1. WMO Symposium Toulouse 2005 Wind Forecasting at Hong Kong International Airport S.Y. Lau Hong Kong Observatory

2. WMO Symposium Toulouse 2005 2 types of user requirements Air traffic controllers –Runway change – headwind/tailwind Dry – 10 kt, Wet – 5 kt Nowcasting – extension of monitoring network through the installation of weather buoys and LIDAR Airlines/pilots –Crosswind limit Wide body plane - 20 kt Usually of the order of 18 to 24 hours – statistical and probabilistic forecast

3. WMO Symposium Toulouse 2005 Strong crosswind due to Kompasu

4. WMO Symposium Toulouse 2005 Probability of 20 kt crosswind if the forecast track is perfect Probability isopleths 4 17

5. WMO Symposium Toulouse 2005 Track perturbation Statistical –Based on past (1999-2002) forecast position errors Dynamical –Based on NWP model spread from model ensemble –ECMWF, JMA, NCEP, UKMO, JMA Typhoon model, HKO ORSM

6. WMO Symposium Toulouse 2005 25 perturbed tracks within 85% the bivariate Gaussian distribution for position uncertainties 11 2 2 33 4 4 5 5 6 6 7 7 8 8 9 910 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

7. WMO Symposium Toulouse 2005 Track of Kompasu July 2004

8. WMO Symposium Toulouse 2005 statistical dynamical

9. WMO Symposium Toulouse 2005

10. WMO Symposium Toulouse 2005 User Interface

11. WMO Symposium Toulouse 2005

12. WMO Symposium Toulouse 2005 Limitations Probability isopleths not separated according to TC intensity Size of TC not taken into account Asymmetric structure of TC not taken into account Arrival/presence of northeast monsoon could result in earlier onset of high crosswind

13. WMO Symposium Toulouse 2005 Thank you

14. WMO Symposium Toulouse 2005 Tornado on 6 Sep 2004

15. WMO Symposium Toulouse 2005 extension of monitoring network Nowcasting

16. WMO Symposium Toulouse 2005 AWARE AWARE (Anemometer-based Windshear Alerting Rules – Enhanced) launched in mid-2004 Based on wind readings at 6 runway anemometers & TMT & 5 weather buoys Alerts out of ground truths TMT Weather buoys Runway anemometers Weather buoy

17. WMO Symposium Toulouse 2005 AWARE alert

18. WMO Symposium Toulouse 2005 Merits of AWARE… Enhanced detection of WS associated with:Enhanced detection of WS associated with: –Sea breeze –Gust front –Shear line

19. WMO Symposium Toulouse 2005 Nowcasting extension of monitoring network

20. WMO Symposium Toulouse 2005 Kompasu Hong Kong