snowwman
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Posts posted by snowwman
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Indeed, the correlation here appears weak, but only if you're taking of extremes (la Nina and El Nino). Here, cool side of neutral touching on la Nina seems to be ideal, though you need to factor- in the QBO and solar activity (as measured by cosmic ray influx, not sunspots (as there's a delay in the former, which is what influences the jet- stream, relative to the latter, in odd- numbered cycles).
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The blob seems to have moved East, and partly extends to the Mediterranean; this is likely to reflect atmospheric dynamics rather than ocean currents, but in any case, it might indicate a tendency for a more Southerly- tracking jet this year. The jet seems to have flowed- around the edges of this blob over the years, and this resulted In December 2015 being record- breakingly mild. If the anomaly stays where it is this year, however, we may be in for a very diiffent December, and winter generally.
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Yes, ECMWF is going for the 25th at the moment. However, I've noted a slight tendency to underplay Easterlies at the equator at times, and if this also applies to 60N, then the vortex may be somewhat later.
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CPC now puts Nina ahead of Nino for winter:
, with neutral the preferred option. However, the way the models have been trending, I say that the most likely outcome is La Nina.
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After a string of summers feturing heatwaves or repetitive Spanish plumes, every summer since 2014, I'm happy with the way this Summer has turned out, on the whole although GFS's insistence, now in the ensemble mean, on a height- rise over our shores, is rather worrying. I'm hoping that ECMWF is has it nailed and that this Summer ends mercifully.
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Latest SST are out-
http://www.cpc.ncep.noaa.gov/data/indices/wksst8110.for
and show a cooling in all enso regions.
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Amazingly fast cooling in the far Pacific:
http://weather.unisys.com/surface/sfc_daily.php?plot=ssa&inv=0&t=cur
. At this rate, we'll get a La Nina very soon.
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On 8/2/2017 at 06:24, jvenge said:
It changed quickly, but I'd expect the next ENSO watch to up the chances of La Nina, lower the chances of El Nino, but likely still keep neutral as the form horse.
Indeed, I think it's difficult to imagine El Nino continuing to be preferred over La Nina. The move toward Neural as the most likely outcome by winter's start will eventually result in La Nina being the most likely outcome, I think, and as has been mentioned, CFv2 has been keen on this possibility of late.
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On 08/03/2017 at 08:56, Yarmy said:
Berlin have updated the QBO numbers for July:
http://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/singapore2017.dat
Monthly mean zonal wind components ( 0.1 m/s) at Singapore (48698), 1N/104E 2017 hPa JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 10 2 10 -162 -270 -286 -304 -331 12 76 75 -40 -229 -280 -294 -329 15 112 123 73 -142 -268 -300 -309 20 142 159 131 52 -207 -287 -310 25 161 169 145 117 -85 -254 -294 30 171 177 153 136 58 -145 -256 35 169 185 155 141 116 38 -81 40 165 170 158 146 136 110 57 45 155 166 141 134 149 126 99 50 132 145 107 118 148 134 111 60 77 94 28 66 114 136 123 70 15 36 10 50 73 126 127 80 -22 21 11 30 39 94 88 90 -55 -21 -1 -13 3 25 72 100 -150 -80 -38 -49 -53 -26 -10
http://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/qbo_wind_pdf.pdf
Second most negative first two months at the 30mb level on record, if my calculation using the FUB data is correct.
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On 31/07/2017 at 10:20, comet said:
Whether it be negative or positive qbo no one really knows what actual forcing it has on the other teleconnects. I have my own theory that when the qbo is in either phase in a very strong mode it does not bode well for the prospects of cold for the UK in winter. it is basically a lottery that no one knows the answers to. The same can be said for strat warmings as we have seen the last couple of years, yes we may be able to predict when a warming is more likey than not given the qbo state etc but we are definitely no nearer forecasting what likey impacts the warming would have and where.
Last year the met came a cropper announcing that they cold now reliably predict UK winters a year in advance due mainly to GLOsea 5 etc only to fail at the first hurdle
There's no clear link unless you factor in solar activity. I recall a study by Labitzke et al which concluded that the vortex is weak in Easterly QBO winters at solar minimum and in Westerly QBO winters at solar maximum.
Where I probably agree is the link between split stratospheric vortexes and cold winters- I can find no link in the research I've done which confirms the oft- quoted causative effect; indeed, a split strat. vortex might even be harmful, though certainly a disturbed vortex may be crucial.
This link:
http://journals.ametsoc.org/doi/full/10.1175/JAS3883.1
might provide some useful links, though I haven't had time to read it.
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19 minutes ago, sebastiaan1973 said:
Thanks guys.
