Hurricane Katrina came ashore in South Florida during the evening hours of Thursday, August 25. The peak winds at landfall were about 75 kt Ð a Category 1 hurricane. Despite the fact that Katrina was just a minimal hurricane, there was significant damage to main regions impacted, including downed trees, power outages, and widespread enormous rainfall amounts (e.g., up to 20 inches estimated by radar at some locations in Miami-Dade county). A gust of 91 kt was measured at RSMAS on Virginia Key. The storm took a jog toward the southwest at landfall, bringing the eye over north Miami-Dade county and through central Miami-Dade as it tracked west- southwest toward Florida Bay. The storm moved faster than expected and spent less time over land than expected, emerging into the Gulf of Mexico by 12 UTC Friday.

Because the forecasts had called for Katrina to spend much longer over land, no flights were tasked for this Friday. Also, the NRL P-3 evacuated to Patuxent River, MD, in anticipation of possible tropical-storm force winds. For tomorrow, N43RF tasked for a combination SFMR/fix mission, with fix responsibilities at 15, 18, and 21 UTC. The plan calls for an attempted coordination between N43RF and the NRL P-3 during this tasked mission. The coordination will occur during the northwest-oriented downwind leg of the rotating figure-4 pattern for N43RF, which will be located on the northeast side of the storm. A slight modification of the standard figure-4 tasked pattern has been sought from NHC. This modification involves changing the downwind leg on the northeast side from a straight line to one that is oriented along the inner edge of the anticipated rainband (Fig. 33). The NRL P-3 will takeoff from Patuxent River and fly to the storm, recovering in Tampa at the end of the mission. N42RF is down for continued installation and integration of the IWRAP instrument.

Katrina continued to move toward the west-southwest and strengthened to a Category 2 hurricane during the afternoon hours. An eye appears to be forming in infrared satellite imagery during the evening hours (Fig. 34). Track guidance (Fig. 35) indicates that the storm is likely to come ashore somewhere between the coast of the Florida panhandle and Louisiana on Monday morning. The orientation of convective bands seems to be changing from a maximum on the southeast side to the east side, as revealed by radar imagery (Fig. 36). It is anticipated that these bands will become oriented along the northeastern side of the storm tomorrow as the northeasterly shear associated with the strong ridge north of Katrina (Fig. 37) relaxes and the orientation of convection becomes dominated by the motion of the storm. It is during the time that N43RF and the NRL P-3 will be located in the system.

For the following day (Sunday), N43RF is tasked for another SFMR/fix missions, with fix responsibilities at 18 and 21 UTC. Because only 2 fix times are required, there is the possibility of having time to work a rainband in coordination with the NRL P-3. This possibility will be explored as the time approaches. For Monday, a landfall mission may occur. If NHC does not task the P-3, then a research mission may be flown if the storm is anticipated to be a major hurricane at landfall.

Elsewhere in the Tropics, the tropical wave in the central Atlantic continues to persist, with a flare-up of convection in the nighttime hours (Fig. 38). Global models continue to forecast this system, if it develops, to curve toward the north at around 50-55 W, well out of range of possible operations.

Rob Rogers
HRD Field Program director