Quiet Now: But Possible Gorge Ice & Flooding Midweek?

A very nice break today…only .02″ of rain in P-Town!  That’s our 14th wet day of course, but far more reasonable.

BMAC Rain Two Day Total

As of this evening we have 10.22″ of rain for the month, the wettest month since November 2006!  The wettest ever recorded at PDX is 13.35″ in December 1996.  I remember that year…we had two ice storms east metro on the 26th and 28th (or 29th?), then warm and wet.  In fact it’s interesting to note that we haven’t seen a big metro ice storm since that time.  As I recall near the end of that event at one point it was 32 at PDX but 55 with a south wind at Hillsboro at the same time!

But I digress…

I think there is a very good chance we are living through what will be PDX’s wettest month ever recorded.  We only need to get 3″ in the next 2+ weeks.  We’ll get at least 2″ of that just by this Saturday at the latest.

MarkHeadlines_FloodPortland

I don’t see a setup for a big flood in the next 7-10 days as the pattern appears to be generally cooler than normal with the jet stream over or south of us at times.  That should keep much of the precipitation above 3,000′ in the form of snow.

We DO have a warm and wet system for Wednesday night and Thursday.  Rainfall totals looks pretty impressive again.  Maybe 1.50-2.50″ precipitation in the metro area with higher amounts in the mountains and southern Oregon.

A new and possibly serious weather event has cropped up today in models:  a complicated and messy Gorge freezing rain/snow event underneath the heavy rain westside during this period.  A setup where we could see flooding issues at the same time a severe winter storm is occurring just 50 miles away.

The problem is that during the day Wednesday a cool airmass near the surface is sliding south through the Rockies.  The approaching low pressure then sucks the cold air right into the Columbia River Gorge just as the precipitation gets going Wednesday evening.

The GFS, WRF-GFS, GEM, and to a lesser extent the ECMWF and our RPM models show this event.  I was hoping it would go away in the evening run of models but it’s actually even more impressive/scary (if you live in the Gorge) now.  The WRF-GFS has at least 8-10 millibars easterly flow (raging east wind) by Thursday morning with tons of precipitation falling through a 4,000′ thick below-freezing airmass in the central/eastern Gorge.  About 2″ liquid precip in the central Gorge would equate to 15″ or more snow and/or a crippling ice storm in the central/western Gorge.  Ice would be thicker than what we went through 2 weeks ago; this is a much wetter system.  The 00z WRF-GFS meteogram for Hood River shows 24 hours of freezing precipitation (snow, then freezing rain).

We’ll keep a very close eye on this event as we get closer; it’s definitely a possibility that models are overdoing the amount of cold air that gets into Eastern Washington and that could mean temperatures far more marginal for frozen precip.  If so, I would expect them to back off quite a bit in the next 48 hours.

Regardless of the total rain we get…we’re going to see more mud & landslide issues over the next 10 days.  Our soils are soaked and don’t want to see another set of downpours late week!

Chief Meteorologist Mark Nelsen

 

 

57 Responses to Quiet Now: But Possible Gorge Ice & Flooding Midweek?

  1. Jason Hougak says:


    It’s the 18Z GFS but it’s still a thing of beauty.
    Play that jaws theme song… 🎶dudunt… dudunt… 🎶😆
    00z at 61% complete we’ll see if they become the odd couple or join in matrimony

  2. Jason Hougak says:

    I’m riding tomorrow, forecast looking amazing for Timberline and Meadows to continue base building. Has anyone seen the 18Z GFS, New Years Eve -12C 850mb temps with PDX -1F for the low… I know it the whacked out 18Z but it’s gotta hit every nowNthen right. I’m skiing around Crater Lake that week into the New Year and it could be dangerous up at 8K!!! Seriously watching those models whether this is going to happen.

    http://wxweb.meteostar.com/sample/sample.shtml?text=KTTD

    • The 18Z was advertising the same thing for the Xmas week but that never materialized. We shall see if this develops into something.

