Real Time Storm Surge Guidance: Past and Future Jason G. Fleming Rick Luettich University of North Carolina Institute of Marine Sciences April 20, 2009

The Team University of North Carolina: Rick Luettich, Jason Fleming, Janelle Fleming, Rob Weaver, Crystal Fulcher University of North Carolina: Rick Luettich, Jason Fleming, Janelle Fleming, Rob Weaver, Crystal Fulcher Louisiana State University: Robert Twilley Louisiana State University: Robert Twilley University of Notre Dame: Joannes Westerink University of Notre Dame: Joannes Westerink Corps: Nancy Powell and the Emergency Operations Center Corps: Nancy Powell and the Emergency Operations Center

Original Surge Guidance Motivation in 2006 Project pursued in aftermath of Katrina Project pursued in aftermath of Katrina More accurate and detailed guidance sought for storm surge More accurate and detailed guidance sought for storm surge Guidance needed in real time, updated as storm approached, focus on canal gates Guidance needed in real time, updated as storm approached, focus on canal gates Result: Lake Pontchartrain Forecast System Result: Lake Pontchartrain Forecast System

Gated Structures

Original LPFS in a Nutshell Autonomous software using ADCIRC Autonomous software using ADCIRC Text advisories from NOAA to drive embedded Holland model Text advisories from NOAA to drive embedded Holland model Consensus track and static ensemble Consensus track and static ensemble Mesh bathymetry acquired from previous projects with the Corps Mesh bathymetry acquired from previous projects with the Corps Compute resources from LSU and Corps Compute resources from LSU and Corps Automated graphical output Automated graphical output

The Original (2006) Grid

Track Uncertainty

Static Ensemble Members 1. NHC Consensus storm, 5 day forecast 1. NHC Consensus storm, 5 day forecast 2. Storm with 20% higher wind speed 2. Storm with 20% higher wind speed 3. Storm with 20% slower forward speed 3. Storm with 20% slower forward speed 4. Storm that veers along right of cone of uncertainty 4. Storm that veers along right of cone of uncertainty 5. Storm that veers along left of cone of uncertainty 5. Storm that veers along left of cone of uncertainty

Lessons Learned 2006 Reliability through redundancy Reliability through redundancy Redundant Computing Resources Redundant Computing Resources –Priority access guaranteed only at ERDC –LSU computers used as backup –UNC resources used as tertiary backup Redundant Communications Redundant Communications –Mirrored results at 4 websites –Enhanced notification s to include advisory numbers and log file

2007 System Enhancements Multi-machine development at LSU Multi-machine development at LSU Added hotstart capability Added hotstart capability Generalized system for portability and redundancy Generalized system for portability and redundancy

Coldstart system

Hotstart System

2007 Season Relatively Quiet LPFS provided surge forecasts to the Corps for 2 storms LPFS provided surge forecasts to the Corps for 2 storms –Hurricane Dean –Tropical Depression 10 Surge forecasts delivered within minutes after hurricane advisories Surge forecasts delivered within minutes after hurricane advisories All forecasts in 2007 were for minimal surge All forecasts in 2007 were for minimal surge

2008 Season Enhancements Leverage FEMA work for expansion to West Bank of Mississippi River (larger grid)‏ Leverage FEMA work for expansion to West Bank of Mississippi River (larger grid)‏ Improved wind model to estimate central pressure in forecast Improved wind model to estimate central pressure in forecast Google Earth contours of High Water Marks Google Earth contours of High Water Marks Latest version of ADCIRC (time-varying tau0 and globalio)‏ Latest version of ADCIRC (time-varying tau0 and globalio)‏

Enhanced 2008 Grid

2008 Grid: Chandelier Islands

2008 Season Retrospective

2008 Gulf Coast Storms Dolly, Edouard, Fay, Gustav, Ike Dolly, Edouard, Fay, Gustav, Ike Guidance output provided from the LPFS to the Corps for each storm Guidance output provided from the LPFS to the Corps for each storm –Dolly: 15 Advisories –Edouard: 8 Advisories –Fay: 35 Advisories –Gustav: 11 Advisories (Extended Coverage)‏ –Ike: (Extended Coverage)‏

