Tropical cyclone activity and forecasts - February 2008
Tropical cyclone activity
| NWP | NEP | NAT | NI | SWI | AUS | Total | |
|---|---|---|---|---|---|---|---|
| Total number ending during the month | 0 | 0 | 0 | 0 | 4 | 3 | 7 |
| NWP | NEP | NAT | NI | SWI | AUS | Total | |
|---|---|---|---|---|---|---|---|
| Fame | 13S | SWI | 25 January | 01 February | 80 | 60 | |
| Gula | 14S | SWI | 27 January | 02 February | 85 | 85 | |
| Gene | 15P | AUS | 27 January | 06 February | 90 | 85 | |
| Hondo | 16S | SWI | 04 February | 24 February | 125 | 115 | |
| - | 17S | AUS | 07 February | 10 February | 40 | 30 | |
| Ivan | 18S | SWI | 07 February | 21 February | 115 | 100 | |
| Nicholas | 19S | AUS | 13 February | 20 February | 80 | 80 |
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.
Tropical cyclones still active at the end of the month
| Name | Identifier | Basin | Start date |
|---|---|---|---|
| - | 20P | AUS | 28 February |
| Ophelia | 21S | AUS | 29 February |
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.
Individual tropical cyclone summaries
Name: FAME Identifier: 13S
Basin: SOUTH-WEST INDIAN
Start date: 27.01.2008 End
date: 01.02.2008
1-minute MSW: 80 knots
10-minute MSW: 60 knots
| 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 | 37 | -28 | -275 | **** | **** | **** |
| Mean DY | -15 | 7 | 111 | **** | **** | **** |
| Mean AT | -1 | 1 | -26 | **** | **** | **** |
| Mean CT | 32 | -15 | -294 | **** | **** | **** |
| Track skill (%) | **** | 34 | **** | **** | **** | **** |
| Mean DPE | 52 | 94 | 296 | **** | **** | **** |
| 2006-7 DPE * | 54 | 130 | 283 | 458 | 665 | 802 |
| Intensity skill (%) | **** | 33 | 100 | **** | **** | **** |
* DPE for all storms in the 2006-7 season in the SWI basin
 |
Plot of the storm's observed track and forecasts |
Fame was a tropical storm for a fairly brief period. One 48-hour forecast and three 24-hour forecasts were verified.
Name: GULA Identifier: 14S
Basin: SOUTH-WEST INDIAN
Start date: 27.01.2008 End
date: 02.02.2008
1-minute MSW: 85 knots 10-minute MSW: 85 knots
| 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 | -1 | -34 | -56 | -251 | -217 | -284 |
| Mean DY | -6 | 31 | 0 | -148 | -261 | -445 |
| Mean AT | -11 | -4 | 9 | -77 | -133 | -385 |
| Mean CT | -1 | 28 | 12 | -248 | -268 | -358 |
| Track skill (%) | **** | 61 | 66 | 40 | **** | **** |
| Mean DPE | 83 | 116 | 193 | 474 | 375 | 538 |
| 2006-7 DPE * | 54 | 130 | 283 | 458 | 665 | 802 |
| Intensity skill (%) | **** | -40 | -25 | -33 | -50 | 0 |
* DPE for all storms in the 2006-7 season in the SWI basin
 |
Plot of the storm's observed track and forecasts |
Track forecast errors were generally below last season’s average for this storm. Skill scores were very high. There was a slow and right-of-track bias in longer lead time forecasts.
Name: GENE Identifier: 15P
Basin: AUSTRALIAN (S Pacific)
Start date: 27.01.2008 End
date: 06.02.2008
1-minute MSW: 90 knots 10-minute MSW: 85 knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 19 | 17 | 15 | 13 | 11 | 9 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 100 |
| Mean DX | -5 | -25 | -109 | -254 | -651 | -1022 |
| Mean DY | 21 | 8 | -39 | -58 | -50 | -40 |
| Mean AT | -8 | -9 | 40 | -16 | -290 | -617 |
| Mean CT | 6 | 12 | -13 | -235 | -326 | -407 |
| Track skill (%) | **** | 18 | -32 | -109 | **** | **** |
| Mean DPE | 79 | 106 | 243 | 437 | 765 | 1110 |
| 2006-7 DPE * | 72 | 153 | 355 | 665 | 1075 | 1537 |
| Intensity skill (%) | **** | 29 | 7 | 23 | -9 | 33 |
* DPE for all storms in the 2006-7 season in the AUS basin
 |
Plot of the storm's observed track and forecasts |
The model initially failed to predict the recurvature of Gene and long lead time track errors were large. However, they were still below last year’s average due to the poor performance in this region last year. Skill scores were only positive at T+24.
