|Friday, Aug 9, 2013|
On August 8th, NOAA issued its updated Atlantic hurricane season outlook, saying that the season is shaping up to be above normal and that it could be very active. The season has already produced four named storms, with the peak of the season – mid-August through October – yet to come.
“Our confidence for an above-normal season is still high because the predicted atmospheric and oceanic conditions that are favorable for storm development have materialized,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, a division of the National Weather Service. “Also, two of the four named storms to-date formed in the deep tropical Atlantic, which historically is an indicator of an active season.”
The conditions in place now are similar to those that have produced many active Atlantic hurricane seasons since 1995, and include above-average Atlantic sea surface temperatures and a stronger rainy season in West Africa, which produces wind patterns that help turn storm systems there into tropical storms and hurricanes.
The updated outlook calls for a 70% chance of an above-normal season. Across the Atlantic Basin for the entire season – June 1 to November 30 – NOAA’s updated seasonal outlook (which includes the activity to date of tropical storms Andrea, Barry, Chantal, and Dorian) projects a 70 percent chance for each of the following ranges:
- 13 to 19 named storms (top winds of 39 mph or higher), including
- 6 to 9 hurricanes (top winds of 74 mph or higher), of which
- 3 to 5 could be major hurricanes (Category 3, 4 or 5; winds of at least 111 mph)
These ranges are above the 30-year seasonal averages of 12 named storms, six hurricanes and three major hurricanes.
The updated outlook is similar to the pre-season outlook issued in May, but with a reduced expectation for extreme levels of activity. Motivating this change is a decreased likelihood that La Niña will develop and bring its reduced wind shear that further strengthens the hurricane season.
Other factors are the lack of hurricanes through July, more variability in the wind patterns across the tropical Atlantic Ocean and slightly lower hurricane season model predictions.