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Met Office seasonal forecasting for winter 2010-11

Met Office seasonal forecasting for winter 2010-11. Jeff Knight (with thanks to many colleagues). The main event: December. December 2010. Snow at Land’s End. Courtesy of Mike Kendon (NCIC). Public execution of Charles 1 st 1649 (only 10 years before series starts). December 2010.

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Met Office seasonal forecasting for winter 2010-11

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  1. Met Office seasonal forecasting for winter 2010-11 Jeff Knight (with thanks to many colleagues)

  2. The main event: December

  3. December2010 Snow at Land’s End Courtesy of Mike Kendon (NCIC)

  4. Public execution of Charles 1st 1649 (only 10 years before series starts) December 2010 The coldest December since 1890 December 2010: Central England Temperature series 3 voyages of Captain Cook 1768 - 1779 Queen Victoria’s coronation 1838 World War 11914-1918 The second coldest December in a series from 1659 Courtesy of Mike Kendon (NCIC)

  5. UK Temperatures: recent winters

  6. 2009-10 and 2010-11 Christmas Eve 2010 Satellite Receiving Station, Dundee University 1150 GMT 7 January 2010Photo: NASA/GSFC, MODIS Rapid Response.

  7. Met Office Winter Forecast 2010-11

  8. DJF Met Office Seasonal Forecastfor UK Government Outlook for December 2010 – February 2011 For the period December 2010-February 2011, there is a 25% chance of mild conditions, a 30% chance of near-average and a 45% chance of cold conditions over northern Europe. For precipitation, there is a 25% chance of wet conditions, a 35% chance of near-average and a 40% chance of dry conditions over northern Europe.

  9. GloSea4 ‘November’ ensemble DJF GloSea4 L85

  10. Temperature terciles from Nov L85 GloSea (1996-2009 climate)

  11. Precipitation terciles from Nov(1996-2009 climatology) L85 GloSea (1996-2009 Climate)

  12. Nino3.4 plumes: GloSea4-EC-EUROSIP Charts courtesy of ECMWF

  13. Cluster analysisFereday et al. (2008), J. Climate • 6 two month seasons, 10 clusters per season • North Atlantic / Europe region • Clusters from observed 1850-2003 daily mean MSLP dataset • For 2004 onwards use NCEP reanalysis • Remove seasonal mean from NCEP MSLP • Assign each field to closest cluster

  14. ND 2010 cluster frequencies Highest number of days for ~100 and ~50 years respectively

  15. ND 2010 Clusters

  16. Oct-Nov North Atlantic SST October 2011 14-21 Nov 2011

  17. North Atlantic Sub-Surface temperature October May Rodwell and Folland (2002), Q. J. R. Meteorol. Soc.

  18. Quasi-Biennial Oscillation W phase of QBO → stronger polar vortex, less chance of a stratospheric warming event So perhaps switch to zonal at end of winter? This is also the signal from La Niña

  19. ‘Canonical’ JF La Niña clusters

  20. Later Forecasts

  21. JFM, FMA from preceding month JFM FMA D-J-F

  22. Stratosphere?

  23. JF 2011 cluster frequencies

  24. JF 2011 Clusters

  25. Worldwide

  26. La Niña Teleconnections • During La Niña the rainfall that normally falls out over the Pacific shifts west

  27. Global precipitation

  28. Queensland

  29. Conclusions • GloSea4 did a reasonable job in predicting the likelihood of a cold winter • In later forecasts, however, it wanted to retain the cold for too long • Consistency with EuroSIP and other models • Other factors such as La Niña, Atlantic SSTs and the QBO were considered alongside models • Potential additional influences were the continuing low solar activity (Ineson et al., 2011), low sea-ice, ...

  30. Advertisement For various long-range forecasts including decadal global temperature forecasts and seasonal tropical storm forecasts: http://www.metoffice.gov.uk/science/specialist/long-range For the seasonal probability maps, ENSO forecast and skill scores: http://www.metoffice.gov.uk/science/specialist/seasonal

  31. Questions and answers

  32. Title

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