ECMWF Ensembles

Unless you’re a hard core weather geek, just skip down to the previous post.

Here are the 4 week ensemble 500mb anomaly charts from last night’s 00z monthly run:

500za_week1_bg_NA

500za_week2_bg_NA

500za_week3_bg_NA

500za_week4_bg_NA

 

And here is the 00z GFS 850mb temp ensemble chart; interesting that there are a few more members this evening showing colder solution around next Monday-Tuesday.

tseries_850t_000-384_Portland

106 Responses to ECMWF Ensembles

  1. HVmike says:

    It is interesting to me to see how the rushing in the central part of the US is keeping us so warm, is this common this time of the year?

  2. marcus says:

    hr 240 on the 12z ECMWF and the 18z GFS are virtually the same. they both show the beginning stages of a northerly track where eventually the arctic front comes surging down the Fraser river valley!

  3. Beyond day 10 I would put the chances of a modified or true arctic blast at 10-20%, so not great.

  4. alohabb says:

    Yes no,flip flop,he said she said,coke pepsi,home depot lowes,shell chevron,tast great less filling,apple android……… The back and forth yes and no snow game is madening! ahhhhhhh

  5. Marcus says:

    I want to say that I saw this happening on the end of the 12z ECMWF run,arctic blast surging south out of Canada I just wasn’t sure how far south it would go!

  6. pappoose in scappoose says:

    Hahaah! This is by no means a certainty!
    We must be relentlessly on watch!

    National Weather Service Portland or
    257 PM PST Tuesday Jan 8 2013

    The surface front reaches the coast late tonight…and the Willamette Valley during the morning. Forecast soundings from the NAM bufr at Astoria and Hillsboro show evidence of the low level thermal profile going isothermal…but this is occurring above the lowest 1000 feet…and this is at the trailing end of the heavier precipitation. So there are signs that snow level is trying to get lower…but as of now it looks like freezing levels only get to 1500 feet at the peak of precipitation. Therefore…generally expect snow to be confined at or above the Coast Range passes during the morning…but this is by no means a certainty…and precariously close to being a burst of snow. Even the pdx sounding drives the freezing level down in intense cooling to 1300 feet by 17-19z. It is during this time that the 4 km WRF-nmm is depicting some strong bands of precipitation with the front…so snow flakes in the higher West Hills are possible too. Very low confidence here in more than anything but a mix…but it will bear watching.

    • alohabb says:

      ” i have no confidence in my forecast” is such a great thing to hear! LOL

    • germantownsummit1000' says:

      I’m girding my loins and fueling the generator. Beer and other, less important, provisions already laid in.

      They’ve been wrong before and the margin is thin…

      …W7EEYORE notwithstanding.

  7. Jordan (Raleigh Hills, 420') says:

    18Z GFS has a nice little burst of precip across the Portland metro and areas east & west 03-09 UTC Thursday (Wednesday night). Temps look at or below freezing across the area, especially east of the metro. Could be a quick few inches for somebody, but i’m sure the 00z and 06z runs won’t look the same considering the main energy dives south and east. Friday night into sat, maybe an uptick in shower activity. 18z NAM draws a broader low with more precip.

    Also looks pretty darn cold Fri night / Sat morn, maybe down below 20 in a few places on the eastside. We’ll see if it gets that cold. Could be another cold night Sunday night and Monday night, but less cold each night.

  8. 18z GFS
    I’m not sure if you can call it a trend, but this is the 2nd or 3rd consecutive run of the GFS with a similar 500mb progression and pattern change around day 10 of offshore ridge collapsing, then rebuilding with some retrogression shown.

    Axis is around 147-150 W amplifying well up through Alaska with a favorable tilt/orientation.

    It is interesting if anything that we’re seeing this what seems to be consistency building and timing has moved up on this run.

