After several days of working its way across the open and at times hostile Atlantic Ocean this week, Hurricane Erin found more favorable conditions and exploded in intensity on Friday night. Shortly before noon on Saturday, the National Hurricane Center declared that Erin had reached Category 5 status, the most powerful kind of hurricane.
This determination is based on sustained winds, which were measured by a US Air Force Hurricane Hunter aircraft on Saturday at 160 mph.
There is some good news: Erin is threading a needle with its projected track. Although it should pass close to several landmasses between now and next Thursday, Erin should remain far enough away to avoid catastrophic damage. Erin is presently passing to the north of the Caribbean islands, and will turn northward before reaching the Bahamas and the Eastern United States. Later next week it should follow a path that takes it between Atlantic Canada and Bermuda.
Forecasters have a reasonable amount of confidence in this track as trusted models have become fairly consistent in their output.
Getting big, fast
There is a sobering side to all of this as well. Erin only became a hurricane at 11 am ET on Friday, as it tracked north of the Leeward Islands. It was the first hurricane of the Atlantic season, which has been relatively slow to rumble to life this year.
Credit: National Hurricane Center Forecast track for Hurricane Erin. Forecast track for Hurricane Erin. Credit: National Hurricane Center
However, Erin's growth since then has been historic. Although the Category of a hurricane is based on its sustained winds, a more accurate measurement of a storm's intensity is its central pressure, measured in millibars. The standard pressure at the surface of the Earth is 1,013.25 mb. As they intensify, the central pressure of hurricanes drops, and the lower the pressure the more intense the storm.
According to meteorologist Sam Lillo, Erin deepened by 70 millibars in 24 hours from Friday morning to Saturday morning. This makes Erin the most rapidly intensifying hurricane, before Sept. 1, ever measured in the Atlantic Ocean.