i carefully watch the initial development of invests on the goes satellite loops from the nhc, as i am sure most readers of this forum do. when an invest attains tropical depression status, but prior to the time when (and if) it attains tropical storm status, when i "check" the tropical forcast points box at the top of the loop display, the center of the system is characterized by a small "L" along with the forcast points. why is it that when i "check" the "nws fronts" box as well, the center of the system is also characterized by an "H"? Both the "L" and the "H" are in the same location. this "H" disappears, as does the "L" upon reaching tropical storm status and is replaced with the tropical storm icon. i think i've got all that right, but i might be mistaken about exactly when the "H" no longer appears.