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Grupo de Meteorologia e Climatologia na Universidade de Aveiro climetua.fis.ua.pt

Predictability of Extreme Weather Events. Alfredo Rocha, Tiago Luna, Juan Ferreira, Ana Carvalho and João Sousa 05-07-10. Grupo de Meteorologia e Climatologia na Universidade de Aveiro http://climetua.fis.ua.pt. Departamento de Física.

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Grupo de Meteorologia e Climatologia na Universidade de Aveiro climetua.fis.ua.pt

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  1. Predictability of Extreme Weather Events Alfredo Rocha, Tiago Luna, Juan Ferreira, Ana Carvalho and João Sousa 05-07-10 Grupo de Meteorologia e Climatologia na Universidade de Aveiro http://climetua.fis.ua.pt Departamento de Física

  2. Some research centres do research in meteorology (i.e. weather forecasting) and climate. • This effort should produce added value to better forecast of extreme events (amongst others) as a public service. • This requires strong and well defined colaboration between Universities and State Laboratories. • It is also needed more critical mass of high quality in meteorology/climate research. Model validation Ensemble forecasting Forecast verification Data assimilation Major tasks which require collaboration

  3. How can research (at Unis and RUs) contribute to better prediction of Extreme Weather Events 3 case-studies: • Flash floods and land slides in Madeira on the 20th February 2010 • Wind storm in the Torres Vedras region on the 23rd December 2009 • Precipitation event in the Lisbon/Setúbal region on the 18th February 2008 These events have not been (fully) predicted by operational weather forecast institutions

  4. 1. Extreme precipitation event - Madeira – 20th February 2010 Questions: 1. Was the event predictable? 2. If yes: How long before? With maxima correct? Without phase error? 3. Origin: Synoptic or ographic? 5. Relevance of model horizontal resolution and parametrizations?

  5. The cause of the catastrophe was not just meteorological • There have been similar precipitation amounts in the past without catastrophe Model WRF-ARW 3.1 Initial and Boundary conditions Forecasts (3h-3h) and Analyses (6h-6h) from GFS 0.5ºx0.5º

  6. D1 – 25 x 25 km D2 – 5 x 5 km D1 – 25 x 25 km D2 – 5 x 5 km D3 – 1 x 1 km Simulations with Weather Research and Forecasting (WRF) model D1 – 25 x 25 km D2 – 5 x 5 km operational

  7. Madeira ‘as seen’ by WRF 1 km horizontal resolution zmax ~ 270 m – A model is always a model! IM stations with hourly prcp data

  8. Were ICs and BCs (GFS forecasts) good? Diference (%) of 3-D integrated precipitable water GFS forecasts and GFS Analyses ‘Break’ of predictability? Some predictability at 3 days?

  9. Accumulated Prcp (mm/day), on the 20.02, D03 – 1 x 1 km ICs - 00h 20.02.2010 Similar maxima for 5 x 5 km Topography determinant

  10. ICs 00h 20.02 Average PRCP (mm/day) - south coast 2-3 h Phase errors

  11. Local PRCP run 7 (D03) / IM (without cumulus parametrization) ICs 00h 20.02 Phase and amplitude +/-correct!

  12. 12h 2d 24h 36h 5d 3d 4d 7d 6d

  13. 60 50 40 30 20 10 0 0 Obs - IM PRCP (mm/h) - Funchal ICs from 12h of 13.02 (7 days) till 06h of 19.02 (1 day) Daily amounts +/- OK, but intensity wrong!

  14. Conclusions: • Some predictability from 3 days. ICs e BCs (GFS forecasts) are determinant • Precipitation of orographic origin • Horizontal resolution not important for regional PRCP but important for local PRCP • Local PRCP +/- correct (phase and amplitude) only for ICs 12h prior to the event • Cumulus parametrization not important

  15. 2. Wind storm in the Torres Vedras region on the 23rd December 2009 • Max wind gust at IM Stations: • Torres Vedras – 141.8 km/h – 4:40 am • Cabo Carvoeiro – 140.4 km/h – 4:50 am Max wind gust estimated by IM using Doppler Radar: ~ 200 km/h propagating SW to NE

  16. Simulations with WRF: 1 x 1 km horizontal resolution 25 to 85 vertical levels ICs 00h 22.12.2009 Parametrization of wind gusts (ECMWF Newsletter, 119, Spring 2009, 15-18). Operational at WCMWF since Sep. 2008. Total gust = turbulent gust + convective gust Applied to WRF output

  17. X X X X Max. (WRF) inst. Windspeed 00h-06h Max. Turbulent wind gust 00h-06h m/s Max ~70 km/h

  18. Max. Convective wind gust 00h-06h Max. Total wind gust 00h-06h m/s Max ~20 km/h Max >160 km/h

  19. 3. Precipitation event in the Lisbon/Setúbal region on the 18th February 2008 • 118 mm/day - Record daily PRCP at Lisboa/Geofísico • 36 mm/h 4 - 5 am in Lisbon • 40 mm/h 11 – 12 am in Setúbal

  20. Observations

  21. 5 WRF simulations • Two WRF operational spatial configurations/resolution OP1 and OP2 • Two different sets of parametrizations • Assimilation of radiosonde and surface data for one domain/param. configuration

  22. OP1 L (d01) = 25 kmL (d02) = 5 km Vertical levels = 27 OP2 L (d01)= 21 km L (d02) = 7 km Vertical levels = 26

  23. WRF Set 1 – PRCP 05-06 UTC

  24. WRF Set 2 – PRCP 05-06 UTC

  25. WRF Set 1 + Assim. – PRCP 05-06 UTC…..not good!

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