    Towards the end of the run things really get their act together will likely arctic blast. http://mag.ncep.noaa.gov/gfs/18/gfs_npac_384_500_vort_ht.gif
    This is a reasonable and realistic handling of the 500mb pattern. We’ll see if 00z this evening continues to latch onto this idea.

  9. runrain says:

    Nice – 60 deg in Roseburg right now.

    • runrain says:

      Only 64 in Phoenix, AZ right now and they are expected to have trouble getting out of the 40’s by this weekend.

    • W7ENK says:

      What baffles me is how — this happened last winter — an area in Mexico that had never recorded a temperature below freezing in something like 140-some years of continuous records can see temperatures plummet into the single digits, while we up here in the PNW struggle to see even a few measly wet snowflakes at 33 degrees.

      Phoenix struggling to get out of the 40s, but we’ll be 800 miles closer to the source of cold air, and we’ll be roughly the same?

      San Francisco and LA had snow just a few years back while we were in the 40s and 50s, how did it skip us??

      Why is it so hard to get cold air here??? It’s those damn Rockies!! Someone should blast a hole through those mountains somewhere in BC/Alberta, angle it SW-ish, help us out a little.

  10. Ben T says:

    Am I interpreting things correctly that basically an arctic blast could happen soon but nobody really knows and basically we just have to wait?

    • W7ENK says:

      Yes, as always. And, there’s a fairly high probability you’ll be waiting until at least mid/late November.

    • Ben T says:

      :( Oh PNW weather. The way I look at it is, we rarely ever get great Winter snowstorms, but when we on occasion get them that makes them that much better. There’s a certain mystique about storms in this area of America that makes them special even if rare. With that said, I sure hope their frequency improves.

  11. Sifton says:

    Well, so much for “warmer,sunnier” weather today Mark……….

    • W7ENK says:

      Hey, he got the warmer part right! 54 over yesterday’s 51, low/mid 50s over last week’s upper 30s low 40s. I’d say that’s warmer.

  12. *BoringOregon* says:

    Lol that was a funny comment about checking the weather blog 3 days a week. What was kgw saying that it was going to snow over a foot last night above 500’`did any one see that?

  13. Man it is downright balmy out.

  14. paulbeugene says:

    Tues 11:15

    Still not betting on any snow on the valley floor during the hours after the front passes through tomorrow morning. Seems that central and south valley residents may get more precip but that will be liquid. Might get a dusting at some point Thursday…perhaps more likely farther south. Convergence zone snow possible in usual location east of Puget Sound..Wednesday night (see SEA AFD).

    General idea for the weekend and beyond…not all that impressed with the system rounding the ridge, diving into the region this weekend…..not expecting much precip….behind that we get into dry northerly flow. The ECMWF model (at least the operational runs) have trended toward keeping the ridge just offshore, with almost a rex (high over low) block developing, followed by retrogression of ridge around day 9-10. There is very cold air in Canada throughout the period.

    A bit on the sudden stratospheric warming. This is not something that happened weeks ago…it has been in the past week…and there is a 2-3 week lag between the onset of warming and the end result of disruption of the polar vortex, which is delivery of arctic air to more southern latitudes. I think there is reasonable consensus that the second half of January will be colder for the lower 48 than the first half of the month…the question being who will be cold first. My bet is we have highs in the upper 30s to low 40s by this weekend…and will get some increase in offshore flow with time, with nighttime minimums lower than shown on GFS MOS….with lows in 20s in most places by early next week, with some 15-20 lows in clear areas without wind or fog….highs then in 35-42 range.

    Who knows what will happen after that. The most likely scenarios will either be the ridge over G of AK shifting onto the coast with relatively mild temps beyond day 8… or the ridge will shift west and allow the displacement of the arctic air (associated with the stratospheric warming) into SW Canada and possibly pac NW. Even less likely is the ridge pinching off to the N allowing westerlies to kick in. My guess is 60 percent chance of scenario 1 (nice weather but boring)….30 percent chance of arctic blast between days 10-20, and 10 percent chance of undercutting westerlies.

