The London-based weather forecast group for an insurance brokerage said its latest storm outlook predicts greatly increased activity with one more hurricane hitting the United States.

The announcement came from Tropical Storm Risk, a consortium of experts on insurance, risk management and seasonal climate forecasting led by the Benfield UCL Hazard Research Centre.

TSR said there prediction is for two hurricane strikes a number that includes Hurricane Dolly, which hit Texas last month.

Based on current and projected climate signals TSR said it predicts both Atlantic basin and U.S. landfalling hurricane activity will be 90 percent above the long-term (1950-2007) norm. This compares to 35 percent above-norm predictions the group issued July 4.

TSR said the forecast has risen due to the establishment in July of tropospheric wind patterns in the lowest atmospheric region–an event which favors increased hurricane activity.

It explained that once these patterns form, they tend to persist through the main hurricane months of August and September.

The consortium also predicted a 97 percent probability of an above-normal Atlantic hurricane season, a 3 percent probability of a near-normal season and a negligible chance of a below-normal season.

The meteorologists said they now foresee 18 tropical storms for the Atlantic basin as a whole, with nine of these being hurricanes and four or five of these hurricanes being intense in category. This compares to long-term norm values of ten, six and three, respectively.

TSR forecasted a 91 percent probability of above-normal U.S. landfalling hurricane activity, an 8 percent likelihood of a near-normal season and only a 1 percent chance of a below-normal season.

The two hurricanes to hit the United States will be among five tropical storm strikes, TSR said. One hurricane strike is predicted on the Caribbean Lesser Antilles.

If the forecast comes true, TSR said the total of 18 tropical storms would equal the third highest total recorded in a North Atlantic season since 1950.

Professor Mark Saunders, the TSR lead scientist and head of Weather and Climate Extremes at the Benfield UCL Hazard Research Centre at University College London, gave a number of reasons a very active hurricane season is expected.

He mentioned:

o Weaker than normal trade winds that will permit more and stronger storms to spin up.

o Temperature of the sea waters between West Africa and the Caribbean are likely to be slightly warmer than normal, thereby providing extra heat and moisture to help power the development of storms within the hurricane main development region.

o Tropospheric winds over North America, the east Pacific and the North Atlantic that are favorable for steering developing Atlantic hurricanes toward U.S. shores during August and September.

o Historical precedents for all years since 1950 with very active June/July hurricane activity, as has been the case this year, have subsequently been very active for seasonal hurricane activity.

TSR forecasts are online at www.tropicalstormrisk.com.

This article updated Aug.7, 9:01 a.m.

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