Tropical system very likely to impact Louisiana and Acadiana

Posted at 5:44 PM, Jul 09, 2019
and last updated 2019-07-09 21:42:49-04

A disturbance in the extreme Northeastern Gulf of Mexico has a high chance of developing into a tropical cyclone over the next day or two as it drifts southwestward and then westward toward Louisiana by this weekend.

The system will likely become a tropical depression, and by most computer model accounts, will become a tropical storm; if so, the name will be "Barry".

While the magnitude and exact track of this system remains uncertain. it does appear this system will bring a flooding rain threat, elevated tides, and perhaps tropical storm winds (sustained winds greater than 39 mph) to portions of Louisiana, but exactly when and where are a day or two away from being determined.

Model consensus brings near tropical storm conditions to the offshore leasing blocks off of the Southeast Louisiana Coast in the Gulf of Mexico beginning Thursday, with weather from this system impacting Louisiana Friday and continuing into Saturday.

While the GFS model is weaker (lower end tropical storm), farther west, and a little slower with landfall Saturday afternoon, the European Model is stronger (high end tropical storm), farther east, and makes landfall earlier (predawn hours) Saturday morning.

Flooding rainfall will be very likely near and east of center of storm wherever it may go.

Unfortunately, this leaves Acadiana and Louisiana residences and business little time to react to whatever develops, which may range from a tropical depression, to most likely a tropical storm...and it could become a higher end tropical storm per the latest European and a few other models not shown.

In fact, if and when the National Hurricane Center (NHC) begins to issue advisories on this system, tropical storm watches and warnings will likely be issued for portions of Louisiana simultaneously.

There is even an outside chance there may be a hurricane watch pending NHC analysis over the next 24-36 hours.

Intensity forecast range remains mostly in tropical storm territory with the GFS on the lower end with max winds near the center near 55 mph offshore and 30-40 mph inland, while the Euro is much stronger producing 45-65 mph sustained winds with gusts to 80-85 possible over portion of Eastern Louisiana.

The ICON Model splits the difference between the GFS and Euro and landfall, but also maintains a stronger storm...along with much higher storm impacts in Acadiana.

It is also noted that the UKMET, Euro and ICON models all have pressure at landfall close to hurricane range...but for now, that's a low end chance.

Regardless of intensity, this system will all but guarantee the threat of heavy flooding rains across portions of Southern Louisiana with area-wide rain totals over a two day period near the storms center in the 5-10" range.

Isolated rainfall amounts may approach the 15-25" range east of where the center goes, which will certainly lead to serious flooding...but where that will occur, is impossible to call at this point.

It should be noted that 50-75 miles west of where a potential landfall may occur could see very little rain.

The GFS Model with the farther west landfall puts most of Acadiana in the target zone for the possibility of flooding rainfall.

The European Model with a more eastward landfall in the state, puts much of Eastern Louisiana and most of Acadiana out of the major flood threat, but some flooding rains would still be in the forecast for Iberia, Lower St Martin and St Mary Parishes north and eastward.

It cannot be stressed enough that average errors on the center of tropical systems 2-3 days can be more than 100 miles, and we still currently do not have a definitive center, so there may very well be large errors from this update to the next...or one that might come tomorrow or Thursday.

The intensity of the system and where the center of circulation center makes landfall will be detrimental in forecasting storm surge, where tides will be most elevated, and whether wind damage may be a possibility.

For now, based on only model data and experience, below is the best guess on Acadiana's impacts from this system, which has changed greatly since Monday, and may continue to change vastly based on future track, intensity and landfall time.

All these factors, perhaps including the possibility of some tropical tornadoes, are yet to be determined.

The bottom line, everyone in Acadiana should be prepared for the possibility of flooding rainfall, and have your tropical/hurricane supplies ready to go...and yes, there is a small chance this system could intensify close to hurricane strength (or at the very least a strong tropical storm) just prior to landfall.

Finally, it should be noted that 48 to 72 hours out, forecast models have roughly a 100 mile error on where the center will ultimately go...that means we all have to be prepared for a storm until further clarity is revealed.

Plan on the worst weather to arrive late Friday and continuing into Saturday, but that could change or get extended well into Sunday depending on the speed of the system.

Stay with KATC, and social media for the very latest as forecasts, and anticipated conditions, will likely change until an identifiable system gets situated in the open waters of the Gulf of Mexico.