State Tropical and Heavy Rain Update – 230 PM CDT – Wednesday July 16

Here is an update regarding the heavy rain threat through Saturday, associated with a tropical disturbance forecast to move through the Gulf.

Changes from previous update:  

• There are no significant changes since this morning
• This disturbance is still disorganized, and the location of the highest rainfall totals is still fluctuating, so further changes to the forecast could occur

• There is a MEDIUM (40%) chance of tropical cyclone development over the next 2 days before this disturbance moves inland.
• This disturbance is forecast to move west/west-northwest through the northeastern and north-central Gulf today and Thursday and move inland between midday Thursday and early Friday morning.
• A Flood Watch remains in effect for portions of southern Louisiana (see graphic below for exact times and locations)

Confidence:

• Confidence remains low that this system will develop into a tropical depression or stronger. Even if the system develops into a tropical cyclone, it is expected to remain weak.
• Confidence is medium to high that this system will bring a threat of locally heavy rain to southern portions of Louisiana, especially on Thursday and Friday.
• Confidence in exact rainfall values and the locations of the highest rainfall totals remains low

Heavy Rain and Flooding Impacts:

• Regardless of development, the system forecast to move through the Gulf will bring multiple rounds of heavy rain during the Wednesday through Saturday time frame, with the greatest threat Thursday and Friday.
• The current forecast calls for 3-6″ across portions of southern LA through Saturday (mainly along and south of I-10 corridor) with potential for up to 10″ in some localized areas (especially along the coast)
• Ponding of water in low-lying and poor-drainage areas is likely, with potential for more significant impacts (such as water approaching low-lying structures) if the higher-end rainfall totals are realized.
• A combination of a neap tide cycle (low range between high and low tide) and winds below tropical storm strength, will result in little to no threat of coastal flooding

The graphics below highlight both the tropical weather outlook and rainfall threats associated with this system.

The next update will be sent Thursday morning, or earlier if conditions warrant. Please do not hesitate to reach out with any questions. You can reach our office by emailing nws.neworleans@noaa.gov or by calling 985-649-0429 or 504-522-7330. Use extension 4 to reach one of the meteorologists on duty.