    • High Desert Mat says:

      Jason, if you liked the 18z, you’re going to love ❤ the 00z. Much more amplification with the ridge, colder 850’s for us, and moisture. I can’t wait to see the ensembles, hope it wasn’t an outlier. You should shoot me a text 541-639-6922.

    • Boring Oregon says:

      You know everybody can see your numbre right, Mat?

  3. Melinda says:

    Will Corbett see anything or will we only get rain? On the radar it looks really close as to if Corbett gets hit or not

  4. John Liu says:

    Digressing a tiny bit – what are your thoughts (anyone) on whether we get sticking snow in the lowland Portland metro area this winter?

  5. paulbeugene says:

    The last significant PDX ice storm I experienced was while I was a pediatrics resident at OHSU in Dec 1996. I was on call at Emanuel Children’s Hospital. Doernbecher/OHSU was on divert as all the roads up the hill were closed due to ice or downed trees, so I was on the hook for everything that needed to be admitted to the hospital that night. It was rough. We lived in SW PDX at the time. I can recall at least a half inch if not 3/4″ on the branches.

    • Oh yeah, late Christmas night into the 26h was absolutely horrible. We had over 1″ of ZR here. It was destructive and devastating to all of the trees. We had some tough and go moments at my home. The power lines sagged over each other causing incredible arching which eventually caught my elm tree on fire. This also caused very loud explosions that shook the windows. Fire Department was called out. Then, the maple tree split in half taking out the power line to the house. We were without power for 6 days and after a short few hours we had to take refuge at a friends. We certainly weren’t going to huddle in the house with temps in the 30s! It was very treacherous going just making it to their house. Thanks for all of your insight and analysis today. We’re moving into another active pattern and potentially cold/snowy if the 500mb pattern amplifies a bit further Maybe with the -PNA forecast near/after Christmas we’ll see that. The 500mb anomaly looked a bit better on 18z. I shot you a message on Facebook also, Paul.

    • jimbo says:

      Thanks guys. Keep us posted

  6. soundpalette says:

    Whats the forecast for winter break week?

  7. Jason Hougak says:

    I love this exciting weather, keeping us All wondering what’s next!

    • Garron (1/3 of a mile from Hillsboro airport) says:

      Jason, you’ve got to be lovin the up coming forecast for the mountains! Shawn Weagle sounds like Bob Barker on the price is right when he reveals another 1-3 feet of snow in the next few days for the mountains.

  8. W7ENK says:

    WINTER STORM WATCH
    NATIONAL WEATHER SERVICE PORTLAND OR
    301 PM PST TUE DEC 15 2015

    http://inws.wrh.noaa.gov/weather/alertinfo/27468900

  9. WEATHERDAN says:

    Interesting weather ahead the next 10 days. Currently 42 and gloomy. Peace.

  10. paulbeugene says:

    Snow levels looking low-ish for Christmas on the 18z for some parts of Oregon, with the low approaching from the SW toward the S/Central OR Coast. The kind of scenario when things can go isothermal and the snow levels fall, much like they did in Roseburg and points south a couple days ago

    • paulbeugene says:

      that’s 10 days away. If it were Dec 28 or 22 wouldn’t mention but hey it’s Christmas, who wouldn’t want a bit of a surprise.

  11. gidrons says:

    The Euro 12z looks even wetter. Buttloads of rain and probably slides. Odds are that some unfortunate families will be asking Santa for a new house.

  12. paulbeugene says:

    Looking at the North Pacific Ocean view of the GFS model run 18z, looks like a good slug of tropical/subtropical moisture from near the dateline gets incorporated into the Autobahn jet and slugs into Oregon and Northern California next Monday evening/Tuesday, with 850mb temps climbing to 4C, 2-3 inch rains/24h at valley floor and more than that in the mountains, on top of the snow already on the ground. At last check, the Willamette Basin reservoir capacity was at 22%, so that helps but reservoirs may be filling some between now and then. It is looking dicey

    • High Desert Mat says:

      Paul, if you’ll gander at the 18z ensembles, it looks as if they actually got cooler overall. That Monday timeframe you speak of is really a quick warm up that goes back to about -4C quickly. By the looks of those ensembles it seems to be cooling off albeit slightly, more and more each day. Tonight’s runs will be very telling I would assume.

