Hurricane Hanna Makes Landfall on Texas Coast

While Tropical Storm Gonzalo was affecting T&T this morning, Tropical Storm Hanna in the Gulf of Mexico strengthened into the first hurricane for the 2020 Atlantic Hurricane Season. The average date for the first Atlantic hurricane is August 10.

Hurricane Hanna also intensified from 45 MPH to 80 MPH maximum winds in the past 24 hours, as of 11:00 AM, making it the first rapidly intensifying named storm of the 2020 Atlantic Hurricane season. Rapid intensification is typically defined to be greater than or equal to 35 MPH intensification in 24 hours.

At 9:00 PM AST, the center of Category 1 hurricane Hanna was located near latitude 26.6 North, longitude 97.8 West. Hanna is moving toward the west-southwest near 7 MPH (13 KM/H) and this motion is expected to continue through Sunday. On the forecast track, the center of Hanna should continue to move farther inland over southern Texas tonight and move into northeastern Mexico on Sunday.

Maximum sustained winds are near 85 MPH (140 KM/H) with higher gusts. Rapid weakening is expected as Hanna moves farther inland. Hurricane-force winds extend outward up to 30 miles (45 KM) from the center and tropical-storm-force winds extend outward up to 90 miles (150 KM).

The estimated minimum central pressure based on surface observations is 975 millibars.

Hurricane Hanna Forecast Cone as of 8:00 PM AST Saturday 25th July 2020. (National Hurricane Center)
Hurricane Hanna Forecast Cone as of 8:00 PM AST Saturday 25th July 2020. (National Hurricane Center)

Watches & Warnings

Hurricane Hanna Watches and Warnings as of 8:00 PM AST Saturday 25th July 2020. (National Hurricane Center)
Hurricane Hanna Watches and Warnings as of 8:00 PM AST Saturday 25th July 2020. (National Hurricane Center)

A Storm Surge Warning is in effect for:

  • Port Mansfield to Sargent Texas

A Hurricane Warning is in effect for:

  • Port Mansfield to Mesquite Bay Texas

A Tropical Storm Warning is in effect for:

  • Barra el Mezquital Mexico to Port Mansfield Texas
  • Mesquite Bay to High Island Texas

A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 24 hours in the indicated locations. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area, in this case within the next 12 hours. Preparations to protect life and property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 hours.

Interests elsewhere along the Texas and Louisiana coasts should monitor the progress of Hanna. Interests in northeastern Mexico should also monitor the progress of this system.

Hazards Affecting Land

Hurricane Hanna as of 9:00 PM Saturday 25th July 2020. (Weathernerds)
Hurricane Hanna as of 9:00 PM Saturday 25th July 2020. (Weathernerds)

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide:

  • Port Mansfield to Baffin Bay TX – 2 to 4 ft
  • Baffin Bay to Sargent TX, including Corpus Christi Bay, Copano Bay,
    Aransas Bay, San Antonio Bay, and Matagorda Bay: 3 to 5 ft
  • Mouth of the Rio Grande to Port Mansfield TX: 1 to 3 ft
  • North of Sargent to High Island TX, including Galveston Bay: 1 to
    2 ft
Hurricane Hanna Peak Storm Surge Forecast as of 4:00 PM Saturday 25th July 2020. (Weathernerds)
Hurricane Hanna Peak Storm Surge Forecast as of 4:00 PM Saturday 25th July 2020. (Weathernerds)

The deepest water will occur along the immediate coast near and to the right of the landfall location. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.

WIND: Hurricane conditions are expected in the warning area this afternoon. Tropical storm conditions are expected to begin in the warning area later this morning.

RAINFALL: Hanna is expected to produce 6 to 12 inches of rain with isolated maximum totals of 18 inches through Sunday night in south Texas and into 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 in south Texas. 3 to 5 inches of rain is expected along the upper Texas and Louisiana coasts.

Hurricane Hanna rainfall forecast as of 1:00 PM Saturday 25th July 2020. (Weathernerds)
Hurricane Hanna rainfall forecast as of 1:00 PM Saturday 25th July 2020. (Weathernerds)

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

TORNADOES: A few tornadoes are possible today and overnight over
parts of the lower to middle Texas coastal plain.

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

Tropical Storm Hanna Forecast Discussion

NOAA Doppler weather radar data from Brownsville and Corpus Christi, Texas, along with reconnaissance data from the Air Force Hurricane Hunters indicate that Hanna has continued to strengthen this afternoon. A 30-nmi-wide eye remains distinct in the radar data, and dropsonde and 700-mb flight-level-level height data from the aircraft indicate that the central pressure has decreased to 973 MB.

The aircraft measured a peak 700-mb flight-level wind speed of 86 kt on its last outbound leg, which equates to about 77 kt at the surface. Coincident with the flight-level wind data were SFMR surface wind speeds of 80 kt. In addition, Doppler velocity values have been averaging close to 100 kt between 5000-6000 ft in the northern and northeastern eyewall, which converts to 80-kt surface wind speed estimates. Based on these data, the initial intensity has been increased to 80 kt. No further strengthening is anticipated before the center of Hanna’s eye makes landfall along the south
Texas coast in a few hours.

Doppler radar and aircraft reconnaissance fixes indicate that Hanna has finally made the much-anticipated turn toward the west-southwest, now showing an initial motion of 255/07 kt. A west-southwestward motion is expected to continue for the next 48 hours, which will take Hanna well inland over south Texas, followed by eventual dissipation in about 48 h over the mountains of northeastern Mexico. The new NHC track forecast remains unchanged from the previous advisory and lies near the center of the tightly packed consensus models.

Key Messages

  1. Life-threatening storm surge will continue along portions of the Texas coast from Port Mansfield to Sargent, where a Storm Surge Warning is in effect. Residents in these locations should follow the advice given by local emergency officials.
  2. Hurricane conditions will continue within the Hurricane Warning area along the Texas coast through this evening. Strong winds will also spread inland across portions of South Texas where Tropical Storm and Hurricane Warnings are in effect.
  3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains will result in life-threatening flash flooding and isolated minor to moderate river
    flooding.

Forecast Discussion by Forecaster Stewart from the NHC.

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