Tropical cyclone activity and forecasts - July 2008
Tropical cyclone activity
| NWP | NEP | NAT | NI | SWI | AUS | TOTAL | |
|---|---|---|---|---|---|---|---|
| Total number ending during the month | 2 | 7 | 3 | 0 | 0 | 0 | 12 |
| Name | Identifier | Basin | Start date | End date | 1-minute MSW | 10-minute MSW |
|---|---|---|---|---|---|---|
| Boris | 02E | NEP | 27 June | 04 July | 65 | - |
| Cristina | 03E | NEP | 27 June | 01 July | 45 | - |
| Douglas | 04E | NEP | 02 July | 04 July | 35 | - |
| Bertha | 02L | NAT | 03 July | 20 July | 105 | - |
| - | 05E | NEP | 05 July | 07 July | 30 | - |
| Elida | 06E | NEP | 12 July | 19 July | 90 | - |
| Kalmaegi | 08W | NWP | 14 July | 20 July | 90 | 75 |
| Fausto | 07E | NEP | 16 July | 22 July | 85 | - |
| Cristobal | 03L | NAT | 19 July | 23 July | 40 | - |
| Dolly | 04L | NAT | 20 July | 24 July | 85 | - |
| Genevieve | 08E | NEP | 21 July | 27 July | 65 | - |
| Fung-wong | 09W | NWP | 24 July | 29 July | 95 | 75 |
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
None
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 62 km x 42 km at the equator.
Individual tropical cyclone summaries
Name: BORIS Identifier: 02E
Basin: NORTH EAST PACIFIC
Start date: 27.06.2008 End date: 04.07.2008
1-minute MSW: 65 knots 10-minute MSW: - knots
| 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 | 57 | 20 | 0 |
| Mean DX | -9 | -30 | -30 | -26 | 184 | **** |
| Mean DY | -13 | 5 | -11 | -192 | -189 | **** |
| Mean AT | 3 | 13 | -17 | -79 | -181 | **** |
| Mean CT | -5 | -11 | -43 | -181 | -186 | **** |
| Track skill (%) | **** | 29 | 20 | -48 | **** | **** |
| Mean DPE | 33 | 88 | 183 | 295 | 260 | **** |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
| Intensity skill (%) | **** | 82 | 33 | 50 | -100 | **** |
* DPE for all storms in the 2007 season in the NEP basin
A plot of the storm's observed track and forecasts
Track forecast errors were below last season’s average at all lead times except T+72. Skill scores were positive at T+24 and T+48. There was a left-of-track bias and the model showed an unusually low detection percentage indicating that it tended to dissipate the storm too soon.
Name: CRISTINA Identifier: 03E
Basin: NORTH EAST PACIFIC
Start date: 27.06.2008 End date: 01.07.2008
1-minute MSW: 45 knots 10-minute MSW: - knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 4 | 2 | 0 | 0 | 0 | 0 |
| Detection rate (%) | 100 | 100 | **** | **** | **** | **** |
| Mean DX | 22 | -60 | **** | **** | **** | **** |
| Mean DY | 21 | 56 | **** | **** | **** | **** |
| Mean AT | -15 | 47 | **** | **** | **** | **** |
| Mean CT | 20 | 61 | **** | **** | **** | **** |
| Track skill (%) | **** | 50 | **** | **** | **** | **** |
| Mean DPE | 37 | 78 | **** | **** | **** | **** |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
| Intensity skill (%) | **** | 100 | **** | **** | **** | **** |
* DPE for all storms in the 2007 season in the NEP basin
A plot of the storm's observed track and forecasts
Cristina was only briefly a tropical storm and just two forecasts were verified. Track errors for these forecasts were low and skill scores high.
Name: DOUGLAS Identifier: 03E
Basin: NORTH EAST PACIFIC
Start date: 02.07.2008 End date: 04.07.2008
1-minute MSW: 35 knots 10-minute MSW: - knots
| 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 | 19 | **** | **** | **** | **** | **** |
| Mean DY | -39 | **** | **** | **** | **** | **** |
| Mean AT | -45 | **** | **** | **** | **** | **** |
| Mean CT | -7 | **** | **** | **** | **** | **** |
| Mean DPE | 64 | **** | **** | **** | **** | **** |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
* DPE for all storms in the 2007 season in the NEP basin
A plot of the storm's observed track and forecasts
Douglas was briefly a tropical storm and no forecasts were verified.
Name: BERTHA Identifier: 02L
Basin: NORTH ATLANTIC
Start date: 03.07.2008 End date: 20.07.2008
1-minute MSW: 105 knots 10-minute MSW: - knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 35 | 31 | 30 | 29 | 27 | 25 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 96 |
| Mean DX | 18 | -1 | -39 | -95 | -153 | -216 |
| Mean DY | 16 | -1 | -48 | -141 | -211 | -207 |
| Mean AT | -2 | -44 | -91 | -182 | -162 | -183 |
| Mean CT | 7 | -6 | -10 | -32 | -86 | -216 |
| Track skill (%) | **** | 53 | 57 | 37 | **** | **** |
| Mean DPE | 42 | 92 | 183 | 352 | 486 | 618 |
| 2007 DPE * | 63 | 102 | 151 | 179 | 228 | 265 |
| Intensity skill (%) | **** | 0 | 17 | -7 | -23 | 30 |
* DPE for all storms in the 2007 season in the NAT basin
A plot of the storm's observed track and forecasts
Bertha was the longest lived July Atlantic hurricane on record. Early forecasts had a left-of-track bias. The slow down and dip south-eastwards was generally well predicted, although the rate of acceleration north-eastwards was not. Hence, track errors at long lead times were large and there was a slow bias. At shorter lead times track errors were better and the model showed considerable skill over CLIPER.
