That's the normal header for declaring a Tropical Depression~Without Reconnaisance. The mileage is probably due to the scaling and skew of the satellite images. It gives a rough idea of the area, if you are in or near the depression though. However...Most mariners and locals would probably know that a depression was forming from the winds and weather.
Interesting note. Jim Cantore just mentioned the three above systems on the Tropical Update on TWC.