No sooner do I publish a table with hurricane forecasts than one of the forecasters changes his prediction. That would be Philip Klotzbach of Colorado State. (In the past the forecasts were attributed to William Gray, but starting this year, he moves to second author.)
CSU increased its estimates and has moved to a point estimate from a range. Here’s an updated table:
CSU raised its forecast because it didn’t like these developments:
- Neutral El Niño and weak La Niña. El Niño discourages storm development, so you’re glad to have him around. Unfortunately, he’s not. When La Niña is around, there’s less wind shear across the Atlantic, and wind shear helps break up storms.
- Near-record surface sea temperatures in the tropical and North Atlantic. Warm water makes for stronger hurricanes, and more of them.
- The high pressure found over the Azores in April and May was weaker than usual. This usually leads to weaker trade winds. Stronger trade winds deter hurricane development.
And the effect of all that oil on hurricanes? Not much, say the academics.
We do not anticipate that the oil spill will have any noticeable impact on tropical cyclone intensity or frequency. The strong winds of a tropical storm or hurricane should sufficiently mix the oil and water that there should be no noticeable alterations in broad- scale evaporation and sensible and latent heat flux.
The entire CSU paper is here.