Effects of Synoptic Surveillance on model forecasts for
11 September 1999 0000 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 | 121. | 160. | 123. | 179. | 241. | 213. | 210. | 236. | 254. | 233.
| AVAL | 100. | 181. | 175. | 226. | 189. | 263. | 246. | 233. | 267. | 338.
| %IMP | 17% | -13% | -42% | -26% | 22% | -23% | -17% | 1% | -5% | -45%
|
| GFNO | 104. | 182. | 183. | 180. | 157. | 158. | 157. | 99. | 136. | 196.
| GFAL | 68. | 105. | 52. | 38. | 22. | 67. | 124. | 185. | 213. | 322.
| %IMP | 35% | 42% | 72% | 79% | 86% | 58% | 21% | -87% | -57% | -64%
| INTENSITY (kt)
| MODEL | 12 h | 24 h | 36 h | 48 h | 60 h | 72 h | 84 h | 96 h | 108 h | 120 h
|
| AVNN | -59. | -41. | -65. | -86. | -94. | -69. | -56. | -62. | -43. | -33.
| AVAL | -39. | -29. | -48. | -66. | -71. | -45. | -34. | -37. | -24. | -16.
| %IMP | 34% | 29% | 26% | 23% | 24% | 35% | 39% | 40% | 44% | 52%
|
| GFNO | 18. | 31. | 10. | -11. | -18. | 0. | 8. | -2. | 12. | 23.
| GFAL | 21. | 32. | 8. | -10. | -25. | 1. | 11. | 20. | 13. | 17.
| %IMP | -17% | -3% | 20% | 9% | -39% | und% | -38% | -900% | -8% | 26%
|
| SHNO | -11. | 2. | -15. | -32. | -41. | -20. | -10. | -17. | 0. | 11.
| SHAL | -12. | -1. | -19. | -38. | -49. | -26. | -17. | -27. | -11. | 0.
| %IMP | -9% | 50% | -27% | -19% | -20% | -30% | -70% | -59% | und% | 100%
|
| DSNO | -11. | 2. | -15. | -32. | -41. | -20. | -10. | -17. | 0. | 11.
| DSAL | -12. | -1. | -19. | -38. | -49. | -26. | -17. | -27. | -11. | 0.
| %IMP | -9% | 50% | -27% | -19% | -20% | -30% | -70% | -59% | und% | 100%
| | ||||||||||
| 14/1200 UTC 25.4N 76.3W Near Alice Town, Eleuthera 84 h into the forecast | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 23.96 | 74.46 | 82.0 | 245.1 | San Salvador, Bahamas
| AVAL | 23.95 | 74.61 | 84.5 | 234.7 | San Salvador, Bahamas
| %IMP | 75% | 4%
|
| GFNO | No landfall forecast
| GFAL | 23.94 | 74.52 | 74.0 | 242.1 | San Salvador, Bahamas
| %IMP |
|
|
14/1900 UTC 26.3N 77.1W Near Cherokee Sound, Abaco 91 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 26.71 | 78.04 | 106.0 | 104.0 | Grand Bahama Island, Bahamas
| AVAL | 26.64 | 78.63 | 106.5 | 156.8 | Grand Bahama Island, Bahamas
| %IMP | -3% | -51%
|
| GFNO | No landfall forecast
| GFAL | 25.18 | 78.03 | 93.0 | 155.4 | Andros Island, Bahamas
| %IMP |
|
|
16/0630 UTC 33.8N 78.0W Near Cape Fear, NC 126.5 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
|
| AVNN | No landfall forecast
| AVAL | No landfall forecast
| %IMP |
|
| GFNO | No landfall forecast
| GFAL | 28.56 | 80.52 | 112.5 | 633.2 | Merritt Island, FL
| %IMP |
| | |||||||||||||||||||||||||||||||||||||||
Figure 1. NCEP 850 - 200 hPa mean wind analysis for 11 September 1999 0000 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 0000 UTC. The best track is shown in black.
Figure 3. Ensemble perturbation variance at the nominal sampling time 11 September 1999 0000 UTC from the previous day NCEP ensemble forecast. The green circles represent the dropwindsonde locations.
Figure 4. Initial condition differences in the 850 - 200 hPa mean wind between the no and all dropwindsonde cases for 11 September 1999 0000 UTC. The green circles represent the dropwindsonde locations.
