Task: Question Generation
Input (English): Background Paragraph: When the subtropical ridge in the Northwest Pacific is stronger than normal, it leads to a wet monsoon season for Asia.[18] The subtropical ridge position is linked to how far northward monsoon moisture and thunderstorms extend into the United States. Typically, the subtropical ridge across North America migrates far enough northward to begin monsoon conditions across the Desert Southwest from July to September.[19] When the subtropical ridge is farther north than normal towards the Four Corners, monsoon thunderstorms can spread northward into Arizona. When suppressed to the south, the atmosphere dries out across the Desert Southwest, causing a break in the monsoon regime.[20]. 
Story: 2018 was a very wet year for the Four Corners area,  because of the subtropical ridge, 2019, on the other hand was a dry year influenced by the same weather phenomenon that lacked strength in this year.
Output (English): Which year did the subtropical ridge move farther north?