TS Hannah Continues to Veer toward Valley; Threat to Houston Reduced

Overnight, TD 8 turned into Tropical Storm Hannah. Hannah’s track continues to take it toward Corpus and the Rio Grande Valley. The shift in direction compared to earlier projections means wind and rainfall threats to Houston are reduced. However, tropical storm warnings remain up for most of the Texas coastline, including San Luis Pass to the Rio Grande Valley.

Rainfall Amounts

Hanna should produce heavy rains, but the heaviest will fall in South Texas.

While portions of south Texas could see 10 to 15 inches of rain this weekend, rainfall amounts in the Houston area should average 3-5 inches along the coast and 1-3 inches inland.

Jeff Lindner, Harris County Meteorologist
Infrared imagery shows building of Hannah.
Rainfall accumulation for storm duration
Total accumulation in north Harris County is likely to be only 1-2 inches from Hannah.

Of course, that should hold down the risk of flash flooding in the Lake Houston Area, but Lindner says the Weather Service will likely issue flash flood warnings for portions of SE Texas later today. NOAA currently gives the north Houston area only a marginal chance of flash flooding.

Houston has only a 5-10% chance of flash flooding from Hannah.

Hannah Could Strengthen to 65 MPH

National Hurricane Center expects Hanna to strengthen and bring tropical-storm-force winds to portions of the Texas coast. NHC brings Hanna to a 65mph tropical storm at landfall. How long it takes any inner core to form today will determine if Hanna could potentially become a weak hurricane as suggested by some of the hurricane models.

Most tropical storm force winds should miss Houston.

Winds in the Lake Houston Area will not be that strong, of course, but could still reach 20 mph, according to forecasters.

Not the Weekend for Offshore Boating

Lindner says, “Wave heights near the center of Hanna will build today. As the system intensifies, waves could reach 10-15 ft tonight. Some of this wave action will move toward the upper TX coast with seas building today into the 4-6 foot range and 6-9 foot range tonight into Saturday. Large swells generated by the system will result in wave run-up and elevated tides of 1-3 feet starting later today and lasting into much of Saturday along the upper and mid TX coast. Minor coastal flooding will be possible at times of high tides in the typical sensitive areas along the coast.”

Forecast track shows Hannah coming onshore Saturday at 1PM in south Texas.

In summary, the brunt of the storm should miss us. But we will still get sideswiped.

The organization of Hanna will need to be monitored closely today and tonight. For up-to-the-minute status reports and forecasts, visit the National Hurricane Center’s website.

Posted by Bob Rehak on 7/24/2020 at 9:15 am

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