La Nina Forecast 2018

Discussion in 'Advanced weather & chasing' started by Warren Faidley, Jan 11, 2018.

  1. Warren Faidley

    Joined:
    May 7, 2006
    Messages:
    1,100
    Likes Received:
    353
    I thought about titling this thread "The State of the 2018 Chase Season" as a joke, but after last year, it's not funny.

    So I received the ENSO outlook today and it forecasts the current weak / moderate La Nina will continue through the winter with a transition into ENSO neutral conditions during the spring.

    I know there are many theories about the effect of La Nina / El Nino on chase seasons but the general consensus leans towards a slightly less active May / June.

    W.
     
    • Agree Agree x 1
  2. Jonathan Beeson

    Joined:
    Jan 12, 2015
    Messages:
    50
    Likes Received:
    36
    Overall activity notwithstanding, the biggest thing La Nina does it trigger a drought across parts of the western and central US, pushing the dryline further east come May. This has consequences in two areas: 1) It can lead to more activity E of the Mississippi River as we get more instances of a dryline pushing east without mixing out. This can lead to some BIG outbreaks across Dixie and the OV such as Super Tuesday and the 2011 Super Outbreak. (The 1974 Super Outbreak was a post-Nina winter as well). 2) Across the plains, while it isn't always a death knell for areas west of I-35 (Such as 2008), a Nina year usually isn't a good thing if you're hoping to be able to chase in friendly terrain. The Upslope Plains and the Panhandles usually don't get much as they're often mired in drought conditions. This often forces the dryline to set up close to I-35, which obviously isn't particularly what you want as a chaser as you're now contending with major metro areas and the transition zone between the Great Plains to the west and the more forested areas to the east.

    Does that mean May and June are going to be duds? Not necessarily. May 2011 had that big sequence late month, but as I noted above, it stayed generally along and E of I-35 and didn't offer much in more of the traditional chasing terrain.
     
    • Like Like x 1
    • Agree Agree x 1
  3. Mark Blue

    Staff Member

    Joined:
    Feb 19, 2007
    Messages:
    2,508
    Likes Received:
    217
    I hope I didn’t misunderstand your comments regarding 2008, but my memory of 2008 was of chaseable storms daily even west of I-35. The upslope season along the front range was prolific with chases on offer darned near every afternoon from late May through early June. May 22, 2008, was a big day, with the Windsor, CO half mile wide tornado. That day’s event took place west of I 35 http://www.spc.noaa.gov/climo/reports/080522_rpts.html as evidenced by the map from SPC.

    In any event I hope we get a decent year in 2018 whatever takes place.
     
  4. Jonathan Beeson

    Joined:
    Jan 12, 2015
    Messages:
    50
    Likes Received:
    36
    That's actually what I meant. 2008 was an odd year in which the Upslope and High Plains was very prolific and active despite coming off a Nina. That's something you don't often see, although it is possible.
     
  5. Jason Boggs

    Joined:
    Oct 31, 2013
    Messages:
    365
    Likes Received:
    268
    I might be wrong, but I think the big news this year will be wildfires, especially in the TX Panhandle and southern KS. If you recall, we've had some decent rainfall in the past couple of years which in turn has resulted in a LOT of vegetation growth (fuel for the fire). Now we are in a drought again. The TX Panhandle and southern KS has not had any measurable precip in at least 85-90 days.

    I recall in 2006 (wildfire year) that I would wake up in Amarillo and see dewpoints in the upper 50's to low 60's. By noon the dewpoint would drop to the upper 30's, and the dryline would be way out in western or central OK. I fear this year will be a repeat if things don't change very drastically in the next couple of months.
     
    • Informative Informative x 1
  6. Warren Faidley

    Joined:
    May 7, 2006
    Messages:
    1,100
    Likes Received:
    353
    I think Jason is right. I don't see any climate shift to suggest an overall pattern change that would move activity west during the traditional periods of May and June. My (non-climatologist) opinion is that average chasing territory is slowly moving east every year. Of course there will be isolated, even major events west of OKC, but they are fewer and fewer. The fire danger in the southern Plains will likely be off the charts this year.
     
    • Agree Agree x 1
    • Informative Informative x 1
  7. John Farley

    Joined:
    Apr 1, 2004
    Messages:
    1,311
    Likes Received:
    271
    I am no fan of La Nina. It has already royally screwed up the ski season in the southern Rockies, and now it could do the same to the chase season in the southern plains as others have pointed out. All that drought over the southern plains would certainly seem to me to push the best potential for storms east, and maybe north as well. And the wildfire danger won't just be high in the southern plains, it will also be high in the southern Rockies (where I live) if this dry pattern continues much longer. Regarding the chase season, one can hope that there will be some decent setups at least occasionally despite the overall pattern, but when a good setup comes along west of I-35, better jump on it because there may not be too many others. Time will tell.
     
