Hurricane Harvey Intensifies, Will Be Strongest Texas Coastal Bend Landfall in 47 Years
By Jon Erdman
Hurricane Harvey continues to intensify and will be the nation's first Category 3 landfall in almost 12 years tonight or Saturday morning, poised to clobber the Texas Gulf Coast with devastating rainfall flooding, dangerous storm-surge flooding and destructive winds this weekend that could leave parts of the area uninhabitable for an extended period of time.
After a slight pause overnight, Harvey has re-intensified with maximum sustained winds of 110 mph. Harvey is located just under 150 miles southeast of Corpus Christi, Texas, moving northwest at around 10 mph.
Harvey's central pressure has plummeted once again Friday morning, approximately another 17 millibars in just a few hours as another rapid intensification phase kicks in.
Outer rainbands are already spiraling ashore as far north as Galveston Bay, bringing brief heavy rain and gusty winds.
Water levels were already 1 to 2 feet above average tide levels as of Friday morning from S. Padre Island, Texas to Calcasieu Pass, Louisiana.
Current Radar, Winds
A hurricane warning has been issued for a portion of the Texas coast, from north of Port Mansfield to Sargent, including the city of Corpus Christi. A hurricane warning means hurricane conditions are likely within the watch area. In this case, hurricane conditions are likely within 12 to 24 hours.
Importantly, tropical storm-force winds may begin to affect the hurricane-warned area above as soon as late Friday morning, making final preparations difficult.
Tropical storm warnings are in effect from north of Sargent to High Island, Texas, including the cities of Houston and Galveston. Tropical storm warnings are also in effect from north of Port Mansfield to the mouth of the Rio Grande River.
The National Hurricane Center also issued its first-ever public storm surge warning, which includes a swath of the Texas coast from Port Mansfield to High Island. This means a life-threatening storm surge is expected in the warned area in the next 36 hours. This warning does not include Galveston Bay, but does include Galveston Island and the Bolivar Peninsula.
Storm Surge Alerts
With a favorable environment that includes deep, warm Gulf of Mexico water, and low wind shear, Harvey will continue to strengthen, and will likely be a Category 3 hurricane at landfall along the Texas coast overnight Friday night or early Saturday morning.
After making landfall, Harvey will be caught in a zone of light steering winds aloft that will stall the circulation for more than two days.
Once moving again, potentially by Monday, Harvey's center may re-emerge over the Gulf of Mexico, opening up the possibility of some restrengthening before a final landfall in Louisiana. But that remains highly uncertain, as stalled or slow-moving tropical cyclones are notoriously difficult to forecast.
Harvey may also be the strongest landfall in this area known as the Texas Coastal Bend since the infamous Category 3 Hurricane Celia hammered the Corpus Christi area in August 1970 with wind gusts up to 161 mph, damaging almost 90 percent of the city's businesses and 70 percent of its residences and destroying two hangars at the city's airport.
Harvey will bring a mess of coastal impacts, including storm-surge flooding, high surf with battering waves and damaging winds.
Devastating Rainfall Flooding
A tropical cyclone's rainfall potential is a function of its forward speed, not its intensity.
With Harvey stalling for a few days, prolific rainfall, capable of devastating flash flooding will result near the middle and upper Texas coast.
To illustrate this, it's possible Harvey's heavy rain may not entirely exit the areas of Texas it soaks until sometime next Thursday, and may not exit the Mississippi Valley until next Friday.
Here are the latest rainfall forecasts from the National Hurricane Center and NOAA's Weather Prediction Center. Keep in mind, locally higher amounts are possible where rainbands stall.
- Middle/Upper Texas Coast: 15 to 25 inches, with isolated totals up to 35 inches.
- Deep South Texas, Texas Hill Country east to central, southwest Louisiana: 7 to 15 inches.
- Other affected parts of Texas into the Lower Mississippi Valley: 7 inches or less.
This forecast is subject to change depending on the exact path of Harvey, locations of rainbands and how long it stalls. Generally, areas along and east of Harvey's path are in the greatest threat of flooding rainfall.
Among the biggest uncertainties is the heavy rain potential in central Texas, including for the flood-prone cities of Austin and San Antonio. That all depends on how far inland and to the west Harvey tracks and how long it stalls in that area.
Flash flood watches have been issued for much of southeast, southern and parts of central Texas.
The ground is already quite saturated in many of these areas from what has been one of the wettest starts to August on record.
Long-Lived Surge, Wind Threats
Harvey's slow movement will also likely lead to additional long-lived impacts from wind.
To the east of Harvey's center, a persistent fetch of south to southeast winds will build swells over the western Gulf of Mexico. As Harvey strengthens, coastal flooding and added storm surge will peak along parts of the Texas and Louisiana coasts through late Friday night into early Saturday morning with Harvey's landfall.
Here are the latest storm surge forecasts, according to the National Hurricane Center. Note that these inundations above ground level are worst-case scenarios along the immediate coast if the peak surge coincides with high tide.
- N. Entrance of Padre Island Nat'l Seashore to Sargent, Texas: 6 to 12 feet.
- Sargent to Jamaica Beach, Texas: 5 to 8 feet.
- Port Mansfield to N. Entrance of Padre Island Nat'l Seashore, Texas: 5 to 7 feet.
- Jamaica Beach to High Island, Texas: 2 to 4 feet.
- Mouth of the Rio Grande River to Port Mansfield, Texas: 2 to 4 feet.
- High Island, Texas, to Morgan City, Louisiana: 1 to 3 feet.
Here are the times of high tide Friday night into Saturday night, all in local time.
Given Harvey's expected slow crawl near the coast, at least some coastal flooding, along with battering waves, could persist for several days, over multiple tide cycles along the Texas and southwest Louisiana coast into next week.
This coastal flooding and wave action could increase if Harvey's center re-emerges over the Gulf and intensifies, potentially leading to a second storm surge along parts of the Louisiana or upper Texas coast next week. Again, this part of the forecast is highly uncertain at this time.
Coastal Flood, Waves, Wind Setup
Furthermore, this water rise from the Gulf of Mexico won't allow rain-swollen rivers and bayous to drain, compounding the inland flood threat.
Destructive Wind Threat
If that wasn't enough, there's the winds.
High winds capable of downing numerous trees, powerlines and damaging structures can be expected where the eyewall of Harvey tracks.
Furthermore, persistent winds, even if they are not particularly high-end if Harvey is over land, could down more trees than they otherwise would given the rain-soaked or flooded ground, possibly for several days as Harvey lingers.
Potential Power Outages
Check back with weather.com for updates on Harvey.
Reposted with permission from our media associate Weather Underground.