Hurricane Irma Spaghetti

As of 11:00 A.M. Atlantic Standard Time (11:00 A.M. EDT), Hurricane Irma is centered 1580 miles east of the Leeward Islands. It has sustained winds up to 110 mph. Medium range forecast models like the GFS (Global Forecast System) and the ECMWF (European Center for Meteorology & Weather Forecasting's model, commonly referred to as the "Euro") actually are run as "ensembles" containing a number of different runs of the same model. By altering the initial conditions a bit and re-running the model, the different solutions of the various ensemble members give us an idea of the margin of error for that model. We can plot each of the ensemble member solutions on a map to visually gauge where a storm is most likely to track and what the margin of error is. These types of plots are frequently referred to as "spaghetti plots" because of the similarity in appearance of the final product to the comfort food. Below are the latest spaghetti plots from the Euro and GFS showing the forecast track of Irma from each ensemble member. The plots will always be closer together over the near-term time frames, then spread out more with each day further out as the uncertainty increases. Spaghetti plots should be taken with a grain of salt. Sometimes the mostly likely track of a storm is represented by a consensus of the spaghetti plots. This is usually a good starting point. In some cases, one or a few of the solutions become preferred over the rest of the ensemble members. I will comment on that as Irma moves further west.

ECMWF Plots:

GFS Plots:

Here is the latest forecast discussion from the National Hurricane Center (NHC)

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