    • Agree Agree x 1
  8. JamesCaruso

    Joined:
    Jul 5, 2009
    Messages:
    593
    Likes Received:
    210
    I remember hearing Dr. Greg Forbes speak at ChaserCon 2014 about the correlation between large scale patterns such as El Niño / La Niña and tornados / tornado outbreaks. Although I can’t recall the details, I remember my main takeaway at the time was that any possible correlation was inconclusive at best. This may not have been as granular as addressing the impact in our favored regional chasing areas, i.e. west of I-35. Below is a link to the presentation if anyone is interested. Unfortunately, it is poor quality; you can hear Dr. Forbes fine, but won’t be able to see his slides up on the screen.




    Sent from my iPad using Tapatalk
     
    • Like Like x 2
  9. Jason Boggs

    Joined:
    Oct 31, 2013
    Messages:
    365
    Likes Received:
    268
    I think this pretty much speaks for itself... Untitled.png
     
  10. Jonathan Beeson

    Joined:
    Jan 12, 2015
    Messages:
    50
    Likes Received:
    36
    I wouldn't go so far as to say we're seeing a permanent trend towards I-35 as the new "average" chasing terrain. I'd argue that, if you consider strong/violent tornadoes, that always HAS been the "average" area for our biggest events.

    Consider this: There have been 59 tornadoes rated F/EF-5 in the modern era of rating storms. Of those 59 EF-5 tornadoes, only 16 have spent a portion of their life W of the I-35 corridor.

    If you narrow it down further to EF-5 tornadoes that spent their entire life cycle W of I-35, this drops the number even more, from 16 to 10. There are 8 EF-5 tornadoes alone that are within 20 miles or so of I-35 at some point along their track, and only 7 are what I would consider to be a significant distance W of I-35.

    Even if you go down to EF-4 tornadoes in say.. the state of Oklahoma where I-35 splits the state almost exactly in half, the highest density of EF-4 tornadoes occur along the I-35 corridor, give or take about 30 miles in either direction. There's only a handful of storms in the western part of the state a good distance away from I-35, and they are very spread out. The vast majority of tornadoes spend at least part of their track no more than 30 or so miles west of I-35 or they cross it at some point.

    While the most photogenic storms may be a good distance west of I-35, in terms of raw numbers, the I-35 corridor has always been the tornado hotbed of the great plains.
     
    • Like Like x 2
    • Informative Informative x 1
  11. Jeff Duda

    Jeff Duda Resident meteorological expert
    Staff Member

    Joined:
    Oct 7, 2008
    Messages:
    2,741
    Likes Received:
    1,089
    Haven't read much of the other responses here, so apologies if I am duplicating this, but my understanding of La Nina on the following spring tornado season is an increase in tornadoes in the lower Mississippi River valley area (E OK, AR, MS, E TX, LA).
     
    • Agree Agree x 2
    • Like Like x 1
  12. Brett Roberts

    Joined:
    Jan 7, 2006
    Messages:
    479
    Likes Received:
    342
    During my time chasing from 2006-present, there's never been a La Nina winter/spring with lush vegetation and frequent quality setups over the southern High Plains (W TX/Panhandles/SW KS). On the other hand, every single El Nino winter/spring has featured lush vegetation, evapotranspiration, and at least several good setups in that region (2007, 2010, 2015, 2016).

    It's true that ENSO correlations with tornado activity over the CONUS as a whole, and for many sub-regions of the central U.S., are ill defined. However, if you really hone in on the southwesternmost corner of the Plains, the evidence appears strong in favor of Nino and against Nina. Of course, some La Nina years are still active in areas immediately W of I-35 like W OK and C KS, and it seems to matter less (in terms of drought) as you get N of I-70. I just wouldn't expect to be chasing lots of setups with manageable LCLs in the Panhandles this year, if experience is any guide.

    My only other thought is that weakly- to moderately-cool ENSO winters where we're trending toward neutral or warm by late spring do not have a great track record, so hopefully, the "spring barrier" is at play in the latest forecasts.
     
    • Like Like x 2
  13. Warren Faidley

    Joined:
    May 7, 2006
    Messages:
    1,100
    Likes Received:
    353
    I believe the overall drought pattern is likely playing a bigger role in the reduction of severe weather west of I-35. I'm not sure if there is enough data to connect the ENSO patterns to larger scale climate changes.
     
    • Agree Agree x 1
  14. James Gustina

    Joined:
    Mar 9, 2010
    Messages:
    611
    Likes Received:
    218
    Thankfully the drought isn't 2014-levels of bad yet but I'll echo the sentiment of neutral/La Niña winters generally resulting in crap seasons, specifically through late April. It's hard to foresee consistent setups with serviceable moisture west of the Cross Timbers should there be no multi-day precip event between now and the end of February.
     
