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National Hurricane Center 2011 Forecast Verification. John P. Cangialosi and James L. Franklin Hurricane Specialist Unit National Hurricane Center NOAA Hurricane Conference 29 November 2011. Verification Rules.

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National Hurricane Center 2011 Forecast Verification

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National hurricane center 2011 forecast verification

National Hurricane Center 2011 Forecast Verification

John P. Cangialosi and James L. Franklin

Hurricane Specialist Unit

National Hurricane Center

NOAA Hurricane Conference

29 November 2011


Verification rules

Verification Rules

  • Verification rules unchanged for 2011. Results presented here are preliminary.

  • System must be a tropical or subtropical cyclone at both forecast initial time and verification time. All verifications include depression stage (including GPRA goals).

  • Special advisories ignored (original advisory is verified.

  • Skill baselines are recomputed after the season from operational compute data. Decay-SHIFOR5 is the intensity skill benchmark.


2011 atlantic verification

2011 Atlantic Verification

VT NT TRACK INT

(h) (n mi) (kt)

============================

000 392 9.7 1.7

012 354 29.3 5.8

024 311 45.7 9.3

036 273 61.2 11.6

048 237 74.2 13.7

072 187 110.6 16.5

096 151 169.5 17.0

120 127 253.1 18.1

Values in green exceed all-time records.

48 h error GPRA targets

Track: 87 n mi (met)

Intensity: 13 kt (missed)

So what else is new?


Atlantic track errors vs 5 yr mean

Atlantic Track Errors vs. 5-yr Mean

Official forecasts were better than the 5-year mean, though the season’s storms were “easier” than normal.


2011 track guidance

2011 Track Guidance

Official forecast skill very close to consensus aids (even a little better)

EMXI and GFSI best models overall.

GFS ensemble mean not as good as deterministic GFS.

Continued poor performance of GFNI and NGPI. Bad year for EGRI.

HWRF and GHMI middle of the pack.

BAMM beat both regional models at 96 and 120 h.


Atlantic track errors by storm

Atlantic Track Errors by Storm

Bret, Don, Irene, Katia,

Lee, Rina, Sean

successes

Struggled with Maria, Ophelia

214.8

174.2

133.2

89.5

50.6


Ophelia s reformation

Ophelia’s Reformation

120 h

forecast

Verifying

position


Atlantic track biases

Atlantic Track Biases

North

VT% of total error

24 h 20%

48 h 32%

72 h 34%

96 h 31%

120 h 34%

120 h

96 h

72 h

48 h

West

East

24 h

South


Atlantic intensity errors vs 5 yr mean

Atlantic Intensity Errors vs. 5-yr Mean

Official forecast errors were a little better than the five-year mean but the season’s storm were easier to forecast than normal.


2011 intensity guidance

2011 Intensity Guidance

No operational aid was skillful at or beyond 72 h.

Dynamical models performed very poorly.

LGEM was best individual model overall.


Atlantic intensity bias

Atlantic Intensity Bias

VT% of total error

24 h 12%

48 h 16%

72 h 16%

96 h 25%

120 h 27%


2011 east pacific verification

2011 East Pacific Verification

VT NT TRACK INT

(h) (n mi) (kt)

============================

000 236 7.8 1.6

012 214 25.5 6.6

024 195 40.5 11.2

036 177 53.2 13.6

048 157 69.6 14.8

072 119 106.8 17.1

096 87 158.8 19.2

120 57 176.3 17.1

Values in green exceeded all-time lows.


E pacific track errors vs 5 yr mean

E. Pacific Track Errors vs. 5-yr Mean

Even though the season’s storms were much harder than normal to forecast, the official forecast errors were still lower than the 5-year mean.


E pacific intensity errors vs 5 yr mean

E. Pacific Intensity Errors vs. 5-yr Mean

Official forecasts were about the same as the 5-year mean, even though the season’s storms were quite a bit harder than normal.


2011 track guidance1

2011 Track Guidance

Official forecasts near the TVCE and FSSE.

EMXI best model in this basin too.

GFS ensemble mean is quite skillful and better than the deterministic GFS.

EGRI and NGPI performed well in the EPAC.

GHMI middle of the pack, HWRF trails.

BAMS and BAMM beat the regional models at 96 and 120 h.


2011 intensity guidance1

2011 Intensity Guidance

Official forecasts performed better than most of the guidance.

Good year for GFNI, much better than GHMI and HWFI.

Statistical and consensus models are pretty close.


2011 genesis forecast verification

2011 Genesis Forecast Verification

Atlantic

East Pacific

Atlantic forecasts well calibrated throughout. Much improved this year.

Some progress made in reducing the east Pacific under-forecast bias.


Summary

Summary

  • Track and intensity forecasts in both basins were better than their long-term means. In the East Pacific, these forecasts were better than what would have been expected based on forecast difficulty.

  • EMXI is the best model in both basins. GFS ensemble mean was a good performer in the East Pacific.

  • Numerical guidance for intensity had little or no skill, particularly in the Atlantic. Regional hurricane models (GHMI and HWFI) were disappointing.

  • Genesis forecasts improved (especially in the Atlantic).


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