Technical discussion of why you should not believe everything you hear about the projected plots of Hurricanes:
‘…spaghetti plots are not good decision-making tools. Sorry, they’re just not. To understand why, let’s take a look at the models on Nate Silver’s plot, which he shared with his 2.5 million followers at 7:34pm ET Tuesday:
XTRP: This is not a model. It is simply a straight-line extrapolation of the storm’s current direction at 2pm Tuesday.
TVCN, TVCX: These are useful, as they are consensus forecasts of global model tracks. NHC: This is the official forecast from the National Hurricane Center.
TABD, TABM, TABS: These are simple statistical models, which are essentially useless for track forecasting.
NVGM: Useful, but the model is from about 8am ET, or 12 hours before Silver posted the graphic. Wildly out of date.
HMON: This is NOAA’s new hurricane model, but it was badly wrong during Hurricane Harvey. Also 12 hours old. Essentially useless.
HWRF: This is NOAA’s primary hurricane model, and while it’s OK, it is nearly 12 hours old. Not useful.
COTC: A version of the US Navy’s global model, which is kind of meh for hurricanes and is 12 hours old.
AVNO, AEMN: Two variants of NOAA’s premiere global model, the GFS. Both are worth looking at, but again the forecasts are 12 hours old.
CMC, CEMN: Two variants of the Canadian global model, which is worth looking at, but again the forecasts are 12 hours old.
UKM: The UK Met Office’s global model, which is definitely worth looking at. But the forecasts are 12 hours old.
CLP5: Not a model at all. Just a forecast based on where storms in this location historically go.
This is the essential problem with spaghetti plots. To the untrained eye, all models are created equal, when they most certainly are not. Plots like this also often include forecasts that are 12 or more hours old, which is generally out of date when it comes to hurricanes. Finally, the world’s most accurate model, the European forecast system, is proprietary and not included on such plots.So what should you do? First and foremost, pay attention to the National Hurricane Center, which publishes updated track and intensity forecasts every six hours. I know a lot of these forecasters personally, and they are absolute pros without agendas who dedicate their summers to getting these forecasts right. There are no absolutes in track and intensity forecasts, and there is a lot of uncertainty. They understand all of this as well as anyone can…’
Source: Ars Technica