not being pessimistic but just that where the higher odds lie. We just really need moisture so keep our current wet and mild weather coming because we really do need lots of rain and mountain snow. If Portland has a chance this year for the goods I think it’s late January to February. My guess is a couple of inches at best. For over here in central oregon specifically sunriver we’ve had 20 inches of snow which is 70% of normal. I think we will end up with 35-45 inches unless we get a crazy cold and snowy February which at this point I’m more likely to believe than anything happening in January.

  11. JohnD says:

    And Andy!

  12. Roland Derksen says:

    A dreary start to 2021 here- more rain today and tomorrow. Sooner or later this pattern will change. Hope it’s sooner!

  13. Chad says:

    If we cross our fingers and eat some lucky charms our chances increase also.

    Think maybe we should just hope for a late April snowstorm and early June wind event at this pace, Erik what our you wise thoughts oh puppet master?

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