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Subject: F2) What are those track and intensity models that the Atlantic forecasters are talking about in the hurricane and tropical storm Discussions?

Contributed by Sim Aberson and John Kaplan

The major hurricane track forecast models run operationally for the Atlantic, Eastern Pacific, and Central Pacific hurricane basins are:

  1. The basic model that is used as a "no-skill" forecast to compare other models against is CLIPER (CLImatology and PERsistence), which is a multiple regression statistical model that best utilizes the persistence of the current motion and also incorporates climatological track information (Aberson 1998). Surprisingly, CLIPER was difficult to beat with numerical model forecasts until the 1980s.
  2. The Beta and Advection Model (BAM), follows a trajectory in the pressure-weighted vertically-averaged horizontal wind from the Aviation model beginning at the current storm location, with a correction that accounts for the beta effect (Marks 1992). Three versions of this model, one with a shallow-layer (BAMS), one with a medium-layer (BAMM), and one with a deep-layer (BAMD), are run. BAMS runs using the 850-700 mb layer, BAMM with the 850-400 mb layer, and BAMD with the 850-200 mb layer. The deep-layer version was run operationally for primary synoptic times in 1989; all three versions have been run four times per day since 1990.
  3. A barotropic hurricane track forecast model LBAR, for Limited-Area Barotropic Model, is being run operationally every 6 hours.
  4. The NOAA Global Forecast System (GFS), formerly known as the Aviation and MRF models (Lord 1993) has been used for track forecasting since the 1992 hurricane season. An ensemble of lower-resolution runs is available four times daily.
    Current information on the GFS
  5. A triply-nested movable mesh primitive equation model developed at the Geophysical Fluid Dynamics Laboratory (Bender et al 1993), known as the GFDL model, has provided forecasts since the 1992 hurricane season. One version (GFDL) uses GFS fields for boundary conditions; a second version (GFDN) uses NAVGEM fields for boundary conditions.
    Current information on the GFDL model
  6. A doubly-nested movable mesh primitive equation non-hydrostatic model known as HWRF (for the Hurricane Weather Research and Forecast Model), has provided forecasts since 2006. It uses GFS fields for boundary conditions (Gopal et al 2012).
    Current information on HWRF
  7. The United Kingdom Meterological Office's global Unified model is utilized for forecasting the tracks of tropical cyclones around the world (Radford 1994). NHC starting receiving these operationally in 1996.
    Current information on the Unified Model
  8. The United States Navy Global Environmental Model (NAVGEM) is also a global numerical model that shows skill in forecasting tropical cyclone track (Fiorino et al. 1993). This model was also first received operationally at the National Hurricane Center during 1996. An ensemble of lower-resolution runs is available twice daily.
    Current information on NAVGEM
  9. The Canadian Meteorological Center's Global Environmental Multi-scale Model (GEM) provides forecasts twice per day. An ensemble of lower-resolution runs is available twice daily.
    Current information on GEM
  10. The European Centre for Medium-Range Weather Forecasts's Integrated Forecast System (IFS) provides forecasts twice per day. It has proven to be the best model for track forecasting, and is the highest resolution global model available. An ensemble of lower-resolution runs is available twice daily.
    Current information on the IFS
  11. The Japanese Meteorological Agency's Global Spectral Model (GSM) provides forecasts, both in high-resolution deterministic runs and lower-resolution ensemble runs.
    Current information on the GSM

The full list of models used in the Atlantic and Eastern and Central Pacific is available here. Various types of consensus models (ensemble means) are available from these models.

Despite the variety of hurricane track forecast models, there are only a few models that provide operational intensity change forecasts for the Atlantic and Eastern and Central Pacific basins:

  1. Similar to the CLIPER track model, the SHIFOR (Statistical Hurricane Intensity Forecast model) is used as a "no-skill" intensity change forecast. It is a multiple regression statistical model that best utilizes the persistence of the intensity trends and also incorporates climatological intensity change information (Jarvinen and Neumann 1979). SHIFOR has been difficult to exceed until recent years.
  2. A statistical-synoptic model, SHIPS (Statistical Hurricane Intensity Prediction Scheme), has been available since the mid-1990s (DeMaria and Kaplan 1994). It takes current and forecasted information on the synoptic scale on the sea surface temperatures, vertical shear, moist stability, etc. with an optimal combination of the trends in the cyclone intensity.
  3. The Logistic Growth Equation Model (LGEM) uses the same inputs as the SHIPS model but uses a dynamical scheme. The intensity is determined by a logistic growth equation contrained by the maximum potential intensity as derived from the sea surface temperature. LGEM differs from SHIPS in that it accounts for changes in environmental conditions rather than using values averaged over the forecast period.
  4. The GFDL and HWRF models, described above in the track forecasting models, also issue forecasts of intensity change.
  5. A statistical scheme for estimating the probability of rapid intensification has been developed (Kaplan et al 2010) and is now being used operationally. The RI scheme employs synoptic and persistence information from the SHIPS model to estimate the probability of rapid intensification (24 h increase in maximum wind of 35 mph or greater) every 6 hours.

Information on the performance of these models is available after each season here.

Last updated : May 23, 2013

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