WGT has nothing to do with Kat's Calculator but their (daily?) minor tweaks on "environmental factors" will require that you make adjustments: specifically to account for wind changes in both direction and velocity.
Pick a practice hole, enter the requested variables, ding the shot, make corrections, use the Mulligan feature, and repeat until the ball goes where it should - then play your match.
FYI, I have seen changes in crosswind offsets of as much as .3 foot per MPH of wind and 15% addition/subtractions on head and tail winds.