Name: - Identifier: 05E
Basin: NORTH EAST PACIFIC
Start date: 05.07.2008 End date: 07.07.2008
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 and forecasts
Name: ELIDA Identifier: 06E
Basin: NORTH EAST PACIFIC
Start date: 12.07.2008 End date: 19.07.2008
1-minute MSW: 90 knots 10-minute MSW: - 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 | 86 | 0 |
| Mean DX | 15 | 14 | -36 | -96 | -139 | **** |
| Mean DY | -15 | 30 | 111 | 158 | 102 | **** |
| Mean AT | -3 | 25 | 86 | 165 | 220 | **** |
| Mean CT | -18 | 31 | 113 | 162 | 77 | **** |
| Track skill (%) | **** | 26 | 38 | 28 | **** | **** |
| Mean DPE | 49 | 91 | 175 | 287 | 349 | **** |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
| Intensity skill (%) | **** | 67 | 20 | 50 | 60 | **** |
* DPE for all storms in the 2007 season in the NEP basin
A plot of the storm's observed track and forecasts
Like Boris, Elida was another storm with a poor detection percentage at longer lead times. However, track forecast errors were below last season's average and the model showed skill over CLIPER. There was a slight fast bias in forecasts.
Name: KALMAEGI Identifier: 08W
Basin: NORTH WEST PACIFIC
Start date: 14.07.2008 End date: 20.07.2008
1-minute MSW: 90 knots 10-minute MSW: 75 knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 11 | 9 | 7 | 5 | 3 | 1 |
| Detection rate (%) | 100 | 100 | 100 | 80 | 33 | 0 |
| Mean DX | 3 | 31 | 143 | 219 | 387 | **** |
| Mean DY | -17 | -16 | 91 | 206 | 78 | **** |
| Mean AT | -22 | -25 | 55 | 222 | 298 | **** |
| Mean CT | -4 | 46 | 196 | 136 | 252 | **** |
| Track skill (%) | **** | 34 | 34 | 25 | **** | **** |
| Mean DPE | 73 | 109 | 256 | 307 | 391 | **** |
| 2007 DPE * | 70 | 136 | 201 | 276 | 404 | 517 |
| Intensity skill (%) | **** | 78 | 71 | 50 | 100 | **** |
* DPE for all storms in the 2007 season in the NWP basin
A plot of the storm's observed track and forecasts
Track forecast errors were just above and below last season’s average at various lead times. Skill scores against CLIPER were positive. There was a right-of-track bias in forecasts overall.
Name: FAUSTO Identifier: 07E
Basin: NORTH EAST PACIFIC
Start date: 16.07.2008 End date: 22.07.2008
1-minute MSW: 85 knots 10-minute MSW: - 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 | -2 | -97 | -133 | -129 | -153 | -137 |
| Mean DY | 11 | -58 | -172 | -304 | -403 | -462 |
| Mean AT | 5 | 35 | -3 | -44 | -26 | 22 |
| Mean CT | 12 | -101 | -217 | -330 | -411 | -432 |
| Track skill (%) | **** | 23 | 30 | 11 | **** | **** |
| Mean DPE | 44 | 131 | 231 | 345 | 431 | 483 |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
| Intensity skill (%) | **** | 40 | 0 | 0 | 50 | 0 |
* DPE for all storms in the 2007 season in the NEP basin
A plot of the storm's observed track and forecasts
Track forecast errors were mostly just above last season's average. There was a left-of-track bias in forecasts. Skill scores against CLIPER were positive.
Name: CRISTOBAL Identifier: 06W
Basin: NORTH ATLANTIC
Start date: 19.07.2008 End date: 23.07.2008
1-minute MSW: 40 knots 10-minute MSW: - knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 7 | 5 | 3 | **** | **** | **** |
| Detection rate (%) | 100 | 100 | 100 | **** | **** | **** |
| Mean DX | 29 | 2 | -43 | **** | **** | **** |
| Mean DY | -37 | -36 | -33 | **** | **** | **** |
| Mean AT | 1 | -19 | -60 | **** | **** | **** |
| Mean CT | 46 | 31 | -1 | **** | **** | **** |
| Track skill (%) | **** | 59 | 57 | **** | **** | **** |
| Mean DPE | 53 | 75 | 160 | **** | **** | **** |
| 2007 DPE * | 63 | 102 | 151 | 179 | 228 | 265 |
| Intensity skill (%) | **** | 20 | -33 | **** | **** | **** |
* DPE for all storms in the 2007 season in the NAT basin
A plot of the storm's observed track and forecasts
The model gave good prediction of the storm’s acceleration towards the north-east. Skill scores against CLIPER were high.
