A band of water that stretches from Mexico all the way up to Alaska is 1 to 2 degrees warmer right now than its average, said Scott Braun, a research meteorologist at NASA's Goddard Space Flight Center. The warmer water acts as a source of energy for the hurricane — evaporation off the water allows the storm to keep forming clouds at higher temperatures, and direct heat off the ocean heats the storm from underneath.
Atmospheric conditions around Patricia are the other half of the recipe, and they also favorable for Patricia, Braun told CNBC. The air is very moist, and there is very little vertical wind shear — the differences in wind speeds at different heights that typically would weaken the storm by tilting it or tearing it apart. The dry air and the lack of vertical wind shear means there is very little that can stop the storm from building intensity.
"This is a combination of extreme ocean conditions with favorable atmospheric conditions," Braun said. "You have very warm sea surface temperature, a deep warm water layer, very moist air, and very little vertical wind shear."
Braun said that the storm seemingly came out of nowhere in part because rapid intensification events are hard to predict.
"Conditions [around Patricia] were certainly ripe for rapid intensification, but it was on the extreme side of rapid intensification," Braun said. "Wind speed increased by about 95 knots in 24 hours, about 70 knots higher than the forecast."
"It is the type of event you can almost never forecast, because while we know that these rapid intensification event occur, they are so extreme that if you are wrong, you are 'the boy that cried wolf,'" he said.