A tropical depression formed off Mexico's southern Pacific coast today, prompting authorities to issue a tropical storm warning for a coastal region popular with tourists. <br/><br/>The US National Hurricane Center said the storm was centered about 165 kilometers south-southwest of Puerto Angel. <br/><br/>The hurricane center's forecast said the depression is expected to strengthen into a tropical storm as it approaches the coast of Oaxaca state in the coming days. <br/><br/>The Center said, heavy rain and flash flooding are likely along Mexico's southern coast.