BOM today suggesting that an El Nino may be in the offing, but looking at the SOI 1998 and 1981, as examples, both had values well in the -ve at this time and 1981 was a monster year (one of the best ever).....so I remain hopeful....
don't worry. As far as i can recall BOM have been predicting El Nino at regular intervals for the last 5 years. Although they will be right at some stage. Pissing in the wind.
Weather....sure....but it could as easily be in Conversation - given that we have a few farmers who ski and we all like water and we all love skiing!
The Spring Predictability Barrier: we’d rather be on Spring Break http://www.climate.gov/news-feature...ctability-barrier-we’d-rather-be-spring-break
JJA skill improves to about 50% in May -- still pretty ordinary. Note that's for the IRI dynamic model group as a whole, as at about a decade ago (2002-2011). One hopes they've improved a touch since then, and that the better ones (CFSv2, POAMA) outperform the pack.
We are already in an El Nino and the atmosphere is responding unlike this time last year. The SOI is dodgy measure at the best of times and when you think about it, how is a two point source index going to capture every El Nino, each with their own unique characteristics with respect to location of strongest SST anomalies etc. If you look at this El Nino, the main tongue of warm SSTs is displaced north of the equator and the convective storms are located well away from Tahiti. So how is Tahiti going to pick up this anomaly well? That said check out the Australian Sat pic right now and compare it to the central tropical Pacific and this shows that there is large scale anomalous convection in the Pacific and large scale decent and convective suppression over Australia and Indonesia. Australian region http://www.ssec.wisc.edu/data/geo/index.php?satellite=mtsat&file=jpg Pacific http://www.ssec.wisc.edu/data/geo/i...e=fd&file=jpg&imgoranim=img&anim_method=flash All 4 regions are now in El Nino status. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/ssta_c.gif The most telling thing about this event compared to last year is that the convection has shifted to the warm anomalies in the mid tropical Pacific and these SSTs are much stronger and more expansive than this time last year. This convection has been there consistently for the last month and is getting stronger. This ultimately alters the surface wind circulation which also acts as a feed back reducing the risk of strong trade winds and upwelling cooling to kill the Nino like last year. The IRI ensemble forecasts are a joke by the way. Not worth looking at because there are so many bad models in there. They only agree on an El Nino when the El Nino is already in place.
Don't want to see N3.4 > +0.8°C for say two months in a row Falls? Anyway, it's very close however you want to judge. The satpics sure are striking; puts some meat on the date line OLR plot ("outgoing longwave radiation" ≈≈ 1 - cloudiness; plot is for 7.5S-7.5N, 170E-170W -- about the longitude of Fiji / extreme eastern tip of NZud): Notice what happened last year -- had turned around by now. SOI was presumably chosen for the long historical record rather than representativeness of the phenomenon. It's far from ideal, but actually correlates pretty well with local ENSO effects. I presume that's because Darwin is sufficiently close to the "up end" of the seesaw, even if Tahiti is not so near the "down end".
Lake Mead lowest on record, and will go lower before the next northern winter rains come: http://www.usbr.gov/lc/region/g4000/hourly/mead-elv.html. Yanks are praying for El Niño.
I Monitor ENSO and other Teleconnections virtually every day in my job. One of the striking things about all these indices is they are great pieces of research and give wonderful insight into global circulation but are next to useless for use as a forecasting tool. Take the Nino 3.4 region. El Nino is declared after 3 consecutive months of exceeding the threshold but the changes in global circulation can and often do start in first month of exceeding the threshold. This means that when you go back and look at previous El Nino events then you are quite possibly missing the true atmospheric response to it by up to 3 months. I am observing an El Nino response to the global atmosphere now and that is all I need to know from a forecasting perspective.
Off topic but here's some cool stuff of the hydrology of the new channels and rapids the Colorado is carving into the former Lake Mead lakebed. http://www.durangobill.com/GCTourSuperimposition.html
In theory, given that we are odds on for a >+1 probably basin wide El Nino during JJA then this season should struggle on Natural snow, but a regular supply of cool air on an eastern side of a big semi default high pressure should enable decent snow making potential. 1982 for example was a dire year for natural snow but was cold. If the snowmaking now in place was there then, it would have been probably a half decent season with sunny cool days and good piste cover but poor offpiste. All that said each El Nino is unique which is why statistical correlations are weak especially given so few samples. I think from memory (probably wrong) that Nino years have early snow peaks then fade. Not in a place right now to check.
