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
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: MATSA Identifier: 09W
Basin: NORTH-WEST PACIFIC
Start date: 31.07.2005 End date: 07.08.2005
1-minute MSW: 90 knots 10-minute MSW: 80 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.
Track forecast errors were below last season's average and skill scores were high for this typhoon. There was a slow bias in forecasts.
Name: HARVEY Identifier: 08L
Basin: NORTH ATLANTIC
Start date: 02.08.2005 End date: 08.08.2005
1-minute MSW: 55 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NAT basin
A plot of the storm's observed track and forecasts.
Forecast errors were below last season's average at all times except T+96. Skill scores were high. The north-eastward turn of the storm was fairly well predicted.
Name: - Identifier: 01C
Basin: NORTH-EAST PACIFIC (Central)
Start date: 02.08.2005 End date: 08.08.2005
1-minute MSW: 55 knots 10-minute MSW: - knots
There are no verification statistics or forecast plot for this tropical
cyclone since its 1-minute averaged winds did not reach tropical storm
strength.
A plot of the storm's observed track.
Name: IRENE Identifier: 09L
Basin: NORTH ATLANTIC
Start date: 04.08.2005 End date: 18.08.2005
1-minute MSW: 85 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NAT basin
A plot of the storm's observed track and forecasts.
Irene briefly became a tropical storm before being downgraded to a
tropical depression for a few days. It then regained tropical storm
and later hurricane strength. Just forecasts during the tropical storm
(or stronger) stage are verified.
Track forecast errors were low at short lead times, but above last season's
average at longer lead times. Skill scores were high and the recurvature
and acceleration of the hurricane were well forecast.
Name: FERNANDA Identifier: 06E
Basin: NORTH-EAST PACIFIC
Start date: 09.08.2005 End date: 16.08.2005
1-minute MSW: 75 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NEP basin
A plot of the storm's observed track and forecasts.
Forecasts for Fernanda were excellent with low track forecast errors. The west and south of west turn in the storm's track were well forecast.
Name: SANVU Identifier: 10W
Basin: NORTH-WEST PACIFIC
Start date: 10.08.2005 End date: 13.08.2005
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.
Sanvu was relatively short lived. Forecasts of landfall location were good. 24-hour forecast errors were above last season's average, but 48-hour forecasts had lower than average errors.
Name: GREG Identifier: 07E
Basin: NORTH-EAST PACIFIC
Start date: 11.08.2005 End date: 15.08.2005
1-minute MSW: 45 knots 10-minute MSW: - knots
Table of Mean Error Statistics
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* DPE for all storms in the 2004 season in the NEP basin
A plot of the storm's observed track and forecasts.
Forecast errors for Greg were low and skill scores high.
Name: - Identifier: 10L
Basin: NORTH ATLANTIC
Start date: 13.08.2005 End date: 14.08.2005
1-minute MSW: 30 knots 10-minute MSW: - knots
There are no verification statistics or forecast plot for this tropical
cyclone since its 1-minute averaged winds did not reach tropical storm
strength.
A plot of the storm's observed track.
Name: MAWAR Identifier: 11W
Basin: NORTH-WEST PACIFIC
Start date: 19.08.2005 End date: 27.08.2005
1-minute MSW: 130 knots 10-minute MSW: 95 knots
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* DPE for all storms in the 2004 season in the NAT basin
A plot of the storm's observed track and forecasts.
There was a slight right-of-track bias in forecasts for Mawar, but in general the track, including recurvature and landfall, were well predicted. Track forecast errors were low and skill scores high.
Name: HILARY Identifier: 08E
Basin: NORTH-EAST PACIFIC
Start date: 19.08.2005 End date: 25.08.2005
1-minute MSW: 90 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NEP basin
A plot of the storm's observed track and forecasts.
Some forecasts had a left-of-track bias. Track forecast errors were above last season's average at some lead times, but below at others. Skill scores were only positive at T+48.
Name: GUCHOL Identifier: 12W
Basin: NORTH-WEST PACIFIC
Start date: 20.08.2005 End date: 25.08.2005
1-minute MSW: 60 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.
Track forecast errors were below last season's average up to the 48-hour lead time, but greater at 72-hours. However, skill scores against CLIPER were high.
Name: JOSE Identifier: 11L
Basin: NORTH ATLANTIC
Start date: 22.08.2005 End date: 23.08.2005
1-minute MSW: 45 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NAT basin
A plot of the storm's observed track and forecasts.
Jose was a brief tropical storm and no forecasts were verified.
Name: KATRINA Identifier: 12L
Basin: NORTH ATLANTIC
Start date: 23.08.2005 End date: 30.08.2005
1-minute MSW: 150 knots 10-minute MSW: - knots
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* DPE for all storms in the 2004 season in the NAT basin
A plot
of the storm's observed track and 00Z forecasts.
A plot of the storm's observed track and 12Z forecasts.
During Katrina's formative stages (prior to Florida landfall), forecast tracks were too slow and predicted recurvature too far east. However, once the hurricane had become established in the Gulf of Mexico forecasts became consistent and correctly predicted lan