The normal procedure is that on the Shabbos before Rosh Chodesh we bless the upcoming month, announce the exact date and time of the molad, which is when the New Moon will be visible in Jerusalem, and let everyone know what day, or days, Rosh Chodesh falls during the following week. This is what we do before we begin every month, except for the month of Tishrei. On the Shabbos preceding Tishrei, which is this Shabbos, we omit Birchas HaChodesh.
There are various explanations as to why we treat Tishrei differently than all other months. Some suggest that the practice of Birchas HaChodesh was instituted simply to let people know when the new month actually begins. With Tishrei this is not necessary since people have been preparing for the New Year, which commences with the first day of Tishrei, for the entire month before, during the month of Elul. Everyone knows when it is; there is no need for a reminder.
Others suggest a different approach: Rosh HaShana, the first of Tishrei, is a fresh start. It is the day when Creation is renewed, and thus, we are also given the opportunity to define ourselves anew. The slate is wiped clean, and the pen is put into our hands to write an innovative story, different from that which was there before. As such, the new month of Tishrei, and the New Year, needs no blessing from the previous month. It stands on its own, apart from the precedent of the past, waiting to be blessed by our new actions.
May our collective and individual dreams come to fruition this year.
Lea and I would like to take this opportunity to wish you all a Shana tova and a kesiva víchasima tova.