A weather disturbance meandering over the southern United States is headed for the warm waters of the Gulf of Mexico. It’s expected to develop into a tropical depression or tropical storm in the days ahead, and maybe even a hurricane.
“There is a high probability (80%) that a tropical depression is likely to form by the end of the week over the northern Gulf of Mexico,” wrote the National Hurricane Center on Monday morning.
There is potential for a considerably stronger storm to develop if it lingers over unusually warm temperatures in the Gulf of Mexico. Assuming the system becomes strong enough to earn a name, it will be called Barry.
Irrespective of how strong it gets, it is set to drop loads of rain somewhere along the Gulf Coast between the Florida panhandle and Texas. Totals of half-a-foot to a foot of rain seem a decent bet near the track if the storm does indeed develop, and there are scenarios that could deliver more than that.
Currently, an area of disturbed weather stretches across Alabama and Georgia and is slowly dropping south.
The disturbed weather is expected to emerge over water on Tuesday, and some computer modeling suggests it will quickly organize.
Once over water, the system would pull something of a U-turn Friday and Saturday and impact areas along the north-central Gulf Coast between the Florida panhandle and coastal Mississippi, a computer model had suggested. But some of the newer data suggests the target may be farther west into coastal Louisiana or Texas. The timing of any landfalling tropical system is uncertain, but some time over the weekend seems most likely.
The specifics of tropical storm development are notoriously difficult to predict. The placement of the flare-up of showers and thunderstorms in a disturbance’s formative stages can have significant consequences on how strong any storm becomes and where it subsequently tracks.
Forecasters are closely monitoring a zone of high pressure building over the contiguous United States. If it becomes more powerful and builds east, like last night’s European model suggests, it could help push the system westward in the Gulf toward Louisiana and Texas. A weaker high pressure system would keep the system closer to the north-central Gulf Coast.
If there was a cone of uncertainty to capture the zone of possible landfall locations now, it would cover much of the U.S. Gulf Coast.
Tropical weather expert Michael Lowry, who works for the Federal Emergency Management Agency, shared a map of modern-named systems to make landfall in the United States during July. History seems a decent guide for this event, at least as far as potential coastal targets go.
A vast majority of U.S.-named tropical weather systems that form in July affect the Gulf of Mexico. The primary centers of action are clustered around the north-central and northwestern Gulf. “[Not] all storms were big windmakers, [but] most were prolific rainmakers,” Lowry noted.
While the details of the system’s track and intensity remain in flux, a heavy rain event somewhere along the coast seems almost inevitable.
Through day seven, the National Weather Service Weather Prediction Center foresees widespread rainfall totals of about half-a-foot right to the northern Gulf, from Louisiana to Florida.
Depending on the details, at least 6 to 12 inches of rain would be likely from a landfalling system, given its expected slow forward motion. The hardest-hit areas could see totals considerably higher.
Although the rainfall graphic above currently favors landfall along the north-central Gulf, a shift westward is an increasing possibility.
Rain from tropical systems such as this is typically heavy enough for flooding.
The area from southwest Louisiana into northeast Texas would be most vulnerable to flooding given recent heavy rainfall. In and around Houston, precipitation has run 150 to 200 percent above average for the past several months. Areas in the north-central Gulf have been much drier.
Details on this developing storm should begin to become clearer over the next few days as it emerges over the Gulf of Mexico and matures.