." >>> "pbs newshour weekend" is made possible by judy and josh westin, joyce v. hale, the wallet family, in memory of miriam and ira d. wallet, the cheryl and phillip milstein family, bernard and irene schwartz. corporate funding is provided by mutual of america, designing customized, individual, and group retirement products. that's why we're your retirement company. additional support is provided by -- and by the corporation for public broadcasting and by contributions to your pbs station from viewers like you. thank you. from the tish wnet studios in new york, hari sreenivasan. >> thanks for joining us. a large, dangerous storm system is sweeping through the middle of the nation. the storm spawned tornados that did extensive damage in the small central illinois community of washington. in chicago, tens of thousands of fans attended the ravens/bears football game were advised to leave the stands and take cover. the game was suspended for nearly two hours. the storms, which are unusual for this time of year, also produced high winds and torrential downpours. in

judy and josh westin. the wallic family in memory of miriam and ira dean wallic. cheryl and philip willstein family. bernard and irene schwartz. roslyn p. walter. corporate funding is provided by mutual of america. designing customized, individual and group retirement products. we're your retirement company. additional support is provided by -- the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> narrator: on the entire west coast of the americas, there is no other estuary like san francisco bay. immense in size, covering over 1,600 square miles, it is one of the great estuaries of the world. >> estuaries are the part of the planet where land and sea come together. it's magic in a lot of ways. >> narrator: it was an estuary of breathtaking abundance, a marvel of nature. >> so on a per acre basis, this is more productive than the rain forest, more productive than the redwood forest, more productive than coral reefs. these are the most biologically productive regions on earth. >> narrator: next on "sa

pbs "news hour weekend" is made possible by judy and josh westin, joyce b.wall be onning family in

pbs "news hour weekend" is made possible by judy and josh westin, joyce b. the wall be onning family in memory of ira d. wallick and bernard and irene schwartz, rosalynn p. walter. pacific islanders and communications, corporate funding is provided by mutual of america, designing customized, individual and group retirement products. that's why we are your retirement company. additional support is provided by -- and by the corporation for public broadcasting and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios in lincoln center in new york. >> good evening. thanks for joining us. the united states and the world's other major powers today hailed the interim agreement struck last night with iran over that country's nuclear program. >> the united states, together with our close allies and partners took an important first step toward a comprehensive solution that addresses our concerns with the islamic republic of iran's nuclear program. under terms of the six-month deal announced in the middle of the night in gen