• Category Archives PDO
  • Digging Deeper As Winter Nears…

    Thanksgiving is only a week away (where on earth does time go?!) and more and more folks are asking what we think winter will hold for central Indiana.  In case you missed it earlier this fall, here’s our official Winter Outlook.

    We’re continuing to dig in and monitor new data that’s streaming into the office, as well as ocean profiles.  With that said, we wanted to share some of our findings with you this morning with respect to how various ocean regions can impact our weather this winter.

    We’re noticing significant changes, particularly in the north Pacific, with the famous “warm blob” emerging (image 1). This is a big factor that aided in persistent cold; wintry weather during the ’13-’14 winter (images 2-3). Notice the difference from last year, too (image 4). This isn’t a full blown cold PDO (Pacific Decadal Oscillation) yet, but trending in that direction and “ups the ante” for cold, wintry conditions, locally this year.

    What makes seasonal forecasting so challenging (and fun :-)) are the multiple features that can impact a forecast.  We’ve talked about the importance of ENSO (various types of Nino and Nina events) in past updates, as well as low solar and QBO.  All of these moving parts and pieces are coming together in a manner that seems to be favoring more of a cold, wintry regime, locally, this year.  Is that us saying another blockbuster 2013-2014 winter awaits?  Absolutely not (there are other differences noted above with the SST configuration).  However, it is suggesting that this winter will be absolutely nothing like the past couple…

    Might want to think about getting the snow blower tuned up!

    More later today on the short-term.  Make it a great Thursday!


  • Winter Ideas…

    We continue to finalize our winter forecast, which will be posted, as always, here later this month.

    As little as only a few months ago, data suggested a major La Nina for the upcoming winter season.  That data has since backed off significantly.  In fact, some runs suggest we’re back into a weak-ish El Nino state by spring.  At the very least, we are confident on avoiding a strong La Nina this winter and lean more in the direction of a weak Nina, at best, to neutral signal.  The CFSv2 is interesting, as always, with the spread in region 3.4.

    nino34monadj

    sstanimIn addition to the central PAC anomalies, we also are keying in on some other items of interest in the overall SST configuration:

    I. Warmth in the GOA (Gulf of Alaska)

    Argues for central cold this winter, spreading east with time.

    II. Warmth off the eastern seaboard

    Will likely serve to limit the ability for the cold to spread east early on in the season

    92916sstThe SST CA model is quickly becoming one of our more trusted seasonal forecast models.  We note how it becomes increasingly bullish on a central and eastern trough as winter wears on (by the way, this is likely to go deep into spring this year, too).

    screen-shot-2016-10-02-at-10-52-54-am

    screen-shot-2016-10-02-at-10-53-04-amCold overwhelms the pattern and when you combine it with the active storm track (noted by the green hues, suggesting above normal precipitation through our neck of the woods), confidence is continuing to grow for an above normal snow season.

    screen-shot-2016-10-02-at-10-58-16-am

    screen-shot-2016-10-02-at-10-58-05-amThe SST configuration on the JAMSTEC would suggest a cold, stormy set-up, locally.  That said, while it sees the above average precipitation, it’s awfully warm at the surface.

    ssta-glob-djf2017-1sep2016

    tprep-glob-djf2017-1sep2016

    temp2-glob-djf2017-1sep2016The NMME (to no surprise…) would suggest a very warm, wet winter.

    screen-shot-2016-10-02-at-11-08-26-am

    screen-shot-2016-10-02-at-11-09-00-am

    screen-shot-2016-10-02-at-11-08-47-amAs a reminder, our complete and final annual winter outlook will be posted here during the second half of October.  That will include additional model data, along with several other points behind our reasoning for our winter forecast.  As we always do, we’ll put “pen to paper” when it comes to our winter forecast, including our expected temperature and snowfall anomalies.  Given the data above, including the warm JAMSTEC and NMME, it’s going to be very, very hard to see a warm winter here.  In fact, our idea is for the exact opposite, given the SST configuration, and lines up more closely with the SST CA idea at this point.  We’re also in the camp of a very, very active storm track through the Ohio Valley.  “Big-hitter” potential is present from a winter storm perspective, especially given that we are likely to see resistance from the SE ridge.

    Much more later this month…


  • More Winter Chatter…

    Now that we’re in September (where does time go?!) we wanted to touch base on some of our latest thinking as we rumble closer to winter…

    * Our official 2015-2016 IndyWx.com Winter Forecast will be posted in mid October.

      
    The latest sea surface temperature anomaly chart continues to point out items of interest:

    • Strong El Niño in play, but….this is also highlighted by recent cooling in Niño 1+2 and a “spreading out” of warm anomalies into Niño 3 and 3.4, or more centrally based.

      

    • Positive PDO (warmer than average eastern PAC waters). This supports western Canada ridging and associated warmer conditions than average across the west, with cold favored east.

      
    It’s a “battle” of two juggernauts and it’ll be fascinating to watch the fight unfold. The strong niño argues for warmer, drier than normal times this winter, but the positive PDO, or Pacific Decadal Oscillation, argues for the opposite (see the past two winters for most recent examples).

    No niño is like another, and one can’t simply broad brush a seasonal forecast based solely on the ENSO state. Many other factors play crucial roles in seasonal forecasting.

    At this stage in the game, we would lean more in the direction of an “average” winter than one that’s dry and milder than average. If we had to pick snowier than average or less than average snow we would lean towards the snowier regime. This is based off the warm north and east anomalies in the Pacific. It’s important to factor in that positive PDO just as much as the strong niño. 

    Speaking of the positive PDO, here’s what meteorological winter looks like during positive phases from a temperature perspective.

      
    The constructed analog SST model is going towards that look:

       

     Also, see the JAMSTEC’s idea. Very similar, huh?

      
    We could go on and on about why this winter is going to be a challenging one, but the main “meat of the message” that we’re trying to get across is the idea that we have a long way to go and a lot of “players” on the field. To build a winter forecast that rests solely in the hands of the niño isn’t providing the public a fair idea for what lies ahead to close 2015 and into 2016. 

    Much more later!