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Probabilistic and Ensemble Surge Modeling at NOAA/NWS

Probabilistic and Ensemble Surge Modeling at NOAA/NWS. NOAA-USACE Coastal R&D Workshop 5/5/2011 Arthur Taylor – NOAA/NWS. Forecast Uncertainty. Ensemble Products. Where we are today P-Surge P robabilistic Storm Surge Response (<48 hr of landfall) MEOW M aximum E nvelope O f W ater

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Probabilistic and Ensemble Surge Modeling at NOAA/NWS

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  1. Probabilistic and Ensemble Surge Modeling at NOAA/NWS NOAA-USACE Coastal R&D Workshop 5/5/2011 Arthur Taylor – NOAA/NWS

  2. Forecast Uncertainty

  3. Ensemble Products Where we are today • P-Surge • Probabilistic Storm Surge • Response (<48 hr of landfall) • MEOW • Maximum Envelope Of Water • Readiness (48hr – 120 hr of landfall) • MOM • Maximum Of the MEOWs • Planning / Mitigation (>120 hr of lanfall)

  4. Climatological Products Potential Surge • P-Surge • Probabilistic Storm Surge • Response (<48 hr of landfall) • MEOW • Maximum Envelope Of Water • Readiness (48hr – 120 hr of landfall) • MOM • Maximum Of the MEOWs • Planning / Mitigation (>120 hr of lanfall)

  5. Maximum Envelope Of Water • User selects: • Category (Cat 3) • Landfall direction (wnw) • Forward speed (15 mph) • Initial tide (High)

  6. MOM: Maximum Of MEOWs • User selects: • Category (Cat 3)

  7. Forecast Products • P-Surge • Probabilistic Storm Surge • Response (<48 hr of landfall) • MEOW • Maximum Envelope Of Water • Readiness (48hr – 120 hr of landfall) • MOM • Maximum Of the MEOWs • Planning / Mitigation (>120 hr of lanfall)

  8. Hurricane Ivan: A case study

  9. Katrina Advisory 23

  10. P-surge - Vary Cross Track

  11. P-Surge – Vary Other Variables • Size: Small (30%), Medium (40%), Large (30%) • Forward Speed: Fast (30%), Medium (40%), Slow (30%) • Intensity: Strong (30%), Medium (40%), Weak (30%)

  12. P-surge Error Distributions • Error distributions are computed for cross track, along track and intensity by: • Assuming a normal distribution • Using a 5-year “mean absolute error” and getting the standard deviation (sigma) from:

  13. Probability of >= 5 feet of Surge

  14. Surge Height Exceeded by 10% of Ensemble Members

  15. Current Status Summary • MEOW/MOM • Climatological Potential Surge • Take maximum of ensemble members • P-surge • Weights based on representative storms (not a random sampling) • Varies cross track, along track, intensity and size • Based on 5-year error statistics • P-surge Planned Improvements: • Above Ground Level vs Above Datum • Provide timing information • Couple Tides

  16. Future Probabilistic Surge • Couple to wind ensembles • Tropical – HFIP/HWRF ensemble members • Tropical – p-wind ensemble members • Extratropical – GFS ensemble members • Multiple storm surge models • Extratropical – ESTOFS (ADCIRC) & ETSS (SLOSH) • Extratropical – Others • Couple to other wind forecasts • Tropical – Spaghetti plots • Extratropical – NDFD, NAM, etc.

  17. Pro’s and Con’s of:Future Probabilistic Surge • Pro: • Moves away from 5 year average errors • Ensemble members tied more closely to the current storm • A larger variety of models (both wind and surge) should create a better spread • Con: • How do we assign weights? • How do we maintain multiple surge models? • Hard to calibrate / validate reliability • Computation resource constraints

  18. Probabilistic MEOW/MOM? • Is there a way to assign probabilities to the MEOW/MOM ensemble members? • How do we get probabilistic products for 48-hr to 120-hr before landfall? • Should we derive • Exceedance MEOW/MOMs? • Duration Information?

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