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Tropical cyclone activity and forecasts - September 2005

1. Tropical cyclone activity

1.1 Tropical cyclones ending during the month

  NWP NEP NAT NI SWI AUS TOTAL
Total number ending during the month 6 5 6 1 0 0 18
 
Name Identifier Basin Start Date End Date 1-minute MSW 10-minute MSW
Talim 13W NWP 26 August 02 September 125 95
Lee 13L NAT 28 August 02 September 35 -
Nabi 14W NWP 29 August 08 September 140 95
Maria 14L NAT 01 September 10 September 100 -
Nate 15L NAT 05 September 10 September 80 -
Khanun 15W NWP 05 September 12 September 115 85
Ophelia 16L NAT 06 September 18 September 75 -
Jova 10E NEP 12 September 25 September 100 -
Kenneth 11E NEP 14 September 30 September 115 -
Vicente 16W NWP 15 September 18 September 40 45
Pyarr - NI 16 September 19 September 45 40
Lidia 12E NEP 17 September 19 September 40 -
Philippe 17L NAT 17 September 24 September 70 -
Rita 18L NAT 18 September 25 September 150 -
Max 13E NEP 18 September 22 September 70 -
Damrey 17W NWP 20 September 27 September 90 80
Saola 18W NWP 20 September 26 September 90 80
Norma 14E NEP 23 September 27 September 55 -

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

Name Identifier Basin Start Date
Longwang 19W NWP 25 September
Otis 15E NEP 28 September
- 19L NAT 30 September

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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 13 11 9 7 5 3
Detection Rate (%) 100 100 100 100 100 100
Mean DX 11 -4 32 36 182 307
Mean DY -11 33 63 103 311 263
Mean AT -10 6 -18 3 -41 -164
Mean CT -4 27 73 113 356 340
Track skill (%) **** 16 44 59 **** ****
Mean DPE 45 106 176 224 447 551
2004 DPE * 49 134 228 367 498 610
Intensity skill (%) **** 27 33 43 -20 33


* DPE for all storms in the 2004 season in the NWP basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 1 0 0 0 0 0
Detection Rate (%) 100 **** **** **** **** ****
Mean DX 29 **** **** **** **** ****
Mean DY 11 **** **** **** **** ****
Mean AT 24 **** **** **** **** ****
Mean CT 21 **** **** **** **** ****
Mean DPE 33 **** **** **** **** ****
2004 DPE * 51 135 222 296 367 569


* DPE for all storms in the 2004 season in the NAT basin

Link to plot 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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 19 16 14 12 11 9
Detection Rate (%) 100 100 100 100 100 100
Mean DX 5 -65 -166 -288 -319 -474
Mean DY 13 -7 -149 -339 -472 -697
Mean AT 8 6 -82 -292 -506 -839
Mean CT 4 -81 -202 -298 -306 -240
Track skill (%) **** 26 -4 -84 **** ****
Mean DPE 62 104 254 472 617 908
2004 DPE * 49 134 228 367 498 610
Intensity skill (%) **** 38 29 17 -27 -78


* DPE for all storms in the 2004 season in the NWP basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 16 14 12 10 8 5
Detection Rate (%) 100 100 100 100 88 100
Mean DX 4 -18 -41 -88 -178 -177
Mean DY 7 46 57 79 -83 -147
Mean AT -1 5 8 27 -217 -213
Mean CT -9 -51 -118 -63 -51 -82
Track skill (%) **** 36 46 27 **** ****
Mean DPE 41 116 177 285 330 444
2004 DPE * 51 135 222 296 367 569
Intensity skill (%) **** 0 17 60 43 60


* DPE for all storms in the 2004 season in the NAT basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 10 8 6 4 2 0
Detection Rate (%) 100 100 100 100 100 ****
Mean DX -29 -115 -226 -482 -812 ****
Mean DY 2 -15 -2 -3 78 ****
Mean AT -26 -129 -213 -456 -812 ****
Mean CT -7 -36 -94 -138 -136 ****
Track skill (%) **** 49 66 65 **** ****
Mean DPE 54 152 257 491 825 ****
2004 DPE * 51 135 222 296 367 569
Intensity skill (%) **** -50 0 0 0 ****


* DPE for all storms in the 2004 season in the NAT basin

Link to plot 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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 14 12 1- 8 6 4
Detection Rate (%) 100 100 100 100 100 100
Mean DX 15 15 -6 -75 -170 -164
Mean DY 8 -20 -112 -209 -334 -456
Mean AT 4 -22 -72 -113 -194 -459
Mean CT 16 18 -63 -173 -303 -277
Track skill (%) **** 30 46 53 **** ****
Mean DPE 55 131 222 284 508 820
2004 DPE * 49 134 228 367 498 610
Intensity skill (%) **** -17 0 -25 67 50


* DPE for all storms in the 2004 season in the NWP basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 22 20 18 16 13 11
Detection Rate (%) 100 100 100 100 100 100
Mean DX 1 -34 -45 -29 62 -5
Mean DY 3 -1 24 74 45 -77
Mean AT 1 -29 -18 64 92 -66
Mean CT -3 -18 -24 -66 -30 -78
Track skill (%) **** 53 68 56 **** ****
Mean DPE 32 83 110 211 229 257
2004 DPE * 51 135 222 296 367 569
Intensity skill (%) **** 20 78 38 54 64


