JACKSONVILLE, Fla. - This year the National Hurricane Center had its best year ever forecasting hurricane tracks in the Atlantic Basin. This means next years hurricane track cone will get narrower.
The NHC issues the cone of uncertainty out to 5 days and the width of the cone is based on the average error over the past five years.
Because forecast uncertainty in a storm increases farther out in time, this results in the widening "cone" shape.
The average 2012 to 2016 error at 24 hours is a narrow 45 miles and expands to 211 miles by day 5. This year's preliminary verification is around 30 miles at 24 hours and 155 miles error at day 5.
The red line shows greater NHC forecast track accuracy compared to the 5 year average (dotted line) and well below statistical models(solid gray).
Part of the forecast success is due to more dropsondes this year which feed details about a storm into forecast numerical weather models. This helps computers visualize the initial state of a storm resulting in a better forecast.
The European model recent upgrades showed this season with it outperforming all others including the official NHC forecast in Hurricane Irma.
During Irma, the ECMWF had the lowest forecast errors (orange) and the NHC forecast averaged second best (light pink).
Also seven of the 17 named storms this season were Cabo Verde systems which tend to follow a more predictable path along the trade winds in the central Atlantic.
While the NHC produces forecasts for periods extending from 12 through 120 hours, the 48-hour forecast is often important for emergency managers and preparedness actions. The 2017 season 2 day error is near 50 miles.
Official verification statistics for these measures are usually available by January or February of the following year.
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