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  1. The first few years of the NCEP data from 1948 are particularly ropey.
  2. Regarding ECM 850 temperatures - they are by and large not representing warm air advection but rather more dry air subsidence under the anticyclone - therefore the lapse rate is reduced and the surface temperatures are not as high as estimated (-see the ECM charts on weather.us as evidence - very warm or even hot but temperatures not widely into the 30s never mind record range)
  3. 30°C is hot but one thing it isn't with 12°C dew point is particularly humid. Always gets confused by people in this country who equate the two, oppressive humidity would see the same temperature with dew points maybe around 25°C.
  4. Too many +s and -s, they state stationary wavenumber 1 background state in the high latitudes. Not sure why GLAAM and GWO gets dragged into this.
  5. Sorry, the past two GFS runs represent a 'downgrade' with regards the BH weekend, markedly cooler and with the chance of being still slightly unsettled to begin with on the Saturday. Fine weather later is no good when everyone is back at work, though typical!
  6. Looking like an increasing chance of a reasonable BH weekend, but depending on the ridging or position of an anticyclone there is the risk of a cool easterly onshore flow off the North Sea for eastern parts, better further west (and also south with short sea crossing from warm continent). The chart below for Saturday 5th pretty much representative for Friday-Monday on today's GFS 06z -
  7. Quite remarkable, while not quite as extreme overall a quicker turn around occurred in 1866 when the mean CET for April 27th was a firmly summery 16.5°C and just two days later winter returned with a CET of 3.8°C
  8. Interesting, the ECM switches towards earlier GFS runs, while the GFS tends towards the previous ECM -
  9. The 12z GFS actually slightly worse than earlier, Saturday looking good for the southern half of the UK but the ridge isn't enough to prevent fronts progressing south on Sunday. Fine weather still in the minority in the ensembles, could easily go pear shaped looking at the spread -
  10. Both runs have troughing over the UK from the Bank Holiday Monday onwards, but it is the 06z which gives the better weekend by far til that point, temperatures 4 degrees warmer - 0z 6z The difference is because on the 0z the low pressure to the north west drives a cold front southwards over the UK on Friday into the near continent - here in the early hours of Saturday all the UK in cool PM air, with the increased ridging behind the front - whereas on the 6z the front weakens as it is draped across the UK and the cooler air heads more east-northeastwards. As a knock-on this allows a plume of warmth over the continent to be much closer to the UK instead of towards Russia -
  11. Yes, quite a change from the previous run None of GEFS members from same time show anything particularly similar.
  12. Interesting answer, however wavelength and amplitude are separate distinct wave characteristics
  13. Despite the coldest March 1st in the 247 years of the daily CET, and the 2nd coldest March 2nd and March 18th, the spring to April 11th at 5.69°C is only 0.3 degrees below the long term average of 5.99°C. This seems cold in the context of warming springs in recent years, however it is a full 2.65 degrees warmer than the same period just 5 years ago in 2013. 2006 and 1996 were cooler also whilst from the 1980s, of the four years 1984-7, 1985 was marginally warmer and the other three were colder than this year.
  14. Was going to post a v-wind anomaly Hovmoller chart to illustrate this, but that tweet is conveniently in response to this -
  15. For some time the GEFS have been predicting the summer wind reversal at the end of the runs for around 13th-15th April - but the GFS has only recently consistently come into agreement about a week away - The GEOS from the 4th however still has weak westerlies (~3 m/s) for the 13th. As posted previously, not a 'final warming' but gradual dissipation with the increasing insolation, as expected. Meanwhile, an interesting paper with regards to the effects of mountains has just been published, Orography and the Boreal Winter Stratosphere: The Importance of the Mongolian Mountains - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2018GL077098 - new so paywalled at the moment, but a pre-submission version is available here - https://atmos.washington.edu/~david/White_etal_GRL_submitted2.pdf
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