1. Tropical cyclone activity
1.1 Tropical cyclones ending during the month
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Basin name abbreviations:
NWP : North-west Pacific (west of 180° E)
NEP : North-east Pacific (east of 180° E)
NAT : North Atlantic
NI : North Indian (west of Malay Peninsula)
SWI: South-west Indian (west of 90° E)
AUS: Australian (east of 90° E)
1-minute MSW: Maximum sustained wind (knots) averaged over 1
minute (JTWC Hawaii, NHC Miami, CPHC Hawaii)
10-minute MSW: Maximum sustained wind (knots) averaged over 10
minutes (JMA Japan, Southern Hemisphere RSMCs and TCWCs)
Note: Although 1-minute average winds should be stronger than
10-minute average, this may not be the case here since estimates are
obtained from different warning centres.
1.2 Tropical cyclones still active at the end of the month
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2. Forecast error statistics
The Met Office global Numerical Weather Prediction model produces a 6-day forecast every 12 hours. The performance of the model in forecasting this month's tropical cyclones is assessed below. Mean error statistics for each storm that ended during the month are presented together with a final table of statistics for all storms ending this month. Verification is performed at 24 hour intervals up to forecast time T+120. Some mean error statistics for last year's storms are included for the purposes of a comparison. The present global model has a resolution of 0.5625°x 0.375°x 50 levels. This is equivalent to a horizontal resolution of 62km x 42km at the equator.
2.1 Individual tropical cyclone summaries
Name: DORA Identifier: 10S
Basin: SOUTH-WEST
INDIAN
Start date: 28.01.2007 End
date: 09.02.2007
1-minute MSW: 115 knots
10-minute MSW: 105 knots
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* DPE for all storms in the 2005-6 season in the SWI basin
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Plot of the storm's observed track and forecasts |
The model failed to predict the leftward turn early in the storm’s life. Having shown some skill in predicting the subsequent rightward turn, it again failed to predict the final leftward turn. The consequence of this was track forecast errors much higher than last season’s values and no skill against CLIPER.
Name: - Identifier: 11P
Basin: AUSTRALIAN
(S Pacific)
Start date: 04.02.2007 End
date: 05.02.2007
1-minute MSW: 35 knots 10-minute
MSW: 30 knots
There are no verification statistics or forecast plot for this tropical cyclone since its 10-minute averaged winds did not reach tropical storm strength.
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Plot of the storm's observed track and forecasts |
Name: NELSON Identifier: 12P
Basin: AUSTRALIAN (Gulf of Carpentaria)
Start date: 06.02.2007 End date: 07.02.2007
1-minute MSW: 45 knots 10-minute MSW: 55 knots
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* DPE for all storms in the 2005-6 season in the AUS basin
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Plot of the depression's observed track and forecasts |
Nelson was only briefly a tropical storm and just one forecast was verified.
Name: ENOK Identifier: 13S
Basin: SOUTH-WEST INDIAN
Start date: 09.02.2007 End date: 11.02.2007
1-minute MSW: 55 knots 10-minute MSW: 60 knots
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* DPE for all storms in the 2005-6 season in the SWI basin
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Plot of the storm's observed track and forecasts |
Enok was only briefly a tropical storm and just one forecast was verified.
Name: FAVIO Identifier: 14S
Basin:
SOUTH-WEST INDIAN
Start date: 14.02.2007 End date: 23.02.2007
1-minute
MSW: 125 knots 10-minute MSW: 100 knots
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* DPE for all storms in the 2005-6 season in the SWI basin
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Plot of the depression's observed track and forecasts |
Track forecast errors were near to average for Favio. The model did a fairly good job in predicting the gentle curve of the track around the southern tip of Madagascar and the turn north-westwards towards Mozambique. Skill scores against CLIPER were high. Predicting the precise location of landfall was made harder by the oblique angle of approach to the coast. However, the model gave an early and consistent indication of the threat to Mozambique posed by this strong cyclone.
Name: HUMBA Identifier: 16S
Basin:
SOUTH-WEST INDIAN
Start date: 21.02.2007 End date: 27.02.2007
1-minute
MSW: 70 knots 10-minute MSW: 75 knots
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* DPE for all storms in the 2005-6 season in the SWI basin
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Plot of the storm's observed track and forecasts |
Forecasts for Humba were good – track forecast errors were below last season’s average and skill scores were positive.
2.2 Summary of all tropical cyclones
Mean error statistics for all tropical cyclones (of at least tropical storm strength) which have ended this month are shown below.
Total number of depressions ending this month: 6
Number of storms used in statistics below: 5
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* DPE for all southern hemisphere storms in 2005-06 season
Comments:
Dora was the longest lived storm of the month and due to the poor results
for this storm the figures for the month as a whole are also poor.
Track forecast errors were above last season’s average, although
skill scores against CLIPER were modestly positive. The overall intensity
tendency skill score was 17%.