2008 Lessons Learned Very active season Very active season Broadest participation in the surge guidance process to date Broadest participation in the surge guidance process to date True stress test of surge guidance system True stress test of surge guidance system

2008 Season Lesson: Outages Machine failures common during storms Machine failures common during storms Changing grids or increasing processors mid-season may expose bugs not observed in off-season Changing grids or increasing processors mid-season may expose bugs not observed in off-season Must peform off-season testing with exact in-season configuration Must peform off-season testing with exact in-season configuration

2008 Season Lesson: Spatial Coverage Season began with sl15light grid Season began with sl15light grid –Lake Pontchartrain and West Bank –“Only” 770k nodes Wandering storm tracks pointed to need for wider spatial coverage (all of S. LA)‏ Wandering storm tracks pointed to need for wider spatial coverage (all of S. LA)‏ sl15 grid (2.2M nodes) employed for Gustav/Ike (processing power)‏ sl15 grid (2.2M nodes) employed for Gustav/Ike (processing power)‏

2008 Season Lesson: Temporal Coverage Corps interested in storm surge before official forecast is issued Corps interested in storm surge before official forecast is issued Emergency responders interested in hindcasts in immediate aftermath Emergency responders interested in hindcasts in immediate aftermath –areas of likely inundation –property damage assessments for aid estimates

2008 Season Lesson: Accuracy Symmetric vortex model does not use all information in advisory Symmetric vortex model does not use all information in advisory Asymmetric vortex model is more accurate Asymmetric vortex model is more accurate Far field winds may be more important than previously thought Far field winds may be more important than previously thought

2008 Season Lesson: Ensemble Static ensemble of 5 storms is too generic Static ensemble of 5 storms is too generic –right and left edges of cone may not be within area of interest –does not take into account variations in RMW –ignores tracks that coincide with particularly vulnerable areas (under construction, etc)‏ Need a dynamically variable ensemble Need a dynamically variable ensemble

2009 Changes and Enhancements ReliabilityFlexibilityCoverageTimelinessAccuracy

Reliability Limit the number of in-season changes Limit the number of in-season changes  in-season changes make rigorous testing more difficult  LPFS2009 will be more flexible reducing the need for late changes Implement structured testing Implement structured testing  run more forecasts in test mode  test mode carefully designed to cover all possible situations

Flexibility ADCIRC input files more easily swapped ADCIRC input files more easily swapped Number and character of storms in ensemble may be dynamically modified, advisory-by-advisory Number and character of storms in ensemble may be dynamically modified, advisory-by-advisory Number and location of output stations dynamically modifiable Number and location of output stations dynamically modifiable

Coverage Geography: full Louisiana coastline Geography: full Louisiana coastline Early stages: cover pre-official forecast period Early stages: cover pre-official forecast period Late stages: advise after landfall for emergency responders Late stages: advise after landfall for emergency responders

Timeliness Fast turnaround of results will require greater processing power Fast turnaround of results will require greater processing power 640 CPUs on Sapphire produced a result in 1 hour (per storm, sl15 light, 5 day fcst)‏ 640 CPUs on Sapphire produced a result in 1 hour (per storm, sl15 light, 5 day fcst)‏ Therefore, 3-storm ensemble will require 1920 CPUs to produce results in one hour on sl15light grid... Therefore, 3-storm ensemble will require 1920 CPUs to produce results in one hour on sl15light grid...

Accuracy Pleased with the accuracy of our surge guidance in 2008 season Pleased with the accuracy of our surge guidance in 2008 season Detailed comparison of measured data and surge guidance is still ongoing Detailed comparison of measured data and surge guidance is still ongoing Enhanced accuracy in 2009 season via Enhanced accuracy in 2009 season via  use of most up-to-date bathymetry  transition to asymmetric vortex wind model

Conclusions Broad participation has provided a tremendous boost to the guidance process Broad participation has provided a tremendous boost to the guidance process The efforts, frustrations and successes of the 2008 season have informed the development of LPFS The efforts, frustrations and successes of the 2008 season have informed the development of LPFS The 2009 season will build on past experiences to provide the most reliable, timely and accurate surge guidance available The 2009 season will build on past experiences to provide the most reliable, timely and accurate surge guidance available