RF19: 18-6-2002 19:02 - 22:38

 

P3 Flight Log:

The forecast from the day before was for a diffuse dryline to form in the western Oklahoma and Texas Panhandles and also in western Kansas. Owing to the strong cap, the possibility for convection initiation was marginal. We called the P-3 down and watched in horror as strong convection broke out along the dryline. The forecast for June 18 was for a better chance for convection to break out along the dryline. The best westerly push was north of Garden City with less chance for convection to the south. The P-3 and King Air were set for a 12:00 CDT takeoff followed by the LearJet at 13:00. The Norman ground armada departed in the morning and were expected to arrive in the target region by midafternoon. Actual takeoff for the P-3 was 11:36 am. Unfortunately, we had trouble with ELDORA from the beginning. It simply would not start up. The problem was serious enough that we contemplated terminating the mission and heading back to Will Rogers Airport. I was informed by the pilots that we needed to remain airborne until at least 14:00 in order to burn enough fuel to land. We had nothing to lose so I told the NCAR people to do whatever they could to fix the radar. In the meantime, Jace decided that this was a good time to perform the Lenschow maneuvers. [After several e-mail exchanges, phone calls, and confusion, Jace was able to talk to Al (before we took off) back in Boulder to get a full explanation of the Lenschow maneuver.] Meanwhile, Jonathan Emmett decided to call Eric Loew back at NCAR for help. Eric was able to immediately identify the problem based on the error messages. He told Jonathan that it was probably a damaged fiber optics cable. With a great deal of calmness and ingenuity, Jonathan used a flashlight to shine through each suspected cable until he found the damaged one. Eric then recommended where Jonathan could steal a cable from a nonessential area to replace the damaged one. Finally, some reprogramming of the software was required so that the system would bypass the nonessential area where the stolen cable was pulled from. Bottom line??.?it worked!! Special kudos to Jonathan and Eric for pulling off a minor miracle. ELDORA came up at approximately 2:00 pm. Since the Liberal ground crew were already working an area south of Garden City a set of dropsondes were released at approximately 1:30 pm. We descended into the same area and located what we thought was the dryline and immediately set up a box pattern. We executed the same pattern a number of times as the boundary slowly retreated northwestward. Another set of drops was released about 4:10 pm. We became a little worried when the skies were still clear late into the afternoon but John Brown told us that convection would develop later in the day. Soon after John?s update, a cloud line developed to the west of the dryline. The cloud line appeared to form a wishbone pattern with the boundary we were working. Once again, this was a difficult pattern to fly since both boundaries could not be sampled simultaneously. To add to our difficulties, LEANDRE was shutting down for no apparent reasons. The problems continued until approximately 3:40 pm when LEANDRE shut down for the remainder of the flight. We later found out that a fan switch had inadvertently been turned off. Weak convection appeared to develop along the cloud line and not the boundary that we were working. As the convection initiated I decided to break off our pattern to perform approximate east-west legs through both lines. Both boundaries were associated with moisture discontinuities, however, the western boundary was accompanied by an incredibly speed discontinuity. The speed went from 17-19 m/s to almost calm conditions as you penetrated from east to west. After much debate, I decided to tell the LearJet not to release a third leg of drops as weak convection developed. I didn?t feel that this case was optimal and wanted to save the sondes for another day. We departed the region and landed back at OKC at 7:40 pm.

Flight Track:



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