Monday, June 19, 2017

Minor Coastal Flood Event Likely Along U.S. Gulf Coast This Week

A developing area of low pressure near the northern Yucatan Peninsula will likely generate a minor coastal flood event along the U.S. Gulf Coast this week. The National Hurricane Center forecasts an 80% chance of tropical cyclone development within the next 48 hours and a 90% chance of tropical cyclone development within the next five days, in 8AM EDT update from Mon Jun 19.

If this system develops it would be the third named storm of the Atlantic Hurricane Season, named Cindy.

Deep convection firing near the northern Yucatan Peninsula will likely develop into a tropical cyclone in the Gulf of Mexico in the next two days, according to the National Hurricane Center.

The two main global forecast models, the European and American (GFS), have consistently shown different solutions for the forecast track. The European model has favored a more westward track, while the GFS has favored a more eastward solution.

The two models are showing more consensus this morning, as they are splitting the difference. The European model favors a forecast track into the west-central Gulf of Mexico by Tuesday evening local time, which would bring onshore winds possibly exceeding tropical storm force into southeast Louisiana.

The European model forecast for Tuesday evening local time. Note strong onshore winds in southeast Louisiana. Image:

Note the strong (30 kt) shore-parallel winds forecast for coastal Texas. Such winds effectively generate coastal flooding due to Texas' coastal profile and Ekman transport, which turns water to the right of the wind direction in the Northern Hemisphere. Therefore, this scenario would cause minor coastal flooding from the Florida Panhandle through coastal Texas.

The GFS model favors a track into the north-central Gulf of Mexico, with strong onshore winds from southeast Louisiana through the Florida Panhandle. Offshore winds are forecast for south Louisiana and the Upper Texas Coast, while strong onshore winds buffet the Florida Panhandle.

The American (GFS) model for Tuesday evening local time. Note strong onshore winds along the Florida Panhandle. Image:

In this scenario, minor coastal flooding would occur from extreme southeast Louisiana through the Florida Panhandle, with offshore winds generating lower-than-normal water levels from south-central Louisiana through much of the Texas coast.

It is important to not follow the precise track at this point, as the forecast will become more refined throughout the day Monday. Regardless of where the system tracks, it is looking more likely that some locations along the U.S. Gulf Coast will observe coastal flooding late Tuesday into early Wednesday.

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