at 10:10 AM by Pierce Larkin

Incredible Rainfall Along the Gulf Coast

The same mid and low level low that has advected a deep and rich moisture profile into our region is currently spinning along the Gulf Coast. This system is fairly incredible, as it has already broken records for precipitable water here, and to our south.

The system is tropical in nature, and has been compared to a deteriorating Tropical Depression as it comes ashore and weakens, but is caught in weak mid and upper level flow. That is essentially what has happened to our south. The system developed along the northwestern Florida coastline, and has slowly moved eastward within very weak upper level flow.

Because of the tropical nature of this system, it has drawn some of the more amazing PWAT values I have ever seen with it. With the 09z run of the SREF model this morning, it initialized the PWATs at or above 4 standard deviations above normal for much of Louisiana.

The area in the blue circle has PWAT values at least 3 standard deviations above normal (aka a historically moist air mass). h/t cms.met.psu.edu
The area in the blue circle has PWAT values at least 3 standard deviations above normal (aka a historically moist air mass). h/t cms.met.psu.edu

In addition to this, the 12z soundings from across the central Gulf Coast are breaking records for precipitable water values for this date and time.

The SPC PWAT climatology for Jackson, Mississippi. 12z August 12 is selected, and the record for that day is boxed in black. h/t SPC
The SPC PWAT climatology for Jackson, Mississippi. 12z August 12 is selected, and the record for that day is boxed in black. h/t SPC
The Jackson, Mississippi sounding from this morning. The PWAT value recorded is boxed in black. It bested the old record by nearly 0.30". h/t SPC
The Jackson, Mississippi sounding from this morning. The PWAT value recorded is boxed in black. It bested the old record by nearly 0.30″. h/t SPC

This amount of moisture in the atmosphere had led to some incredible rainfall rates, and thus, flash flooding along the Gulf Coast. The National Weather Service in New Orleans, LA has issued multiple Flash Flood Emergencies, including one along I-55. Check out some of the images.

Keep these folks in your thoughts and prayers as they endure this level of flooding, as it doesn’t come around very often.