  15. Marcus says:

    Good short term ECMWF run boring middle and la la land still shows arctic front sliding south just how far will it come?

  16. Ben T says:

    Are ya’ll getting prepared with your rain sleds and your rain shovels? Are you ready to make rain angels?

  17. …this is interesting, from the buffalo AFD…: AREA FORECAST DISCUSSION
    NATIONAL WEATHER SERVICE BUFFALO NY
    953 PM EST MON JAN 7 2013

    THE SECOND PATTERN CHANGE WILL BEGIN TO SHOW ITS CARDS BY THE MIDDLE
    OF THE MONTH. A MAJOR SUDDEN STRATOSPHERIC WARMING EVENT IS UNDERWAY
    AND NEARING COMPLETION. SUDDEN STRATOSPHERIC WARMING EVENTS ARE
    FAVORED TO OCCUR DURING AN EASTERLY PHASE OF THE QUASI-BIENNIAL
    OSCILLATION /QBO/…WHICH IS THE PHASE THE STRATOSPHERE IS IN THIS
    WINTER. THE SUDDEN STRATOSPHERIC WARMING CAUSES A DRAMATIC
    WEAKENING…AND SOMETIMES ENTIRE BREAKDOWN OF THE STRATOSPHERIC
    POLAR VORTEX…AND A GREAT WEAKENING OR EVEN REVERSAL OF THE
    STRATOSPHERIC POLAR NIGHT JET. THE GFS FORECASTS THIS TO OCCUR OVER
    THE NEXT WEEK AT THE 2MB LEVEL.

    THE RESULT OF ALL OF THIS IS THE GENERATION OF STRONG HIGH LATITUDE
    BLOCKING AS THE DRAMATIC CHANGES IN THE STRATOSPHERE FEED DOWN INTO
    THE TROPOSPHERE. HIGH LATITUDE BLOCKING FORCES THE COLDEST AIR SOUTH
    OUT OF THE HIGH ARCTIC AND TOWARDS THE MID LATITUDES…AND ALSO
    FAVORS LASTING STRONGLY NEGATIVE EPISODES OF ARCTIC OSCILLATION /AO/
    AND NORTH ATLANTIC OSCILLATION /NAO/. THIS TYPICALLY BEGINS TO TAKE
    PLACE 10-15 DAYS AFTER THE SUDDEN STRATOSPHERIC WARMING EVENT. HOW
    LONG IT LASTS CAN VARY…BUT TYPICALLY THE COLD PATTERN LASTS FOR AT
    LEAST A FEW WEEKS…AND OCCASIONALLY CAN PERSIST THROUGH THE REST OF
    WINTER.

    AS ALL OF THIS IS OCCURRING…THE MJO IS FORECAST BY THE GEFS
    ENSEMBLES TO WEAKEN AND FADE AWAY IN ABOUT 10 DAYS. THE PACIFIC
    NORTH AMERICAN PATTERN /PNA/ IS FORECAST TO REMAIN NEGATIVE OVER THE
    NEXT 10 DAYS…WHICH WILL DIRECT THE FIRST BATCHES OF COLD INTO THE
    WESTERN AND EVENTUALLY CENTRAL UNITED STATES. GEFS ENSEMBLE MEMBERS
    SUPPORT A TREND TOWARDS A NEUTRAL OR POSITIVE PNA BY THE MIDDLE OF
    THE MONTH…WHICH SHOULD ALLOW THE GROWING COLD TO SPREAD EASTWARD.

