• Category Archives La Nina
  • A Word (Or Two) On Where We Think This Pattern Is Going…

    Before we get into the updated thinking on the pattern, lets review what we have out:

    • Step-down process to cooler/ colder weather begins in mid-November.
    • Thanksgiving-Christmas period, as a whole, turns wintry and is snowier than average.
    • Our complete 2016-2017 Winter Outlook can be found here.

    The first week of November has featured an incredibly warm start to the month. (Image courtesy of MRCC).

    month-tdevSpeaking of warmth, 2016 has been a very warm year.

    ncep_cfsr_t2m_anom_ytd(The cold of 2014 seems so long ago…)

    ncep_cfsr_t2m_anom_2014Back to present.  We’ve targeted the middle part of November to finally beginning “bucking” the recent warm trend.  This won’t happen overnight and will be a battle of back and forth, initially.  Thus, the “step-down” label.  To be clear, November, as a whole, will finish much warmer than average.  It’s virtually impossible to counter the incredibly warm start.  That said, we do anticipate “jabs” of colder air working in here over the next couple weeks. For instance, this weekend will feature lows in the 20s for most and highs not making it out of the 40s Saturday afternoon.  (The average low and high at IND Saturday are 37 and 54).

    Despite being in a weak La Nina, the pattern is taking a while to respond.  Remember, we’re coming off one of the strongest El Ninos on record.  Until we slow the PAC jet, significant, long-lasting, changes won’t occur.  We can lean on the AAM (Atmospheric Angular Momentum) forecast for clues as to when this may occur.  You can read more about the AAM here.  My fellow local weather compadres, Michael Clark, Ed Valley, and Kirk Hinz have also written/ blogged extensively about the AAM and resulting impacts.

    gfsgwo_1

    gfs1When we look at the AAM forecast (above), we note the westerlies may begin to slow (indicative of the negative values) in the 8-10 day period.  This is crucial and, simply put, has to happen for the pattern to begin shifting into more of a position to allow sustained cold to enter the equation.  We want to reiterate that this, in and of itself, doesn’t create the cold, but instead allows the pattern to begin shifting away from the Nino-like (warm) regime into more of a La Nina pattern, as a whole.  – Hey, you have to start somewhere.

    If we can finally get the westerlies to slow, other elements are in play that could (and should) lead to a colder pattern as we move forward.  Our (3) big teleconnections are in a position favorable for cold for mid/ late November, into early Dec.

    cw5yrrsxaaefhiy-jpg-largeAdditionally, the EPO is forecast negative off the GEFS and EPS. (Images courtesy of Weatherbell.com).

    eps_epo_bias

    gefs_epo_12Again, this is a cold signal. (Image courtesy of Madusweather.com).

    eponew_neg_11novThe ensemble data is also beginning to key-in on higher heights (blocking) developing over the top.  Notice the significant changes in the overall look to the pattern between now and days 11-16. (Images courtesy of Weatherbell.com).

    cw5qrw0wgaaphxr-jpg-largeIn summary, and in the face of *most* seasonal data that is screaming warm, warm, warm, we still don’t have any significant changes to our overall thinking of “step-down” mid-November giving way to more sustained wintry-like conditions in the overall sense from the Thanksgiving-Christmas period.  Time will tell and only the Good Lord knows what the future holds, but we’ve done far too much work and research to throw the “game plan” in the trash before the game even begins…


  • 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…


  • Saturday Morning Rambles…

    1.) An absolutely stunning late February day is dialed up, with lots of sunshine and moderating temperatures.  We’re going mid 50s this afternoon.

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    2.) Though warm (lower 60s), Sunday will offer up showers by the afternoon/ evening.

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    3.) Mid and late week remains a challenge.  Do we have a leader-follower situation?  Time will tell.  We’re still leaning mostly wet for the Tuesday-Wednesday storm for now.  The late week system could offer up accumulating snow prospects (ala. ECMWF, GEM).

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    4.)  The period opens warm, but we shift much colder than average by the end of the week.

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    5.) We continue to look into spring and summer.  With the dramatic shift expected to a La Nina, fun times will ensue.  Hot, dry summer around these parts followed by a snowy winter?  Hmmmm….

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