A tropical depression-like storm with tropical depression-like impacts
The storm system responsible for the record rains formed a distinct surface low just inland along the Alabama coast on August 11, with a central pressure of 1013 mb.
By August 13, the low had drifted over northwest Louisiana, and intensified to a central pressure of 1007 mb. Like a tropical depression, the low had a warm core, and the counter-clockwise flow of air around the storm brought huge amounts of tropical moisture from the near record-warm waters of the Gulf of Mexico and northwest Atlantic northwards over land.
The amount of moisture in the atmosphere over the Gulf Coast region over the past week has been nothing short of phenomenal. Over multiple days, soundings of the atmosphere collected by weather balloon from locations such as New Orleans have measured record or near-record amounts of precipitable water (the amount of moisture in the atmosphere over a given point), often in the 2.5” to 2.75” range; sounding data extends back to 1948 in most cases. Sunday morning’s precipitable water of 2.61” in Lake Charles, LA, was among the top-ten values on record for that station.
The storm system responsible for the record rains formed a distinct surface low just inland along the Alabama coast on August 11, with a central pressure of 1013 mb.
By August 13, the low had drifted over northwest Louisiana, and intensified to a central pressure of 1007 mb. Like a tropical depression, the low had a warm core, and the counter-clockwise flow of air around the storm brought huge amounts of tropical moisture from the near record-warm waters of the Gulf of Mexico and northwest Atlantic northwards over land.
The amount of moisture in the atmosphere over the Gulf Coast region over the past week has been nothing short of phenomenal. Over multiple days, soundings of the atmosphere collected by weather balloon from locations such as New Orleans have measured record or near-record amounts of precipitable water (the amount of moisture in the atmosphere over a given point), often in the 2.5” to 2.75” range; sounding data extends back to 1948 in most cases. Sunday morning’s precipitable water of 2.61” in Lake Charles, LA, was among the top-ten values on record for that station.