Francine will drench MS Coast with record-breaking humidity in the air. How much rain will fall?

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Of all hurricanes, Francine is expected to be a major storm for southern Mississippi.

Continuous rain fell along the Mississippi coast Tuesday morning, but Harrison County Emergency Management Director Matt Stratton said, “That’s just the beginning.”

The National Hurricane Center is predicting up to 12 inches of rainfall in some spots along the Mississippi coastline. Francine is expected to make landfall as a hurricane in Louisiana Wednesday afternoon or evening.

Coastal areas of Mississippi were placed under a storm surge warning Tuesday morning, meaning life-threatening flooding could occur within the next 48 hours. The storm surge is expected to reach 2-4 feet, with some areas reaching 6 feet.

The hurricane center said large parts of Mississippi and Louisiana are expected to see 4 to 8 inches of rain through Friday morning.

“This rainfall could lead to significant flooding and urban flooding,” the hurricane center warned.

Timing of rainfall in Francine

Meteorologist Ben Noll of New Zealand’s National Institute of Water & Atmospheric Research said on Twitter that Francine will be a record breaker for humidity.

“Likely stemming from record-high oceanic heat content in the Gulf of Mexico and similar to Hurricane Debby in August, Francine is expected to have record-breaking water precipitation values,” he wrote, citing the forecast of one of the hurricane models, the ECMWF. Observable water indicates how much moisture the atmosphere holds.

“Precipitation water helps meteorologists understand how much moisture is in a column of air, from the ground to the top of the atmosphere,” Noll said. “This weather variable has been on a strong upward trend, especially over the past two years.

“With Francine, southern Louisiana could see rainfall totals of over 4 inches, while western Mississippi could reach 3.5 inches, adding another set of records to this map later this week.”

He said values ​​above 3.5 inches in Mississippi would break September records.

“Overall,” Noll concluded, “this speaks to the overwhelmingly moist nature of the atmosphere near Francine and the severity of the flood threat over the next few days.”

Stratton said thunderstorms will efficiently convert the water vapor in the warm, tropical air into rain.

The chance of flash flooding along the Mississippi coast is at least 40%, except for extreme southeastern Jackson County, where the chance is lower.

Rainfall is expected to increase as the day progresses, he said, and remain heavy at times through Thursday morning. The forecast is for 6-8 inches of rain in Hancock and western Harrison County, he said. Jackson County should see 4-6 inches of rain.