Tropical Storm Debby
Tropical Cyclogenesis Experiment

(940911I Aircraft 43RF)

Scientific crew
Chief Scientist F. Marks
Doppler Scientist H. Willoughby
Cloud Physics Scientist R. Black
Dropwindsonde Scientist J. Franklin
Workstation J. Griffin
Observers Fremmel (Radian Corp.)
One IMAX individual
One Mexican AF Meteorologist

This document is divided into 3 sections (Each section is written by the Chief Scientist):

Mission Briefing

N43RF's flight on 11SEP94 was the only flight on the second day of the tropical cyclogenesis experiment in Debby. It was intended to be the same as on the 10th but it was flown in the opposite direction and modified to allow for Debby's proximity to Cuba and Hispaniola. We had the option of breaking off the pattern after the initial east-to-west leg and returning to Miami through the Windward Passage if the storm was too weak to work with or too close to land.

Mission Synopsis

We left Barbados at 1854 UT on 11SEP94 and reached our initial point, 17N 67W at 2050. From the IP, we flew westward along 17N under the convective anvil through confused winds on the east side of the wave axis. We crossed the axis at 72.7W, passing into clear air and consistent wind from the northeast. At 76W, the end of the east-to west leg, we turned toward the southeast on the diagonal leg to the southernmost point, 15N 73.1W. The south to north leg was a little west of the wave axis because we needed to enter the Windward Passage between Haiti and Cuba. North of the center we deviated to the northwest, entered the passage, and followed it north of the islands. The north end of the passage was filled by sea-breeze convection from the islands. The fina l point of the pattern was north of the islands at 23.5N 73.6W. From their we followed airways to Opa-Loca, recovering at 0234 UT on 12SEP94.

Mission Evaluation and Problems

This mission showed that the exposed surface center is a reliable reference point that can be located visually if the aircraft is within a degree of latitude of its position in clear air at 500 hPa-but only in daylight, bright moonlight, or if there is a lot of lightning. The center's association with a prominent cumulonimbus complex can be a help. The north, south, and west legs were essential to delimiting the cyclone anticyclone couplet, but much of the interesting dynamics appeared to be in the southe ast quadrant. If we had not used so much range in the ferry from Miami, a better flight plan would have been: initial north-south leg, diagonal leg to east of the center, east to west across the center, then a shorter diagonal to northwest of the center, and finally northwest to southeast across the center to Barbados.