    WHAT ALL OF THIS TECHNICAL JARGON MEANS IS THAT THERE IS MODERATE TO
    HIGH CONFIDENCE IN A PATTERN CHANGE TOWARDS MUCH COLDER WEATHER FOR
    THE CENTRAL AND EASTERN UNITED STATES STARTING AROUND THE MIDDLE OF
    JANUARY…WITH COLD LIKELY PEAKING IN LATE JANUARY INTO EARLY
    FEBRUARY. THERE IS THE POTENTIAL FOR THE COLDEST AIR WE HAVE SEEN IN
    AT LEAST SEVERAL YEARS DURING THIS PERIOD. WHAT SNOW POTENTIAL THIS
    WILL BRING IS MUCH MORE UNCERTAIN DUE TO UNKNOWN DETAILS WITH
    SYNOPTIC STORM TRACK AND LAKE EFFECT POTENTIAL.

    • Ben T says:

      That sounds intense and very wordy!

    • W7ENK says:

      Sounds to me like the typical near-brush with cold in the West followed by a significant dump of really cold arctic air down the back side of the Rockies, into the plains and then across to the Eastern Seaboard. While New Orleans and Orlando see snow and ice, we’ll be 55 degrees and partly cloudy once the initial accidental spill of cold into “The West” clears out. PNW early spring, anyone? That should make some of you happy.

    • Longview 400 ft says:

      Hello Larry, how did you end up in Vernonia? Are you travelling around the state this winter?
      Just curious.

    • Chris s says:

      My take on that is cold until further notice in the east, easy bake oven death ridge in the west.😒

    • JohnD says:

      There have been years where there is impact
      of some duration coast to coast. It would be
      soooooo great if we just got some retrograding
      of the ridge.

    • @longview…I’m the host at the lake this winter!

    • …what i wonder is what has happened for our weather in previous episodes of sudden stratospheric warming????

    • Somebody posted an article the other day similar to this. Stratospheric warming? The sky’s the limit :)

    • W7ENK says:

      The last 5 SSW events I could find:

      November 2009
      November 2010
      February 2011
      February 2012
      December 2013

    • W7ENK says:

      Note: Those months listed are for the observed onset of SSW. You need to look 10-14 days downstream for the effects at lower latitudes.

    • W7ENK says:

      And that was supposed to be January 2012, BTK error, sorry.

    • chris s says:

      Erik, if that is correct then i believe the previous 4 you listed all lead to some sort of arctic air intrusion for us. As in Dec 09′, the brief event during Thanksgiving time in 2010, then Feb 11 we had about a 3 day stretch, and finally last year i know we saw snow in March, especially down south in the valley. I still feel that we may end up losing out this time and have that ridge sit right on top of us, but lets hope not.!!

    • W7ENK says:

      True, but every one of those with the exception of December 2009 was minor, brief and transitory, and produced virtually nothing in the way of snowfall for PDX, certainly nothing significant.

      November 2009 event: Led to the bitter cold (single-digits in many western valley locations) dry cold snap about the 7th of December. No precip. Dom Perignon.

      November 2010 event: Gave PDX a mere sprinkling of graupel before drying out with the passage of an arctic front on November 23, a cold two days over Thanksgiving, then moderating out over the holiday weekend.

      February 2011 event: PDX saw snow down to 500′ before a cold airmass moved in on the 24th, lasted two days, then left. Almost an exact repeat of February 2010, but I didn’t see that one referenced in connection to an SSW event.

      January 2012 event: No arctic front, just very cold NNW flow off the Pacific, significant snow points North of Portland on the 19th as an overrunning system punched into the area, low passed just North of Portland bringing epic snowfall within 20 miles of the city. A brief bout with wet, sloppy snow (about an inch) overnight a few days later, but southerlies took over and transitioned to rain before sunrise. Snow at the lowest elevations PDX-South lasted maybe 8 hours tops. Again, a repeat in March 2012, but no reference to an SSW event that I could find.

      December 2013 hasn’t happened yet… I’m tired today. :yawn:

      December 2012/January 2013 event: We’ll have to wait and see, I guess.

      I have no idea if a SSW event preceded December 2008.

