Re: I'm having other issues now too at NOAA
Posted by Chris in Tampa
on 4/21/2017, 2:31 am
|The cone looks small because there is only one forecast point in the track, the 12 hour position. Also, the image is really zoomed out, maybe so you can see where it is in relation to US.|
"The cone represents the probable track of the center of a tropical cyclone, and is formed by enclosing the area swept out by a set of circles (not shown) along the forecast track (at 12, 24, 36 hours, etc). The size of each circle is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle."
(page has not been updated for 2017's cone yet)
Here are the values used for the Atlantic cone, for last year and this year:
This year the cone will be a little smaller at every hour interval.
Compared to last year's cone:
12: -1 nautical miles
24: -4 nautical miles
36: -3 nautical miles
48: -6 nautical miles
72: -8 nautical miles
96: -6 nautical miles
120: -26 nautical miles
The 12 hour forecast cone is currently shown because Arlene is not forecast to last much longer. If the cone is already set for 2017, the circle that is used at the 12 hour forecast point would only be 1 nautical mile less for its radius than last year, 2 nautical miles in diameter less, which wouldn't be perceptible so zoomed out.
If you want to see how good the NHC has gotten over the years...
First, track errors from 1989 - 2016...
Going back further, track errors from 1970 - 2016...
They've come a long way on track!
Here are intensity errors from 1990 - 2016...
Intensity remains more challenging.
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