The correlation is pretty weak between peak depth and SOI: ... perhaps it's better between say integral depth and Nino3.4, but I think overall the lowish ENSO correlation is just because other factors dominate the variance, e.g. local sea surface temperatures: http://gergs.net/2015/03/snow-depth-prediction-mk-iv/spencers_correlations_rev1-2/. Regards peak timing and ENSO, haven't looked, but it's on the to-do list. There is a long term trend to earlier peaks: http://gergs.net/2014/07/peak-timing/spencers_creek_peak_date/ (1982 was early, but not exceptionally so).
It's a big river in a sparsely vegetated catchment. Sedimentation of big-river storages is a major issue that is generally ignored by proponents. Sediment filling times can be as short as a few hundred years ... what do you do then? Responses like say the low level sluices in the Three Gorges Dam basically don't work. Probably it's better not to dam large sediment-laden rivers, but try to tell the worshipers of hydrotechnics (see China and the Mekong).
Also, Colorado = Red River. In its natural state it was closer to slurry than clear water, IIRC Powell & co had problems with thirst as it was so difficult to get drinkable water from it.
BoM predicted El Nino at around the end of 2009 / beginning of 2010. What happened is that we ended with a massive Pacific swing to La Nina inside of six months. BoM didn't predict El Nino during the record-breaking double-dip La Nina from 2011 to 2013. BoM predicted El Nino briefly during early 2014 but then backed off, while other international agencies still were forecasting a 'proper' event. In 2014 the ocean initiated three El Nino events (i.e eastward subsurface waves of warm water) but the atmosphere never coupled to help sustain the shifted thermocline. Against most SST indices 2014 was a weak El Nino event, but by atmospheric indices it never coupled. We are now coupled however and are in El Nino.
30 day SOI just went out the back door and is now back at El Nino levels. 90 day is not quite there yet. https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/ meanwhile - sea temps have cooled slightly all across the central pacific - a lot of that brown was red/orange last week. http://earth.nullschool.net/#curren...rlay=sea_surface_temp_anomaly/equirectangular it might just be a short sharp El Nino and collapse very quickly. IMO it all depends on what happens with additional kelvin waves from west to east in the next couple of months. Both PG and Falls Expat are saying the atmospheric coupling to the ocean is now quite apparent. Hence the sharp fall in SOI numbers the last week driven by what I assume is another burst of winds towards the east?? It will be interesting to see the next mid month sub-surface temperature chart updates - they probably won't be included in tmw's ENSO update that was reported in SMH last Friday as going to be end-of-the-world-as-we-know-it stuff. The April 15 chart ( http://www.bom.gov.au/climate/enso/#tabs=Sea-sub–surface ) seemed to suggested the last KW was ay the down welling stage in the eastern pacific - with the cool water coming in behind it from the west. Hence the slight cooling now showing up in the near real time view earth.null is now showing for SSTs. The same slight ocean wide cooling also seems to be showing up in the Indian Ocean view or earth.nullschool which would fit with the BOM forecasts for IOD to drop slightly in the next few weeks. As to winter, I'll be more than happy with an early cold season with 100 cm across Perisher in min July. Last lifts at around 4 on same quality snow as the morning is fine by me.
http://earth.nullschool.net/ Another anomalous Westerly wind burst occurring with Typhoon Dolphin which should push another kelvin wave eastwards. I suspect the NW Pacific Typhoon season will be very active this year especially in the early part of the season. If so then further warming will occur.
Of course whilst most of the attention is focusing in on the developing El Nino at the moment, the developing +ve Indian Ocean Dipole has gone under the radar a bit and some say this is more important for rainfall in Australia anyway. http://www.bom.gov.au/climate/enso/#tabs=Indian-Ocean If you combine the +ve IOD and El Nino then the rainfall anomalies do not make for pretty reading. http://www.bom.gov.au/climate/IOD/positive/#El Niño
According to BOM "The seven positive IOD/El Niño years used are 1963, 1972, 1977, 1982, 1994, 1997 and 2006." According to Snowy Hydro readings .. 63/72 both good - 77 average early/late good - 94 average - 97 average early/late good - 2006 - season from hell. From what I could see only 2006 was a complete dog. Rest were so so early on, before coming good later on in the season. Does it not remain a gamble any year with just a few good dumps determining the outcome? A near repeat of 2014 would be a good outcome. As long as it does not rain. As for the rest of the eastern seaboard - the rest of the year could be dry and windy ahead of lots of fires in Spring.
That basically came up out of nowhere -- POAMA had IOD continuing neutral just a month ago. Others not yet agreeing: (UK Met smokin' what?) Do you think it'll strengthen further, Falls?
