A tropical disturbance in the Gulf of Mexico may deliver more torrential rain and flash flooding this week to flood-weary parts of the South.

For now, this broad trough of low pressure over the southwest Gulf of Mexico just west of the Yucatan peninsula is accompanied by an upper-level area of low pressure to its northwest.

The National Hurricane Center indicates there is a high chance this area of low pressure, known as Invest 91-L, will develop into a tropical depression or storm through Tuesday or early Wednesday. This system is currently producing a large area of showers and thunderstorms with winds to near gale force (39 mph or greater) in the region.

Surface pressures are already quite low. One buoy observation in the southwest Gulf of Mexico reported a surface pressure of 1007.9 millibars early Sunday morning.

However, relatively strong wind shear (winds changing with height) near Invest 91-L may keep thunderstorms disorganized as the system moves across the western Gulf of Mexico early this week. If the system somehow manages to develop into a tropical storm it would be named Bill. This appears to be the “worst-case scenario” right now, as the system will not have much time over the Gulf to develop before moving inland.

An Air Force Reserve Hurricane Hunter mission is scheduled to investigate this system Sunday afternoon and evening and another mission is scheduled for Monday morning.

Even if tropical development does not occur, this surge of tropical moisture will bring a dangerous flash flood threat to parts of Texas and Louisiana early to midweek. Generally, 3 to 5 inches of rain can be expected, with locally higher amounts possible.

his is an area that has already had record rainfall and flooding in May, so additional heavy rainfall, should quickly trigger renewed flash flooding.

Furthermore, locally heavy rain is likely over the next day or so ahead of the tropical disturbance.

A CoCoRaHS station near Seguin, Texas measured 6.81 inches of rain in just 12 hours ending Sunday morning. The observer, there, said pasture and road flooding was worse than the Memorial Day event.

n addition to the threat from rainfall, high surf and rip currents are likely and even some minor coastal flooding cannot be ruled out along parts of the Texas and Louisiana coasts.

Late this week, the remnant system and its moisture may get drawn north, then northeast into the Ozarks, mid-Mississippi Valley and Ohio Valley, leading to a threat of locally heavy rain, there.