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Mission Summary

980922I Aircraft 43RF
Hurricane Georges
Synoptic Flow Mission

Scientific Crew (43RF)
Lead ScientistH. Willoughby
WorkstationJ. Griffin
GPS sonde scientistC. Landsea

Mission Briefing:

Flight 980922I was one sortie of a two-aircraft synoptic surveillance mission flown around Hurricane Georges. It originated and terminated at Opa Locka, FL. The objective was to fly eastward along a circuitous route north of the Greater Antilles to locate the subtropical ridge axis and scout for weakness in the ridge. These data, combined with observations in the Bahamas and Carribean from N49RF were intended to improve the initialization of the operational forecast cycle for 23/00 Z and add to the ensemble of multi-aircraft GPS sonde synoptic surveillance missions.

Mission Synopsis

N43RF took off from Opa Locka, FL, at 1728 UTC on 22SEP98, flew northeastward, reaching the initial drop point (29° 30' N, 78° 30' W) at 1827 UTC. We then flew east along 29° 30' N to 70° 00' W, just above the 500 hPa level in 15kt westerly winds north of the ridge axis, then southeast to 27° 30' N, 67° 30' W. The first six sondes worked beautifully, but the seventh, at this position, lost telemetry. We dropped a second instrument 14 nmi south of the nominal drop point. As we continued south along 67° 30' W we reached the ridge axis near 25° 45' N where we deployed drop 8 in calm winds. It reported a 1012 hPa surface pressure. Drop 9, near 24° N was in easterly flight-level flow (115° at 8 kt) south of the ridge. From that point as we flow SSE to 22° N, 68° 33' W. We were clearly in Georges' circulation as we turned westward along 22° N and climbed to 443 hPa. Surface pressures were about 1011 hPa. Crop 11 at 71° W was a fast fall that reported no winds. We turned NNE, and dropped a backup 45 nmi farther aling track. At 24° N, we turned north along 70° W, climbed to 424 hPa, remaining in easterly winds until after we passed 26° N and turned NW. By the time we reached the next drop point (27° 44' N, 72° W) we were in weak westerlies again, north of the ridge. These winds continued as we flew westward along 27° 44' N, then turned WSW to recover at Opa Locka, FL, at 0123 UTC on 23SEP98; a 7 hour 55 minute duration flight.


Flown as briefed. Another multi-plane synoptic surveillance mission in the ensemble.


Everything worked well. Of the 19 sondes deployed only 2 failed outright: drop 7 lost telemetry and drop 11 was a fast fall with no winds.

Hugh E. Willoughby

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