Figure 1. Flight plan for 20190831H2 mission for Dorian

Figure 2. Actual flight track for 20190831H2 mission for Dorian

Mission Plan :

his was an EMC-tasked NOAA42 Tail Doppler Radar (TDR) mission with a proposed butterfly pattern (Figure 1), as well as a NESDIS Ocean Winds add-on. The pattern was executed well.

Mission Summary :

Figure 2: Infrared satellite image of Hurricane Dorian valid at 0146 UTC 01 September 2019.

Figure 3: Hurricane Analysis and Forecast System (HAFS) analysis of 850-hPa vorticity and 200-hPa wind valid at 00 UTC 01 September 2019.

Dorian had strengthened from the previous day, and was a strong Category 4 hurricane with 130-knot winds during the flight. Figure 2 shows an infrared satellite image of Dorian during the time of the flight. The storm had grown in size (in terms of the CDO) and the core was more symmetric, although there was still some hint of asymmetry due to shear from the NW. Analzyed 200-hPa winds at this time showed that Dorian was embedded in an area of light upper-level flow, with a well-established outflow channel to the east and south of the TC.

Figure 4: 2-km TDR reflectivity/wind for the 20190831H2 mission (image from Paul Reasor).

Figure 5: TDR radial velocity for the second pass across the center during the 20190831H2 mission (image from Paul Reasor).

Mission Evaluation / Problems :

Figure 6: SFMR wind speed (colors) and dropsonde locations (brown squares) along the flight track during the 20190831H2 mission (Image from Heather Holbach).

The mission was successful in gathering and delivering TDR data. 3 successful passes across the center were made, and two NESDIS ocean-winds passes through the eyewall were also accomplished (Figure 6). There were no major problems with the flight. 31 sondes were dropped and the data was good on 30 of the 31. No AXBTs were dropped on this mission. The data gathered throughout the flight showed a storm that had continued to intensify to the threshold of Category 5 status, with flight level winds of ~145 kt and SFMR winds of ~150 kt (Figure 7). These values were supported by dropsonde winds, including one sonde with 151 kt mean winds in the lowest 150 m of the sounding (Figure 8).

Figure 7: Flight level, SFMR, and dropsonde-adjusted wind speeds along the flight track for 20190831H2, along with the extrapolated pressure and altitude (Image from Heather Holbach).

Figure 8: Dropsonde winds from a dropsonde launched in the NW eyewall during the 20190831H2 mission.