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 which 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 0.83°x 0.55°x 39 levels. This is equivalent to a horizontal resolution of 93km x 62km at the equator.
2.1 Individual Tropical Cyclone Summaries
Name: MORAKOT Identifier: 10W
Basin: NORTH-WEST PACIFIC
Start date: 01.08.2003 End date: 05.08.2003
1-minute MSW: 65 knots 10-minute MSW: 45 knots
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* DPE for all storms in the 2002 season in the NWP basin
A plot of the storm's observed track and forecasts.
Only a few forecasts were verified for this typhoon. Track forecast errors were above last season's average at T+24 and near to average at T+48. The model showed skill over CLIPER at T+48 only.
Name: ETAU Identifier: 11W
Basin: NORTH-WEST PACIFIC
Start date: 03.08.2003 End date: 09.08.2003
1-minute MSW: 110 knots 10-minute MSW: 80 knots
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* DPE for all storms in the 2002 season in the NWP basin
A plot of the storm's observed track and forecasts.
Despite having a right-of-track and slow bias during its early stages, forecasts for this typhoon were very good, with the recurvature and landfall generally well predicted. The model showed high levels of skill against CLIPER.
Name: GUILLERMO Identifier: 07E
Basin: NORTH-EAST PACIFIC
Start date: 07.08.2003 End date: 13.08.2003
1-minute MSW: 50 knots 10-minute MSW: -
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* DPE for all storms in the 2002 season in the NEP basin
A plot of the storm's observed track and forecasts.
Guillermo was only a tropical storm for a brief period. Forecast errors at T+24 and T+48 were above last season's average, although skill scores were positive at T+48. There was a right-of-track bias in forecasts.
Name: HILDA Identifier: 08E
Basin: NORTH-EAST PACIFIC
Start date: 09.08.2003 End date: 13.08.2003
1-minute MSW: 35 knots 10-minute MSW: -
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* DPE for all storms in the 2002 season in the NEP basin
A plot of the storm's observed track and forecasts.
Hilda was only briefly a tropical storm. T+24 forecast errors were above last season's average.
Name: ERIKA Identifier: 08L
Basin: NORTH ATLANTIC
Start date: 14.08.2003 End date: 17.08.2003
1-minute MSW: 65 knots 10-minute MSW: -
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* DPE for all storms in the 2002 season in the NAT basin
A plot of the storm's observed track and forecasts.
Only two forecasts were verifiable as Erika raced across the Gulf of Mexico towards landfall. Errors were lower than last season's average for these forecasts. Although recorded only as a tropical storm in 6-hourly advisories issued by the National Hurricane Center, it has been recorded here as a hurricane due to comments made in one of these advisories that hurricane status was probably reached at landfall.
Name: KROVANH Identifier: 12W
Basin: NORTH-WEST PACIFIC
Start date: 15.08.2003 End date: 26.08.2003
1-minute MSW: 90 knots 10-minute MSW: 65 knots
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* DPE for all storms in the 2002 season in the NWP basin
A plot of the storm's observed track and forecasts.
Krovanh formed from tropical depression 12W which had dissipated a few days earlier. There was a right-of-track bias in forecasts, but track errors were low and skill scores high on the whole. Landfall over southern China was well predicted up to three days in advance.
Name: - Identifier: 01C
Basin: NORTH-EAST PACIFIC (Central)
Start date: 15.08.2003 End date: 17.08.2003
1-minute MSW: 30 knots 10-minute MSW: -
There are no verification statistics or forecast plot for this tropical cyclone since its 1-minute averaged winds did not reach tropical storm strength.
A plot of the depression's observed track.
Name: VAMCO Identifier: 13W
Basin: NORTH-WEST PACIFIC
Start date: 19.08.2003 End date: 20.08.2003
1-minute MSW: 35 knots 10-minute MSW: 35 knots
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* DPE for all storms in the 2002 season in the NWP basin
A plot of the storm's observed track and forecasts.
Vamco only briefly reached tropical storm status and no forecasts were verified.
Name: - Identifier: 09L
Basin: NORTH ATLANTIC
Start date: 21.08.2003 End date: 22.08.2003
1-minute MSW: 30 knots 10-minute MSW: -
There are no verification statistics or forecast plot for this tropical cyclone since its 1-minute averaged winds did not reach tropical storm strength.
A plot of the depression's observed track.
Name: IGNACIO Identifier: 09E
Basin: NORTH-EAST PACIFIC
Start date: 22.08.2003 End date: 27.08.2003
1-minute MSW: 90 knots 10-minute MSW: -
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* DPE for all storms in the 2002 season in the NEP basin
A plot of the storm's observed track and forecasts.
Track forecast errors were below last season's average for this hurricane and skill scores positive at T+48 and T+72. Intensity skill scores were also very good.
Name: GRACE Identifier: 11L
Basin: NORTH ATLANTIC
Start date: 30.08.2003 End date: 31.08.2003
1-minute MSW: 35 knots 10-minute MSW: -
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* DPE for all storms in the 2002 season in the NAT basin
A plot of the storm's observed track and forecasts.
Grace only briefly reached tropical storm status and no forecasts were verified.
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:- 11
Number of storms used in statistics below:- 9
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* DPE for all Northern Hemisphere storms in 2002 season
Track forecast errors were low for this month's storms as a whole compared to last season and skill scores were high. There was a slow and right-of-track bias overall. The average intensity tendency skill score for the month was 13%.
