Verification of tracks made of Grace

I made one track of Hurricane Grace, before it was assessed as a tropical cyclone. I made one more track after cyclogenesis. Additionally, within 504 hours of cyclogenesis, there were twelve instances, when I missed cyclogenesis entirely.

Marty will be considered continuation of Grace for position error calculations - however, it will not be considered Grace for calculation of hits, misses and false detections.

As of this analysis, best track positions for Grace, as well as best track / tropical cyclone report positions for Marty, are available August 9, 18Z thru August 27, 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 one track (made before operationally recognized cyclogenesis), range, average and median of formation times was August 17, 06Z.

In the 14 cases (2 tracks, before the tracks and data agreed, that Category 3 would remain the peak intensity, and 12 complete misses), peak intensity ranged between Category -2 and  Category 4. Average was Category -1.43 and median was Category -2.

In the two tracks (made before operationally recognized dissipation), dissipation times ranged between August 16, 12Z and August 26, 06Z. Average and median was August 21, 09Z.

At the lead time of 1 day (24 hours), there were 0 hits, 0 false detections and 1 miss. 1 available position comparison produces an average error of 44 nautical miles.

At the lead time of 2 days (48 hours), there were 0 hits, 0 false detections and 2 misses. 1 available position comparison produces an average error of 92 nautical miles.

At the lead time of 3 days (72 hours), there were 0 hits, 0 false detections and 2 misses. 1 available position comparison produces an average error of 138 nautical miles.

At the lead time of 4 days (96 hours), there were 0 hits, 0 false detections and 2 misses. 1 available position comparison produces an average error of 142 nautical miles.

At the lead time of 5 days (120 hours), there were 0 hits, 0 false detections and 2 misses. 1 available position comparison produces an average error of 220 nautical miles.

At the lead time of 6 days (144 hours), there were 1 hit, 0 false detections and 2 misses. 1 available position comparison produces an average error of 131 nautical miles.

At the lead time of 7 days (168 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 110 nautical miles.

At the lead time of 8 days (192 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 206 nautical miles.

At the lead time of 9 days (216 hours), there were 1 hit, 0 false detections and 1 miss. 1 available position comparison produces an average error of 345 nautical miles.

At the lead time of 10 days (240 hours), there were 1 hit, 0 false detections and 2 misses. 1 available position comparison produces an average error of 536 nautical miles.

At the lead time of 11 days (264 hours), there were 0 hits, 1 false detection and 3 misses. 1 available position comparison produces an average error of 884 nautical miles.

At the lead time of 12 days (288 hours), there were 0 hits, 1 false detection and 4 misses. 1 available position comparison produces an average error of 1064 nautical miles.

At the lead time of 13 days (312 hours), there were 0 hits, 1 false detection and 4 misses. 1 available position comparison produces an average error of 1233 nautical miles.

At the lead time of 14 days (336 hours), there were 0 hits, 1 false detection and 4 misses. 1 available position comparison produces an average error of 1304 nautical miles.

At the lead time of 15 days (360 hours), there were 0 hits, 0 false detections and 4 misses. No available position comparisons.

At the lead time of 16 days (384 hours), there were 0 hits, 0 false detections and 5 misses. No available position comparisons.

At the lead time of 17 days (408 hours), there were 0 hits, 0 false detections and 6 misses. No available position comparisons.

At the lead time of 18 days (432 hours), there were 0 hits, 0 false detections and 7 misses. No available position comparisons.

At the lead time of 19 days (456 hours), there were 0 hits, 0 false detections and 6 misses. No available position comparisons.

At the lead time of 20 days (480 hours), there were 0 hits, 0 false detections and 8 misses. No available position comparisons.

At the lead time of 21 days (504 hours), there were 0 hits, 0 false detections and 8 misses. No available position comparisons.

Circle coloration scheme

Here are the tracks once again.

August 11, 18Z:

August 15, 12Z:

The complete misses were from the following model cycles:

July 24, 00Z
July 24, 18Z
July 25, 12Z
July 26, 18Z
July 27, 12Z

July 27, 18Z
July 29, 12Z
July 30, 12Z
August 1, 18Z
August 3, 12Z

August 4, 12Z
August 7, 18Z