Effects of Synoptic Surveillance on model forecasts for
11 September 1999 1800 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 | 30. | 46. | 62. | 101. | 64. | 56. | 152. | 225. | 398. | 667.
| AVAL | 63. | 79. | 68. | 153. | 234. | 222. | 359. | 400. | 623. | 1022.
| %IMP | -110% | -72% | -10% | -51% | -266% | -296% | -136% | -78% | -57% | -53%
|
| GFNO | 76. | 98. | 120. | 157. | 156. | 146. | 136. | 179. | 195. | 276.
| GFAL | 15. | 15. | 22. | 42. | 56. | 70. | 118. | 153. | 257. | 353.
| %IMP | 80% | 85% | 82% | 73% | 64% | 52% | 13% | 15% | -32% | -28%
| 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. | -79. | -100. | -85. | -61. | -62. | -56. | -44. | -41. | -8.
| AVAL | -40. | -56. | -75. | -66. | -44. | -41. | -37. | -25. | -36. | -14.
| %IMP | 32% | 29% | 25% | 22% | 28% | 34% | 35% | 43% | 12% | -75%
|
| GFNO | 16. | -2. | -19. | -11. | 11. | 2. | 1. | 14. | 11. | 23.
| GFAL | 20. | 3. | -15. | -6. | 13. | 25. | 15. | 22. | 12. | 16.
| %IMP | -25% | -50% | 21% | 45% | -18% | -1150% | -1400% | -57% | -9% | 30%
|
| SHNO | 2. | -16. | -33. | -21. | 0. | -5. | -5. | 11. | 18. | 48.
| SHAL | 1. | -19. | -38. | -27. | -6. | -11. | -12. | 3. | 9. | 39.
| %IMP | 50% | -19% | -15% | -29% | und% | -120% | -140% | 73% | 50% | 19%
|
| DSNO | 2. | -16. | -33. | -21. | 0. | -5. | -5. | 11. | 18. | 48.
| DSAL | 1. | -19. | -38. | -27. | -6. | -11. | -12. | 3. | 9. | 39.
| %IMP | 50% | -19% | -15% | -29% | und% | -120% | -140% | 73% | 50% | 19%
| | ||||||||||
| 14/1200 UTC 25.4N 76.3W Near Alice Town, Eleuthera 66 h into the forecast | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 25.22 | 76.25 | 67.5 | 20.6 | Eleuthera Island, Bahamas
| AVAL | 23.03 | 73.80 | 58.5 | 365.4 | Samana Cay, Bahamas
| %IMP | -400% | -1674%
|
| GFNO | 27.23 | 76.33 | 71.5 | 203.3 | Near Eleuthera Island, Bahamas
| GFAL | 24.25 | 74.45 | 56.5 | 226.1 | San Salvador, Bahamas
| %IMP | -73% | -11%
|
|
14/1900 UTC 26.3N 77.1W Near Cherokee Sound, Abaco 73 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
| AVNN | 26.52 | 78.60 | 81.0 | 151.2 | Grand Bahama Island, Bahamas
| AVAL | 24.62 | 78.45 | 80.0 | 230.6 | Andros Island, Bahamas
| %IMP | 13% | -53%
|
| GFNO | 27.23 | 76.33 | 71.5 | 128.5 | Near Eleuthera Island, Bahamas
| GFAL | 26.79 | 78.56 | 81.5 | 155.0 | Grand Bahama Island, Bahamas
| %IMP | -467% | -21% |
|
|
16/0630 UTC 33.8N 78.0W Near Cape Fear, NC 108.5 h into the forecast
| MODEL | LAT | LON | TIME | ERROR | LOCATION
|
|
| AVNN | No landfall forecast
| AVAL | 27.19 | 80.16 | 96.5 | 762.9 | Stuart, FL
| %IMP |
|
| GFNO | 33.83 | 77.82 | 103.0 | 16.9 | Cape Fear, NC
| GFAL | 32.56 | 80.12 | 109.0 | 240.5 | Seabrook Island, SC
| %IMP | 91% | -1323%
| | ||||||||||||||||||||||||||
Figure 1. NCEP 850 - 200 hPa mean wind analysis for 11 September 1999 1800 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 1800 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 1800 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 1800 UTC.