Guide to Early Cycle Intensity Plots

This page lists the TECH identifiers of the various intensity forecast aids that may appear in the early cycle intensity plots on this site. To learn more about TECH identifiers, click here. For general information about the difference between late cycle and early cycle forecast aids, click here. To learn what a vortex tracker is, click here.

TECHs of the forecast aids shown in this plot

The TCGP plotting system is currently configured to plot the early cycle intensity guidance, as well as select late cycle intensity guidance that has been adjusted to match the time of the early cycle guidance. If one of the forecast aids listed here does not appear in the plot, this means that it was not available in the source a-deck at the time the plot was created. When a system has been newly designated or upgraded to a tropical depression, it is common to only have a few forecast aids available.

Official forecast:

• OFCI: NHC official forecast from previous forecast cycle (adjusted 6 hours to present cycle)

Early cycle statistical forecast aids:

• SHF5: A climatology and persistence model for intensity, also known as SHIFOR5 (5-day version)

Early cycle statistical-dynamical forecast aids:

• SHIP: Statistical Hurricane Intensity Prediction Scheme (SHIPS) model
• DSHP: Decay SHIPS model (reduces the SHIPS model forecast to account for weakening when the storm is inland)
• LGEM: SHIPS Logistic Growth Equation (LGE) forecast model

Multilayer global-dynamical models:

In addition, the following late cycle track forecast aids are also plotted on the early cycle track plots. Generally, these are very complex models that are run at various national modeling centers. All of these forecast aids are adjusted 6 hours ahead to the present cycle:

• AVNI/GFSI: Previous cycle's run of the NWS Global Forecast System (GFS) model
• NGPI: Previous cycle's run of the Navy Operational Global Prediction System (NOGAPS)

Multilayer regional-dynamical models:

• HWRI: Previous cycle's run of the NWS/Hurricane Weather Research and Forecasting (HWRF) model
• GFDI: Previous cycle's run of the NWS/Geophysical Fluid Dynamics Laboratory (GFDL) model
• GFTI: Previous cycle's run of the NWS/GFDL model (using the GFS vortex tracker)
• GFNI: Previous cycle's run of the NWS/GFDL model (using the NOGAPS model fields)
• GHMI: Previous cycle's run of the GFDL model with intensity adjustment
• COTI: Previous cycle's run of the Navy COAMPS model (HFIP version)

Consensus intensity aids

Finally, the following consensus intensity aids are plotted on the early cycle intensity plot. Generally, these are a weighted average of several diverse models, or a simple average of all the ensemble members of a particular ensemble forecasting system. In general, the consensus aids are considered early cycle aids since they use the interpolated output of the late models.

• ICON: Average of DSHP, LGEM, GHMI/2, and HWFI/2
• IVCN: Variable consensus (weightings can vary) of DSHP, LGEM, GHMI/2, HWFI/2, and GFNI/2
• IV15: Variable consensus (weightings can vary) of various Stream 1.5 models under evaluation by HFIP
  

Frequently asked questions

Often users ask why other forecast aids are not included in the early cycle intensity plots. This section is meant to answer these questions.

Where can I find more information about the details of these different models and forecast aids?

In the future we plan to offer a comprehensive guide to all the forecast aids featured in this site. In the meantime, please refer to the very useful Technical Summary of the National Hurricane Center Track and Intensity Models.

Why don't you include the projections of the European Centre for Medium Range Forecasting (ECMWF) model?

The ECMWF model is run by a 28-nation European consortium who jointly fund the operations and development of that model. As such, access is generally restricted to member states or commercial users who are willing to pay for the model output. They do provide low resolution fields of their deterministic run, although these are at too coarse of a resolution to run a vortex tracker on.

Why don't you include the intensity projections from the UK Met Office model?

The intensity projections of the UK Met Office model do not always have reliable skill. The providers of these data asked us not to show these projections in the intensity guidance plots.

Why don't you include the projections from the North American Model (NAM)?

The NAM model's intensity projections are normally not very skillful compared with the other dynamical intensity models shown here. In the future, TCGP may feature another type of plot for experimental or less skillful intensity models. We will include the NAM in that new type of plot.