August 2017 Tropical Cyclones Report

North Atlantic

In August, Hurricane Harvey ended a record-long major hurricane (Category 3 or stronger) landfall drought in the United States. Prior to Harvey, the last major hurricane to make landfall in the U.S. was Wilma on October 24, 2005. This major hurricane drought surpassed the length of the eight-years from 1861-1868 when no major hurricane struck the United States' coast. On average, a major hurricane makes landfall in the U.S. about once every three years. The reliable record of landfalling hurricanes in the U.S. dates back to 1851.

Significant Events

Hurricane Harvey Satellite Image – Aug. 25, 2017
Source:NOAA's NNVL

Harvey was a long-lived tropical cyclone that formed east of the Lesser Antilles on August 17^th. Over the course of about a week, Harvey traversed the Lesser Antilles, Caribbean Sea, and Yucatan Peninsula as a tropical storm and tropical depression. Once the system moved into Bay of Campeche on August 23^rd the storm encountered favorable conditions for rapid development — warm sea surface temperature and low wind shear. As the storm moved to the northwest it quickly strengthened to tropical storm and then hurricane strength on August 24^th. On the 25^th Harvey continued to rapidly intensified to a category 4 hurricane with maximum sustained winds of 130 mph and a central minimum pressure of 938 mb. Late in the day on the 25^th Harvey made landfall near Rockport, Texas at peak intensity. After making landfall, the system moved very slowly before meandering back off shore on August 28^th as a tropical storm. On August 29^th Harvey made another landfall near the Texas/Louisiana border as a strong tropical storm. Harvey weakened to a remnant low on September 1^st as it moved into the Lower Mississippi Valley.

Harvey was noteworthy for several reasons. Hurricane Harvey was the first major hurricane to make landfall in the U.S. since Hurricane Wilma in 2005, ending a record-long 12-year streak of no major hurricanes hitting the United States. The slow moving nature of the storm dropped torrential rainfall across northeastern Texas and southwestern Louisiana. The hardest hit areas included the Houston, Beaumont, and Port Arthur areas of Texas. Many locations received over three feet of rain over the five-days that Harvey slowly moved through the region with precipitation totals over 40 inches common and a few isolated totals of 50 inches or more. Pending final review, these precipitation totals in excess of 50 inches will surpass the 5-day and tropical storm related precipitation totals for the contiguous United States. The Houston NWS Weather Forecast Office received 43.38 inches of rain, the highest 5-day precipitation total on record for any major U.S. city. The heavy rains led to unprecedented flooding in Houston and surrounding areas. Tens of thousands of people were displaced due to flood waters with thousands of homes and businesses destroyed. At least 70 fatalities were blamed on the storm and Harvey will likely rank among the costliest natural disasters to ever impact the nation.

East Pacific

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