Question:
i am wondering if the atmospheric rivers from the western pacific near Hawaii would even exist if Hawaii was not there?
Answer:
Atmospheric rivers are narrow corridors of concentrated moisture in the atmosphere, typically originating over warm ocean waters. These features are driven by large-scale weather patterns, such as the interaction of jet streams, ocean temperatures, and pressure systems.
Hawaii’s location in the Pacific does not directly cause atmospheric rivers to form. Instead, what DOES create atmospheric rivers are:
- Moisture Source: The formation of ARs near Hawaii (we often call it the “Pineapple Express”) relies primarily on the vast expanse of warm, moist air over the tropical and subtropical Pacific Ocean. The warm waters near Hawaii help sustain and feed ARs, but the island itself has little influence.
- Topographic Influence: Hawaii’s mountainous terrain influences local weather, causing orographic lifting and enhanced rainfall. However, it does not significantly impact the broader structure of atmospheric rivers.
Would ARs Exist Without Hawaii?
Yes:
- The large-scale processes that generate atmospheric rivers, such as the interaction between tropical moisture and mid-latitude weather systems, are not dependent on Hawaii.
- The warm ocean waters of the Western Pacific would still provide the necessary moisture to fuel these systems, even if the Hawaiian Islands were absent.
Impact Without Hawaii
If Hawaii didn’t exist, the following would happen:
- No Local Enhancement: No Hawaii would mean no localized intensification of rainfall caused by the islands’ mountains, but the atmospheric river would still bring heavy rain to downstream regions like California or the Pacific Northwest.
- Path Unchanged: Atmospheric rivers would still flow from the tropics to mid-latitudes, guided by jet streams and pressure systems.
