The 16 storm 2003 Atlantic hurricane season (click to enlarge) — a possible analogue for 2007?
As we get closer to hurricane season–and especially once the season starts–the forecasts become increasingly reliable. We’re still a month away, though, so what follows should be taken, as always, with a grain of salt.
Nevertheless, we now have two more forecasts predicting–as previous forecasts have consistently done–a quite active Atlantic hurricane season.
One just released forecast comes from Tropical Storm Risk (PDF), a group whose methodology relies upon assessing sea-surface temperatures (SSTs) and trade wind speed over the Caribbean and tropical Atlantic. Based upon this methodology, Tropical Storm Risk now forecasts 16.1 total storms (plus or minus 3.8), 8.9 hurricanes (plus or minus 2.6), and 4.0 intense hurricanes (plus or minus 1.5). This is a very slight downscaling from their forecast of last month (16.7 named storms, 9.4 hurricanes, and 4.2 intense hurricanes, all plus or minus yada yada).
Meanwhile, I’ve become aware of a paper that is in press at the Journal of Geophysical Research – Atmospheres that introduces a new Atlantic forecasting methodology and also includes a prediction for this year. The paper, entitled “The Influence of Climate State Variables on Atlantic Tropical Cyclone Occurrence Rates,” is by Thomas A. Sabbatelli and Michael E. Mann of Penn State University. Using a statistical technique based on SSTs and the state of the El Nino-Southern Oscillation, they reached the following conclusion:
Based on statistical models of annual Atlantic TC counts developed in this study and current forecasts of climate state variables, we predicted m=15±4 total named storms for the 2007 season.
Which, of course, is just slightly lower than the Tropical Storm Risk forecast.
Meanwhile, forecasts (PDF) of the state of ENSO continue to show that we’re in neutral conditions, with a possible transition into a La Nina state over the next 3 months. If that’s right, then El Nino will not be around to save the Atlantic from a busy hurricane season this year.
As usual, take it all with a grain of salt. But start thinking about it.
The next forecasts, from William Gray of Colorado State University and from NOAA, will be out towards the end of the month.
P.S.: You may have heard about the latest paper by Chris Landsea, challenging the notion that global warming is increasing annual Atlantic storm counts. I’ll have more on this soon.