Mark’s Thoughts on Winter 2012-2013

Let’s get this out of the way…I DON”T MAKE WINTER FORECASTS.  The reason should be obvious; we don’t have much skill in forecasting winter weather months ahead of time.  Each Fall the Oregon Chapter AMS DOES have a What Will the Winter Be Like meeting.   This year it’ll be on Saturday, November 17th and the public is welcome.  At this meeting 2-4 forecasters get up and give their outlook for the winter.  Skill hasn’t been so hot in the past; I’d say less than 50% accuracy.  That has kept me away.

That said, some winters offer more skill than others.  So last night, while my wife was catching up on The Walking Dead, for fun I decided to see what we MIGHT see this upcoming winter.  This is not a forecast, although it’ll sure look like one.  That way if I’m right by next spring, I can edit out that last sentence and claim it was a forecast.  If it’s wrong, I’ll need to delete these two sentences.  Nice eh?

Global oceanic/atmospheric conditions play a big role.  We know that two of these have some effect on our wintertime weather.  One is the ENSO, or El Nino/Southern Oscillation.  The other is the PDO, or Pacific Decadal Oscillation. 

Let’s take ENSO first.  El Nino is a warming of the tropical Pacific waters and La Nina is a cooling.  We know El Nino winters tend to feature drier than average weather and warmer than average temperatures.  Snowpack is often lower too.  On the flip side, La Ninas tend to give us wetter than average winters and cooler than average conditions with heavy mountain snowpack.  The latter is what we have seen for the past two winters and early spring. 

This summer we’ve seen weak El Nino conditions set in, although the anomaly has recently gone back into “neutral” territory the last couple weeks.  The loop above shows sea surface temp anomaly in the tropical Pacific; only slightly above average.  Take a look at the latest “plume” of model forecasts, where +0.5 and above is considered El Nino and -0.5 and below is La Nina.  Anything in-between is considered Neutral.  Note that models generally have either weak El Nino or Neutral conditions through the winter.

And this is just the Climate Forecast System (CFS) model forecast:

It shows weak El Nino fading to neutral during the winter.  The story here is that it’s most likely going to be a very weak El Nino or neutral winter, but on th “nino-ish” side.  We are very unlikely to see even weak La Nina conditions.  This is one clue for this winter.

The 2nd factor is the PDO.  We are currently in a cool phase of the PDO and that is expected to continue through the winter or possibly go “neutral” by late winter.  In general, we tend to have cooler and wetter winters/springs in this pattern as Nate Mantua talked about in his Oregon AMS presentation a few weeks back.

I’ve always believed in the truth of the old saying, “All This Has Happened Before and Will Happen Again”, popularized most recently by BSG.  So what the frack does this mean?  Well, we tend to see certain patterns return regularly, and by looking back through history we might be able to get an idea what we might see in the future.

So, once again for fun, I decided to go back through historical records and find winters where these two conditions were matched. 

What did I look for? 

1.  ONI (Oceanic Nino Index) of 0.0 to +1.0 during at least the Fall and early Winter.  That’s neutral to weak El Nino years.  I specifically discounted neutral years on the La Nina side.  That would be 0.0 to -0.5

2. PDO below zero for the majority of the winter, or at least the first half.  These are cool PDO winters.  I did not take just “cool regime”  years, but anytime we were in a cool period of months.  Nate Mantua breaks down the winters separately, but I just stuck with monthly values.

I came up with:
–  15 neutral to weak El Nino winters
–  7 occurred in a cold PDO
The winters are: 1952-1953, 1953-1954, 1968-69, 1977-78, 1990-1991, 1994-1995, 2006-2007
– It’s important to point out that 1968-69 and 1994-1995 were both right on the border of weak-moderate El Nino, so while I’m not discounting those two winters, I use those with a lot of hesitation, especially considering the first was one of the roughest winters in the past 50 years!

