Since St. Croix is a bit south of St. Thomas and St. John, I'd anticipate that Earl will pass about 100 miles to the northeast of St. Croix around mid-afternoon on Monday (perhaps a little earlier). Although Earl should be a 100+mph hurricane at that time, sustained tropical storm force winds should only extend about 60 miles to the southwest of the center, so worst case conditions are probably going to be winds at 35mph gusting to 45mph - perhaps an isolated gust to 50mph. Obviously if Earl's track stays further to the south the winds on St. Croix will be stronger. When the storm passes by, let us know what the conditions were.

Added: 11PM NHC update nudges the track a little to the south, but not that much. Looks like Earl will pass about 90 miles to the northeast of St. Croix with tropical storm force winds extend about 70 miles to the southwest at that time - but thats not enough to change anything (yet).
ED