Above, hurricane activity in the Gulf of Mexico during a La Niña condition is considerably worse than the activity recorded during the El Niño condition as is shown here by the number of recent storms. El Niño also brings the perk of more rain.
Hurricane activity in the Gulf of Mexico during an El Niño condition is considerably better than the activity recorded during the La Niña condition as is shown here by the fewer number of storms during its time.
USWB graphic
Rainfall amounts plotted on this graph clearly indicate the current dry spell is the worst since records have been kept. The lowest line in the graph shows the amount of rain received in 2011.
Scientific information indicates this storm season may see fewer hurricanes than forecast. The same data could mean more rain.
Both possibilities hinge on the development of El Niño — a condition of warmer water in the eastern Pacific.
“It’s developing, and it’s expected to persist into next spring,” says John Metz, warning coordination meteorologist.
Statistically, an El Niño condition results in less favorable conditions for hurricane formation. It also usually results in a wetter South Texas fall, winter and spring.
El Niños alternate with La Niñas, when the waters in the eastern Pacific are cooler than normal; each usually forms between April and June and persists from nine months to a year. They typically reoccur every two to seven years.
Colorful graphics used in his presentation indicate the severity of the current drought.
“South Texas is in a severe drought,” Metz explains. “The area is running seven-year rainfall deficits of 17 to 34 inches. The current dry spell is the worst on record, worse than 1919, the 1930s or the 1950s.”
But an El Niño could change that.
“It would mean above-normal rainfall for Bee County,” Metz said.
Another El Niño effect is increased wind shear in the Atlantic. A potential tropical system encountering high winds going in one direction, with high winds going in an opposite direction at a higher altitude, tends to tear storm cells apart.
In an area that traditionally depends on rain from tropical systems to replenish the watershed, the forecast for a more subdued hurricane season is a mixed blessing.
Meteorologists are warning that this year’s abnormally quiet season — there have been only two named storms so far, both occurring before the official start of the season — cannot be taken for granted because the traditional peak for storms to develop is just beginning.
“In any given year, two-thirds of the hurricanes develop after August,” Metz says. Since records have been kept, 21 hurricanes have hit Texas in August – 10 were major storms; of the 25 systems that formed in September, 10 were major storms.
By October, the threat of a Texas Gulf Coast landfall is almost minimal.
Usually, systems that appear in June and July form in the Gulf of Mexico and they are weaker.
Storms that are born in the Atlantic Basin in August and September are more dangerous, Metz explains. Because they spend more time over the water before making landfall, they have more time to strengthen.
Two named storms before the start of the season is no indicator of a season’s total activity, either. When it happened in 1887, there were 19 named storms that season. But when it happened in 1908, the season saw only 10 named storms.
What meteorologists fear is a growing false sense of security among those living in South Texas, because, in the last 41 years, only five category 3 or above storms have made landfall in Texas, two near Brownsville and three in the Houston-Beaumont area.
As they repeat each year, landfall of a major hurricane along the Central/South Texas coast isn’t a matter of if, but when.
Those living on the coast can take heart in another set of data: the number of hurricanes each season runs in cycles. Between 1978 and 1994, the season recorded 27 major storms. From 1995 to 2011, 65 major storms developed, more than double.
“The indication,” Metz says, “is that we are beginning to enter a quieter period again.”
That may be confirmed early next month, when both the National Hurricane Center in Miami and the Colorado State University hurricane forecast team issue their revised forecast for the remainder of the current season.
Bill Clough is a reporter at the Bee-Picayune and can be reached at 358-2550, ext. 122, or at beepic@mySouTex.com.
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