Mission Plan :

The plan called for a butterfly pattern, entering from south, and modified to make surewe do not fly within 12 nm of land. There is time for other modules at the end of the three passes. System is still not a depression as of the takeoff time.

Mission Summary :

AL92 remained a disturbance throughout the beginning of the flight. Despite having ample convection, a seemingly good satellite signature, and flight-level winds approaching 5 kt, aircraft has been unable to close off a low-level center for many days. Three passes through the supposed center of the system were made during the flight, centered at 1715, 1810, and 1926 UTC. The operational radar analysis on the aircraft failed during the first pass. The second passed failed to show a closed circulation at any levels because the plane remained well to the north of Hispaniola and Puerto Rico where the center was. However, by the third pass (Fig. 1), a closed circulation is evident from near the surface up to at least 14.5 km. Deep convection was seen by the tail radar with reflectivities measured up through 17.5 km. At this time, even though the center was inland, based on Air Force and NOAA data, NHC declared the system to be a tropical cyclone. The process by which the tropical wave and its convection finally developed a closed circulation, especially with the land interaction, is a definite avenue for further genesis research. After the butterfly pattern was completed, a large area of convection was seen on the lower-fuselage radar south of Hispaniola, so a convective burst module was completed. The P3 flew around three sides of the convection, releasing dropwind sondes at each of the turn-points (though, unfortunately, some of these dropwindsondes failed). Interestingly, a mid-level circulation could be seen in the radar analyses (Fig. 1) in this region. At 2018 UTC, the aircraft flew through a second flight-level center in this region, though this center was not as clearly defined as the cyclone center itself. This area also had constant lightning seen through the aircraft windows. The dropwindsonde data (Fig. 2) show a southwest-to-northeast tilted vortex extending from 700 hPa down to the surface. Satellite imagery (not shown) suggested that this area of convection lasted a few more hours before dissipating, and it did not become a major player in the future evolution of what became Fay. It will be interesting to initialize models with these data to see the interaction of this feature, land, and the cyclone itself.

Figure 1: Operational radar analyses from the third pass by the center of the cyclone, centered at 2126 UTC, 14 August, at (right to left) 3 km, 5 km, and 7 km altitude, respectively.

Problems :

Mission Data