The Intersection

Overnight and up through this morning, Hurricane Flossie in the Northeast Pacific--having started out as a category 1 storm--rapidly intensified into a weak Category 4 with a well defined eye, as you can see in the infrared image below:

I think it's fair to say Flossie's behavior took everyone by surprise. The National Hurricane Center forecasters were not predicting it, or anything close. Neither were the models. This is yet another indication of how bad we still are at forecasting hurricane intensity.

But you can't blame the forecasters, really. I'm looking at some of the same data they did, and I'm just scratching my head. Typically, in order to rapidly intensify a hurricane needs deep warm water. But look at the figures below, first the Northeast Pacific sea surface temperatures as of August 10, and then the tropical cyclone heat potential as of the same date. (Click the images for higher resolution.)

As best I can tell, Flossie rapidly intensified between 135 and 140 W Longitude and 10 and 15 N Latitude. The SSTs in the area were warm enough to support a hurricane, of course, as the figure above shows. But as you can see from the next image (tropical cyclone heat potential), there was hardly a hurricane bullseye in this area in terms of a deep patch of warm water of the sort that one might expect:

So what the heck was Flossie doing? Beats me...perhaps this has something to do with the fact that Flossie is a very small storm as hurricanes go. Or perhaps there were very cold temperatures aloft in the storm outflow region, increasing the potential intensity that Flossie could achieve. But those are just guesses, I honestly don't have a clue. I wonder what the forecasters think, but am not really getting any sense from reading their discussions.

In any event, Flossie has now passed 140 W and has become the responsibility of the Central Pacific Hurricane Center, based in Honolulu. Let's hope the storm doesn't continue to frustrate expectations--if it does, we may find ourselves contemplating possibility of a significant hurricane landfall on the islands. For now, though, Flossie is still far from Hawaii and expected to weaken as it gets closer...