Spaghetti Models Explained: What Those Tangled Hurricane Lines Actually Mean

Quick Answer: What a Spaghetti Model Is

A spaghetti model is not a model. It is a plot.

Every hurricane season, a graphic circulates showing a tangle of colored lines fanning out from a storm, each one a different projected path. The nickname comes from the obvious resemblance. What the graphic actually contains is a set of individual computer forecast tracks, drawn on one map so you can compare them.

The single most important thing to know: a spaghetti plot is a picture of uncertainty, not a forecast. No line on it is the answer, including the one heading straight at you. The official National Hurricane Center forecast, drawn down the middle of the cone of uncertainty, is the answer. The plot exists to tell you how confident anyone should be about it.

Where the Lines Come From

Each strand on the plot has one of four origins, and they are not the same kind of thing.

Separate forecast models. Different weather centers run different global models. The American GFS, the European ECMWF, the UK Met Office model, the Canadian model, and several hurricane-specific models each produce their own track for the same storm. These are genuinely independent attempts, built on different physics, resolutions, and data assimilation. We compare how the major models differ in our guide to GFS, HRRR, and the model lineup.

Ensemble members from a single model. One model gets run dozens of times from very slightly different starting conditions, because the true state of the atmosphere is never known exactly, and operational ensembles usually perturb the model physics as well. Each run is a "member." Thirty lines from one ensemble are not thirty opinions. They are one model exploring how much its answer moves when you nudge the inputs, which is the whole point of an ensemble forecast.

Means and consensus aids. Some lines are not runs at all. TVCN, HCCA, AEMN and EEMN are computed from other tracks on the same plot, by averaging them or weighting them. They often verify better than any single model, but they cannot confirm the lines they were built from. When a consensus aid agrees with the models feeding it, that is arithmetic, not corroboration.

The official forecast. OFCL is the National Hurricane Center's own track. A human forecaster produces it using the guidance, the consensus aids, and judgment about which models are handling this particular storm well. It is not derived mechanically from the other lines, and it is the one line on the plot that carries watches, warnings and the cone.

A plot mixing all four looks like fifty independent forecasts and is nothing of the sort. That distinction matters more than any single line's position.

Decoding the Labels

The identifiers on a spaghetti plot are the least intuitive part, and most sites do not explain them. These are ATCF codes, the naming scheme forecasters use internally. The exact strings vary between plotting sites, but the common ones are stable.

Label	What it is
OFCL	The official NHC forecast track, not a model
AVNO / GFS	The American Global Forecast System
AEMN	The mean of the GFS ensemble (GEFS)
AC00, AP01 to AP30	Individual GEFS ensemble members, control run plus perturbations
EMX	The European ECMWF high-resolution model
EEMN	The mean of the ECMWF ensemble
UKM / UKX	The UK Met Office global model
CMC	The Canadian global model
NVGM	The US Navy's NAVGEM
HFSA / HFSB	HAFS-A and HAFS-B, NOAA's current hurricane-specific models
TVCN	A consensus track, an average of several models rather than a model itself
HCCA	A corrected consensus that weights members by past performance

Two details worth knowing. Many codes have an "I" variant, such as GFSI or EMXI, meaning the track has been interpolated and shifted to line up with the storm's current observed position, which makes older model runs comparable to newer ones. And consensus entries like TVCN are usually among the better performers over a season, which is a hint about how to read the picture: the middle of the pack tends to beat the outliers.

The NHC maintains a technical summary of its track and intensity models with the authoritative list.

What the Plot Does Not Show

Intensity. A spaghetti plot is almost always a track plot. It shows where models think the center will go and says nothing about whether the storm will be a tropical storm or a Category 4 when it gets there. A tight cluster of lines can accompany enormous uncertainty about strength, which is a separate forecast problem and often a harder one. See rapid intensification for why.

Size. The lines trace the center. Hurricane-force winds, rainfall, and storm surge extend well beyond it, sometimes by hundreds of miles. A location a comfortable distance from every strand can still be inside the hazard area.

Timing. Most plots do not label when each track reaches each point. Two lines crossing the same coastline can represent landfalls two days apart.

Equal skill. This is the big one. A raw plot draws every line at the same weight, including experimental models and models with poor track records, because a plotting script has no opinion. Forecasters do have an opinion, informed by seasons of verification statistics, and they discount accordingly.

Why the Picture Keeps Changing

Global models run on fixed cycles. The American guidance initializes at 00, 06, 12, and 18 UTC, so it refreshes every six hours. The ECMWF, UKMET, and Canadian tracks, and their ensemble means, run at 00 and 12 UTC only, so they refresh every twelve. When a cycle finishes, the tracks belonging to that model are redrawn while the rest stay put.

That is why a plot you screenshot in the evening can look meaningfully different by the following morning, and why a track that terrified social media at midday can quietly disappear from the next run. The atmosphere did not swerve. The model got six hours of fresh observations, including data from reconnaissance aircraft and dropsondes if they are flying the storm, and revised.

