An early image of Hurricane Harvey surface winds as seen by the NASA SMAP radiometer on August 24, 2017 at 12:30 UTC, before they reached hurricane-force level. Maximum winds 51 kn (26 m/s). From these satellite data, the 34kn and 50kn radii estimates (in nautical miles) at 12:30 UTC were
Note that the radii were calculated by visually locating the center of the storm, which was not clearly visible at that time. These estimates have an uncertainty of about 10%. The estimated location of the center of the storm in this image is 266.875E, 23.875N.
The wind field here and the estimates of the radii are provided for verification purpose.
SMAP did not have a full view of the storm after it reached hurricane-force level. A partial view of the SE quadrant on Aug 26 0UTC (not shown), just before landfall, observed maximum winds of 48 m/s (94 kn). The NE quadrant was too close to land to be measured by SMAP.