Tropical Atlantic off to a busy start
By Skip Rigney
The seventh and eighth tropical storms of the year formed this past week, making this the fastest start to an Atlantic hurricane season on record.
Tropical Storm Gonzalo formed Wednesday morning halfway between Africa and the islands that arc across the eastern entrance to the Caribbean Sea. Gonzalo has continued to trek westward along the southern periphery of the huge high pressure system that sprawls across the Atlantic most of each summer.
Gonzalo will approach those Caribbean islands today and enter the Caribbean tonight. Meteorologists call the eastern Caribbean Sea a hurricane graveyard, particularly during July. Sinking air and wind shear create a hostile environment for tropical cyclones in the region. That’s particularly true for small cyclones such as Gonzalo. For most of its lifetime, winds greater than 40 miles per hour have been confined to a small area less than 30 miles from the center of Gonzalo.
Today the storm is still two thousand miles from us. Even if Gonzalo survives it’s journey across the Caribbean, which is doubtful, Thursday is the soonest we would need to pay attention to it.
Closer to home, a tropical depression formed in the Gulf of Mexico Wednesday night 300 miles south of the Mississippi Coast. By Thursday night, winds had strengthened to 40 miles per hour and the system was christened Tropical Storm Hanna.
Fortunately for us, the same Atlantic high pressure system that is steering Gonzalo into the eastern Caribbean’s hurricane graveyard is linked with high pressure centered over the Great Plains and has pushed Hanna westward toward Texas. However, even after the center of Hanna’s low level circulation moves inland in south Texas today, forecasters predict it will leave behind a trough of low pressure in the northwestern Gulf. In conjunction with the circulation around the big Atlantic high pressure system, that means a continuation of moisture-rich southeasterly winds for the northern Gulf Coast from Tallahassee to Houston and all points in between.
So, expect above normal numbers of showers through at least Monday. When tropical air masses extend from the surface up high into the atmosphere, the resulting warm clouds often produce rain drops through a process that doesn’t involve ice crystals. That warm process can be very efficient, which has the potential to produce some especially heavy downpours. Also, while daytime is still the preferred time for these showers, we will have a higher chance of rain at night and early morning than we see in our typical summertime pattern.
Although none of the storms this year in the Atlantic basin (which includes the Gulf of Mexico and Caribbean Sea) have been strong, the season is way ahead of schedule in terms of overall activity. In an average Atlantic hurricane season, there would only have been two named systems by August 1st. On average we don’t have eight named storms until late September according to statistics compiled by the National Hurricane Center in Miami (www.nhc.noaa.gov/climo/). Before Hanna, which was named on July 23rd, the earliest that there had been eight named storms was August 3rd in 2005, a year which went on to have the busiest tropical Atlantic season ever.
You may recall the “K” storm that year.
It was named Katrina.