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)
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: PRAPIROON Identifier: 07W
Basin: NORTH-WEST PACIFIC
Start date: 31.07.2006 End date: 04.08.2006
1-minute MSW: 70 knots 10-minute MSW: 70knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
There was a left-of-track bias in forecasts resulting in track forecast errors above last season's average. The model showed skill over CLIPER only at T+72.
Name: FABIO Identifier: 07E
Basin: NORTH-EAST PACIFIC
Start date: 31.07.2006 End date: 03.08.2006
1-minute MSW: 45 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NEP basin
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A plot of the depression's observed track |
Fabio was only briefly a tropical storm and just two forecasts were verified.
Name: CHRIS Identifier: 03L
Basin: NORTH ATLANTIC
Start date: 01.08.2006 End date: 05.08.2006
1-minute MSW: 55 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NAT basin.
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Plot of the storm's observed track and forecasts |
The model tended to dissipate Chris too soon, although the dissipation did eventually occur. 24-hour forecasts had errors below last season's average.
Name: GILMA Identifier: 08E
Basin: NORTH-EAST PACIFIC
Start date: 01.08.2006 End date: 03.08.2006
1-minute MSW: 35 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NEP basin.
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Plot of the storm's observed track and forecasts |
Gilma was only briefly a tropical storm and no forecasts were verified.
Name: SAOMAI Identifier: 08W
Basin: NORTH-WEST PACIFIC
Start date: 04.08.2006 End date: 10.08.2006
1-minute MSW: 140 knots 10-minute MSW: 95 knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
Forecasts for Saomai had no significant biases. Track forecast errors were below last season's average. At lead times up to 72 hours, landfall predictions were a little too far to the north. Skill scores against CLIPER were good
Name: MARIA Identifier: 09W
Basin: NORTH-WEST PACIFIC
Start date: 05.08.2006 End date: 10.08.2006
1-minute MSW: 65 knots 10-minute MSW: 60 knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
The nature of the sharp turn in Maria's track just short of Japan was not well forecast, although recurvature was predicted. Hence, track forecast errors were slightly above last season's average. Skill was positive at T+24 and T+48.
Name: BOPHA Identifier: 10W
Basin: NORTH-WEST PACIFIC
Start date: 06.08.2006 End date: 10.08.2006
1-minute MSW: 50 knots 10-minute MSW: 50 knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
The southward turn of Bopha (due to interaction with Saomai) was well predicted by the model. Hence, track forecast errors were near to or below average and skill scores high.
Name: WUKONG Identifier: 11W
Basin: NORTH-WEST PACIFIC
Start date: 12.08.2006 End date: 20.08.2006
1-minute MSW: 50 knots 10-minute MSW: 50 knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
Forecasts for Wukong were complicated by interaction with and absorption of Sonamu. The model handled this reasonably well, with track forecast errors near to or below last season's average. Skill scores were very high.
Name: SONAMU Identifier: 12W
Basin: NORTH-WEST PACIFIC
Start date: 13.08.2006 End date: 16.08.2006
1-minute MSW: 45 knots 10-minute MSW: 40 knots
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* DPE for all storms in the 2005 season in the NWP basin.
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Plot of the storm's observed track and forecasts |
Name: HECTOR Identifier: 09E
Basin: NORTH-EAST PACIFIC
Start date: 15.08.2006 End date: 23.08.2006
1-minute MSW: 90 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NEP basin.
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Plot of the storm's observed track and forecasts |
Forecasts for Hector had a left-of-track bias which resulted in track errors being above last season's average at lead times of 72 hours and greater. Skill scores were positive.
Name: ILEANA Identifier: 10E
Basin: NORTH-EAST PACIFIC
Start date: 21.08.2006 End date: 27.08.2006
1-minute MSW: 105 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NEP basin.
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Plot of the storm's observed track and forecasts |
Forecasts for Ileana were very good in every respect. Track forecast errors were low, skill scores against CLIPER and for intensity were high.
Name: DEBBY Identifier: 04L
Basin: NORTH ATLANTIC
Start date: 21.08.2006 End date: 27.08.2006
1-minute MSW: 45 knots 10-minute MSW: -
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* DPE for all storms in the 2005 season in the NAT basin.
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Plot of the storm's observed track and forecasts |
Track forecast errors had a slow bias, which resulted in forecast errors at 48 and 72-hour lead times being high. There was no skill over CLIPER.
Name: - Identifier: 13W
Basin: NORTH -WEST PACIFIC
Start date: 24.08.2006 End date: 25.08.2006
1-minute MSW: 30 knots 10-minute MSW: -
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Plot of the storm's observed track and forecasts |
There are no verification statistics or forecast plot for this tropical cyclone since its 1-minute averaged winds did not reach tropical storm strength.
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: 13
Number of storms used in statistics below: 12
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* DPE for all northern hemisphere storms in 2005 season
Track forecast errors were near to or below last season's average for this month's storms. Skill scores against CLIPER were good. The overall intensity tendency skill score was 37%.
