Living in the Heights in Arlington the amounts I reported where always suspect especially in Spring. Admittedly never used a board or the 6hr. spotter (correct) training technique. A 1/2 dozen random measurements away from drifts. Wanting to contribute giving a more accurate spread to the NWS. Washington St where the house was, was atop a 300ft hill, visually noticeable from top to bottom surrounds.
The only person to question the accuracy was myself.