On 7 Marheshvan, Jews in Israel begin reciting "Barech Alenu" in the Amida prayer, instead of "Barechenu." Outside Israel, however, we continue reciting "Barechenu" until the beginning of December. The question thus arises as to which Beracha Israelis should recite when they travel abroad between 7 Marsheshvan and the beginning of December.
It is clear that if an Israeli resident comes to America with the intention of remaining for an extended period of time, such as for a year or two, then he is considered an American resident and thus recites "Barechenu." But when it comes to those who visit for a brief period, such as Shelihim ("messengers") who come from Israel to collect money for their institutions and stay in America for only a week or two, we find some debate among the Halachic authorities.
Hacham David Yosef, in his work Halacha Berura (vol. 6, pp. 185-6), concludes that if an Israeli resident leaves Israel before 7 Marheshvan, then he should recite "Barechenu," like the communities in America, even after this date. Since he left Israel before Israeli communities began reciting "Barech Alenu," he continues reciting "Barechenu" until he returns to Israel. Nevertheless, he should insert the words, "Ve’ten Tal U’matar Li’bracha" in the Beracha of Shema Kolenu, in order to retain some connection with his community back in Israel, which began reciting "Barech Alenu."
However, if an Israeli resident leaves Israel after 7 Marheshvan, and thus has already begun reciting "Barech Alenu," then he should continue doing so even during his stay in America. This gives rise to an interesting question in a case where an Israeli visitor serves as the Hazan in the synagogue. Although he would certainly recite "Barech Alenu" in his silent Amida, he has a problem when it comes to the repetition, which he recites on behalf of the congregation. On the one hand, he cannot recite "Barech Alenu," because the congregation still recites "Barechenu." At the same time, he cannot recite "Barechenu," as he has already begun reciting "Barech Alenu." Hacham David therefore writes that in such a case he should recite "Barechenu," and silently add the words, "Ve’ten Tal U’matar Li’bracha" in the Beracha of Shema Kolenu. In this way, he fulfills his personal obligation while also repeating the Amida according to the practice of the congregation.
Summary: Israeli communities begin reciting "Barech Alenu" on 7 Marheshvan, whereas in the Diaspora they start reciting "Barech Alenu" only in the beginning of December. An Israeli visitor who left Israel before 7 Marheshvan continues reciting "Barechenu" even from 7 Marsheshvan, but adds the words "Ve’ten Tal U’matar Li’bracha" in Shema Kolenu. If he left Israel after 7 Marheshvan, then he continues reciting "Barech Alenu."
