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Tracking and Forecasting Hurricanes. By John Metz Warning Coordination Meteorologist NWS Corpus Christi, Texas. NATIONAL HURRICANE CENTER MIAMI, FLORIDA. Hurricane Track Forecasting. L. H. L. L. H. L. Overview of Models.
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Tracking and ForecastingHurricanes By John Metz Warning Coordination Meteorologist NWS Corpus Christi, Texas
NATIONAL HURRICANE CENTER MIAMI, FLORIDA
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Overview of Models • Statistical Models: CLIPER, NHC90, NHC91, NHC98, SHIFOR, SHIPS, DSHIPS • Steering models: BAMS, BAMM, and BAMD • Simplified Dynamic Models: LBAR • 3-D Dynamic Models:GFS, NOGAPS, UKMET, ECMWF, Canadian, Japanese, GFDL, GFDN, HWRF • Ensemble Models: TCOA, TVCA, TCCN, TVCC, CGUN, FSSU Don’t know anything about Current state of the atmosphere Know basic general information about current state of atmosphere Know basic general information about current state of atmosphere Most powerful models that know a lot about current state of atmosphere Statistical models that average the output from 3-D dynamic models. Can reduce biases in models with good results.
GFDL NGP GFS EGRI
Summary • There have been big advances in track forecasting by dynamical models over the past several years • A consensus of high-quality track prediction models is an extremely powerful tool for track prediction • Sound meteorological reasoning is still needed to get the most out of model-predicted tracks • Improved observation of the environment, has had a positive impact on track predictions by the NCEP global model (GFS)
Example – Hurricane Claudette Wind Direction
Estimating Intensity • Aircraft reconnaissance flight-level winds • Satellite imagery using the Dvorak technique. • Surface observations: ships, buoys, land stations (infrequent) • GPS dropwindsondes
The Dvorak Technique Tropical cyclones have characteristic cloud patterns that correspond to stages of development and certain intensities.
Satellite Wind Data Available Today Future? High Resolution Super High Resolution
Aircraft Reconnaissance 90 kt 95 kt 105 kt 90 kt Observations taken at 10,000 ft are used to estimate intensity
Dropsonde Friction decreases wind in the lowest 1500 ft of the eyewall.
NASA’s Global Hawk Unmanned Airborne System Hurricane Earl’s eye as seen from the Global Hawk
Summary • Intensity forecasting is not as advanced as track forecasting. Intensity skill essentially goes to zero by 5 days. Do not expect the wind speed predictions beyond 3 days to be skillful. • Current guidance is provided mainly by statistical models. Improvements in these models, using oceanic heat content, inner core convection, and rapid intensification criteria, are currently being made. • Dynamical models have shown little or no skill in intensity forecasting. However, in time, improvements to these models offer hope for the future.