TSR downgrades 2007 storm forecast

The Tropical Storm Risk (TSR) has downgraded the hurricane forecast from 55% above-norm in June to 40% above-norm in July. According to a Benfield news release, the reason for the reduction is that the trade wind speed over the tropical North Atlantic in August-September will be stronger than previously thought. This would suppress hurricane activity by reducing the available cyclonic vorticity and by increasing vertical wind shear.TSR says the increase in trade wind speed is because La Nina, forecast for August-September, is not as strong as thought before. With this forecast reduction, it is now most unlikely that 2007 will witness devastation similar to either 2004 or 2005, TSR professor and lead scientist Mark Saunders said, calming concerns over a repeat of the 2004-05 U.S. hurricane seasons. TSR’s updated July prediction includes: A 72% probability of an above-normal (i.e. within the top one-third of years historically) Atlantic hurricane season; 15 tropical storms for the Atlantic basin as a whole, with eight of these being hurricanes and three or four intense hurricanes; A 73% probability of above-normal US landfalling hurricane activity, a 20% likelihood of a near-normal season and only a 7% chance of a below-normal season; Four tropical storm strikes on the U.S., two of which will be hurricanes.