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Interitus

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  1. Iver Water Works 33.9°C at the same time (3pm). The significance? Nobody has seemed to notice that data is available from this other site, but it is barely 3 miles from Heathrow weather station and shows the difference of being semi-rural vs next to carparks, runways and apron.
  2. Maybe not, the 06z GFS today has +ve 10mb winds til April 28th, then a few days weak reversal then weakly +ve again. Normal reversal by about April 12th, so much for the theory that it happens earlier in years without SSW lol.
  3. Mentioned this before, basically the strength of the vortex is related to the temperature gradient between the pole and the mid-latitudes, so simply put, pole colder than mid-lats = stronger vortex and vice versa. But interestingly, the 10mb zonal wind is more sensitive to temperature gradient at lower levels than at 10mb itself. Using the difference between the 80 and 50°N temperatures from MERRA reanalysis, over all days since 1979 the zonal wind correlation to 10mb temperature is 0.80, but with 30mb temperature it is 0.97 and 50mb it's 0.96. So while seeing a warming appearing at 10mb may hint at an SSW, a wind reversal at 10mb is unlikely if the warming doesn't progress to the 30mb level or below and reversing the temperature gradient there.
  4. Yes, exactly this. Corralling people indoors in typical temperature and humidity is the perfect environment for virus transmission. Whilst they survive best in the liquid droplets from coughs/sneezes, it seems slightly counterintuitive but coronaviruses survive drying for some time and remain viable. Being outdoors in the open air reduces chance of transmission and also solar UV quickly inactivates them. Number of papers written but for example see research on original SARS CoV - https://www.hindawi.com/journals/av/2011/734690/ SARS dried of plastic survived 5 days at 22-25°C 40-50% RH with only slight loss of infectivity. Seriously should be hoping for some decent weather to help with this but of course dependent on measures on social distancing and self-isolation which come into force.
  5. The action has been higher up, this chart shows GFS 1mb zonal wind from 8/3 when the forecast splits occurred, to 13/3 and actually wave 1 displacement has been indicated. For a number of days wind reversal stuck around the 240+ hr uncertainty range, but today's 00z and 06z brought it down to 231 and 201 hours respectfully - Doesn't look like having large effect at 10mb or below at the moment. edit: Incidentally, does anybody else find those temperature charts slightly distracting with the multiple colour scales and repeated whites?
  6. Nah, his tweets are high quality, but splits in particular depend on fairly specific tropospheric patterns which are typically modeled wrongly at the end of a 16-day forecast. Of course it's more than reasonable to highlight the possibilities, but time and again when people make these forecasts in this thread they're invariably incorrect, Maybe because splits are seen as a bit of a holy grail by cold lovers, it's certainly not popular when it is suggested that it is an unlikely outcome!
  7. Unfortunate that every time he links that paper on the back of a couple of GFS runs into far long range, the forecast promptly evaporates as quickly as it appeared! There's a lesson there....
  8. Not really, the northern extent of the Antarctic peninsula is exaggerated by its proximity to the Weddell sea which reaches much further south (though is frozen most of the time so is effectively 'land') there are parts of the eastern Antarctic which are also outside the Antarctic circle. Nothing to do with map projection, Marambio base on Seymour Island is at 64°14' S, nine degrees south of Cape Horn. The equal distance further south at 73° is well into much of the mainland. Marambio is also marginally closer to the South Pole than Nuuk / Godthab, the capital of Greenland is to the North Pole. Is Nuuk not part of Greenland proper? What also must be remembered is that the most extreme cold is at high altitude from sites such as Amundsen-Scott (South Pole) at 9300 feet or Vostok 11,400 feet. In that regard similar to Summit on Greenland at 10500 feet and, incidentally, just shy of 73°N. Whatever, Marambio is substantially colder than Nuuk, mean daily temperatures are below freezing all year round. The last fast ice round Seymour island retreated this year after mid-January, the equivalent of mid-July in the northern hemisphere would be well into the Arctic circle, and now at the end of summer ice floes still circle the island. As such, a temperature reading above 20 degrees is notable regardless of how the significance of a single Fohn event is viewed. However, the Antarctic peninsula has warmed, with the associated reduction and loss of ice shelves eg Prince Gustav, Larsen A etc. And it doesn't have to be representative of the whole continent to be the highest temperature recorded any more than the cooler parts of the UK were represented by Cambridge last year for example.
  9. The 19.8°C was from Signy Island. Seymour Island is only little over 40 miles from the Antarctic mainland, but further south than the tip of the Antarctic peninsula - so actually it's Antarctica which is closer to South America than Seymour Island, go figure.
  10. It should do, assuming the global model providing the boundary conditions performs accurately.
  11. The lack of any deep cold as opposed to surface inversions has meant that the high altitude sites of Aonach Mor and Cairngorm achieved their minima of -9.0 and -9.1°C on the morning of November 13th. The incessant wind probably helped too.
  12. It is because planetary waves are better able to propagate upwards in a 'properly' formed vortex with a typical structure and vertical wind profile than one that has previously weakened and recovers which may have layers of negative wind shear acting as a barrier to propagation.
  13. In December 2018 the polar ozone increased with the wave driving prior to the SSW but when this occurred at the start of January the ozone shot up to record levels for the time of year - https://ozonewatch.gsfc.nasa.gov/meteorology/figures/ozone/to3capn_2018_toms+omi+omps.pdf A paper currently in review (not yet published) examines the 2018/9 ozone season describes this, from the abstract - https://www.atmos-chem-phys-discuss.net/acp-2019-1093/ Incidentally, you are trying to find signs of the SSW in the average >80°N surface temperature?
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