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 0.83°x 0.55°x 38 levels. This is equivalent to a horizontal resolution of 93km x 62km at the equator.
Click here for details of the TC verification technique and an explanation of error statistics and their sign conventions.
2.1 Individual Tropical Cyclone Summaries
Name: MINDULLE Identifier: 10W
Basin: NORTH-WEST PACIFIC
Start date: 23.06.2004 End date: 04.07.2004
1-minute MSW: 125 knots 10-minute MSW: 90 knots
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* DPE for all storms in the 2003 season in the NWP basin
A plot of the storm's observed track and forecasts.
Forecast errors fluctuated either side of last season's average for this storm. Early forecasts were very good , but then the model failed to pick up on the sharp northward turn towards Taiwan at an early stage, so producing some large errors. The model showed modest skill over CLIPER at T+24 and T+48 and there was a left-of-track bias in forecasts.
Name: TINGTING Identifier: 11W
Basin: NORTH-WEST PACIFIC
Start date: 25.06.2004 End date: 04.07.2004
1-minute MSW: 75 knots 10-minute MSW: 85 knots
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* DPE for all storms in the 2003 season in the NWP basin
A plot of the storm's observed track and forecasts.
The direction of motion of this storm was very well forecast, although the model had a slow bias. Forecast errors were below last season's at all lead times except T+72. Skill scores against CLIPER were good.
Name: - Identifier: 02E
Basin: NORTH-EAST PACIFIC
Start date: 02.07.2004 End date: 03.07.2004
1-minute MSW: 25 knots 10-minute MSW: -
A plot of the storm's observed track.
There are no verification statistics or forecast plot for this tropical cyclone since its 1-minute averaged winds did not reach tropical storm strength.
Name: - Identifier: 01C
Basin: NORTH-EAST PACIFIC (Central)
Start date: 05.07.2004 End date: 05.07.2004
1-minute MSW: 25 knots 10-minute MSW: -
A plot of the storm's observed track.
There are no verification statistics or forecast plot for this tropical cyclone since its 1-minute averaged winds did not reach tropical storm strength.
Name: BLAS Identifier: 03E
Basin: NORTH-EAST PACIFIC
Start date: 12.07.2004 End date: 15.07.2004
1-minute MSW: 50 knots 10-minute MSW: -
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* DPE for all storms in the 2003 season in the NEP basin
A plot of the storm's observed track and forecasts.
Only a couple of T+24 forecasts were verified for this storm. These had a slow bias resulting in large forecast errors, although skill scores were still good.
Name: KOMPASU Identifier: 12W
Basin: NORTH-WEST PACIFIC
Start date: 13.07.2004 End date: 16.07.2004
1-minute MSW: 45 knots 10-minute MSW: 45 knots
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* DPE for all storms in the 2003 season in the NWP basin
A plot of the storm's observed track and forecasts.
The model again had a slow bias for this storm, so was too late in its prediction of landfall. T+24 errors were near to last season's average.
Name: CELIA Identifier: 04E
Basin: NORTH-EAST PACIFIC
Start date: 19.07.2004 End date: 25.07.2004
1-minute MSW: 70 knots 10-minute MSW: - knots
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* DPE for all storms in the 2003 season in the NEP basin
A plot of the storm's observed track and forecasts.
Track forecast errors were low for this hurricane - particularly up to T+72. Skill scores against CLIPER were high and biases small. The intensity tendency skill scores were also high.
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:- 7
Number of storms used in statistics below:- 5
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* DPE for all Northern Hemisphere storms in 2003 season
Comments:
Overall, track forecast errors were near to last season's average for this month's storms. A modest amount of skill was shown over CLIPER and there was a slow bias in forecasts. The intensity tendency skill score for the month's storms was 39%.
