Wind Forecasting to Win Races on the San Francisco Bay

Talk given my Mike Dvorak, the founder of Sail Tactics, to the St. Francis Yacht Club's Wednesday Luncheon series on Wed, Aug 13, 2014.

1. Wind Forecasting to Win Races on the San Francisco Bay St. Francis YC Wed Yachting Luncheon August 13, 2014 Mike Dvorak, PhD Sailor’s Energy Sail Tactics Vallejo, California
2. Talk Overview •From wind power to sailing forecasts •Wind forecast accuracy •SailTactics.com, as accurate as possible •Winning forecast examples •Future of wind forecasts in the SF Bay
3. Wind Power  Sailing Forecasts 3 ~20km Simulation of turbulent downslope winds at the National Wind Technology Center, Boulder, CO
4. California Offshore Wind Energy Study: North Side Out the Gate Favored Wind Speed Source: Dvorak, M. J., Archer, C. L., and Jacobson, M. Z., (2010). California offshore wind energy potential. Renewable Energy. Funnel flow at the GG Bridge: • Northside flow additive • Southside flow subtracts Better Wind Good Wind Of course tidal currents are also a consideration
5. Summertime Flow Just Offshore: 12:00 pm
6. Summertime Flow Just Offshore: 1:00 pm
7. Summertime Flow Just Offshore: 2:00 pm
8. North Side Favored, Not Always Typical Summertime Flow 2012 Pac Cup, Day 2 Starts Use good mirco/mesoscale models so you don’t get stuck Reanalysis from the 2012 Pac Cup, SailTactics.com high-resolution model
9. Errors in Wind Power Forecasting 9 Forecast length (minutes) Forecast Error (% of wind farm) Adopted from Ahlstom, et al., 2013 and WEPROG Persistence best: You don’t need a strategist to tell you which way the wind blows… Physics based model (e.g. Sail Tactics) best: 40 minutes plus Stochastic + machine learning best: 10-40 minutes
10. Accurate Sailing-Wind Forecasting • Physics-based weather models are necessary beyond 40 minutes • Forecast error increases over time, i.e. yesterday’s forecast is less accurate than today’s • Having the newest forecast gives strategic advantage (but Rule 41…) 10 What we learned from wind power forecasting:
11. Accurate Sailing-Wind Forecasting What we different do at SailTactics.com: • Create fresh forecasts every morning to improve accuracy • Use supercomputing to deliver just-in-time forecasts • Make beautiful maps that captivate the sailor’s mind 11
12. What 200-meter Resolution Gets You 12 Imagery produced by VAPOR (www.vapor.ucar.edu), a product of CISL at NCAR Angel Island Marin Headlands San Francisco Treasure Island Berkeley Oakland Tiburon Pacific Ocean Richmond
13. Typical summer sea breeze conditions 13 Angel Island Marin Headlands San Francisco Treasure Island Berkeley Oakland Tiburon Pacific Ocean
14. Typical Forecast Accuracy: 2014-03-23 14 Forecast Berkeley Yacht Club Forecast NOAA Richmond RMSE=1.40 ms-1 RMSE=3.06 ms-1
15. Atypical Forecast Accuracy: 2014-05-31 15 Forecast Berkeley Yacht Club Forecast NOAA Richmond RMSE=1.28 ms-1 RMSE=1.10 ms-1
16. Marine Boundary Layer 16 Observation 1000-m resolution domain Forecast model is resolving MBL which is critical for SF Bay flows 1000-m resolution domain 12 hours after init. (0Z sounding)
17. Golden Gate Bridge Sounding • Forecast 200-m domain from Jun 20, 2014 • Strong 13 K inversion • ~250 m height • Coastal range ~300-500 m • Forces flow thru Golden Gate • Moist, fog forming sea air present 17
18. Winning Races with SailTactics.com •Taking advantage of big wind shifts (Ragtime, J/90) •Carrying the right sails (Bodacious+, 1D48) •Finding the breeze during the winter (Sea Breeze, Cal 39-2) 18
19. SailTactics.com Winner 2014 Great Vallejo Taking advantage of wind shifts "We studied your forecast and kept to the right of the fleet to take advantage of the shift to the right expected to take place around 2:30 PM. And the shift of almost 90 degrees happened a few minutes after 2:30 PM as you had predicted, and we passed all boats in our class and about half of the entire fleet.“ -Trig Liljestrand, Skipper, J/90 Ragtime 19 Photo credit: norcalsailing.com
20. 2014 Great Vallejo - Ragtime 20
21. 2014 Great Vallejo - Ragtime 21
22. 2014 Great Vallejo - Ragtime 22
23. 2014 Great Vallejo - Ragtime 23
24. SailTactics.com Winner 2014 YRA 2nd Half Opener Carrying the right sails "The Sail Tactics wind forecast …was very helpful, and contributed significantly to our win of that event. As the forecast indicated, the wind was light at our East Bay start and built significantly in the Central Bay. We carried the #1 jib with a flattener on the main through the brief heavy winds, expecting from the forecast, that the winds would be lighter outside of the bridge – thereby eliminating two costly jib changes." -John Clauser, Skipper, 1D48 Bodacious+ 24 Photo credit: Bodacious+ Facebook page
25. 2014-2nd Half Opener – Bodacious+ 25
26. Wintertime Offshore Flow • Light, northerly winds • Land breeze • Cool Central Valley • Warm ocean • Often counteracted by a late arriving sea breeze 26
27. SailTactics.com Win – Berkeley YC Chowder Sailing the Stormy Streaks 27
28. Model Can Predict the Streaks Found +4 knots near Berkeley Pier Rest of fleet, DDW in light winds from OLY-D Sea Star took the longer route with more pressure Won the race by knowing where to look for pressure
29. Weather Routing with Wind (and Tide) GRIBs 2014 Spinnaker Cup routing (wind GRIBs) 2014 Three Bridge Fiasco Stephan Sonnenschein found winning course (wind + tide GRIBs) stephan_sonnenschein@me.com
30. Sail Tactics TV – Public Displays 30 Displayed at: Modern Sailing Berkeley YC Vallejo YC Display in the bar at the Vallejo YC
31. Conclusions • Wind power forecasting  better sailing forecasts • Created a 200-m resolution forecasting system for SF Bay • Created a responsive website and mapping backend at SailTactics.com • SailTactics.com subscribers  1st place in every major race of 2014 in the SF Bay 31
32. Thanks! Questions? Mike Dvorak mike@sailorsenergy.com Sailor’s Energy Sail Tactics Sea Star finishing a race at the Berkeley Marina Photo credit: Sharon Hind-Smith View example forecasts at SailTacitcs.com