  15. Brett Roberts

    Joined:
    Jan 7, 2006
    Messages:
    479
    Likes Received:
    342
    It's possible this trend is occurring on long timescales, but that region has seen ample rains in March and April the past three years, leading to good ET during the heart of chase season.

    The "W of I-35" part of the southern Plains was ripe for action in 2015 (Elmer, Canadian, Dora, Simla), and it was the epicenter of virtually all the good chase events in 2016. Last year, moisture and LCLs still weren't much of an issue, even though we had few quality events for other reasons.

    The painful stretch from 2011-2014 rightfully concerned folks about whether classic chase country of 70s and 80s lore was undergoing some sort of rapid desertification, but subsequent years helped to quell those concerns, at least for me.
     
    • Like Like x 3
  16. Mark Blue

    Staff Member

    Joined:
    Feb 19, 2007
    Messages:
    2,508
    Likes Received:
    217
    I’ve learned through the years that one cannot underestimate the role ET plays in creating a humid environment in the lowest levels that persists and strengthens as each day passes in conjunction with Spring rains and the northward transport of moisture via the LLJ.
     
  17. Andy Berrington

    Joined:
    Feb 22, 2015
    Messages:
    134
    Likes Received:
    118
    This drought onset during winter certainly doesn't have me very rosy for the upcoming Plains chasing season, nor do some of the mentions of 2014 similarities that have been floating around (with merit). That was not a fruitful spring season for a multitude of reasons, but the main ones being Plains drought (moisture repeatedly underperforming) and repeated eastern troughing/cold shots/northwest flow throughout March-May (and everything had lifted north by June).

    The May 11th event in S NE, despite producing tornadoes of significance, ended up turning into a mess quickly (and was mostly dangerous anyway due to poor visibility) because of an anafront in close proximity to the warm sector, partly due to the remnant cold air mass to the north that lingered deep into spring. This generally caused a lot of problems with RFD character, since the main supercell(s) of the day generally tracked on or parallel to this boundary.

    This is a very specific case/example, but it kind of had everything that turned 2014 into a mess all in one setup (the drought detrimentally affected areas further S/W along the dryline).
     
    #17 Andy Berrington, Jan 23, 2018
    Last edited: Jan 23, 2018
  18. JeremyS

    JeremyS EF2

    Joined:
    Mar 12, 2014
    Messages:
    133
    Likes Received:
    133
    I took a look back at my chase logs from 2014 and it was one of my busiest years for me. It looks like the reason why was because there were a lot of local chases up here in Nebraska and Iowa. Lots of moderate risks in May and June with decent tornado chances, but as you mentioned there were a lot of HP messes so I didn't see a lot of tornadoes that year.
    It's been mentioned that the drought could push things east or even north, which would make sense looking back at 2014 at least.
    However, there was one event that made the year for those that saw it: Pilger!
    Being a bit biased based on my location, I would definitely like a 2014 repeat. I actually think I've chased more in Oklahoma/Texas the last couple of years versus my home state of Nebraska, it's been so quiet up here lately.

     
  19. Royce Sheibal

    Joined:
    Apr 5, 2010
    Messages:
    222
    Likes Received:
    134
    So call me crazy, but I'm wondering if the long term drought conditions brought on by La Nina in the S / High Plains vs the short term heavy early spring rainfalls that often accompany La Nina in the central plains (as happened in 2014) can significantly modify regional scale climates enough that standard fronts / lows in the NE/IA central plains area become dryline-like enhanced boundaries more so than in typical years. Areas south and west are drier and Td's stay low, areas north and east have increased evapotranspiration, with the end result being both stronger CAPE in the warm sector and a stronger trigger method once the boundary leaves the drought zone.
     
  20. Jeff House

    Joined:
    Jun 1, 2008
    Messages:
    323
    Likes Received:
    147
    Tough to put a silver lining on it. Tendency is Td mix-out issues even north, undercutting cold, and the like. Also might face some east of I-35 messes. However, it only takes one good sequence to make a chaser's year.
     
  21. Jonathan Beeson

    Joined:
    Jan 12, 2015
    Messages:
    50
    Likes Received:
    36
    I'm becoming cautiously optimistic for rainfall prospects over the next several weeks. We're beginning to see the western ridge slowly breakdown as well as the southeast ridge beginning to pump up. This may mean good chances for some rainfall across the Front Range and S Plains, as well as perhaps an uptick in activity across Dixie for those of us like me based in that area of the country.
     
    • Like Like x 1
  22. Mark Blue

    Staff Member

    Joined:
    Feb 19, 2007
    Messages:
    2,508
    Likes Received:
    217
    I like what I see with a trough in the West today vs the ever-present ridge we’ve been seeing. Hopefully it’s a good sign, but I’m also cautiously optimistic.
     
    • Like Like x 1

Share This Page