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 0.5625°x 0.375°x 50 levels. This is equivalent to a horizontal resolution of 62km x 42km at the equator.
Verification technique and an explanation of error statistics and their sign conventions
2.1 Individual Tropical Cyclone Summaries
Name: CARINA Identifier: 14S
Basin: SOUTH-WEST INDIAN
Start date: 23.02.2006 End date: 03.03.2006
1-minute MSW: 130 knots 10-minute MSW: 115 knots
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* DPE for all storms in the 2004-5 season in the SWI basin
A plot of the storm's observed track and forecasts.
Track forecast errors for this storm were either near to or above last season's average. Some forecasts had an erroneous westward turn, which resulted in large errors. No skill against CLIPER was shown.
Name: DIWA Identifier: 16S
Basin: SOUTH-WEST INDIAN
Start date: 03.03.2006 End date: 03.03.2006
1-minute MSW: 55 knots 10-minute MSW: 55 knots
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* DPE for all storms in the 2004-5 season in the SWI basin
A plot of the storm's observed track and forecasts.
Forecast errors were below last season's average at short lead times, but above average at longer lead times. There were slow and right-of-track biases at longer lead times. The model showed good skill over CLIPER.
Name: - Identifier: 01W
Basin: NORTH-WEST PACIFIC
Start date: 04.03.2006 End date: 07.03.2006
1-minute MSW: 35 knots 10-minute MSW: 30 knots
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* DPE for all storms in the 2005 season in the NWP basin
A plot of the storm's observed track and forecasts.
01W was a short-lived storm and just one forecast was verified.
Name: LARRY Identifier: 17P
Basin: AUSTRALIAN (Coral Sea)
Start date: 17.03.2006 End date: 20.03.2006
1-minute MSW: 100 knots 10-minute MSW: 100 knots
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* DPE for all storms in the 2004-5 season in the AUS basin
A plot of the storm's observed track and forecasts.
Larry developed into a tropical cyclone just two days before landfall, but was a strong cyclone causing much damage. Track forecasts were a little slow and predicted landfall further south than actually occurred. However, the skill of the 24-hour track forecast was high and the 48-hour error was below last season's average.
Name: WATI Identifier: 18P
Basin: AUSTRALIAN (Coral Sea)
Start date: 19.03.2006 End date: 25.03.2006
1-minute MSW: 80 knots 10-minute MSW: 85 knots
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* DPE for all storms in the 2004-5 season in the AUS basin
A plot of the storm's observed track and forecasts.
Wati followed hard on the heels of Larry and initially headed in the same direction. However, the cyclone slowed dramatically and made a sharp turn to the south-east. Whilst forecasts were not perfect and errors were near to last season's average, this turn was very well handled by the model in general. Skill scores against CLIPER were good.
Name: FLOYD Identifier: 19S
Basin: AUSTRALIAN (SE Indian)
Start date: 20.03.2006 End date: 27.03.2006
1-minute MSW: 115 knots 10-minute MSW: 100 knots
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* DPE for all storms in the 2004-5 season in the AUS basin
A plot of the storm's observed track and forecasts.
Forecasts for Floyd were exceptionally poor. The model persisted with a westerly movement, whereas the cyclone turned south and later south-east. This persistent failing resulted in very large track forecast errors, particularly at longer lead times.
Name: GLENDA Identifier: 20S
Basin: AUSTRALIAN (SE Indian)
Start date: 27.03.2006 End date: 31.03.2006
1-minute MSW: 140 knots 10-minute MSW: 115 knots
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* DPE for all storms in the 2004-5 season in the AUS basin
A plot of the storm's observed track and forecasts.
In contrast to Floyd, Glenda was generally well handled by the model with low forecast errors and high skill scores.
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 2004-5 season
Comments:
This month saw a mixture of good and bad forecasts, which resulted overall
in track forecast errors near to average at short lead times, but above
average at longer lead times. There was a slow bias in forecasts. The
overall intensity tendency skill score was 49%.
