16 May 2003 – Flight 798


Research Flight from OUN


Pilot: Tom Warner


T.O. 17:56 UT


T.D. 19:20 UT (at Shawnee)


Storms began to develop to the north and west as an upper-level wave moved by. A few CG’s were noted by noon. The TELEX balloon people were out the previous evening on a long mission and did not return until 6 AM CDT, and are not available. We decide to go alone and focus on NO distribution in lightning-producing cells, as well as polarimetric radar hydrometeor identification.  Storms cells are short-lived with maximum reflectivities reaching 50 – 55 dBZ prior to take-off.


After take-off, pilot and flight coordinator agree on a target ~50 nmi E of OUN. At 18:02:26 pilot reports he is into bases of clouds. He goes through to the far side of the echo as seen on KTLX then returns.  He reports strong updrafts, hail, and severe turbulence in some locations. He is below cloud base near end of last pass heading toward OUN.


The DMT liquid water probe broke at 18:38 UT. The 2D-C and hail spectrometer images look good. There were some problems with HVPS imagery. Peak updrafts were 10-15 m s-1 with peak cloud liquid water concentration approaching 3 g m-3. P-static was a problem for ground-air communications. The rate-of-climb indicator was not recorded properly. The video camera window broke at 18:55:50 UT during an encounter with hail.


The engine quit momentarily on the return-to-base leg, at ~ 19:22, about 40 nmi out from Norman. It restarted but ran roughly, so pilot elected to land at Shawnee. The problem was eventually diagnosed as ice moving through the carburetor on descent, a problem occasionally noted on flights in which heavy icing is encountered.


Some hail damage was noted on the video window, the sealant on the hail spectrometer pylons, and the coating on the particle charge-detection plates. There was a new electrical discharge pit on the rear elevator.


Time on the video is exact compared to GPS time. The data system time is one second behind.


The last cell penetrated was the 1st intense cell in what became a squall line/front that continued to move eastward and was moving across the Mississippi River by the next morning.