Thursday, November 29, 2012

Improving hurricane intensity predictions

A bit of hurricane folklore has it that hurricanes have a dry side and a wet side - that is, whether you'll get more wind than rain when a hurricane passes through depends on which side of the center you're on. A new report from the NASA Jet Propulsion Lab points out that not only is this folklore true, it may to improve the ability to predict the intensity of hurricanes.
The researchers found the hurricanes that rapidly intensified tended to exist within a moister large-scale environment than weaker storms. The rapidly intensifying hurricanes had statistically significant higher relative-humidity levels in their environments than storms whose intensity was weakening or unchanged.
 . . .
The team found substantial differences in relative-humidity levels between storm quadrants. One factor may be the shape of the Atlantic basin. Hurricanes in the Atlantic usually travel to the west or northwest -- regions that are drier, climatologically-speaking, than from where the storms originated. This causes the front two quadrants of Atlantic hurricanes to be drier than their rear two quadrants.

A unique result the team found is that in their front-right quadrants, rapidly intensifying hurricanes tended to have sharply higher amounts of upper tropospheric moisture near their centers than they did farther from their centers. 

A previous post linking to some good explanations of why predicting hurricane intensity is so complex is here. NASA is "exploring collaborations" that will allow forecasters to incorporate relative humidity data into hurricane prediction system, so we may be able to see test data in the next few years.

No comments:

Popular Posts