Obviously not a very large sample size (one more reason not to do a winter forecast!), but this is what I found:

1.  Precipitation:

These winters were generally wetter than average, definitely not showing the usual El Nino dryness.  Take a look at the national view.  I’ve eliminated the two winters mentioned above, but the only difference adding those back in was normal conditions (instead of dry) in California:

2. Temperature:

That’s interesting, warmer than average across much of the country during those winters.  Now once again I left out the two winters.  When they are put in, our temperature ends up right around average in the Pacific Northwest.  Keep in mind that average or warmer than average doesn’t mean we don’t have an exciting winter and cold/snow.  A three week long epic cold spell in January can be negated by warmth in November and February!

3.  Snowfall & Extreme Cold:

6 of the 7 winters saw 2″ or more snowfall at PDX.  I’ve included the two winters in this case.    It looks like all except 1952-53 had at least some sort of arctic intrusion whether it was an “arctic blast” or arctic air with a brief snowstorm (Feb. 1995 &  Jan. 1954).  The snowfall is in blue below and the coldest winter temp at PDX in green.

1952-53 Trace  18   Marginal arctic airmass in late November
1953-54 10.6″  19  A brief but cold snow/ice storm (like Jan. 1998) in mid January
1968-69 34″  A crazy period from late December all through January, freezes and snowstorms 
1977-78 7.6″  23 Unusual early arctic airmass over Thanksgiving (26/35 day at PDX), again in early January
1990-1991 1.9″  12 2 arctic blasts in mid-late December
1994-1995 5″  16 Feb snowstorm and brief arctic cold.  Also a late November wet snow day with east wind
2006-2007 3.5″  19 Cold January with surprise snowstorm (find it in blog archives!)

4.  Windstorms in the North Willamette Valley and SW Washington:

This one is a big surprise; not what I was expecting.  There were no significant windstorms in any of those years except in December 2006.  We were on the edge of the Hannukah Eve storm that year.  Of course Western Washington really got nailed.  That was probably the strongest windstorm here since the January 2000 event.

5.  A Dry Fall? 

Since it’s been so dry and it appears it’ll continue, I checked into that as well.  Did any of these years feature very dry weather well into October?  Several sure did.

1952 was incredibly dry…less than 3″ of rain from July through November!
1990 was a little dry
1994 was very dry, until the last week of October when many inches fell
2006 was very dry, until the end of October and then all heck broke loose the first few days of November.

So there you go…something to have long discussions and arguments about during the boring weather this upcoming week. 

Feel free to correct anything you feel I left out too.

Chief Meteorologist Mark Nelsen

52 Responses to Mark’s Thoughts on Winter 2012-2013

  1. bgb41 says:

    The 2011-2012 water year has ended. I have created an entry form where users can enter their monthly rainfall for the past year as well as a water year rainfall total. If you have a weather station and would like to be part of this database, please fill out the below form. Thank You!!

  2. Hey, speaking of winter forecasts, when do we start the fun of going on record withour own wishcasts?!

  3. Nice windstorm 45 years ago to the day. Vividly remember the early evening of Oct 2nd, 1967….Even some lightning thrown in if I remember correctly.

    Not looking promising this October…..

  4. paulbeugene says:

    Looking at numerical model output/guidance…GFS has low of 31 for Thursday morning (Oct 4) here in Eugene, whereas NGM has a low of 26. Being that it is so bone dry here, hard to imagine anything but clear skies during the night. Record low for EUG on Oct 4 is 27 set in 1916. If winds die down then we are good for frost. Enjoy the tomatoes while they last.

  5. bgb41 says:

    10/1/2012 Oregon (All) Temperature Summary

    High:95 at AGNESS2( 247 ft) & DW5789 Eagle Poi(1463 ft)
    Low: 76 at RED MOUND(1753 ft)

    High:58 at NERRS MET SITE A(10 ft)
    Low: 27 at DW9630 La Pine (4256 ft ) & Crescent (4462 ft )

    Largest Diurnal Change: 58 degrees
    KLAMATH NWR (86/28 ) (4531 ft )

  6. W7ENK says:

    [Milwaukie, OR] September 2012

    September 2011
    Avg High 79.8°F
    Avg Low 53.8°F
    Avg Temp 66.8°F
    MAX 95.4°F on 9/7/2011
    MIN 44.1°F on 9/28/2011
    Rainfall: 0.82″