Name: DOLLY Identifier: 04L
Basin: NORTH ATLANTIC
Start date: 20.07.2008 End date: 24.07.2008
1-minute MSW: 85 knots 10-minute MSW: - knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 9 | 7 | 5 | 3 | 1 | 0 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | **** |
| Mean DX | 27 | 17 | -36 | -60 | -30 | **** |
| Mean DY | 39 | -41 | -98 | -81 | -78 | **** |
| Mean AT | 1 | -36 | -22 | -4 | -21 | **** |
| Mean CT | 38 | -20 | -100 | -99 | -84 | **** |
| Track skill (%) | **** | 47 | 52 | 80 | **** | **** |
| Mean DPE | 55 | 73 | 112 | 119 | 87 | **** |
| 2007 DPE * | 63 | 102 | 151 | 179 | 228 | 265 |
| Intensity skill (%) | **** | 100 | 20 | 33 | -100 | **** |
* DPE for all storms in the 2007 season in the NAT basin
A plot of the storm's observed track and forecasts
Track forecast errors for Hurricane Dolly were low. Skill scores against CLIPER were high. There was a slight left-of-track bias in forecasts. However, the model showed skill in predicting the deceleration of the hurricane as it approached landfall.
Name: GENEVIEVE Identifier: 08E
Basin: NORTH EAST PACIFIC
Start date: 21.07.2008 End date: 27.07.2008
1-minute MSW: 65 knots 10-minute MSW: - knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 11 | 9 | 7 | 5 | 3 | 1 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | 100 |
| Mean DX | 18 | -73 | -116 | -135 | -72 | -204 |
| Mean DY | -1 | 7 | -76 | -165 | -260 | -311 |
| Mean AT | -21 | 57 | 87 | 103 | 29 | 253 |
| Mean CT | 3 | -9 | -98 | -198 | -295 | -263 |
| Track skill (%) | **** | 6 | 17 | 5 | **** | **** |
| Mean DPE | 42 | 128 | 205 | 260 | 322 | 366 |
| 2007 DPE * | 56 | 112 | 192 | 246 | 453 | 397 |
| Intensity skill (%) | **** | 29 | 7 | 23 | -9 | 33 |
* DPE for all storms in the 2007 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. Skill scores against CLIPER were modest and there was a left-of-track bias.
Name: FUNG-WONG Identifier: 09W
Basin: NORTH WEST PACIFIC
Start date: 24.07.2008 End date: 29.07.2008
1-minute MSW: 95 knots 10-minute MSW: 75 knots
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 9 | 7 | 5 | 3 | 1 | 0 |
| Detection rate (%) | 100 | 100 | 100 | 100 | 100 | **** |
| Mean DX | 9 | -2 | -96 | -189 | -22 | **** |
| Mean DY | 9 | -2 | -96 | -189 | -22 | **** |
| Mean AT | 10 | 41 | -51 | -192 | -213 | **** |
| Mean CT | 12 | -19 | -84 | -102 | 98 | **** |
| Track skill (%) | **** | 3 | 39 | 4 | **** | **** |
| Mean DPE | 88 | 115 | 141 | 256 | 235 | **** |
| 2007 DPE * | 70 | 136 | 201 | 276 | 404 | 517 |
| Intensity skill (%) | **** | 71 | 100 | 33 | 100 | **** |
* DPE for all storms in the 2007 season in the NWP basin
A plot of the storm's observed track and forecasts
Track forecast errors were below last season’s average for this storm. Skill scores against CLIPER were positive.
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: 12
Number of storms used in statistics below: 11
| T+0 | T+24 | T+48 | T+72 | T+96 | T+120 | |
|---|---|---|---|---|---|---|
| Possibly verified | 126 | 102 | 83 | 65 | 49 | 35 |
| Detection rate (%) | 100 | 100 | 100 | 94 | 86 | 74 |
| Mean DX | 6 | -27 | -46 | -81 | -129 | -222 |
| Mean DY | 2 | -6 | -32 | -99 | -183 | -239 |
| Mean AT | -4 | -2 | -18 | -63 | -77 | -150 |
| Mean CT | 7 | -6 | -18 | -58 | -102 | -234 |
| Track skill (%) | **** | 38 | 45 | 30 | **** | **** |
| Mean DPE | 50 | 99 | 188 | 312 | 428 | 587 |
| 2007 DPE * | 66 | 127 | 193 | 262 | 401 | 472 |
| Intensity skill (%) | **** | 41 | 25 | 15 | 0 | 31 |
* Best track DPE for all Northern Hemisphere storms in 2007 season
July 2008 was an active month and there was variety in the magnitude of errors, levels of skill and biases seen for the individual storms. Overall, track forecast errors were near to or slightly above last season’s average. Track skill scores against CLIPER were high. There was a small slow and left-of-track bias in forecasts. Detection percentage was a little low at longer lead times. The overall intensity tendency skill score was 25%.
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