Watching individual runs flip back and forth is the fastest way to exhaust yourself during a hurricane. The NHC issues full advisories every six hours, plus intermediate advisories every three hours once coastal watches or warnings are in effect, and that cadence is the one worth following.

How to Read a Spaghetti Plot in Thirty Seconds

1. Look at the spread first, not the lines. Tightly bunched means the models broadly agree and confidence is relatively high. A wide fan means the outcome is genuinely unsettled and nobody knows yet.
2. Find the cluster, ignore the outlier. The strand furthest from the group is usually the least likely, not a hidden warning. It is also the one most likely to end up in a screenshot.
3. Check what kind of line you are looking at. Thirty members of one ensemble agreeing is much weaker evidence than three separate global models agreeing, and the consensus aids (TVCN, HCCA, AEMN, EEMN) are computed from the other lines rather than run independently, so they cannot confirm them. OFCL is different again: it is the human NHC forecast, informed by the guidance rather than derived from it.
4. Note the run time. A plot from a run that is twelve hours old has already been superseded.
5. Then go read the official forecast. The cone and the advisory text incorporate all of this plus human judgment and a verification record no single line has.

The Screenshot Problem

Spaghetti plots spread on social media faster than any other hurricane graphic, and they spread selectively. A plot showing broad agreement on a fish storm that never touches land is boring. A plot with one strand aimed at a major city is not.

So the plots that reach you have been filtered for alarm before you ever see them, often stripped of their run time, their source, and any indication of which lines came from a serious model. Sometimes they are days old. The graphic itself is a legitimate forecasting tool. Its life as a shareable image is a different thing, and the two are easy to confuse.

If a plot reaches you without a timestamp and a source, treat it as decoration.

Frequently Asked Questions

What are spaghetti models in weather?

They are plots showing many individual computer forecast tracks for the same storm on one map, named for the tangle of thin colored lines. Each line is a separate forecast model, one member of a single model's ensemble, a consensus aid computed from the other tracks, or the official National Hurricane Center forecast. The plot is a way of visualizing forecast uncertainty, not a forecast in its own right.

Are spaghetti models accurate?

The question does not quite apply, because a spaghetti plot is a display rather than a prediction. Individual models on it vary widely in skill, and the National Hurricane Center's official forecast generally outperforms any single one of them over a season. Read the plot for how much the guidance agrees, and take the official forecast as the answer.

What do the letters on a spaghetti model mean?

They are ATCF identifiers for the model behind each track. Common ones include AVNO for the American GFS, EMX for the European ECMWF, UKM for the UK Met Office model, CMC for the Canadian model, HFSA and HFSB for NOAA's hurricane-specific HAFS models, and OFCL for the official NHC forecast. Codes beginning AP or AC are individual members of the GFS ensemble.

Which hurricane model is the most accurate?

There is no permanent winner, and skill varies by storm, by basin, and by how far ahead you look. The consensus aids that blend several models tend to outperform individual models, and the NHC's official forecast, which blends guidance with forecaster judgment, tends to outperform the consensus. That is why the official track is the one to plan around.

Why do spaghetti models change so much?

Global models rerun with new observations on their own cycles, every six hours for the American guidance and every twelve for the European, UK, and Canadian tracks, and the tracks belonging to a model are redrawn when its cycle finishes. Early in a storm's life, small differences in the starting analysis grow quickly, so runs can shift substantially from one cycle to the next. The shifts usually shrink as the storm organizes and gets closer.

Should I evacuate because a spaghetti model line points at my house?

No. Evacuation decisions come from your local emergency management officials and from NHC watches, warnings, and storm-surge products, never from one strand on a model plot. A single line is one possibility among many, and it carries no information about how likely it is.

Where can I see spaghetti models?

Several university and enthusiast sites publish them each season, and the NHC publishes the underlying model guidance along with its own forecast. Whatever source you use, check the run time before you read anything into it.

Always Verify with Official Sources

Model guidance is raw material, not advice. For decisions, use current NHC advisories, the watches and warnings in effect for your location, and instructions from your local emergency management agency. Those are the products built for public safety, and they already account for the guidance a spaghetti plot displays.

Follow Tropical Systems with WeatherAI

WeatherAI's Tropical Weather Hub tracks NHC-centered systems as they develop:

• Active storms and development areas with forecast points, tracks, and the official cone
• Watches and warnings for your saved locations
• Arrival time and wind-speed probability so you can see what the storm means where you are
• Local risk and motion context alongside the national picture

Download WeatherAI for iPhone →

Explore the WeatherAI Hurricane Tracker → · See active storms and development areas →

---

More tropical reading: what the cone of uncertainty does and does not show, how the major forecast models differ, what an Invest designation means before a storm is named, and the hurricane season guide for the climatological timing.