1. SIX INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES 2006 IWTC-VI SAN JOSE, COSTA RICA NOVEMBER 2006 TOPIC 0.1 QUANTITATIVE FORECASTS OF TROPICAL CYCLONES LANDFALL IN RELATION TO AN EFFECTIVE WARNING SYSTEM: TRACK FORECASTS LIXION A. AVILA RSMC MIAMI

2. SIX INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES 2006 IWTC-VI SAN JOSE, COSTA RICA NOVEMBER 2006 TOPIC 0.1 WORKING GROUP: PHILLIPE CAROFF, JEFF CALLAGHAN, JAMES FRANKLIN and MARK DeMARIA

4. Average track forecast errors (nm) for the 1 to 5 day period before landfall (2001-2005)

8. Average Lead Time of NHC Hurricane Warnings By Decade

9. Katrina Track Forecasts 1200 UTC 24 August

10. Katrina Track Forecasts 0000 UTC 27 August

11. Rita Track Forecasts 1200 UTC 21 September Severe left bias in track models

12. Rita Track Forecasts 1200 UTC 22 September Remarkable improvement in track guidance: Likely the impact of surveillance data from the NOAA G-IV jet?

13. Ophelia Track Forecasts (nightmare) 1200 UTC 9 September

14. Wilma Track Models 10/21/05 18z Navy GFDL 72 h NCEP GFDL 72 h U.K. Met. Office 72 h GFS 72 h NOGAPS 72 h Verifying position 10/24/05 18z

15. Excellent example of GUNA consensus: HURRICANE ISABEL, 1200 UTC 11 SEP 2003

16. Not-so-excellent example of GUNA consensus: HURRICANE KATE, 1800 UTC 29 SEP 2003 This is a case where forming a selective consensus can be effective. Not-so-excellent example of GUNA consensus: HURRICANE KATE, 1800 UTC 29 SEP 2003 This is a case where forming a selective consensus can be effective.

17. New Tropical Cyclone Wind Speed Probability Products from NHC Richard Knabb, Chris Landsea, Edward Rappaport, Michelle Mainelli, Chris Lauer, Alison Krautkramer, James Franklin, and Jamie Rhome National Hurricane Center Scott Kiser and Tim Schott - NWS Headquarters Mark DeMaria – NESDIS and John Knaff - CIRA June 2006

18. Existing TPC/NHC Products Used to Convey Uncertainty Watch/ Warning Graphic Indicates forecast track and long-term mean error

19. Need for improved means of conveying tropical cyclone forecast uncertainty to various types of users –New product is about a weather event at any specific location –Conveys chances of wind speeds of at least particular thresholds 34 kt (tropical storm force) 50 kt 64 kt (hurricane force) –Accounts for combined uncertainty in track, intensity, and size –Extends to 5 days –Includes inland locations –Replaced strike probabilities in 2006 Why a new probability product?

20. Challenges and Ongoing Work Significant training and outreach needed –Lessen the focus on exact track forecast –Do users understand probabilities? –Getting familiar with the probability values –Small probabilities of an extreme event Enhancements to graphical products –Faster creation of grids, and the graphics created from them Objective guidance for watch/warning breakpoints Eventual use by NWS forecast offices in their products Verification Gridded products for NDFD

21. Discussion