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.
2.1 Individual Tropical Cyclone Summaries
Name: LOLA Identifier: -
Basin: AUSTRALIAN (South-East Pacific)
Start date: 31.01.2005 End date: 01.02.2005
1-minute MSW: - knots 10-minute MSW: 40 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot of the storm's observed track and forecasts.
Lola was a short-lived storm and only one forecast was verified. JTWC did not assign an identifier to this storm.
Name: GERARD Identifier: 14S
Basin: SOUTH-WEST INDIAN
Start date: 03.02.2005 End date: 05.02.2005
1-minute MSW: 60 knots 10-minute MSW: 60 knots
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* DPE for all storms in the 2003-4 season in the SWI basin
A plot of the storm's observed track and forecasts.
Just two forecasts were verified for this storm. These forecasts had a slow bias resulting in large track forecast errors.
Name: MEENA Identifier: 15P
Basin: AUSTRALIAN (South-East Pacific)
Start date: 03.02.2005 End date: 07.02.2005
1-minute MSW: 125 knots 10-minute MSW: 115 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot of the storm's observed track and forecasts.
The track and acceleration of Meena were well predicted by the model. Track forecast errors were low compared to last season.
Name: HARVEY Identifier: 16P
Basin: AUSTRALIAN (Gulf of Carpentaria)
Start date: 06.02.2005 End date: 07.02.2005
1-minute MSW: 50 knots 10-minute MSW: 85 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot of the storm's observed track and forecasts.
Just two forecasts were verified for this storm before it made landfall. Track forecast errors were very low.
Name: VIVIENNE Identifier: 17S
Basin: AUSTRALIAN (South-East Indian)
Start date: 07.02.2005 End date: 08.02.2005
1-minute MSW: 35 knots 10-minute MSW: 45 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot
of the storm's observed track and forecasts.
Vivienne only briefly reached tropical storm status and no forecasts were verified.
Name: NANCY Identifier: 18P
Basin: AUSTRALIAN (South-East Pacific)
Start date: 12.02.2005 End date: 17.02.2005
1-minute MSW: 125 knots 10-minute MSW: 110 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot of the storm's observed track and forecasts.
Early forecasts for TC Nancy had a right-of-track bias. Later forecasts did well in predicting the interaction with and absorption by TC Olaf.
Name: OLAF Identifier: 19P
Basin: AUSTRALIAN (South-East Pacific)
Start date: 13.02.2005 End date: 20.02.2005
1-minute MSW: 145 knots 10-minute MSW: 125 knots
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* DPE for all storms in the 2003-4 season in the AUS basin
A plot of the storm's observed track and forecasts.
The direction of motion of TC Olaf was well predicted, but there was a very large slow bias resulting in track forecast errors well above last season's average.
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:- 7
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* DPE for all Southern Hemisphere storms in 2003-4 season
Comments:
Overall, track forecast errors were above last season's average for the southern hemisphere. There was a slow and right-of-track bias in forecasts. The overall intensity tendency skill score was 17%.