The Madden-Julian Oscillation (MJO), also known as the 30-60 day oscillation, is the strongest of the intraseasonal
climate oscillations and consists of an eastward propagating pattern of alternately intense and weak tropical
convection and precipitation. It has significant derivative effects on extratropical circulation and intraseasonal climate,
including effects on the North Atlantic Oscillation during northern winter. It has recently been found that
the stratospheric quasi-biennial oscillation influences the amplitude of the MJO during northern winter such that
amplitudes are larger during the easterly phase (QBOE) at 50 hPa than during the westerly phase (QBOW) [Yoo
and Son, GRL, 2016]. The initiating mechanism is a decrease in static stability near the tropopause under QBOE
conditions resulting from relative upwelling associated with the QBO induced meridional circulation. Positive
feedbacks from below further enhance the response during the northern winter season. Here, evidence is presented
that the QBO modulation of the boreal winter MJO is itself modulated by the 11-year solar activity cycle. Using
real-time multivariate (RMM) MJO amplitude and phase data covering the 1980-2015 period (36 years), it is found
that the increase in MJO mean amplitude during December, January, and February (DJF) under QBOE conditions
is especially large under solar minimum (SMIN) conditions while the decrease in MJO amplitude under QBOW
conditions is largest under solar maximum (SMAX) conditions. Consistently, the DJF mean static stability calculated
from ERA-Interim reanalysis data in the lowermost stratosphere over the warm pool region is especially
low under QBOE/SMIN conditions and is largest under QBOW/SMAX conditions. Specifically, while the mean
MJO amplitude in DJF is 33% larger in QBOE than in QBOW, it is 56% larger in QBOE/SMIN than in
QBOW/SMAX. Conversely, the mean MJO amplitude in DJF is only 14% larger in QBOE/SMAX than it is in
QBOW/SMIN. This dependence on the solar cycle is consistent with a solar-induced increase in relative tropical
upwelling under SMIN conditions and a decrease (relative downwelling) under SMAX conditions. However, these
results are based on a limited time record. For example, only 5 winters qualify for the QBOE/SMIN category while
7 winters qualify for the QBOW/SMAX category. During the coming solar minimum, at least one additional winter
in the QBOE/SMIN category should occur (possibly as early as 2017/2018) during which especially large MJO
amplitudes are expected and an initial test of the proposed relationship will be possible.journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-14-00625.1
Much interesting information here. I haven't done the number crunching myself, and I wonder whether there's any increase incidence in phases 7 and 8 during cool end of neutral and a strong upper (or lower-) strat EasterlyQBO.
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17 minutes ago, sebastiaan1973 said:
Cool side? I suspect you mean warm side of neutral ENSO? http://easternmassweather.blogspot.nl/2017/07/preliminary-profiling-of-winter-2017.html
I tend to agree with comet about strong QBO phases.
At the moment, yes, but then the forecasts seem to be moving slowly in the cool direction. CFSv2 even recently forecast a very weak La nina for NDJ, and still, the forecast is for cool side of neutral by then:
http://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml
. Also, there has been a sudden cooling in this region and region 4 (from what I can make out) in the past week. My guess is that the strong Easterly QBO is what's primarily feeding this.
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Yup, 2014 and '15 we had protracted heatwaves here in South Wales, and last year we had so many Spanish Plumes I lost count. I'm grateful for a Summer of more sensible weather, on the whole.
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9 hours ago, Singularity said:
1983-84 saw a mild December followed by tasty January for snow in the north but frustrating elsewhere, due to predominantly polar maritime airmasses, after which February was distinctly uninteresting - well as far as I can gather from various reports. Good thing the QBO isn't the only factor that matters
. The winter was not long past a solar maximum for example - but then again, we're not yet on the right side of the minimum for any significantly different forcing to be expected (based on current literature, anyway).
Overall there is still a lack of particularly strong signals regarding the overall 2017-18 winter prospects but it is only July after all
. Best I can say is that the QBO shouldn't be an obstacle like it was during the last one! I've reached the conclusion that severe winters have more to do with absolute solar activity and the length of time that activity has been anomalously low than they do with relative levels- for example the location in the cycle. Depending on what station you're examining, cosmic ray levels are already at 2009 levels.
Cool side of neutral enso conditions, an Easterly QBO and such levels of solar activity are, from what I can gather, extremely well positioned for an exceptional winter.
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The reason for the "hold- up" in the progression of the Easterly QBO is that the lower levels of the stratosphere were anomalously westerly in the lower strat during the Westerly phase which is on the way out at the moment; actually, by historical standards, there is no hold up- the Easterly QBO is progressing down the stratosphere no less quickly than average, now that it's encountered the anomalously Westerly lower- reaches of the strat; it's just a matter of time before those levels turn Easterly, too. A further point is that winters we consider "Easterly", e.g. 1962/'63, weren't Easterly at the 70mb level until way later than now, and when winter was over!
