Effects of Synoptic Surveillance on model forecasts for
11 September 1999 1200 UTC
FLOYD.
QuickTime movie of DLM wind model
forecasts
QuickTime movie of DLM wind data
increments
| TRACK (km) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MODEL | 12 h | 24 h | 36 h | 48 h | 60 h | 72 h | 84 h | 96 h | 108 h | 120 h
|
| AVNN | 65. | 62. | 123. | 152. | 163. | 133. | 107. | 107. | 131. | 167.
| AVAL | 80. | 151. | 167. | 174. | 226. | 209. | 196. | 204. | 255. | 417.
| %IMP | -23% | -144% | -36% | -14% | -39% | -57% | -83% | -91% | -95% | -150%
|
| GFNO | 102. | 147. | 171. | 146. | 161. | 174. | 155. | 144. | 178. | 256.
| GFAL | 56. | 56. | 63. | 32. | 23. | 32. | 73. | 103. | 154. | 199.
| %IMP | 45% | 62% | 63% | 78% | 86% | 82% | 53% | 28% | 13% | 22%
| INTENSITY (kt)
| MODEL | 12 h | 24 h | 36 h | 48 h | 60 h | 72 h | 84 h | 96 h | 108 h | 120 h
|
| AVNN | -46. | -66. | -87. | -97. | -71. | -61. | -66. | -46. | -36. | -13.
| AVAL | -34. | -56. | -69. | -81. | -64. | -53. | -55. | -35. | -23. | 3.
| %IMP | 26% | 15% | 21% | 16% | 10% | 13% | 17% | 24% | 36% | 77%
|
| GFNO | 29. | 8. | -5. | -16. | 0. | 6. | -3. | 12. | 7. | 14.
| GFAL | 26. | 15. | -9. | -21. | 2. | 13. | 8. | 14. | 13. | 8.
| %IMP | 10% | -88% | -80% | -31% | und% | -117% | -167% | -17% | -86% | 43%
|
| SHNO | 15. | -3. | -20. | -28. | -9. | 1. | -10. | 5. | 15. | 35.
| SHAL | 14. | -4. | -24. | -33. | -15. | -5. | -17. | -3. | 6. | 26.
| %IMP | 7% | -33% | -20% | -18% | -67% | -400% | -70% | 40% | 60% | 26%
|
| DSNO | 15. | -3. | -20. | -28. | -9. | 1. | -10. | 5. | 15. | 35.
| DSAL | 14. | -4. | -24. | -33. | -15. | -5. | -17. | -3. | 6. | 26.
| %IMP | 7% | -33% | -20% | -18% | -67% | -400% | -70% | 40% | 60% | 26%
| | ||||||||||
| 14/1200 UTC 25.4N 76.3W Near Alice Town, Eleuthera 72 h into the forecast | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 25.50 | 76.18 | 68.5 | 16.4 | Near Eleuthera Island, Bahamas
| AVAL | 24.12 | 74.49 | 71.0 | 231.4 | San Salvador, Bahamas
| %IMP | 71% | -1211%
|
| GFNO | 27.38 | 76.51 | 76.0 | 201.0 | Near Abaco Island, Bahamas
| GFAL | 25.06 | 76.14 | 69.5 | 41.1 | Eleuthera Island, Bahamas
| %IMP | 38% | 80%
|
|
14/1900 UTC 26.3N 77.1W Near Cherokee Sound, Abaco 79 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 26.85 | 77.61 | 93.0 | 79.4 | Little Abaco Island, Bahamas
| AVAL | 26.86 | 77.56 | 96.0 | 77.2 | Abaco Island, Bahamas
| %IMP | -21% | 3%
|
| GFNO | 27.38 | 76.51 | 83.0 | 179.7 | Near Abaco Island, Bahamas
| GFAL | 26.75 | 78.26 | 83.0 | 125.7 | Grand Bahama Island, Bahamas
| %IMP | 0% | 30% |
|
|
16/0630 UTC 33.8N 78.0W Near Cape Fear, NC 114.5 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
|
| AVNN | No landfall forecast
| AVAL | No landfall forecast
| %IMP |
|
| GFNO | 33.85 | 78.65 | 118.0 | 60.2 | North Myrtle Beach, SC
| GFAL | 32.50 | 80.18 | 110.5 | 249.0 | Seabrook Island, SC
| %IMP | -14% | -314%
| | ||||||||||||||||||||||||||||||
Figure 1. NCEP 850 - 200 hPa mean wind analysis for 11 September 1999 1200 UTC (Hurricane Floyd).
Figure 2. Track forecasts for the no dropwindsonde (NO or NN) and the all dropwindsonde (AL) runs for the AVN and GFDL models initialized on 11 September 1999 1200 UTC. The best track is shown in black.
Figure 3. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 11 September 1999 1200 UTC.
Figure 4. 12-h forecast differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 11 September 1999 1200 UTC.