Verification of tracks made of Gamma

December 21, 2020

I made nine tracks of Tropical Storm Gamma, before it was assessed as a tropical cyclone. I made one more track after that point. Additionally, within 480 hours of cyclogenesis, there was one instance, when I missed cyclogenesis entirely.

As of this analysis, best track positions are available September 30, 12Z thru October 6, 00Z, 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 nine tracks (made before operationally recognized cyclogenesis), formation times ranged between September 29, 18Z and October 3, 12Z. Average was October 2, 16Z and median was October 3, 06Z.

In the eleven cases (10 tracks, before the tracks and data agreed, that tropical storm would remain the peak intensity, and 1 complete miss), peak intensity ranged between Category -2 and Category 3. Average was Category 0.45 and median was Category 0.

In the ten tracks (made before operationally recognized degeneration), dissipation times ranged between October 2, 18Z and October 9, 06Z. Average was October 5, 22Z and median was October 5, 09Z.

At the lead time of 1 day (24 hours), there were 1 hit, 0 false detections and 0 misses. 1 available position comparison produces an average error of 33 nautical miles.

At the lead time of 2 days (48 hours), there were 1 hit, 0 false detections and 2 misses. 1 available position comparison produces an average error of 56 nautical miles.

At the lead time of 3 days (72 hours), there were 2 hits, 1 false detection and 0 misses. 2 available position comparisons produce an average error of 21 nautical miles.

At the lead time of 4 days (96 hours), there were 2 hits, 1 false detection and 1 miss. 2 available position comparisons produce an average error of 73 nautical miles.

At the lead time of 5 days (120 hours), there were 2 hits, 1 false detection and 1 miss. 2 available position comparisons produce an average error of 221 nautical miles.

At the lead time of 6 days (144 hours), there were 2 hits, 1 false detection and 0 misses. 2 available position comparisons produce an average error of 249 nautical miles.

At the lead time of 7 days (168 hours), there were 3 hits, 1 false detection and 0 misses. 3 available position comparisons produce an average error of 301 nautical miles.

At the lead time of 8 days (192 hours), there were 1 hit, 1 false detection and 2 misses. 1 available position comparison produces an average error of 121 nautical miles.

At the lead time of 9 days (216 hours), there were 1 hit, 2 false detections and 2 misses. 1 available position comparison produces an average error of 342 nautical miles.

At the lead time of 10 days (240 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 354 nautical miles.

At the lead time of 11 days (264 hours), there were 0 hits, 0 false detections and 3 misses. No available position comparisons.

At the lead time of 12 days (288 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 506 nautical miles.

At the lead time of 13 days (312 hours), there were 1 hit, 0 false detections and 0 misses. 1 available position comparison produces an average error of 489 nautical miles.

At the lead time of 14 days (336 hours), there were 0 hits, 0 false detections and 1 miss. No available position comparisons.

At the lead time of 15 days (360 hours), there were 0 hits, 0 false detections and 0 misses. No available position comparisons.

At the lead time of 16 days (384 hours), there were 0 hits, 1 false detection and 0 misses. 1 available position comparison produces an average error of 241 nautical miles.

At the lead time of 17 days (408 hours), there were 0 hits, 0 false detections and 1 miss. No available position comparisons.

At the lead time of 18 days (432 hours), there were 0 hits, 1 false detection and 1 miss. No available position comparisons.

At the lead time of 19 days (456 hours), there were 0 hits, 1 false detection and 1 miss. 1 available position comparison produces an average error of 181 nautical miles.

At the lead time of 20 days (480 hours), there were 0 hits, 1 false detection and 0 misses. 1 available position comparison produces an average error of 193 nautical miles.

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