Satellites do not have the capability to directly measure wind speeds, so they make estimates based upon other observable variables, using instruments such as a scatterometer. Yes, that’s a real word. By these indirect estimates, Oscar had sustained winds between 48 mph and 63 mph (77 kph to 101 kph), which remains well below the threshold for a hurricane (74 mph, 119 kph).
The Air Force aircraft found sustained winds, in a tiny area to be sure, of 85 mph (137 kph). Hence, Hurricane Oscar.
How this happened
Oscar’s development shocked forecasters. There was only a modest indication from satellite imagery, as of Friday, that anything would form; and
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