Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_15416002_1 (chi VARCHAR, nhc_advisory_number VARCHAR)

### Question ###
What is the CHI (Carvill Hurricane Index) when the NHC advisory number is equal to 49b?

### Accurate SQL ###

SELECT chi FROM table_15416002_1 WHERE nhc_advisory_number = "49B"