* DPE for all storms in the 2004 season in the NAT basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 18 16 14 12 10 8
Detection Rate (%) 100 100 100 100 100 100
Mean DX 4 -24 -57 -35 70 45
Mean DY 13 14 -60 -211 -327 -363
Mean AT 5 18 -16 -133 -287 -286
Mean CT 13 1 -80 -163 -138 -164
Track skill (%) **** 32 37 6 **** ****
Mean DPE 32 75 147 271 389 428
2004 DPE * 50 118 188 248 379 481
Intensity skill (%) **** 75 71 50 40 0


* DPE for all storms in the 2004 season in the NEP basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 28 26 24 22 20 18
Detection Rate (%) 100 100 100 100 100 94
Mean DX 13 -57 -163 -273 -366 -465
Mean DY -16 4 52 77 152 239
Mean AT -17 19 82 190 303 478
Mean CT -11 -3 -5 -5 18 -38
Track skill (%) **** 22 19 8 **** ****
Mean DPE 43 116 235 384 526 711
2004 DPE * 50 118 188 248 379 481
Intensity skill (%) **** 23 33 55 10 18


* DPE for all storms in the 2004 season in the NEP basin

Link to plot 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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 3 1 0 0 0 0
Detection Rate (%) 100 100 **** **** **** ****
Mean DX 39 53 **** **** **** ****
Mean DY 19 89 **** **** **** ****
Mean AT 6 -45 **** **** **** ****
Mean CT 68 89 **** **** **** ****
Track skill (%) **** 76 **** **** **** ****
Mean DPE 80 100 **** **** **** ****
2004 DPE * 49 134 228 367 498 610
Intensity skill (%) **** 100 **** **** **** ****


* DPE for all storms in the 2004 season in the NWP basin

Link to plot 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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 5 3 1 0 0 0
Detection Rate (%) 100 100 100 **** **** ****
Mean DX -17 4 -147 **** **** ****
Mean DY 73 145 189 **** **** ****
Mean AT 10 -79 40 **** **** ****
Mean CT 88 150 228 **** **** ****
Track skill (%) **** -108 27 **** **** ****
Mean DPE 102 216 232 **** **** ****
2004 DPE * 85 216 253 289 283 401
Intensity skill (%) **** 100 100 **** **** ****


* DPE for all storms in the 2004 season in the NI basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 2 0 0 0 0 0
Detection Rate (%) 100 **** **** **** **** ****
Mean DX -33 **** **** **** **** ****
Mean DY -49 **** **** **** **** ****
Mean AT -32 **** **** **** **** ****
Mean CT 40 **** **** **** **** ****
Mean DPE 58 **** **** **** **** ****
2004 DPE * 50 118 188 248 379 481


* DPE for all storms in the 2004 season in the NEP basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 12 10 8 6 4 2
Detection Rate (%) 100 100 100 100 100 100
Mean DX 9 3 -84 -238 -272 -172
Mean DY 17 71 107 143 25 -106
Mean AT 4 29 78 131 14 -11
Mean CT 19 18 -131 -201 -245 -221
Track skill (%) **** 23 29 35 **** ****
Mean DPE 43 167 306 299 368 229
2004 DPE * 51 135 222 296 367 569
Intensity skill (%) **** 80 -25 -33 0 100


* DPE for all storms in the 2004 season in the NAT basin

Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 13 11 9 7 5 3
Detection Rate (%) 100 100 100 100 100 100
Mean DX 4 -9 -86 -263 -400 -216
Mean DY 16 -26 -53 -60 45 456
Mean AT 5 -11 36 157 236 479
Mean CT 10 -12 -58 -178 -233 -6
Track skill (%) **** 41 52 48 **** ****
Mean DPE 35 81 157 288 415 511
2004 DPE * 51 135 222 296 367 569
Intensity skill (%) **** 9 33 -43 -60 33


* DPE for all storms in the 2004 season in the NAT basin

Link to plot A plot of the storm's observed track and 00Z forecasts.
Link to plot 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: -

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 7 5 3 1 0 0
Detection Rate (%) 100 100 100 100 **** ****
Mean DX 9 -15 -42 -240 **** ****
Mean DY 10 2 -156 -423 **** ****
Mean AT 10 -9 -118 239 **** ****
Mean CT 14 0 -146 -421 **** ****
Track skill (%) **** 33 64 **** **** ****
Mean DPE 37 101 197 485 **** ****
2004 DPE * 50 118 188 248 379 481
Intensity skill (%) **** 20 100 100 **** ****


* DPE for all storms in the 2004 season in the NEP basin

Link to plot 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

Table of Mean Error Statistics
  T+0 T+24 T+48 T+72 T+96 T+120
Possibly Verified 14 12 10 8 6 4
Detection Rate (%) 100 100 100 88 100 100
Mean DX -1 -67 -175 -355 -493 -601
Mean DY -17 -2 45 56 70 34
Mean AT -2 46 156 321 450 545
Mean CT -15 15 65 65 69 -10
Track skill (%) **** 8 46 52 **** ****
Mean DPE 56 127 201