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Singularity

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Singularity last won the day on September 14 2018

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About Singularity

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    MSc Meteorology

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    New Forest (Western)
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    Meteorology - Science and Observations | Cycling - On and Off Road | Walking or Hiking | Electronic Music Creation
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    The Extremes! Passionate Hater of Drizzle.

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  1. For whatever reason, GFS is making quite a bit more of the eastern LP in the N Atlantic on D6 than any of ECM, UKMO, JMA, GEM and ICON. So, it’s the only one that diverts the northerly flow away from the UK for D6+. Go figure
  2. A Nina-like atmospheric state with a poorly organised tropospheric polar vortex (despite the stratospheric one being much more so) can facilitate some nice 'tall' mid-Atlantic ridges in Oct-Nov, maybe early Dec. Not sure how much longer the trop. vortex will really be able to stay so disorganised, though. Anomalously large Arctic heat + moisture fluxes are a wildcard, as usual in these times of huge sea ice deficits. Regardless, I expect we'll have a few 'toppler' scenarios to ponder over in the coming weeks. Going to be tough for low levels to get much wintry weather out of such things, though. It's not going to help sanity levels that the FV3 core of GFS still seems to have a bit of a cold bias with troposphere temps.
  3. Great read, thanks for sharing. It's funny really, how our official measurements are of conditions that most of us don't experience very often, but of course the point of it is to capture the weather in its 'rawest' form with the least possible modification by humans (excepting the large-scale effects of added CO2 etc). This does mean, though, that there's some value to those unofficial readings from a 'what most of us experience' perspective, provided they're not taken in direct sunlight. Hence I find sites that display those to be of some use when gauging what to expect when heading away from home for a day trip.
  4. Thanks for the blog compliment @Geordiesnow . Good update, definitely worth the double-post - there's a lot of thin, fragmented ice drifting around with the winds. Every time I look around with WorldView, the poor visual state of so much of the ice leaves me feeling a bit unwell. The minimums for extent and to a lesser degree area will be largely down to chance; however the various highs and lows happen to move around during the next fortnight. The central HP cell currently looks short-lived, but the models haven't been doing a great job since the decay of the major blocking regime that dominated the summer, so who knows how long it might actually stick around for. During the refreeze, I gather high pressure is best to have around for the first few months to facilitate a quick initial freeze, after which low pressure is preferable to provide a thick layer of snow cover to protect the ice during the following Apr-Jun. I'm not 100% on this, though!
  5. The 06z on the right has the Atlantic trough more positively tilted again, which cuts of the NE flow sooner. The modelling of this has been pretty poor. The way ECM has gone from the warmest to coolest end of the solutions for Tue-Thu is quite amusing, in a sad sort of way. Just imagine the dramatics that would be occurring if it was January and we were looking for a bitterly cold feed from the northeast!
  6. I've not been able to find any significant correlations with the CET in the UK or 500 hPa height patterns in the eastern N. Atlantic to western Eurasia sector. However, there aren't many past examples of such extreme anomalous warmth covering such a vast swathe of the North Pacific to work with. BUT this does mean we can't be sure that it'll drive a +NAO this winter, even if it is one of the only at all plausible explanations for the DJF updates from the GloSea5 and ECMWF long-range modelling. It'd be just typical though, if it screwed us over when so much else was looking favourable. Using my own past propagation analysis for the QBO, we may even have that in a negative (easterly) state by mid-January, with a bit of luck.
  7. As explained here, the volume situation far outweighs the extent/area one - and it troubles me greatly. Generally, the lower the volume, the more vulnerable the ice is to whatever the weather patterns decide to get up to. Also, not covered in this blog piece (I try to keep them from becoming too complicated), the huge amount of dispersion that has taken place in recent weeks may cause additional trouble. This being if, as I have seen speculated but without much hard evidence (it's difficult to acquire - not enough buoys for starters!), the thin sea ice acts to trap additional heat in the Arctic Ocean by keeping turbulent mixing to a minimum. The ice may also block some radiation of heat into the atmosphere, but I imagine this tends to be insignificant until it starts thickening appreciably Oct-Nov. Given that 2019 has seen an unprecedented (or close to it) amount of oceanic heat uptake due to the exceptional amount of open water during May-July, I'm concerned that the stored heat may restrain the refreeze as much as we saw during the miserable 2016-17 refreeze season. That'd leave the Arctic in need of a summer as extraordinarily kind to the sea ice as 2017's was.