  18. Fairly good news in the short term up here in washington. Today wind storm with gusts to 50 mph expected also a chance at a p.s.c.a late wed thursday time frame those c.z can bring some really big time snow depending on how big they get and how long they last.

  19. dothgrin says:

    This blog is killing me. Now that I am on “weather crack”, I find myself checking this site at least three times a day…of course hoping for good news about white stuff falling from the skies in appropriate to excessive degree. When I would simply visit the NWS site, my hopes would be dashed immediately. Now, with the models and analysis, my hopes fluctuate too much. By the way, the pain of close calls is nothing new to me. I lived in Albuquerque for 32 years, and it was common for snow storms to completely surround the city, but east winds blow the precipitation out to the west side and leave us lamenting over yet another failed system. Oh well…great to be on board anyway!

  20. Garron near Washington Square says:

    and..IT’S GONE!
    Well, better luck next year Western Wash/Or residents. Mark, bring out the winter is over graphic. Time to break out the water skis and yawn chairs, this blog’s gonna get real quiet after these snow flurries blow through. Just kidding, of course! We still got till Valentines Day before I jump off the “winter’s over” cliff.

    • JohnD says:

      Matt Zaffino had an interesting little tidbit
      the other day in the “Oregonian”. Not sure
      who did the research–maybe Steve Pierce–hehe:
      “Downtown Portland has seen more snowy days in
      the last 2/3 of January than any other time of
      year. Jan.15-20 is the peak period. Jan. 19
      has logged measurable snow 15 times going back
      to 1884, the most on record for any calendar
      day in Portland”. Do the math: That is 11.6%
      of the time. Woo Hoo! Wonder when the last
      time was?!

    • Mark Nelsen says:

      Might be the 2-3″ we had in the last half of January 2007?

    • Ron says:

      I’d be interested to see how many of those 15 days occured since 1950. That of course was a huge one in 1950. So if the majority of them happened from 1949 and back I’d say a trend has been set. I don’t have that information handy but not sure just what that means. 11.6% overall but it might be like only 5% since 1950. I’d be curious to know.

    • W7ENK says:

      Good point, Ron.

    • Ted Berry says:

      My birthday is Jan. 20 and I have been in the area since 1953, and I have had snow only once and that was in the late ’50s . Maybe I’ll get one more before my ship sails!

  21. David C says:

    I’m happy with a dusting, too! But Thursday AM looks good for 1/2 inch to an inch. And I’d be more than happy with that! Help me out here; the thicknesses seem good enough, along with 925/850 temps. So is it the southerly component of the upper air and surface winds that are screwing up our chances? I’m still struggling with reading the models. Teach me, master!

    • W7ENK says:

      Lack of moisture is the biggest killer for this one. QPF is extremely low — anywhere from 0.01″-0.08″ total — which would only give us a dusting to a half inch max, and that’s assuming Mt. PacMan doesn’t eat it all before it gets here.

    • Ron says:

      I think the Oregon City-Milwaukie area is several hundred feet below sea level so we are safe from accumulating snow.

  22. pappoose in scappoose says:

    At least a dusting works for me!

    National Weather Service Portland or
    855 am PST Tuesday Jan 8 2013

    As cold air pushes in behind the front later Wednesday and Wednesday night…850 mb temperatures dropping to -6 degree c and 1000 to 500 mb thickness values as low as 522 dm…snow levels appear poised to drop below 1000 feet by
    Thursday morning. While sticking snow is not likely in any one location at the lowest elevations due to a lack of moisture and north flow…the air mass will be cold enough for at least a dusting in a few places.

    • David B. says:

      “Below 1000 feet” does not necessarily (nor even typically) mean “to the valley floors” when it appears in a forecast. So this looks like another event that will be limited to the hills.

    • pappoose in scappoose says:

      The lowest elevation, is the valley floor.

