We've already discussed how the initial source of moisture for the pending storm cycle is being extracted from the tropics and subtropics near Hawaii. Subsequently important is a second filament of moisture originating in the Far East near the Philippines.
Both of these can be seen in the global precipitable water (color contours every 5 mm), 925-mb wind (vectors), and dynamic tropopause pressure (color fill) analysis below. The filament originating near Hawaii is streaming northeastward in the eastern Pacific, whereas the filament originating in the Far East is streaming eastward across the western Pacific.
I think of how far we have come meteorologically compared to the pre satellite era when the ability to identify and trace these moisture filaments was essentially non existent. Today, more than 99% of the data ingested into operational numerical weather prediction models comes from satellites.