A little clarification: In the article posted above reference was made to the month of Nissan starting on a new moon, not a full moon. Two weeks (14 days) from a new moon is always close to the full moon. Actually, as the Jews approached Jerusalem for the passover each night would get progressively brighter and closer to the full moon. I know that at times the calendar allows for an extra month to be inserted. If the Jewish calendar did this then it would add thirty days. The WT always goes with the first new moon closest to the spring equinox.
Appropriately, the date for the Memorial celebration is arrived at as the Jews back then determined the date for the Passover. They began the month of Nisan when they could first see the new moon in the spring nearest the equinox. Passover came fourteen days later.
Since the spring equinox was on March 14 this year that was only about seven days away from the new moon. Therefore, according to their method, they picked the right day.
I just thought that deserved some clarification. If anyone has any information as to why that doesn't match the Jewish calendar I would be interested to find out why. I know some years they are very close.
I remember reading from one of the church fathers about Polycarp taking a trip to Rome to meet with their bishop at the time. They had an argument over the times for the calendar to celebrate Pascha. I know Polycarp went with Nissan 14 as John instructed him and that the Bishop of Rome went with a different method (maybe the one they still use, I'm not sure.) Anyways, they argued and couldn't come to an agreement because Polycarp knew what he had been taught by John and the Bishop of Rome knew what he had been taught as passed down from Peter, Clement, Linus, etc... (Not sure of the order.) Long story short, they each continued to do it the way they did before they met. They still had communion together and didn't break the church up over it.