    • paulbeugene says:

      Once that water is flowing it keeps on flowing til it gets to the Ocean.
      I am really nervous about the prospect of a severe/historic flooding event at some point in next few weeks. The longer we pile on snow in the cascades and stay wet down low, the greater the potential is. Given the El Niño the most likely “exit strategy” to the current pattern would seem to be retrogression of the mean 500mb pattern, resulting in an exceedingly wet and mild period before the ridge and split flow is pronounced enough to dry us out finally.
      I would rather take the Arctic blast option but That is not the typical scenario

    • Garron (1/3 of a mile from Hillsboro airport) says:

      Thanks for your input! Always appreciated, and consistently accurate and easy to decipher. I was reading into Weagle’s AFD tonight, and my take on it in the long term was that we’d be on the northern fringe of the next atmospheric river with lower snow levels, getting hammered in the Cascades. Upon reading your comments, I reread the AFD, and gleamed onto what you are mentioning. That is a serious heads up, and cause for pause. Gonna be quite the week a head for weather geeks!!!

  13. paulbeugene says:

    Difficult forecast ahead in terms of snowfall in Oregon Cascades in next 2-3 days, likewise difficult in terms of how much snow or freezing rain in the Columbia Gorge.

    It does not look like a drying trend will occur for at least next 10 days. Euro operational 12z run has 5-6 inches of rain in the Willamette Valley through day 10. GFS 12z not far behind.

    Beyond day 10 seems more of the same. Euro control run through day 15 concerning for flooding rains with milder pattern, with resulting snowmelt. Will have to wait and see.

  14. Washougal 1100ft says:

    Mark Would this be a west end gorge event ?

    • matt in the gorge says:

      That’s my question too. Where is central/western gorge? When you get some firm data and models. It would be nice to see a gorge micro climate forecast and timeline breakdown. Corbett, Mult falls. Cascade locks. Hood river. The Dalles -east. Rain. Freezing rain. Snow. Flooding. Especially since this appears to be a gorge only event. As usual. Thanks!

    • marinersfan85 says:

      It’s explained in the post.

  15. Justin says:

    ” In fact it’s interesting to note that we haven’t seen a big metro ice storm since that time.”

    You forgetting January 2004, Mark? South metro also got a ton of ice in January 1998 and then there was some significant ice in 2008 and 2014.

    • I was living in Portland that winter and there was a good 1/2″ of ice in N and NE Portland from that storm, on top of 6″ or so of snow. I was living at the foot of the West Hills in the Goose Hollow and had maybe 1/4″ at best of ice but 4-5″ of sleet after 7″ of snow in that event. My theory is that the Gorge outflow hitting the “bump” of the West Hills made the cold layer just thick enough to favor sleet over freezing rain at my location.

      There were multiple forecast failures for much of that storm, all of which had the form of forecasts saying “trust us, it will warm up and start melting Real Soon Now” followed by the cold air failing to scour out and the storm lasting yet another day.

    • Mark Nelsen says:

      I meant a BIG ice storm with thick accumulation. I don’t remember anyone getting more than 1/4″ in January 2004 in the metro area. Maybe Woodburn/Salem had a 1/2″ in 2008? Or was it 2014. No one saw 1-2″ ice accumulation in those storms like in December 1996. I could be wrong of course. Someone better check Storm Reports.

    • Justin says:

      I had at least 1″ of ice in Vancouver in 2004, I think many other spots had about that as well. Really that was probably the biggest ice storm since January 1979 for many of us.

      The December 1996 storm was really relegated to areas close to the river, once you got south of I-84 or north of SR-500, or west of the Willamette, there wasn’t much ice accumulation with those two storms.

