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)
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: TALIM Identifier: 13W
Basin: NORTH-WEST PACIFIC
Start date: 26.08.2005 End date: 02.09.2005
1-minute MSW: 125 knots 10-minute MSW: 95 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 high for this typhoon. Some early forecasts incorrectly predicted recurvature which resulted in a right-of-track bias in the statistics.
Name: LEE Identifier: 13L
Basin: NORTH ATLANTIC
Start date: 28.08.2005 End date: 02.09.2005
1-minute MSW: 35 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.
Lee only briefly attained tropical storm status and no forecasts were verified.
Name: NABI Identifier: 14W
Basin: NORTH-WEST PACIFIC
Start date: 29.08.2005 End date: 08.09.2005
1-minute MSW: 140 knots 10-minute MSW: 95 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.
Forecasts for Super Typhoon Nabi had a left-of-track bias and tended to be too slow. The model only showed skill over CLIPER at T+24. Tracks forecast errors were greater than last season's average at lead times longer than 24 hours.
Name: MARIA Identifier: 14L
Basin: NORTH ATLANTIC
Start date: 01.09.2005 End date: 10.09.2005
1-minute MSW: 100 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 below last season's average for Hurricane Maria and the model showed good skill over CLIPER.
Name: NATE Identifier: 15L
Basin: NORTH ATLANTIC
Start date: 05.09.2005 End date: 10.09.2005
1-minute MSW: 80 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.
Forecasts did not pick up on the rapid acceleration of Hurricane Nate and track forecast errors were above last season's average. However, the model showed considerable skill over CLIPER.
Name: KHANUN Identifier: 15W
Basin: NORTH-WEST PACIFIC
Start date: 05.09.2005 End date: 12.09.2005
1-minute MSW: 115 knots 10-minute MSW: 85 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 forecasts for Typhoon Khanun were generally too slow and had a left-of-track bias, although biases in both directions were observed. Track forecast errors were mixed, but the model showed good skill over CLIPER. Landfall over China was generally well predicted up to 72 hours in advance.
Name: OPHELIA Identifier: 16L
Basin: NORTH ATLANTIC
Start date: 06.09.2005 End date: 18.09.2005
1-minute MSW: 75 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 low for Hurricane Ophelia. Although a few forecasts indicated landfall over South Carolina, the forecast of the slow movement and loop towards the US coast followed by north-eastward acceleration was generally well handled. Skill scores against CLIPER were very high.
Name: JOVA Identifier: 10E
Basin: NORTH-EAST PACIFIC
Start date: 12.09.2005 End date: 25.09.2005
1-minute MSW: 100 knots 10-minute MSW: -
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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.
Track forecast errors were near to or below last season's average for this hurricane. There was a slow and left-of-track bias in longer lead time forecasts due to erroneous interaction with Hurricane Kenneth. Skill scores, particularly at shorter lead times, were good.
Name: KENNETH Identifier: 11E
Basin: NORTH-EAST PACIFIC
Start date: 14.09.2005 End date: 30.09.2005
1-minute MSW: 115 knots 10-minute MSW: -
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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.
Track forecast errors were above last season's average for this hurricane. Forecasts for Hurricane Kenneth were complicated by the presence of Hurricane Jova further east. This resulted in some erratic motion during the lifetime of Kenneth which was not always well handled by the model. Overall, skill scores against CLIPER were positive.
Name: VICENTE Identifier: 16W
Basin: NORTH-WEST PACIFIC
Start date: 15.09.2005 End date: 18.09.2005
1-minute MSW: 40 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 one forecast was verified for this storm.
Name: PYARR Identifier: -
Basin: NORTH INDIAN (Bay of Bengal)
Start date: 16.09.2005 End date: 19.09.2005
1-minute MSW: 45 knots 10-minute MSW: 40 knots
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* DPE for all storms in the 2004 season in the NI basin
A plot of the storm's observed track and forecasts.
The observed maximum sustained winds are taken from NOAA Satellite
Analysis branch and Indian Met. Department estimates. JTWC did not advise
on this system and it was not initialised in the model.
Track forecast errors were near to last season's average for this storm.
Name: LIDIA Identifier: 12E
Basin: NORTH-EAST PACIFIC
Start date: 17.09.2005 End date: 19.09.2005
1-minute MSW: 40 knots 10-minute MSW: -
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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.
Lidia was only briefly a tropical storm and no forecasts were verified.
Name: PHILIPPE Identifier: 17L
Basin: NORTH ATLANTIC
Start date: 17.09.2005 End date: 24.09.2005
1-minute MSW: 70 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 mixed for this hurricane. There was a fast bias during the early stages and a left-of-track bias during the whole lifetime of the hurricane. Track skill scores were good.
Name: RITA Identifier: 18L
Basin: NORTH ATLANTIC
Start date: 18.09.2005 End date: 25.09.2005
1-minute MSW: 150 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 00Z forecasts.
A plot of the storm's observed track and 12Z forecasts.
Track forecast errors were below last season's average at all lead times apart from 96 hours. Track forecasts had a left-of-track bias in common with many other models, bringing Rita ashore along the upper Texas coast. The first forecast to pinpoint the correction location of landfall on the Texas Louisiana border was the 00Z 22nd run, some 55 hours prior to landfall. Skill scores against CLIPER were very high for this hurricane.
Name: MAX Identifier: 13E
Basin: NORTH-EAST PACIFIC
Start date: 18.09.2005 End date: 22.09.2005
1-minute MSW: 70 knots 10-minute MSW: -
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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.
The first forecast for this hurricane had a left-of-track bias. Subsequent forecasts gave better track predictions.
Name: DAMREY Identifier: 17W
Basin: NORTH-WEST PACIFIC
Start date: 20.09.2005 End date: 27.09.2005
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 for this typhoon were close to last season's average. Landfall over Hainan and Vietnam were well predicted. Skill scores against CLIPER were high.
Name: SAOLA Identifier: 18W
Basin: NORTH-WEST PACIFIC
Start date: 20.09.2005 End date: 26.09.2005
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.
The model was unable to predict the timing of recurvature of this typhoon, preferring to stall the system to the south of Japan rather than undergo immediate recurvature as actually happened. The result was very large forecast errors and low skill scores.
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