    • Ron says:

      (Oops, put it in the wrong spot.) ” I think the Oregon City-Milwaukie area is several hundred feet below sea level so we are safe from accumulating snow.’

    • pappoose in scappoose says:

      It’s a given, that Milwaukie won’t get snow. (Dome)

  23. WEATHERDAN says:

    12z gfs looks a lot better. Still not as good as of a couple of days ago, but definitely better than yesterday. What I think we we wind up getting is some Arctic air East of the Cascades with a cool to cold Northerly flow West of the Cascades. We have a fairly good shot at valley floor snow Thursday through Saturday, albeit with limited moisture. However ECMWF continues to go with the Saturday system being fairly moist. Then the drier but quite cool to cold Northerly flow takes over.After that who knows. If the ridge is far enough West of us we get a good amount of cold air. If the ridge is closer to us we get fake cold with strong East gorge winds and a valley fog inversion. Anything however is better than our typical wet and mild midwinter weather we frequently get. And hey with an amplified ridge over us sometimes you get a retrograde. So overall I am ok with the way things are going.

    • Ben T says:

      In weather terms, what is a retrograde?

    • W7ENK says:

      Moving against the normal or typical progression.

    • Ben T says:

      Thanks bro.

    • W7ENK says:

      In this case, large scale weather patterns (ridges, troughs, etc…) at our latitude typically progress from West to East. When a ridge retrogrades, it pushes back from East to West, moving against what normally happens. Doing so would allow the cold air dropping down the East side of the ridge to essentially backfill into our area.

    • Ben T says:

      Ah, I see. And how common is this?

    • W7ENK says:

      Not very. Rob could better answer this, he’s more familiar with the frequency of these large scale things than I am.

  24. Marcus says:

    Jan 20-25 arctic air moves in!

    • Marcus says:

      Nope just a prediction! I was looking at the ECMWF at the end of the run there is a arctic front sliding down. But that’s what we call la la land, but I think we will get it this time, or maybe this is desperation on my part!

    • Hope your right. But we really need snow with the cold alone sucks and a waste of cold air.

    • I really do think we will get cold and snow the long range just been hinting at it too much for a cold blast not to happen. I knw experts like rob, mark will disagree and say it happens all the time etc. But at some point it has to get cold were so close of it all coming togather for a big cold snap with snow.

    • W7ENK says:

      Isn’t that what you said about this weekend’s arctic blast Steve? The one that’s now not coming?? I guess a broken clock is still right twice a day… o_O

    • How you know it”s not coming.? Weekend still a ways off and still a chance we will have a snow storm saturday or night.

    • You will be eating crow when we get a snowstorm this weekend.

    • David B. says:

      It better happen… or I will silently forget that prediction I made earlier. :-)

      Murphy’s Law says it will happen, BUT it will start immediately AFTER the endpoint of the window I gave for it happening passes.

    • W7ENK says:

      That’d be just fine by me. My birthday is the last day of this month, and aside from the year I was born, I’ve never had snow on my birthday, despite it being the only thing I’ve wished for every year for as long as I can remember. I’ve had lots of rainy birthdays, one with a few splats mixed in, some dry, sunny, windy and bitter cold, but never one with actual accumulating (or even falling) snow. Will this finally be the year? Mayhaps, but I’m not holding out much hope.

  25. Ben T says:

    Well this blog died. Anyone up?

  26. Wow…00z GFS isn’t terribly bad now.

    • Ben T says:

      It’s so sad how the models went to heck.

    • W7ENK says:

      Yes, but you were warned this would happen, so it shouldn’t come as a surprise.

      So if you think that was something, just watch it all flip back one more time tomorrow… All Hell will break loose on this blog, and it’ll stay that way right up to OBS time… and then it will fail.

      You want to see real heartbreak?
      Just you wait. :twisted:

    • Ben T says:

      I’m not surprised given history still a little disappointed though. We will see what happens though :) Expecting the worse, and hoping for the best.

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