    • Sifton says:

      I recall 04′ now too, I ripped out my fav water proof pants sleddin/sliddin with my boys on our 100′ backyard “luge” track!
      It was like an ice cream sandwich of ice,snow & ice.

    • W7ENK says:

      I was living in Klamath Falls back in 2004 and I literally had to dig my way into my apartment because my front door was buried under 5 feet of snow that had drifted up to the roofline, but I can’t really speak to the events up here in PDX.

    • High Desert Mat says:

      I was living on NE 20th and Couch during the epic Dec. ’03- Jan. ’04 event. I recall about 12-13 days of constant snow and ice. It was like 5″ snow then 1/2″ ice then more snow and another 1″ of sleet and then another 1/2″ of ice. I remember the Mets for about 5 days saying it was going to warm up daily for those five days but didnt until the 7th if I’m not mistaken. Good times.

  16. Late December 1996 (including Christmas Day) remains one of my favourite weather memories… But I’m still doubting it’s going to happen.

    • *Whoops- I need to complete that last sentence. I should have said “I doubt we’ll have a snowy event like December 1996” or something like that! 🙂

    • I remember that storm. I was visiting my aunt in Portland and got to see the ice storm there, then made it back home for the tail event of the epic snow event in Seattle. I was so tired I only thought to measure the snow on my deck after it had changed to mild 50-degree rain and been that way for several hours, and it was still 23″ deep!

      The snow berms alongside the roads were about even with the roofs of the cars. Truly a surreal scene for the lowlands.

    • Victoria, BC, December 1996:

  17. Eric says:

    December 1996 we had significant weather just before Christmas. Christmas day itself was calm. Then we got smacked with another big storm(s?) between Christmas & New Years.

    I remember this distinctly because we drove out to Multnomah Falls on Christmas day and snuck around the closed barricades and walked up to the bridge. It was a rare day to be at the falls all alone with the water raging from the storm.

    Of course, my wife remembers that day differently because I proposed to her on the bridge at that moment, but I digress! We were going to surprise my family with the announcement when we got together a few days after Christmas, but that never happened due to the bad storms.

    I don’t remember the specifics or the details of the weather, other than to note that Christmas day the weather calmed down just enough for me to execute on the plan. My biggest fear was dropping the ring and having it fall off the bridge, but it is still on her finger to this day.

  18. schmit44 says:

    12/14/2015 Oregon (All) Temperature Summary

    Warmest:
    High:52 at Yaquina Bridge W( 120 ft) & KB7QWZ Garibaldi(10 ft)
    Low: 41 at EW3638 Yachats(33 ft) & ECHO(683 ft) & John Day River B(305 ft) & Celilo – East of(225 ft)

    Coldest:
    High:16 at HOWARD Mt Howard(8150 ft) & ALAKES Haines(7979 ft)
    Low: 5 at Beatty (4320 ft )

    Largest Diurnal Change: 30 degrees
    KLAMATH NWR (42/12 ) (4531 ft )

    Heaviest Rainfall:
    1.55″ at USCRN SITE NEAR(39ft)
    1.20″ at MCKENZIE(4770ft)
    1.20″ at COLD SPRINGS CAM(5940ft)
    1.10″ at ROARING RIVER(4950ft)
    1.10″ at MT HOOD TEST SIT(5370ft)
    1.00″ at BEAR GRASS(4720ft)
    1.00″ at BILLIE CREEK DIV(5280ft)
    0.91″ at CW6811 Grants Pa(947ft)

  19. matt in the gorge says:

    Question about this potential event. Is this a quick blast. Is there going to be warm air to clean it up? Scour out? Or is this going to be prolonged article air and moisture. I’m rather confused. Sounds like the experts are as well. Geeze. Its less than 48 hrs away. You’d think it would be easier to forecast. But I’m just a follower. Not a pro.

  20. Mark bergal says:

    Sounds very interesting

  21. I was wondering if the possible Gorge snow event was going to get your coverage tonight!

  22. Aleta-West Gresham says:

    First?

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