Tropical Storm Hanna Forms In The Gulf of Mexico

Tropical Depression Eight has strengthened into Tropical Storm Hanna on Thursday night. It is now the earliest 8th Atlantic named storm formation on record. The previous earliest 5th named storm formation record in the Atlantic is Harvey on August 3rd, 2005.

At 11:00 PM AST, the center of Tropical Storm Hanna was located near latitude 26.2 North, longitude 91.4 West. Hanna is moving toward the west-northwest near 7 MPH (11 KM/H) and a west-northwestward to westward motion is expected during the next couple of days. On the forecast track, the center of the storm is expected to move across the northwestern Gulf of Mexico on Friday and make landfall along the Texas coast on Saturday.

Maximum sustained winds are near 40 MPH (65 KM/H) with higher gusts. Additional strengthening is expected until the system makes landfall. Steady weakening is expected after Hanna moves inland.

Tropical-storm-force winds extend outward up to 35 miles (55 KM) from the center.

The estimated minimum central pressure is 1002 millibars.

Tropical Storm Hanna Forecast Cone as of 11:00 PM AST Thursday 23rd July 2020. (National Hurricane Center)
Tropical Storm Hanna Forecast Cone as of 11:00 PM AST Thursday 23rd July 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Hanna Watches and Warnings as of 11:00 PM AST Thursday 23rd July 2020. Credit: National Hurricane Center
Tropical Storm Hanna Watches and Warnings as of 11:00 PM AST Thursday 23rd July 2020. Credit: National Hurricane Center

A Tropical Storm Warning is in effect for:

  • Mouth of the Rio Grande to San Luis Pass Texas

A Tropical Storm Watch is in effect for:

  • San Luis Pass to High Island Texas

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

Interests along the Texas and Louisiana coast should monitor the progress of this system. Tropical Storm Warnings may be required for portions of the Watch area later today.

Hazards Affecting Land

Tropical Storm Hanna as of 11:00 PM AST Thursday 23rd July 2020. (Weathernerds)
Tropical Storm Hanna as of 11:00 PM AST Thursday 23rd July 2020. (Weathernerds)

WIND: Tropical storm conditions are expected in the warning area by Friday night or Saturday morning. Tropical storm conditions are possible within the watch area by Friday night or Saturday morning.

RAINFALL: Hanna is expected to produce 3 to 5 inches (75-125 mm) of rain with isolated maximum totals of 10 inches (250 mm) through Monday along the Gulf Coast of the United States from Louisiana to south Texas, and inland to the Mexican states of Coahuila, Nuevo Leon, and northern Tamaulipas. This rain may result in life-threatening flash flooding, rapid rises on small streams, and isolated minor to moderate river flooding.

Tropical Storm Hanna rainfall forecast as of 11:00 PM AST  Thursday 23rd July 2020. (Weathernerds)
Tropical Storm Hanna rainfall forecast as of 11:00 PM AST Thursday 23rd July 2020. (Weathernerds)

SURF: Swells generated by Hanna are expected to increase and affect much of the Texas and Louisiana coasts during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

This system is of no threat to the Windward Islands, including Trinidad and Tobago.

Tropical Storm Hanna Forecast Discussion

The system continues to organize with curved bands becoming better established around the center. The cyclone certainly has the appearance of a tropical storm, and just minutes ago the NOAA Hurricane Hunters found winds to support upgrading the system to a 35-kt tropical storm. Data from the aircraft also show that the minimum pressure has dropped to 1002 mb, indicating that the system is on a developing trend.

Hanna is moving fairly slowly to the west-northwest, with the latest initial motion estimated to be 285/6 kt. This west-northwest motion should continue on Friday, but a turn to the west is expected by Friday night as a subtropical ridge strengthens to the north of the cyclone. This steering flow should take the center of the storm across the southern Texas coast in 36 to 48 hours. After landfall, the storm is forecast to turn south of west across extreme southern Texas and northern Mexico. The models have shifted southward again this cycle, and the NHC track forecast has been adjusted in that direction.

Additional strengthening seems quite likely until the storm makes landfall since it is expected to remain over the very warm Gulf of Mexico waters and in generally low wind shear conditions. After landfall, steady weakening should commence, and the cyclone should dissipate over the rugged terrain of northern Mexico in about 4 days. The NHC intensity forecast is a little above the previous one and at the high end of the guidance given the system’s well-organized structure and a favorable environment.

Due to the southward shift in the track forecast, the tropical storm warning has been extended southward from Port Mansfield to the Mouth of the Rio Grande.

Tropical Storm Hanna is the earliest 8th storm on record. The previous record was in 2005 when Harvey formed on August 3rd.

Forecast Discussion by Forecaster Cangialosi from the NHC.

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