    September 2012
    Avg High 79.8°F
    Avg Low 52.0°F
    Avg Temp 65.9°F
    MAX 95.4°F on 9/7/2012
    MIN 42.4°F on 9/11/2012
    Rainfall: 0.05″

    The Average High temperature was 0.0°F from last year.
    The Average Low temperature was 1.8°F cooler than last year.
    The overall Average temperature was 0.9°F cooler than last year.
    The MAX High was 0.0°F from last year.
    The MIN Low was 1.7°F cooler than last year.

    There was 0.77″ less rainfall than last year.

    • W7ENK says:

      FWIW, starting this month I can begin comparing my monthly stats against the “average” rather than just the previous year. Up to this point, the previous year was the only data I had available, as I began keeping records in October 2010.

  7. MasterNate says:

    So in Summary, an average winter here. Oh well, Im loving this fall summer. could stand a couple of more months of this.

  8. chris says:

    hey just out of curiosity what kind of set up caused the huge snows of the winter of 1893 and 1916? not like we will see it again at least not that bad. thanks 🙂

  9. Oct 17th 2012.

    The day starts mostly sunny with a gentle south wind. After a low of 47f the temp by 11am is 66f. By 1pm the sun is still visible but through a high thin overcast, the south winds are gusty, the temperature is around 72. By 3pm a flat grey sky completely obscures the sun. The temperature has dropped to 62 and the winds are gusting to 30, a light rain starts. By 5pm the rain is steady and the temperature is down to 54, Salem records a gust of 39mph. At 11pm Salem records a peak gust of 44mph. The rain is really coming down now. 0.33 inches since 5pm. Another .40 between 11pm and midnight, the front passes. At 1am the temp is 41 and the wind is 10-20 out of the west. Showers parade in from the northwest. Summer is over.

    • Almost forgot. 5 inches of wet snow at the top of Santiam pass.

    • W7ENK says:

      You did this once before with a forecast over the 4th of July week, and failed miserably. 😆 I still have it in my calendar.

      I’m holding you to this one, too. We’ll see how you do. :mrgreen:

    • W7ENK says:

      I’m assuming this applies to PDX.

    • Chris s says:

      I am more than ready, sounds good to me.😀

    • I think he fails miserably! 🙂
      My forecast….
      October 17th. After a low of 48, the sun rises thru a thin fog which burns off by 11:00 am. The high reaches 69 degrees with a light breeze from the nw.
      People are starting to wish for rain….

    • Mark Nelsen says:

      I’ll go with Boydo’s forecast.

    • W7ENK says:

      I’m holding you BOTH to it!! 😆

      We’ll see who’s closer…

    • Punxsutawney aka HIOPHIL says:

      Actually, after looking at the 00z GFS, boydo might want to change his high to 79-80 with light easterly winds

    • Timmy_Supercell (Hillsboro, OR) says:

      I’m going to say Boydo is probably the closest to being accurate! Sorry but October will not offer any real “stormy” weather. Certainly not a whole lot of rain we’re looking at either. 😛

    • W7ENK Yes, my July 4th cast was way off. Maybe I should try climatology. Much less accountability. My 2020-2030 forecast is…

    • David B. says:

      Based on Mark’s historical analysis, a late (to very late) start to the rains seems like a good bet, so I’ll go with Boydo’s forecast, too.

  10. Punxsutawney aka HIOPHIL says:

    High of 84.1 today at my station is the warmest October temp since at least 2001 here, and perhaps 1991.

    KHIO hit 86.

  11. Ron says:

    Great work Mark, that’s the kind of work you do for us that sets you apart from many other mets.

  12. And then? ….18z GFS shows a hint of promise, perhaps a glimmer of hope towards the very end of the run, well into ‘la-la land’ territory.

    • Joshua in Lake Oswego says:

      Looks good! I won’t hold my breath though. At this point, I just want some precipitation. It is getting a little ridiculous how brown and dry everything is. A lot of trees are losing their leaves already to cope with the stress of no water instead of because of the shorter days and cooler temperatures.