  8. Good response by Jules. Essentially, being a vast, consistently cold and frozen landmass entirely surrounded by gently varying oceans is a far better for your stability than being a smaller, inconsistently frozen ocean flanked on two sides by strongly, rapidly varying landmasses.
  9. We know how much the models struggle with our N. Hemisphere SSWs... so I don't hold out much hope for them resolving the outcome of the much, much rarer S. Hemisphere equivalent. Not sure it's technically a SSW by wind stats yet though; wind still not to -10 m/s at 60*N. Then again, this definition may not be appropriate given the markedly different climatology there.
  10. The cut-off low remains an issue to resolve details-wise. GFS continues to make it a very clean affair, while ECM persists with a slight connection to the polar jet being maintained. The 850s from ECM for this day seem extraordinary for mid-September. Has the 17*C isotherm ever visited the UK this late in the year before? Maybe it did so even later, in 2011? Further into next week, and GFS is still doing the same overall thing as the previous 12z from the model really - just with a trademark adjustment east (so many snowy winter northerlies lost this way...). Some distinctly fresh air still gets wrapped around to bring some cool nights and days falling short of the 20*C mark for most locations next Tue-Thu. Meanwhile ECM continues to keep a weak chain of lower heights in play to the NW and N of the UK, preventing the ridge from building much north of the UK such that we're left basking in stagnating air of mostly tropical maritime air. Could potentially be some issues with low cloud or fog if you're seeking particularly high daytime temps, though. Longer term, continued suggestions of a secondary surge of warmth somewhere in the range of 8-12 days from now by both models. September could prove to be one heck of a two-halves sort of month.
  11. Sometimes cut-off lows can produce some of the wackiest weather patterns at short notice, if the upstream pattern remains amplified. You can really see here, knowing how differently GFS and ECM unfold thereafter, how even the slightest continued connection to the polar jet (the 'nose' formed by the 1020 mb line to the WNW of the UK in the ECM chart) is able to prevent the high pressure across the UK from retrograding to the W/NW of the UK. We've seen that kind of residual connection deny us many a potential wintry northerly in the cold season. For what it's worth, ICON 12z is close to the UKMO 12z, while GEM sits between UKMO and ECM. GEFS and EPS continue to favour the UKMO/ICON 12z or GEM/ECM 12z style outcomes. Even so, I'm keeping an open mind to the cut-off low potential; not going to sit here naively presuming that it will be pleasantly warm during my week off... .
  12. Nice to see some lengthy spells under strong high pressure on offer from GFS. It feels like it's been absolutely ages since we last had one of those! Remains to be seen how far north the high sets up. The ECM 12z offers a near-optimum outcome for very warm days, but GFS 12z takes the high too far north for much of an import of warm air - which we increasingly rely upon in mid-late Sep to lift the temperatures much above the long-term average.
  13. Signs that after a surge of westerlies next week, some strong subtropical ridge amplification through the UK and/or NW Europe may occur, with the big surge of tropical maritime air wrapped up in its circulation. If that happens, it'll be comparable to how the big July hot spell got underway. Not with the extremely high temp potential this time of course! Unless, perhaps, you focus on difference to the average and the ridge drifts only slowly to the east of us - but that's some equally extreme speculation. Basically, the ingredients are there for summer to make a comeback starting around the midpoint of the month. To what extent and for how long is anyone's guess, but IMO it would be surprising not to see at least some appreciable increase in temp maximums (can't be so sure about minimums... if winds stay light under clear skies, the lengthening nights will make themselves felt).
  14. http://mikeventrice.weebly.com/hovmollers.html The discrepancy grows larger still. GFS now predicts a decent strength of Nino walker cell configuration with enhanced rising motion over the Central Pacific, yet it shows no classical response to this over the N. Atlantic and Europe. Well, the 06z briefly tried but that rapidly fell down and the 12z hasn't even given the Euro height rises a go to begin with. Meanwhile, the 00z ECM shows exactly the sort of pattern shift that I'd expect in the D8-D10 range... if it wasn't for a lot of tropical activity taking shape in the N. Atlantic. This inevitably lowers confidence. Either this is an impressive spot of an unusual pattern development relating to Atlantic basin tropical activity, or GFS is making a right mess of how they influence the planetary waves. Going to be really interesting to see which way things go.
  15. Judging by this, a boost to dateline convection ought to encourage some subtropical ridge extension through NW Europe & the UK by 10 days from now, which makes the 12z ECM look a lot more sensible than the 12z FV3. Not that this is saying much; the amount of ridge retraction (i.e. staying west of the Azores High) in the 12z FV3 is unfathomable (at least to me...).
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