- Hurricane Katrina intensified overnight to become a Cat 5 hurricane. Central pressure dropped below 910 hPa with wind speed exceeding 150 mph. TRMM images showed eyewall and rainband structures and provided a good example for scientist to plan today's mission. There were multiple rainbands on east side of the center. It was planned for NRL P3 to join NOAA 43 at the NE quadrant of Katrina to sample rainband structures. Since NOAA 43 was tasked by NHC to do center fixes, it has to fly fixed figure 4 pattern through hurricane center at 15, 18, and 21 UTC. Only a short time period will NOAA 43 be closed to NRL P3. NOAA 43 took off at 16:30 UTC from MacDill and NRL took off at 18:45 UTC. The plan was for NRL P3 to meet with NOAA 43 at ~180 km east of the center at 2200 UTC to sample a rainband. Both P3s would fly outside of the rainbands due to the limitations of the fixed figure 4 pattern. NRL P3 headed west toward Katrina. Just before takeoff, we found that the X-Chat on one of the laptop was expired and the software ask for "registration" (e.g., pay to subscribe). Since there is no internet access on the plane, it becomes a challenge to register online. Michael Bell used his cell phone as a modem attempting to register online. He did pay $20 to registration but it was unsuccessful to revive the X-Chat. We decided to use the ELDORA CAPPI display laptop to run X-Chat for the mission. After NRL P3 took off, Michael and Deanna (U. W student) worked with Charlie using X-Chat to successfully re-installed X-Chat on that laptop. This work paid off as the cappi laptop continuously had problems to connect to chat server during the second half of the mission. Just before NRL P3 arrive the initial point, NRL P3 passed through an other band and got a pretty good jolt (16 m/s updraft and few lesser ones). ELDORA was down but came up after a restart. This turbulence got everyone nervous. After NRL P3 went inside that band, it was mostly stratiform precipitation in between two rainbands. NRL P3 turned S before it encountered the inner rainband. For the next 1.5 hours, NRL P3 find its way in between rainbands to avoid convections waiting for NOAA 43 to arrive. It was quite an experience to navigate P3 using nose radar and ELDORA. NOAA 43 was moving east after an eye penetration to meet with NRL P3. NRL P3 flew in between two rainbands and was in a holding pattern waiting for guidance from NOAA 43. During this period, Iridium was unstable and NRL P3 used satellite phone and VHF radio to communicate with ops center and NOAA 43. It turned out that NRL P3 (NOAA 43) ended on the west (east) side of the rainband, not exactly what we planned in the ops plan. After a coordinated arc leg on the NE quadrant, NOAA 43 left for the figure 4 pattern. Before that happened, NOAA 43 relayed way points for NRL P3 to escape to the east side of the rainband. During the last period, NRL P3 did not receive images for ~40 min even the Iridium was function normally. Fortunately, the path designed by NOAA 43 and ops center led NRL P3 out of the rain quite smoothly. NRL P3 returned to Tampa at 2346 UTC. A total of 16 dropsondes were released at 5 min interval. Only one of them is bad. Interesting vertical structures in these soundings can been identified in the skew-T plot. ELDORA images showed very complex structure (convergence, vertical shear, gust front type flow field) along the rainband. Intense convections (up to 16 km height) can been seen in the primary rainband. This dataset will be very interesting to analyze.
ELDORA Images for this Flight:
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