Plenty Of Moisture (and Rainfall) Ahead With Barry

Louisiana Flood Potential Assessment
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Barry is still a tropical storm – depression later today.

Massive amount of moisture/potential extreme rainfall remains.

Fig. 1: Latest NOAA/NHC 3-day forecast track for Tropical Storm Barry.

Fig. 2-4: Sunday, Monday and Tuesday NOAA/WPC rainfall forecasts.

Fig. 5-6: Latest NOAA/NHC satellite view of Barry indicates the heaviest rain trails the storm offshore in the northwest Gulf of Mexico. Radar depiction indicates widespread rains across Louisiana and Mississippi and highest rainfall per hour rate.

Current data: At 8AM EDT Tropical Storm Barry was located at 31.4N/93.4W or about 80 miles south-southeast of Shreveport, LA. Maximum sustained wind is 45 mph and central pressure is 1005 MB. Movement is north at 6 mph. Louisiana coastal tropical storm and storm surge warnings remain in effect due to high wind and southerly fetch into the coast.

Discussion: Barry has drifted inland and is maintaining tropical storm strength. The attendant rainfall pattern is complex. The heaviest rainfall is well south in a moist south-to-north fetch off the Gulf and into south/east Louisiana and Mississippi. Rainfall rates of 2-3.5 in. per hour are common. The northern extent of the rain is into the western Tennessee Valley and Arkansas. However, the heaviest rain remains offshore in the northwest Gulf of Mexico. Today’s forecast indicates a piece of this offshore extreme rain shifts into the south-to-north moisture fetch previously described bringing heavy squalls to southwest Louisiana today. (The ECMWF model indicates 10 in. of rain could occur from this projected event). The southerly fetch off the Gulf triggers another squall line across southern Louisiana tomorrow while the core rain area shifts to the western Tennessee Valley focused on the Memphis, TN area. The same area (and into Illinois/Indiana) is hit with heavy rain Tuesday. The remains of Barry scatter across the eastern states midweek.

Hazards: The south-to-north wind fetch also featuring heavy squalls into southeastern Louisiana is preventing the storm surge induced water rise from easing. Flooding due to heavy rainfall continues. The rainfall can be hit-and-miss in character but when it’s raining extreme amount can occur. There were no tornadoes reported yesterday. Isolated tornadoes may occur today Louisiana to Arkansas and Mississippi.