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
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.
2.1 Individual Tropical Cyclone Summaries
Name: PERCY Identifier: 20P
Basin: AUSTRALIAN (SE Pacific)
Start date: 25.02.2005 End date: 04.03.2005
1-minute MSW: 140 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.
Track forecast errors were below last season's average for this cyclone. The turn southwards was well predicted on the whole, although longer lead time forecasts were a little fast.
Name: RAE Identifier: 21P
Basin: AUSTRALIAN (SE Pacific)
Start date: 05.03.2005 End date: 06.03.2005
1-minute MSW: 35 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 analysis.
Rae was very short-lived as a tropical storm and no forecasts were verified.
Name: INGRID Identifier: 22P
Basin: AUSTRALIAN (Coral Sea to Timor Sea)
Start date: 06.03.2005 End date: 16.03.2005
1-minute MSW: 135 knots 10-minute MSW: 120 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.
Cyclone Ingrid was an intense storm passing over or close to many areas of Northern Australia. Track forecast errors were well below last season's average and skill scores were very high. There was a slow bias in forecasts and southward turn which occurred near the end of Ingrid's life was predicted to occur too early in some forecasts.
Name: WILLY Identifier: 23S
Basin: AUSTRALIAN (SE Indian)
Start date: 09.03.2005 End date: 14.03.2005
1-minute MSW: 90 knots 10-minute MSW: 75 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.
Track forecast errors were low and skill scores high for this storm. The model had the distinction of having 100% skill in the prediction of intensity tendency.
Name: ROKE Identifier: 02W
Basin: NORTH-WEST PACIFIC
Start date: 13.03.2005 End date: 17.03.2005
1-minute MSW: 65 knots 10-minute MSW: 55 knots
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* DPE for all storms in the 2004 season in the NWP basin
A plot of the storm's observed track and forecasts.
The track of Roke was well predicted by the model with low forecast errors and very high skill scores.
Name: HENNIE Identifier: 24S
Basin: SOUTH-WEST INDIAN
Start date: 22.03.2005 End date: 27.03.2005
1-minute MSW: 65 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.
Track forecast errors were below or near to average for this storm at all lead times except T+96. This one poor forecast erroneously took the storm westwards. Skill scores were positive at T+24 and T+48. There was a right-of-track bias in forecasts.
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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* DPE for all Southern Hemisphere storms in 2003-4 season
Comments :
March was a good month for track forecasting with errors below last season's average and skill scores high. There were no significant forecast biases. The overall intensity tendency skill score was 18%.