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Atlantic Basin Heating Up with Potential Tropical Activity

As we approach the 4th anniversary of Hurricane Harvey, the Atlantic basin is currently heating up with tropical activity. As remnants of one hurricane washing across New England, two more areas of concern move toward the Northeast. A third is heading toward the northwest Caribbean. It’s still too early to tell exactly where these storms will make landfall. But the presence of so many tropical disturbances signals the need to stay alert to daily weather forecasts.

Each of these storms has a 40-60% chance of tropical formation.

Five Day Outlook for Tropical Activity

8 PM outlook on 8/23/2021 indicates the storms heading toward the NW Caribbean have a 50% chance of tropical formation in the next five days. That’s up from 30% this morning.

Retreat of High-Pressure System Over Texas

National Hurricane Center (NHC) forecasts a tropical wave over the eastern Caribbean Sea will form a broad area of low pressure over the southwestern Caribbean Sea by late week. Thereafter, environmental conditions favor gradual development while the system moves west-northwestward to northwestward over the northwestern Caribbean Sea.

In addition to that, another major low pressure area over Mexico and the Bay of Campeche could move into the Gulf by this weekend though no tropical activity is forecast at this time.

Note massive low pressure system moving into Gulf.

Jeff Lindner, Harris County meteorologist, warns that as the high pressure ridge currently sitting over Houston begins to retreat north by Wednesday, “A series of tropical waves and disturbances will move from east to west across the US Gulf coast and into coastal TX from mid week onward. With a significant influx of Gulf moisture, showers and thunderstorms will return as early as Wednesday across much of the area and last likely into next week. Locally heavy rainfall will become an increasing threat by late week and this weekend with tropical moisture firmly in place over the region.”

Historical Norms for Late August

NOAA’s Climate Center shows that the projected path of the current areas of concern should follow historical norms for this time of the year.

This diagram shows the most likely areas for formation for hurricanes in August and their prevailing tracks. Source: NOAA’s Climate Center.

This is one of the reasons why.

Current sea surface temperatures in the Gulf are running 1.5 to 2+ degrees degrees above normal for the next seven days, with the warmer areas nearer the Texas Coast.

Historical Intervals Between Major Hurricanes

NOAA’s Climate Center shows the average interval for major hurricanes striking the Houston area is about every 25 years.

NOAA’s Climate Center also tracks the average return period for MAJOR hurricanes at various points along the coastline. They show that the Houston area can expect on average one major hurricane about every 25 years.

Of course, a hurricane doesn’t have to be major to cause major damage. Allison and Imelda were just tropical storms. And averages are just that – averages. Ike in 2008 and Harvey in 2017 each attained major hurricane status and hit Houston within 9 years of each other.

Posted by Bob Rehak on 8/23/2021 based on information from NHC and HCFCD

1455 Days since Hurricane Harvey