Name: HONDO Identifier: 16S
Basin: SOUTH-WEST INDIAN
Start date: 04.02.2008 End
date: 24.02.2008
1-minute MSW: 125 knots 10-minute MSW: 155 knots
| 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 | 100 | 100 | 100 |
| Mean DX | -10 | -55 | -63 | -14 | 75 | 331 |
| Mean DY | -9 | -5 | -74 | -121 | -187 | -284 |
| Mean AT | -13 | -47 | -66 | -31 | 32 | 227 |
| Mean CT | 8 | -46 | -66 | -31 | 32 | 227 |
| Track skill (%) | **** | 31 | 49 | 65 | **** | **** |
| Mean DPE | 36 | 82 | 153 | 167 | 228 | 448 |
| 2006-7 DPE * | 54 | 130 | 283 | 458 | 665 | 802 |
| Intensity skill (%) | **** | 50 | 60 | 50 | 33 | -50 |
* DPE for all storms in the 2006-7 season in the SWI basin
 |
Plot of the storm's observed track and forecasts |
Hondo was well forecast whilst at tropical storm intensity (or greater). Track errors were low and skill scores high. The abrupt turn of the remnant low to the west was also well predicted and although it never regained tropical storm strength according to RSMC La Reunion, this portion of the track was fairly well forecast (although not verified).
Name: - Identifier: 17S
Basin: AUSTRALIAN (SE Indian)
Start date: 07.02.2008 End
date: 10.02.2008
1-minute MSW: 40 knots 10-minute MSW: 30 knots
There are no verification statistics or forecast plot for this tropical cyclone since its 10-minute averaged winds did not reach tropical storm strength
 |
Plot of the storm's observed track and forecasts |
Name: IVAN Identifier: 18S
Basin: SOUTH-WEST INDIAN
Start date: 07.02.2008 End
date: 21.02.2008
1-minute MSW: 115 knots 10-minute MSW: 100 knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 20 | 18 | 16 | 14 | 12 | 10 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 100 |
| Mean DX | -7 | -101 | -267 | -336 | -367 | -258 |
| Mean DY | -7 | 69 | 120 | 203 | 249 | 355 |
| Mean AT | 9 | 25 | 150 | 237 | 354 | 312 |
| Mean CT | 6 | 47 | 72 | 139 | 227 | 333 |
| Track skill (%) | **** | -8 | -10 | 6 | **** | **** |
| Mean DPE | 41 | 138 | 311 | 419 | 474 | 503 |
| 2006-7 DPE * | 54 | 130 | 283 | 458 | 665 | 802 |
| Intensity skill (%) | **** | 33 | 25 | 43 | 0 | -20 |
* DPE for all storms in the 2006-7 season in the SWI basin
 |
Plot of the storm's observed track and forecasts |
The westward movement of Ivan was initially predicted to occur sooner than it did. Track forecast errors were near to or below last season’s average, although track skill scores were not good.
Name: NICHOLAS Identifier: 19S
Basin: AUSTRALIAN (SE Indian)
Start date: 13.02.2008 End
date: 20.02.2008
1-minute MSW: 80 knots 10-minute MSW: 80 knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 15 | 13 | 11 | 9 | 7 | 5 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 100 |
| Mean DX | -1 | 16 | 120 | 276 | 373 | 475 |
| Mean DY | -14 | 53 | 79 | 131 | 222 | 240 |
| Mean AT | 1 | -11 | -48 | -110 | -48 | 49 |
| Mean CT | 11 | 38 | 110 | 271 | 370 | 450 |
| Track skill (%) | **** | 30 | 8 | 11 | **** | **** |
| Mean DPE | 53 | 100 | 160 | 322 | 442 | 551 |
| 2006-7 DPE * | 72 | 153 | 355 | 665 | 1075 | 1537 |
| Intensity skill (%) | **** | 54 | 82 | 33 | 71 | 20 |
* DPE for all storms in the 2006-7 season in the AUS basin
 |
Plot of the storm's observed track and forecasts |
Forecasts for Nicholas had a persistent leftward bias resulting in landfall too soon. Despite this, Track forecast errors were not particularly high. There was modest skill over CLIPER.
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: 6
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 85 | 73 | 61 | 50 | 40 | 30 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 100 |
| Mean DX | -2 | -43 | -97 | -143 | -234 | -288 |
| Mean DY | -3 | 32 | 26 | 28 | 46 | 79 |
| Mean AT | -3 | -6 | 22 | 10 | -23 | -145 |
| Mean CT | 7 | 17 | 22 | -8 | 21 | 70 |
| Track skill (%) | **** | 28 | 21 | 15 | **** | **** |
| Mean DPE | 57 | 110 | 225 | 372 | 502 | 688 |
| 2006-7 DPE * | 54 | 136 | 298 | 496 | 727 | 870 |
| Intensity skill (%) | **** | 29 | 31 | 28 | 10 | 0 |
* DPE for all southern hemisphere storms in 2006-7 season
Track forecast errors were below last season’s average and skill scores modestly positive this month. Although some storms exhibited track biases, these tended to cancel each other out in the averaged figure for the whole month. The overall intensity tendency skill score was 23%.
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