1. Tropical cyclone activity
1.1 Tropical cyclones ending during the month
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* In the absence of any official name or identifier for this TC, the Met Office used the unofficial identifier `01T `. The name `Catarina' was unofficially used by Brazilian meteorologists.
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)
SAT : South Atlantic
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
None
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: MONTY Identifier: 14S
Basin: AUSTRALIAN (SE Indian)
Start date: 27.02.2004 End date: 02.03.2004
1-minute MSW: 110 knots 10-minute MSW: 95 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 were below last season's average up to T+48, but above at T+72. This was due to early predictions of landfall and acceleration southwards. There was no skill over CLIPER.
Name: EVAN Identifier: 15P
Basin: AUSTRALIAN (Gulf of Carpentaria)
Start date: 01.03.2004 End date: 02.03.2004
1-minute MSW: 35 knots 10-minute MSW: 40 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.
Evan only briefly reached tropical storm status and no forecasts were verified.
Name: GAFILO Identifier: 16S
Basin: SOUTH-WEST INDIAN
Start date: 02.03.2004 End date: 13.03.2004
1-minute MSW: 140 knots 10-minute MSW: 130 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.
Gafilo was an intense cyclone which made landfall near the Madagascan town of Antalaha. It then crossed the island twice before dissipating. Forecast errors were near to or below last season's average and skill scores were high. The location of landfall was well predicted in all but one forecast.
Name: NICKY-HELMA Identifier: 17S
Basin: SOUTH-WEST INDIAN
Start date: 08.03.2004 End date: 13.03.2004
1-minute MSW: 70 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.
Nicky formed in the Australian basin and moved into the South-West
Indian basin where it was renamed Helma. For statistical purposes it
is considered a South-West Indian basin TC.
Forecast performance was mixed for this TC; relatively poor at T+24,
but good at T+48. At T+72 errors were above last season's average, but
the skill score was high.
Name: FAY Identifier: 18S
Basin: AUSTRALIAN (SE Indian)
Start date: 16.03.2004 End date: 28.03.2004
1-minute MSW: 120 knots 10-minute MSW: 110 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.
Whilst forecast errors at T+24 were below last season's average, at longer ranges they were above average. Skill scores were also poor. This was due to the model repeatedly predicting a track parallel to the North-West Australian coast, whereas the TC actually turned southwards and eventually made landfall. Consequently there was a right-of-track bias in forecasts.
Name: - Identifier: 02W
Basin: NORTH-WEST PACIFIC
Start date: 16.03.2004 End date: 22.03.2004
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.
Forecast errors were near to or below last season's average. Skill scores were high and there was a left-of-track bias resulting in some forecasts predicting interaction with The Philippines.
Name: GRACE Identifier: 19P
Basin: AUSTRALIAN (SW Pacific)
Start date: 21.03.2004 End date: 23.03.2004
1-minute MSW: 35 knots 10-minute MSW: 50 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.
Grace was fairly short-lived and just two forecasts were verified. Errors were above last season's average.
Name: OSCAR-ITSENG Identifier: 20S
Basin: AUSTRALIAN (SE Indian)
Start date: 23.03.2004 End date: 28.03.2004
1-minute MSW: 110 knots 10-minute MSW: 95 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.
Oscar formed in the Australian basin and moved into the South-West
Indian basin near the end of its life where it was renamed Itseng. For
statistical purposes it is considered as an Australian basin TC.
The model had a right-of-track bias and errors were higher than last
season's average at T+48 and T+72. The model did not show skill over
CLIPER.
Name: - Identifier: 21S
Basin: SOUTH-WEST INDIAN
Start date: 23.03.2004 End date: 24.03.2004
1-minute MSW: 30 knots 10-minute MSW: 30 knots
There are no verification statistics or forecast plot for this tropical
cyclone since its winds did not reach tropical storm strength.
A plot of the storm's observed track.
Name: - Identifier: 01T
Basin: SOUTH ATLANTIC
Start date: 24.03.2004 End date: 28.03.2004
1-minute MSW: 85 knots 10-minute MSW: -
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* DPE for all Southern Hemisphere storms in 2002-3 season
A plot of the storm's observed track and forecasts.
It is widely agreed that 01T (identifier used by the Met Office) was
the first ever recorded hurricane to occur in the South Atlantic. It
went by various unofficial names including `Catarina' as used by Brazilian
meteorologists.
Met Office forecasts used TC initialisation procedures for most of its
lifetime producing fairly accurate analyses and forecasts. Track forecast
errors were above last year's southern hemisphere average at T+24 and
T+48, but were below at T+72. Forecast tracks were a little slow and
some tended to erroneously turn the hurricane southwards.
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:- 10
Number of storms used in statistics below:- 9
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* Best track DPE for all Southern Hemisphere storms in 2002-3 season
Comments:
This month, track forecast errors were close to last season's average at short forecast ranges, but were above average at longer ranges. Small amounts of skill over CLIPER were shown at T+48 and T+72. Overall there was a slight fast bias and a tendency not to recurve soon enough. The intensity tendency skill score for the month was 17%.
