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.
2.1 Individual Tropical Cyclone Summaries
Name: CINDY Identifier: 03L
Basin: NORTH ATLANTIC
Start date: 03.07.2005 End date: 06.07.2005
1-minute MSW: 60 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.
Only one forecast was verified for this storm and its track error was small.
Name: DORA Identifier: 04E
Basin: NORTH-EAST PACIFIC
Start date: 04.07.2005 End date: 06.07.2005
1-minute MSW: 35 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.
Dora was only briefly a tropical storm and no forecasts were verified.
Name: DENNIS Identifier: 04L
Basin: NORTH ATLANTIC
Start date: 05.07.2005 End date: 11.07.2005
1-minute MSW: 130 knots 10-minute MSW: - knots
Table of Mean Error Statistics
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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.
A couple of forecasts had a left-of-track bias for Hurricane Dennis, but all forecasts at lead times of 60 hours or less gave a good prediction of landfall. Overall, track forecast errors were very low and skill scores high.
Name: EMILY Identifier: 05L
Basin: NORTH ATLANTIC
Start date: 11.07.2005 End date: 21.07.2005
1-minute MSW: 135 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.
There was a right-of-track (northward) bias in early forecasts for Hurricane Emily, but later forecasts were very good, predicting the two landfalls over Mexico very well. Track forecast errors were low and skill scores against CLIPER high.
Name: HAITANG Identifier: 05W
Basin: NORTH-WEST PACIFIC
Start date: 11.07.2005 End date: 20.07.2005
1-minute MSW: 140 knots 10-minute MSW: 105 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 this typhoon, including its early unusual southward component was generally well predicted by the model. Track forecast errors were below last season's average and skill scores against CLIPER were very high.
Name: EUGENE Identifier: 05E
Basin: NORTH-EAST PACIFIC
Start date: 18.07.2005 End date: 20.07.2005
1-minute MSW: 60 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.
Eugene was a short-lived storm and only one forecast was verified.
Name: NALGAE Identifier: 06W
Basin: NORTH-WEST PACIFIC
Start date: 20.07.2005 End date: 24.07.2005
1-minute MSW: 50 knots 10-minute MSW: 45 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 above last season's average for this storm, with a left-of-track bias being present.
Name: BANYAN Identifier: 07W
Basin: NORTH-WEST PACIFIC
Start date: 21.07.2005 End date: 27.07.2005
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 slightly above last season's average at short lead times and were particularly large at longer lead times. This was as a result of not predicting the rapid north-eastward acceleration indicated by a strong slow bias. Despite this, skill scores against CLIPER remained high.
Name: FRANKLIN Identifier: 06L
Basin: NORTH ATLANTIC
Start date: 21.07.2005 End date: 29.07.2005
1-minute MSW: 60 knots 10-minute MSW: -
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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.
Track forecast errors were quite low at short lead times, but larger at longer lead times. The main forecast problem was a failure to predict the slow northward movement for several days before eventual acceleration north-eastwards. The model tended to accelerate the storm north-eastwards and dissipate it too soon. This resulted in some low detection rates. Despite this, skill scores against CLIPER were high.
Name: GERT Identifier: 07L
Basin: NORTH ATLANTIC
Start date: 23.07.2005 End date: 25.07.2005
1-minute MSW: 40 knots 10-minute MSW: -
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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.
Gert only briefly reached tropical storm status and no forecasts were verified.
Name: WASHI Identifier: 08W
Basin: NORTH-WEST PACIFIC
Start date: 28.07.2005 End date: 31.07.2005
1-minute MSW: 45 knots 10-minute MSW: 45 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.
Only a few forecasts were verified for Tropical Storm Washi. Track forecast errors were fairly low.
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:- 11
Number of storms used in statistics below:- 11
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* DPE for all Northern Hemisphere storms in 2004 season
Comments:
Mean track forecast errors were below last season's average at all lead times for this month's storms. Skill scores against CLIPER were also good. Overall, there were no systematic biases in forecasts. The overall intensity tendency skill score was 22%.