    • Yep all the yards around here are yellow, brown, and dead. I see some even the grass is dying off so quickly yards are becoming dirt. I don’t recall that since I was a kid. Also the Sandy River is really low. Oh and it hasn’t rained since? I can’t remember it was a morning with some t-storms. Models show a lot of dry, offshore flow coming which is only going to further exacerbate the situation.

    • Punxsutawney aka HIOPHIL says:

      If PDX hadn’t had that rainfall on the 10th of September, we would be at 73 days and counting without measurable precip if my counting is correct, and remember that was a measly .04”

    • Sifton says:

      PERFECT weather IMHO!

  13. I’d like to hear Mark discuss next weekend’s warm spell and why he thinks Portland will be back up to 80 degrees.

  14. alohabb says: could have left in real simple….TBD


  15. DEL X V says:

    Nice long range discussion, Mark,….thanks for spending the time Now it is time to worry some about the coming increase in Fire Danger,, east and west of the Cascades….

  16. I have liked the 2006-07′ analog. The observed weather is beginning to remind me a lot of 1994. The 1952-53 analog is interesting though that was a 2nd year warm ENSO.

  17. Mark, you have really outdone yourself on this one. Out of many other gems I think this post outshines the rest. I really appreciate how you broke things down and the amount of extensive research you did and the time that went into this. I guess if I learned anything it is that you can’t base things solely off the ENSO/PDO no matter if it’s snow, cold, wind storms, or otherwise, and that especially a neutral signal doesn’t make windstorms anymore favorable than a weak Nino/Nina.

    Thanks again.

    • gidrons says:

      I agree with Rob. Analog years are fun to play with but past performance is no guarantee of future results. A lot us, including me, got sucked into the analog hype from a couple years ago when the super cold nina formed. There are other potential factors. Generally speaking, el nino = split or southerly jet; la nada = strong jet; and la nina = lots of blocking.
      Regardless, I appreciate the research and non-forecast.

    • Analogs are perhaps a tool to look ahead, but again it’s always a roll of the dice it seem… Well unless a PV parks itself 300 miles offshore of Astoria, THEN we would be talking about some weather! 🙂

  18. Punxsutawney (aka HIOPHIL) at work by Sunset High elev ~280 says:

    Well there’s 1952 again. And 1977-78 has been mentioned in other circles. Having looked at the the last 80 years of records for Hillsboro in depth, I can tell you that no two winters, or years are exactly the same! Some are similar, but may have very different ocean conditions on top of it. And that’s one of the problems with analog forecasting.

    The best I think you can do is go with general chance of one thing or another happening. Of course, define “one thing or another”. 😉

  19. SilentReader says:

    based on the information – let’s just call it. Winter is over. 🙂 LOL. when does that usually start? November?

  20. EA_TTD says:

    Mark…this is great stuff and what I come to the blog for. Appreciate the time and effort you put in to it.

  21. David B. says:

    What happened after November in ’52? Did the rains hit with a vengeance, or was the winter as a whole dry? If the former, then it looks like a preponderance of the winters with the same ENSO and PDO configurations as this one started out dry and ended up wet to normal, in addition to most of them also having at least some lowland snow.

  22. Your not-forecast is not not-well researched! Thanks for this.

  23. Mark Nelsen says:

    We’ll have a drought, no snow, no windstorm, and it’ll be even more boring than last winter? Just trying to lower expectations!

  24. W7ENK says:

    Wow, a lot went into this… Nice work, Mark!

    Now I guess we’ll see how it all plays out.

    • Tighe (tie) Shawhan says:

      I agree great work mark. Very interesting stuff. For some reason I felt like it might be really dry and cold. Really cold. But you never know what your going to get here in the NW. Keep up the good work. At first I just wanted to see what the weather did in 1952.. But we know factors in 1952 are different than 2012. So I guess thats out the window. I must note Im a local landscaper so weather is key to how I prepare for my job on a daily basis. Sometimes its tough here in the NW but you guys do a great job.

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