Tracking and ForecastingTracking and ForecastingHurricanesHurricanes

By John MetzWarning Coordination MeteorologistNWS Corpus Christi, Texas

NATIONAL HURRICANE CENTERMIAMI, FLORIDA

NATIONAL HURRICANE CENTERMIAMI, FLORIDA

Hurricane Track Forecasting

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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 aboutCurrent 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.

EGRI

GFDL

NGPGFS

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)

Intensity ForecastingIntensity Forecasting

Hurricane Claudette

Example – Hurricane Claudette

Wind Direction

Hurricane Claudette

• Satellite imagery using the Dvorak technique.

• Surface observations: ships, buoys, land stations (infrequent)

• Satellite imagery using the Dvorak technique.

• Surface observations: ships, buoys, land stations (infrequent)

• Aircraft reconnaissance

flight-level winds

• Aircraft reconnaissance

flight-level winds

• GPS dropwindsondes

• GPS dropwindsondes

Estimating Intensity

Tropical cyclones have characteristic cloud patterns that correspond to stages of development and certain intensities.

The Dvorak Technique

Satellite Wind Data

High Resolution

Super High Resolution

Available Today

Future?

105 kt

90 kt

90 kt95 kt

Aircraft Reconnaissance

Observations taken at 10,000 ft are used to estimate intensity

Friction decreases wind in the lowest 1500 ft of the eyewall.

Dropsonde

NASA’s Global Hawk Unmanned Airborne System

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Hurricane Earl’s eye as seen from the Global Hawk

• 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.

Summary

The End