As Tropical Storm Erika was 350 km east of the Leeward Islands (see the black lines outlining one of the island in bottom left of analyses) a NOAA P-3 mission collected airborne Doppler radar data to use in initializing and evaluating model guidance.
The figure below depicts the aircraft flight track (P-3: yellow line) superposed on the real-time lower fuselage radar and visible satellite imagery.
Included here you see images of the horizontal winds within 180 km of Erika sampled from the tail Doppler radar on the P-3 aircraft during the evening of 26 August 2015. These images are at three altitudes (1 km, 3 km, and 6 km) and are a composite of winds from the P-3 Doppler pattern around Erika. Also plotted on each analysis are the locations of dropsondes deployed by the P-3 (plotted using standard station symbols). These analyses show that Erika maintained a very asymmetric distribution of precipitation at all altitudes, with the bulk of the precipitation primarily in the southeastern quadrant of the storm, particularly at 3- and 6- km altitude. There is indication of a circulation center at 1-and 3-km altitudes, with the strongest winds 50-60 km northeast of the circulation center, but with strong winds extending to 180 km to the north and east of the center. At 6-km altitude there was an indication of a circulation center in the heavy precipitation 125-150 km southeast of the 1-km altitude circulation center, indicative of very strong west-northwesterly shear of the horizontal wind over the low-level center.
All the Tropical Storm Erika radar composites at 0.5-km height resolution are available at: http://www.aoml.noaa.gov/hrd/Storm_pages/erika2015/radar.html.