Verification of tracks made on Maria (2017) using GEFS mean fields



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Above: my predictions for September 20, 12Z, compared to actual position.

I made nine tracks about Hurricane Maria. Additionally, there were three cases, where I missed cyclogenesis. Forecast for peak intensity varied much between tracks, but generally it was with better skill than climatology. The paths taken by the hurricane were very variable, and position errors were generally not systematic.

My intensity analysis begin at September 10, 06Z, which is the earliest time, at which some of my tracks had cyclogenesis. Position analysis begins at first time with best track data, September 14, 00Z. Position analysis ends at last time with best track data, September 30, 18Z. Intensity analysis ends at October 10, 06Z, after which none of my tracks continued.

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 storms as "Category 0", tropical depressions as "Category -1" and non-existence of a tropical cyclone as "Category -2".

I compare intensities only in cases, when either the best track data or my track has a tropical cyclone, or both. In other words, I leave the comparison out of calculations, if both best track data and my track lack a tropical cyclone.

In the 9 tracks, formation times ranged between September 10, 06Z and September 20, 00Z. Median was September 18, 18Z and average was September 16, 08Z.

The 12 peak intensities (complete misses included) ranged between non-formation (Category -2) and Category 5. Median was Category 1 and average was Category 1.4.

Dissipation times ranged between September 22, 12Z and October 10, 12Z. Median was September 26, 06Z and average was September 27, 10Z.

The following lines will have the format:

date and time (UTC) yyyy/mm/dd/hh ... number of true detections ... number of misses ... number of false detections ... number of position comparisons ... number of intensity comparisons ... average error in intensity category ... bias in intensity category ... average error in latitude ... bias in latitude ... average error in longitude ... bias in longitude ... upper limit for scalar error in position (nautical miles)... calculated scalar bias in position (nautical miles)

Actual cyclogenesis:
2017/09/16/12 ... 3 ... 9 ... 0 ... 3 ... 12 ... 1.7 ... -1.3 ... 6.1 ... 5.6N ... 14.0 ... 14.0E ... 900 ... 890
Hitting Dominica:
2017/09/19/00 ... 6 ... 6 ... 0 ... 6 ... 12 ... 5.6 ... -5.6 ... 3.4 ... 1.6N ... 10.1 ... 8.9E ... 620 ... 530
Exiting Puerto Rico:
2017/09/20/18 ... 9 ... 3 ... 0 ... 9 ... 12 ... 2.3 ... -1.7 ... 3.5 ... 0.2N ... 10.0 ... 7.0E ... 610 ... 400
And for lead times:
168h ... 5 ... 4 ... 0 ... 5 ... 9 ... 3.7 ... -3.4 ... 2.0 ... 1.0S ... 1.5 ... 1.5W ... 150 ... 110
192h ... 6 ... 3 ... 2 ... 6 ... 11 ... 3.6 ... -2.5 ... 2.7 ... 0.5S ... 2.6 ... 1.2W ... 220 ... 80
216h ... 5 ... 4 ... 2 ... 5 ... 11 ... 3.7 ... -2.6 ... 3.7 ... 1.3S ... 3.9 ... 0.5W ... 310 ... 80
240h ... 5 ... 4 ... 2 ... 5 ... 11 ... 3.4 ... -2.3 ... 4.2 ... 2.2S ... 5.4 ... 1.1E ... 400 ... 150
264h ... 5 ... 4 ... 3 ... 6 ... 12 ... 3.2 ... -2.0 ... 2.3 ... 0.5S ... 7.7 ... 3.3E ... 460 ... 190
288h ... 4 ... 5 ... 3 ... 6 ... 12 ... 2.9 ... -1.9 ... 6.8 ... 0.1S ... 10.1 ... 3.1E ... 710 ... 180
312h ... 3 ... 6 ... 3 ... 6 ... 12 ... 2.7 ... -1.7 ... 7.3 ... 0.5S ... 9.9 ... 2.1E ... 730 ... 130
336h ... 3 ... 7 ... 2 ... 5 ... 12 ... 2.3 ... -1.3 ... 6.4 ... 0.9N ... 12.9 ... 4.7E ... 850 ... 280
360h ... 3 ... 8 ... 1 ... 4 ... 12 ... 2.1 ... -1.4 ... 6.4 ... 1.2N ... 12.0 ... 12.0E ... 800 ... 710
384h ... 4 ... 8 ... 0 ... 4 ... 12 ... 1.9 ... -1.6 ... 6.8 ... 1.1N ... 16.0 ... 11.5E ... 1020 ... 680
408h ... 3 ... 7 ... 1 ... 3 ... 11 ... 2.1 ... -1.5 ... 6.1 ... 3.9N ... 22.2 ... 22.2E ... 1350 ... 1320
432h ... 3 ... 5 ... 1 ... 3 ... 9 ... 2.0 ... -1.1 ... 5.7 ... 2.4N ... 26.0 ... 26.0E ... 1550 ... 1520
456h ... 3 ... 3 ... 1 ... 3 ... 7 ... 2.1 ... -1.3 ... 6.1 ... 1.1N ... 29.5 ... 29.5E ... 1760 ... 1720
480h ... 3 ... 1 ... 1 ... 3 ... 5 ... 2.2 ... -0.6 ... 6.2 ... 1.0N ... 32.9 ... 32.0E ... 1950 ... 1870

Here are the tracks once again.

September 1, 06Z run:
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September 2, 06Z run:
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September 3, 06Z run:
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September 12, 06Z run:
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September 12, 12Z run:
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September 13, 06Z run:
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September 13, 12Z run:
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September 14, 06Z run:
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September 14, 12Z run:
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The runs with complete misses were:

'September 10, 18Z
September 11, 06Z
September 11, 12Z

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