Verification of tracks made of Jerry using GEFS mean fields

October 23, 2019

I made eight tracks of Hurricane Jerry. Additionally, within 384 hours of cyclogenesis, there were four instances, when I missed cyclogenesis entirely. Peak intensity was typically surprisingly correct, though its timing was not. Errors in speed and longitude of recurving, as well as in initial progression of precursor disturbance, resulted in occasionally huge position errors.

As of this analysis, best track positions are available September 14, 18Z thru September 25, 18Z, 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 eight tracks, formation times ranged between September 12, 06Z and September 22, 18Z. Average was September 16, 23Z and median was September 16, 12Z.

In the twelve cases (8 tracks and 4 complete misses), peak intensity ranged between Category -2 and Category 5. Average was Category +1.42 and median was Category 3.

In the eight tracks, dissipation times ranged between September 19, 06Z and October 5, 12Z. Average was September 28, 00Z and median was September 28, 15Z.

At the lead time of 1 day (24 hours), there were 0 hits, 0 false detections and 0 misses. No available position comparisons.

At the lead time of 2 days (48 hours), there were 0 hits, 0 false detections and 1 miss. No available position comparisons.

At the lead time of 3 days (72 hours), there were 0 hits, 0 false detections and 1 miss. No available position comparisons.

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 74 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 113 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 189 nautical miles.

At the lead time of 7 days (168 hours), there were 3 hits, 0 false detections and 1 miss. 3 available position comparisons produce an average error of 349 nautical miles.

At the lead time of 8 days (192 hours), there were 3 hits, 0 false detections and 2 misses. 3 available position comparisons produce an average error of 409 nautical miles.

At the lead time of 9 days (216 hours), there were 3 hits, 0 false detections and 2 misses. 3 available position comparisons produce an average error of 586 nautical miles.

At the lead time of 10 days (240 hours), there were 2 hits, 2 false detections and 3 misses. 3 available position comparisons produce an average error of 893 nautical miles.

At the lead time of 11 days (264 hours), there were 2 hits, 2 false detections and 4 misses. 3 available position comparisons produce an average error of 943 nautical miles.

At the lead time of 12 days (288 hours), there were 3 hits, 3 false detections and 3 misses. 3 available position comparisons produce an average error of 585 nautical miles.

At the lead time of 13 days (312 hours), there were 1 hit, 4 false detections and 4 misses. 2 available position comparisons produce an average error of 598 nautical miles.

At the lead time of 14 days (336 hours), there were 1 hit, 5 false detections and 5 misses. 2 available position comparisons produce an average error of 666 nautical miles.

At the lead time of 15 days (360 hours), there were 0 hits, 7 false detections and 5 misses. 2 available position comparisons produce an average error of 609 nautical miles.

At the lead time of 16 days (384 hours), there were 1 hit, 6 false detections and 4 misses. 2 available position comparisons produce an average error of 645 nautical miles.

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