A parametric hurricane wind model (“Fitz” Holland B) for intensity, size, and speed specification

1. A parametric hurricane wind model (“Fitz” Holland B) for intensity, size, and speed specification By Pat Fitzpatrick and Yee Lau Geosystems Research Institute Mississippi State University

2. Advantage of this method • 10-meter surface winds match the observed peak eyewall wind • 10-meter surface winds match the observed radius of 34-knots winds • Holland B an iterated solution, not predetermined • Specification of wind direction that can vary radially • Storm motion is included in the iteration, not added afterwards • Vmax=storm speed plus hurricane vortex eyewall • V34=storm speed plus edge of hurricane vortex • This allows a parametric model which: • Matches the National Hurricane Center forecast • Can match hindcast hurricane data for JPM studies, theoretical studies, risk modeling, etc. • Correctly uses storm motion. Many schemes superimpose storm speed translation. This is incorrect usage. Super-positioning changes the wind stress, often artificially increasing the winds. The winds are then faster than Vmax and V34. However, observed winds already include storm motion.

3. Comparison of Storm 140 Winds from JPM-OS (left) versus Fitz Wind Model (right) Odd placement of peak winds in NNE eyewall sector for JPM-OS Our placement based on speed and track direction Everything else matches well

4. Parametric hurricane wind model flow chart

5. Surge Animation Website display http://www.gri.msstate.edu/research/severeweather/ Northern Gulf Coast Storm Surge Prediction Flow Chart NHC’s forecast/advisory report • Movie Maker • Make animation Step 3 • Shell Script (wget) • Download text forecast • ADvanced CIRCulation Model (ADCIRC) • Generate hourly surge data at each grid point • GMT Script • Create hourly • surge plots • Perl Script • Extract storm position, max wind, central pressure and 34-kt wind info Step 4 FEMA MS Finite Element Grid Fitzpatrick’s Parametric Hurricane Wind Model Compute hourly u, v wind components and pressure at each grid point • Fortran Program • Interpolate to hourly data • ASGS Step 1 Step 2

6. Summary • Hypothesis: We propose a Holland B scheme capable of generating a asymmetric vortex which matches peak winds, storm size, and correctly uses translation speed. This scheme has shown advantages over other ADCIRC and SLOSH wind forcing schemes • Simulation system used: ASGS and ADCIRC • Interactions: LSU (Carola Kaiser) and MSU (Pat Fitzpatrick and Yee Lau) • Facilities: LSU and MSU Linux clusters; other workstations; National Hurricane Center data • Analytics: Isaac surge forecast verified reasonably well; Wind scheme verified against JPM-OS dataset • Future goals: • Incorporate new schemes into operations for wind direction, PBL adjustment scheme, and surface pressure; • Examine assumptions in eyewall peak wind placements • Run operationally if necessary this hurricane season • Include in ADCIRC or ASGS software if there is interest • Publish scheme and sensitivity to parameters • More information on portal: • http://ngchc.org/msu-operational-storm-surge-system

7. Portal information • http://ngchc.org/msu-operational-storm-surge-system • http://ngchc.org/flowchart-msu-parametric-hurricane-wind-model • http://ngchc.org/parametric-hurricane-wind-model-intensity-size-and-speed-specification • http://ngchc.org/asgs-and-hurricane-risk-reduction