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12 minutes ago, weirpig said:
looking at the table above if im reading it correctly it does show a strong easterly qbo at 30Hpan after only 2 months of a easterly being recorded at 10hPan is this a good sign?. or am i reading the chart totally ockerd.
The 30mb level isn't negative in the chart yet- only the 10, 15 and 20, but June's value will be negative at 30mb.
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I recall reading that an Easterly QBO renders the vortex weak only during low solar activity; Karin Labitzke did some research on this. I've noted that when geomagnetic indices have been anomalously weak for a few years or when there's a sudden plunge in said indides (e.g. Ap index), cold winters tend to occur. At the moment, it seems to me that cosmic ray monitors suggest that we're at the sort of level we experienced in 2009 and 2010.
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I'd take this over a heatwave hands down.
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I can't abide warm weather, and I was beginning to get that sinking feeling again when ECMwF was suggesting another spell of it. Thankfully, the ensembles weren't backing it, and the expected swing back to unsettled happened this morning.
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What surprises me more than anything is that there's no mention which I can find on the web of the strength of this Easterly QBO. The preliminary data for the first two months of the phase at the 10mb level, the first two months at the 15mb level, and the first month at the 10mb level, suggest, taken as an average, that this is very much the strongest Easterly on record. Also, the fall in wind speed between the penultimate and final month of the Westerly at the 30mb level is the second largest on record, and this Easterly may be the first to propagate from the 30mb to the 50mb level in less than 2 months.
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2 minutes ago, Interitus said:
Well as December had the highest QBO of any winter month in the NOAA data linked above, then obviously your first statement is absolutely correct. However, unless you are less than six years old then you would've experienced December 2010 with QBO 10.97.
Even colder? February 1986 QBO 10.15.
There is no statistical correlation between CET and QBO for December or February, and a tentative 0.24 for January.
However, the data does appear to show cooler CET for eQBO, worth around 0.2°C for December and February and a more notable half degree for January (though Jan 1963 skews this somewhat) and this persists after taking into account that eQBO is stronger than wQBO so the mean is easterly.
When looking at more extreme QBO values greater +/- 1 sd the picture is more muddled - though there is a problem with small and uneven sample sizes so must be taken with a pinch of salt.
The December difference is the same, but both are above average (+0.2 / +0.4).
January seems more clear cut with means of 3.47°C (1963 is worth 0.3 degrees) and 4.75°C - may be reflected in the weak correlation noted above and worthy of some investigation, though is not statistically significant - we have had a prolonged run of generally mild Januaries regardless of QBO.
February has no difference in CET between extreme east or west QBO - this is perhaps the most interesting bearing in mind links between QBO and late winter stratospheric vortex strength.
But, to say that QBO is responsible for whether we have notable cold spells is more than a bit of a stretch.
Nice bit of research. I came to the same conclusion re. Westerly QBOs. They don't spell mild. They seem more likely than Easterly QBOs to be correlated with extreme mild or extreme cold.
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10 minutes ago, booferking said:
Over 40mins since the last post on the model thread says a lot really looking at the ens you can see why trending the wrong way again.
Perhaps the latest GFS run at D16 has found a solution the the difficulty of the Northerly considering the strong vortex over Canada, now gone in this chart:
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37 minutes ago, KTtom said:
All looks fairly positive from my point of view, yes, the easterly looks dead in the water, however deep cold is now seeping south into Europe, with all operationals hinting that pressure will rise again in the Atlantic a good chance of further northerly blasts increasing in intensity especially mid month would be my estimate.
Exactly, KT, and the low heights seeping deep into the Mediterranean, even by ECM:
, will make it difficult for that high to sink.
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8 minutes ago, Daniel Smith said:
The performance of the models this year has been absolutely shocking. No consistent signal, flopping and changing the second something does look like becoming consistent.
Whats the point of running them beyond 3-4 days? They offer absolutely nothing accurate beyond this time frame.
The highly unusual patterns this Autumn/ winter is likely a big factor- it may be more difficult than usual for the models to accurately plot changes. Also means we shouldn't take as correct any model output which suggests mild just because that's what's often happened before.
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. The winter was not long past a solar maximum for example - but then again, we're not yet on the right side of the minimum for any significantly different forcing to be expected (based on current literature, anyway).
. Best I can say is that the QBO shouldn't be an obstacle like it was during the last one! 
E.N.S.O. Discussion
in Spring Weather Discussion
Posted
Probably. We may even be there next month, but any warming pulses would delay that.