Verification of tracks made of Lorenzo using GEFS mean fields

October 24, 2019

I made eleven tracks of Hurricane Lorenzo. Within 384 hours of cyclogenesis, there were no instances, when I missed cyclogenesis entirely. Peak intensity was surprisingly correct, given how anomalous Lorenzo was. Timing of cyclogenesis was excellent, but dissipation times varied a lot. Position accuracy was good, even outstanding at some lead times. A few tracks erroneously brought Lorenzo to Caribbean or nearby, but they were rare, and such erroneous motion happened at long lead times.

As of this analysis, best track positions are available September 21, 06Z thru October 2, 12Z, and as such, position comparisons are possible only for this timespan.

Since I give only SSHS categories in my tracks, I don't calculate intensity errors in units of speed, but in categories. For this purpose, I define tropical or subtropical storms as "Category 0", tropical or subtropical depressions as "Category -1" and non-existence of a tropical or subtropical cyclone as "Category -2".

In the eleven tracks, formation times ranged between September 19, 18Z and September 26, 00Z. Average was September 23, 02Z and median was September 23, 06Z.

In the eleven cases (11 tracks and 0 complete misses), peak intensity ranged between Category -1 and Category 5. Average was Category +2.45 and median was Category 3.

In the eight tracks, dissipation times ranged between September 23, 18Z and October 19, 06Z. Average was October 6, 16Z and median was October 8, 18Z.

At the lead time of 1 days (24 hours), there were 1 hit, 0 false detections and 0 misses. 1 available position comparison produces an average error of 41 nautical miles.

At the lead time of 2 days (48 hours), there were 1 hit, 0 false detections and 0 misses. 1 available position comparison produces an average error of 37 nautical miles.

At the lead time of 3 days (72 hours), there were 1 hit, 0 false detections and 0 misses. 1 available position comparison produces an average error of 51 nautical miles.

At the lead time of 4 days (96 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 61 nautical miles.

At the lead time of 5 days (120 hours), there were 2 hits, 0 false detections and 1 miss. 2 available position comparisons produce an average error of 111 nautical miles.

At the lead time of 6 days (144 hours), there were 2 hits, 0 false detections and 1 miss. 2 available position comparisons produce an average error of 135 nautical miles.

At the lead time of 7 days (168 hours), there were 4 hits, 0 false detections and 0 misses. 4 available position comparisons produce an average error of 149 nautical miles.

At the lead time of 8 days (192 hours), there were 4 hits, 0 false detections and 0 misses. 4 available position comparisons produce an average error of 229 nautical miles.

At the lead time of 9 days (216 hours), there were 5 hits, 0 false detections and 0 misses. 5 available position comparisons produce an average error of 269 nautical miles.

At the lead time of 10 days (240 hours), there were 4 hits, 0 false detections and 2 misses. 4 available position comparisons produce an average error of 439 nautical miles.

At the lead time of 11 days (264 hours), there were 5 hits, 0 false detections and 0 misses. 5 available position comparisons produce an average error of 506 nautical miles.

At the lead time of 12 days (288 hours), there were 5 hits, 0 false detections and 1 miss. 5 available position comparisons produce an average error of 607 nautical miles.

At the lead time of 13 days (312 hours), there were 6 hits, 0 false detections and 1 miss. 6 available position comparisons produce an average error of 724 nautical miles.

At the lead time of 14 days (336 hours), there were 5 hits, 1 false detection and 1 miss. 5 available position comparisons produce an average error of 622 nautical miles.

At the lead time of 15 days (360 hours), there were 5 hits, 2 false detections and 1 miss. 5 available position comparisons produce an average error of 613 nautical miles.

At the lead time of 16 days (384 hours), there were 7 hits, 3 false detections and 0 misses. 7 available position comparisons produce an average error of 667 nautical miles.

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