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: ELITA Identifier: 09S
Basin: SOUTH-WEST INDIAN
Start date: 26.01.2004 End date: 04.02.2004
1-minute MSW: 65 knots 10-minute MSW: 60 knots
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DPE for all storms in the 2002-3 season in the SWI basin
A plot of the storm's observed track and forecasts.
Elita was an unusual storm in that it crossed Madagascar three times, weakening over land and strengthening over sea as it went. The unusual track was generally well predicted by the Met Office model. In detail, forecast errors ate T+24 and 48 were above last season's average, but longer range forecasts had lower errors. Skill scores against CLIPER were very high, which would be expected for such an unusual track.
Name: FRANK Identifier: 10S
Basin: SOUTH-WEST INDIAN
Start date: 27.01.2004 End date: 07.02.2004
1-minute MSW: 125 knots 10-minute MSW: 105 knots
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DPE for all storms in the 2002-3 season in the SWI basin
A plot of the storm's observed track and forecasts.
Tropical Cyclone Frank did not take a straightforward track as it stalled and executed a tight loop before accelerating, then taking a sharp southward turn. The model predicted some, but not all of these twists and turns. Forecast errors were generally above last season's average. The model had a slow and right-of-track bias. Skill scores against CLIPER were fairly high.
Name: LINDA Identifier: 11S
Basin: AUSTRALIAN (SE Indian)
Start date: 29.01.2004 End date: 01.02.2004
1-minute MSW: 45 knots 10-minute MSW: 55 knots
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DPE for all storms in the 2002-3 season in the AUS basin
A plot of the storm's observed track and forecasts.
Tropical Storm Linda was a tropical storm for a relatively short period of time and forecast errors were below last season's average. Skill against CLIPER was only shown at T+48.
Name: FRITZ Identifier: 12P
Basin: AUSTRALIAN (Coral Sea)
Start date: 10.02.2004 End date: 12.02.2004
1-minute MSW: 35 knots 10-minute MSW: 45 knots
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DPE for all storms in the 2002-3 season in the AUS basin
A plot of the storm's observed track and forecasts.
Tropical Storm Fritz spent as much time over land as over water as it crossed from Coral Sea into the Gulf of Carpentaria. The few forecasts made were very good with low errors and high skill.
Name: - Identifier: 01W
Basin: NORTH-WEST PACIFIC
Start date: 11.02.2004 End date: 16.02.2004
1-minute MSW: 45 knots 10-minute MSW: 30 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.
01W briefly attained tropical storm status according to JTWC, but not JMA. No forecasts were verified.
Name: IVY Identifier: 13P
Basin: AUSTRALIAN (SW Pacific)
Start date: 22.02.2004 End date: 29.02.2004
1-minute MSW: 110 knots 10-minute MSW: 90 knots
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DPE for all storms in the 2002-3 season in the AUS basin
A plot of the storm's observed track and forecasts.
Forecast errors for Tropical Cyclone Ivy were near to or below last season's average. Skill scores were very high. There was a slight slow and right-of-track bias. The acceleration and extra-tropical transition of the cyclone were generally well handled.
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:- 6
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* Best track DPE for all Southern Hemisphere storms in 2002-3 season
In terms of track forecast errors, this month's performance was a little worse than last year's average except at T+24 and T+96. However, a couple of storms had unusual tracks and the skill scores against CLIPER indicate that the model performed very well. There was a slow and right-of-track bias in forecasts. The overall intensity tendency skill score this month was 26%.