Fig. 1: Daily Gulf of Mexico SSTA analysis identifies the gathering of much warmer than normal waters by the LOOP Current to the southeast of Louisiana.
Discussion: The LOOP Current in the Gulf of Mexico is a warm stream of water surging north-northwestward from the northwest Caribbean Sea and looping eastward in the north-central Gulf of Mexico then southeastward to the Florida Strait to join the Gulf Stream traveling parallel to the U.S. East Coast. The LOOP Current is a warm stream of water most commonly recognized during tropical cyclone season as a catalyst to intensify tropical storms/hurricanes which pass over the warmer waters and stronger upper ocean heat.
The Loop Current is unusually active in the Gulf of Mexico SSTA pattern right now causing an area of very warm water to gather just-off the southeast coast of Louisiana where the current undergoes the east turn. The pool of very warm water has caused the low-level atmosphere in this region to become unusually moist.
During the past couple days, a deep upper trough over the southwest U.S. has organized and caused a southerly wind fetch across the warm plume off the Louisiana Coast providing buoyant low-level moisture into a frontal trough residing over the northwest Gulf of Mexico States. The result is record rainfall amounts (New Orleans observed 5.54 in. yesterday) with additional excessive rains expected today.
Widespread flooding is currently occurring across all river areas in southeast Louisiana, southern Mississippi and into southern Alabama. More excessive rains are likely today!
As the upper trough over the Southwest U.S. shifts northeastward the excessive rains will shift to the west/southwest Tennessee Valley where life-threatening flash flooding could occur tomorrow coupled with a major severe weather outbreak producing a high risk of tornadoes.
Fig. 2-3: NOAA/WPC excessive rain/flash flood forecast areas for the next 2 days.
Fig. 4-5: NOAA/SPC severe weather regions for the next two days including a potential major tornado outbreak for tomorrow.