You missed out 1982 which was a season from hell as well and a lot worse than 2006 because they had very little or no snow making. It is probably cherry picking but prior to 1982 you could argue due to climate change snow seasons were longer and deeper. So since 1982 those years were pretty lean including 82, 97and 06. Ultimately the rainfall averages shown on the +ve IOD and El Nino combo chart don't lie. It was on average drier than normal therefore snowfalls are likely to be on average lower than normal.
A point you've made before IIRC... Yes the correlation is much weaker in the second half of the record, but note that all five post-1984 winter El Niño years (SOI < 10) had peak depths below the long term average. As I said above, other effects dominate the variance...
I have been monitoring the Indian Ocean region with respect to expected rainfall over India during the monsoon. There have been many papers on how the IOD is more important than El Nino for Indian rainfall and that in El Nino and +ve IOD years the monsoon rains come in much lower. So I noticed over the last month SSTs off the Horn of Africa have been rising rapidly whilst near Sumatra SSTs have remained similar or cooled. This warm pool of the horn of Africa could well disrupt the normal cross equatorial flow of moisture into the N Indian Ocean resulting in a failed or lower monsoon rainfall season. So yes I think the IOD is odds on to strengthen further. You do raise a good point though Gerg. All the indices and papers I have read refer to months or seasonal time scales for these SST anomalies to build, but you only have to look at the recent observed Kelvin waves in the Pacific that these changes can occur on a much faster time scale and I suspect this opens up the potential for a lot of statistical studies in the past being out of sync or inaccurate with respect to timing of the coupling of the atmosphere. It also gets back to my pet theory that SST change does not drive the atmosphere, but rather the other way around. Atmospheric changes alter the SSTs which then have atmospheric feedback. The PDO and El Nino being good examples.
Yes I did miss 82 - I did look it up but left it off the list in error - which is pretty ironic given it's the classic dud year after the classic epic year ie '81 '65 was also a dog year - as was '54 - suggesting that it's the luck of the draw no matter what the macro scale conditions might suggest. Though I don't disagree that the overall trend is lower and earlier snow melts.
Nice plot. Although even if the SOI correlates well with Nino it has limited predictibility on snow seasons though, 2000 being and example where there is a La Nina in place and neutral or +ve SOI. I think the problem lies in the simplistic use of one teleconnection. I always look a multiple telecons at the same time regardless of whether one is very strong or not. You may have a perfect El Nino but a -ve IOD offsetting it. So I use the balance scale technique. If lots of the telecons are on one side of the scales, e.g. say dry, then dry is the most likely outcome. If there are multiple counter acting telecons then confidence is much lower which is the most common case and reason for many seasonal forecast failures. It is only in mega years like 1982 and 1997 that the stars align leading to major atmospheric disruption, but even these had their opposing factors at times.
Yep. For my little games I just use multiple regression, which -- being linear -- is unlikely to represent multiplicatory synergies well. Can you suggest a better way? (BTW, another issue with using SOI is all those spikes. Probably one should try to remove the worst before correlating, maybe based on standard deviations away from a suitable filtered trend -- say a loess or even just a simple Spencers.)
that becomes chicken and egg though.. I once had the conveyor belt ocean current idea explained to me like being magnetic tape, that is written and read in different parts of its cycle.
BOM Australia @BOM_au 8m8 minutes ago Bureau of Meteorology declares #ElNiño. More at http://www.bom.gov.au/climate/enso
Maybe; see graph. SOI (atmosphere) leads Nino3.4 (ocean) in nearly all El Niño onsets: 1982, 1991, 1993, 1994, 1997, 2002, 2004, 2006 and late 2014. Interetingly not the case for La Niña. (There'd be a paper in that, except that I bet it's already been written.)
I'm very interested in '54. I've started leaving it out because it's such an extreme outlier (about a 1 in 10,000 chance in my prediction model). I've been blaming that on the Hydro learning to measure ('54 was their first year), but it was also very thin at Rocky Valley (Falls Creek): http://gergs.net/2014/04/adding-rocky-valley-dam-falls-creek/nsw_victoria_peak_depths/. Anyone know more?
I don't believe so. I think Ocean currents and displacement of sea water into anomalous regions is atmospheric driven. I think the PDO for example is a very long term atmospheric pattern shift, a cycle yet to be reasoned, perhaps solar cycle related, but this is not to say that these SST anomalies don't have real time feedbacks which may act to sustain itself to some extent.
Ha! I wouldn't even begin to know where to start to better your data analysis. Stats are not my forte. Your analysis is great work and much appreciated.
As above, BoM have gone all in http://www.abc.net.au/news/2015-05-...red-drier-hotter-conditions-predicted/6463966 http://www.smh.com.au/environment/w...-nino-event-in-australia-20150512-ggzdgy.html
