What Are Spaghetti Models?
The term "spaghetti models" refers to a plot showing the projected tracks of a tropical cyclone from multiple different numerical weather prediction (NWP) models simultaneously. When you overlay 8–12 different model tracks on the same map, the resulting tangle of lines looks like a plate of spaghetti — hence the name.
Each line on a spaghetti plot represents one model's best estimate of where the storm will go over the next 5–7 days. The models use different mathematical equations, different initial data, and different assumptions about atmospheric physics — which is why they often disagree, sometimes dramatically.
The Eight Models You'll See on Our Tracker
Our Spaghetti Model Viewer displays the eight models that NHC meteorologists rely on most heavily. Here's what each one is and why it matters:
| Model | Full Name | Organization | Why It Matters |
|---|---|---|---|
| GFS | Global Forecast System (FV3-GFS) | NOAA/NCEP | The primary US model. Runs every 6 hours. Often called "the American model." Free and publicly available. |
| ECMWF | European Centre IFS | ECMWF | Widely considered the most accurate global model. Called "the Euro." Runs twice daily. Often leads GFS in track accuracy. |
| CMC | Canadian Deterministic Prediction System | Environment Canada | Good secondary guidance. Runs twice daily at 25km resolution. Often used as a tiebreaker when GFS and Euro disagree. |
| UKMET | UK Met Office Global Model | UK Met Office | Strong European guidance alongside ECMWF. Runs twice daily. Particularly reliable for North Atlantic storms. |
| HWRF | Hurricane Weather Research and Forecast System | NOAA/NCEP | Dedicated hurricane model with nested grids down to 1.5km. Only runs when a storm is active. Excellent for intensity forecasts. |
| HMON | Hurricane Multi-scale Ocean-coupled Non-hydrostatic | NOAA/NCEP | Ocean-coupled hurricane model. Nested grids to 2km. Accounts for ocean cooling beneath the storm — important for rapid intensification forecasts. |
| NAVGEM | Navy Global Environmental Model | US Navy/NRL | US Navy operational global model. Runs every 6 hours. Formerly known as NOGAPS. Useful for longer-range guidance. |
| ICON | Icosahedral Nonhydrostatic Model | DWD (Germany) | German Weather Service global model. Icosahedral grid structure provides uniform global resolution. Available on Tropical Tidbits. |
The Golden Rule: Tight Clustering = Confidence. Wide Spread = Uncertainty.
This is the most important principle for interpreting spaghetti models. When all the model lines cluster tightly together, it means the models are in agreement — and that agreement gives forecasters confidence in the projected track. When the lines spread widely apart, it means the models are uncertain, and you should treat any single track forecast with skepticism.
Wide model spread does not mean the storm is less dangerous — it means we do not yet know where it is going. A storm with a 500-mile wide cone of uncertainty can still be catastrophic; it just means a larger area needs to prepare.
Why Do Models Disagree?
Tropical cyclone track forecasting is one of the most complex problems in atmospheric science. Models disagree for several reasons:
1. Steering Flow Uncertainty
Hurricanes are steered by the large-scale atmospheric flow around them — primarily the subtropical ridge (a high-pressure system) and mid-latitude troughs (low-pressure systems). Small differences in how models represent these steering features can result in dramatically different track forecasts. A storm that tracks 100 miles north or south of the forecast can hit a completely different coastline.
2. Initial Condition Errors
Every model starts with an analysis of the current state of the atmosphere. This analysis is imperfect — there are gaps in observational data, especially over the open ocean. Small errors in the initial conditions can amplify over time, leading to diverging forecasts. This is why model guidance is less reliable beyond 5 days.
3. Different Model Physics
Each model uses different parameterizations — mathematical shortcuts that represent physical processes (like convection and ocean interaction) that are too small to resolve explicitly. These differences in model physics lead to different solutions even when starting from the same initial conditions.
The GFS vs. ECMWF Debate
The most common question in hurricane season is: "Which model is right — the GFS or the Euro?" The honest answer is that neither model is always right, but the ECMWF has historically outperformed the GFS in track accuracy, particularly at longer lead times (4–7 days).
The ECMWF's advantage comes from several factors: higher horizontal resolution, more sophisticated data assimilation, and a larger ensemble. However, the GFS has improved significantly in recent years with the FV3 dynamical core upgrade, and there are individual cases where the GFS outperforms the Euro.
Professional meteorologists do not simply pick one model and ignore the others. They look at the ensemble mean — the average of all model solutions — and weight individual models based on their recent performance for the specific storm and synoptic pattern.
What Spaghetti Models Cannot Tell You
Spaghetti models show track guidance only. They do not tell you:
- Intensity: How strong the storm will be when it arrives. Intensity forecasting is significantly harder than track forecasting and requires specialized models like HWRF and HMON.
- Rainfall: How much rain will fall in a given area. Rainfall totals depend on storm speed, moisture content, and terrain — factors that are separate from track.
- Storm surge: The height of the storm surge depends on the storm's angle of approach, forward speed, size, and the shape of the coastline — not just the track.
- Timing: Small errors in forward speed can shift a landfall by 12–24 hours, which matters enormously for evacuation planning.
The Official NHC Forecast Is the Gold Standard
This cannot be stated strongly enough: for evacuation decisions, always follow the official NHC forecast and your local emergency management agency — not individual model lines.
NHC meteorologists have access to all the model guidance you see on spaghetti plots, plus additional tools, aircraft reconnaissance data, and decades of institutional knowledge. The NHC forecast cone represents the range of likely track scenarios, not a single predicted path. Any point within the cone — and even outside it — can experience dangerous conditions.
Spaghetti models are a tool for understanding uncertainty and building situational awareness. They are not a substitute for official guidance.
Use Our Spaghetti Model Viewer
Our Spaghetti Model Viewer lets you toggle individual models on and off to compare projected tracks. During active storm season, we display real-time model guidance updated every 6 hours. You can also overlay the official NHC forecast track to see how individual models compare to the consensus.