Brewing rainstorm along U.S. Gulf Coast may snap exceptional drought

Soon after rain from one storm dwindles in parts of the Gulf Coast states, a new storm will develop.

AccuWeather meteorologists say the budding storm will likely tap into tropical moisture and unload much-needed drenching rain in areas from Texas to Georgia during the first part of the new week.

A storm and a cold front, responsible for 1-2 inches of rain in Houston and other locations in eastern Texas and Arkansas into Friday morning, will continue to slide to the east and weaken over the Southeastern states as it runs into dry air into Sunday.

However, weak disturbances moving along the stalled front will trigger additional pulses of mainly light rain from coastal Texas to Georgia, northern Florida and parts of the Carolinas over the weekend.

Most of the rainfall will be on the order of 0.25 of an inch over the weekend. However, there can be a few pockets from Mississippi to Georgia where 0.50 of an inch or more may fall.

A dip in the jet stream that helped produce a moderate Santa Ana wind event in Southern California from Thursday to Friday will push across northern Mexico this weekend and then initiate a new storm somewhere from South Texas to the western Gulf of Mexico.

The rainstorm will form near the stalled front near the Gulf Coast this weekend. There is the potential for copious amounts of tropical moisture to become involved as it continues and expands into the middle of next week.

"As the storm crawls northeastward along the stalled front from near the Gulf Coast, a broad zone of 2-4 inches of rain is likely from South Texas to much of Louisiana, central and southern Mississippi, southwestern and central Alabama and the western part of the Florida Peninsula," AccuWeather Senior Meteorologist Brett Anderson said. "Within this zone, pockets of 4-8 inches of rain are likely with an AccuWeather Local StormMax&trade of 12 inches by the conclusion of the storm during the middle of next week."

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The rain will lead to slick roadways and could lead to disruptions to travel, outdoor plans and projects.

If it were not such close company to a frontal zone, the system might end up being one step away from a tropical rainstorm or tropical depression, AccuWeather Senior Storm Warning Meteorologist Brian Wimer said.

For an official tropical depression to develop, a circulatory wind pattern would be needed around a well-defined storm center with a warm core. Winds within a tropical depression are under 39 mph.

AccuWeather meteorologists will also be keeping an eye on the Caribbean Sea for possible tropical development next week.

Regardless of the classification of the upcoming Gulf Coast storm, rain is tremendously needed in the region. For many weeks, areas in much of Louisiana, southern and central Mississippi and northeastern Texas have been experiencing exceptional drought, which is the worst of four stages of drought, according to the United States Drought Monitor.

The drought has been so bad that wildfires have been a problem in normally swampy areas. Smoke from the fires combined with fog in some cases to lead to super fog. The smoky fog was so dense, down to several feet in localized areas, that deadly chain-reaction crashes have occurred on Louisiana interstate highways in recent weeks.

At the same time, drought has expanded to large areas of the southern Appalachians, Piedmont and Atlantic coast locations and continues in areas farther to the west in Texas.

The drought has also been prevalent since the summer over much of the Mississippi River basin and has produced record-low levels in some areas, including at Memphis, Tennessee. The flow of the mighty Mississippi has been reduced so much that salt water has intruded upstream and mingled with the water supply in southern Louisiana.

Hit-or-miss rain events in parts of the Mississippi Watershed recently have allowed river levels to recover up to a few feet, but further dips in levels are likely during the winter.

Since some of the rain from the storm will fall directly on the Delta Region of the Mississippi River, there is likely to be a small bump in water levels, especially if a soaking rain falls on rivers such as the Yazoo and Big Black in Mississippi. The small rise in water levels should also increase stream flow on the lower end of the Mississippi and may help temporarily reverse or slow the encroachment of salt water from the Gulf of Mexico around New Orleans.

Drenching downpours from the rainstorm are not likely to reach everywhere in need across the Southern states. AccuWeather forecasters say there will be a sharp northern edge to the moisture from the southern Plains to the Mississippi and Tennessee valleys and farther east for the Carolinas, eastern Georgia and northeastern Florida.

As is often the case, there is also the risk of dangerous flash flooding in urban and low-lying areas and along small streams and bayous in the setup. The risk of flooding will include, but not be limited to, areas that received drenching rain from Wednesday night to Friday.

Motorists along the I-10 and I-20 corridors are most likely to be affected. Extra travel time may be needed for commuters in cities such as Houston and New Orleans. Forecasters urge motorists to avoid flood-prone streets and highways during heavy rain situations.