NASA Analyzes Hurricane Harvey’s Rainfall, Sees Landfall, August 26, 2017

Harvey, Aug. 26
At 6 a.m. CDT (7 a.m. EDT) on Aug. 26 as Harvey’s center continued to slowly meander over land, NOAA’s GOES East satellite provided an infrared picture of the massive storm. Harvey’s eye was still apparent in the image. Credits: NASA/NOAA GOES Project

MARYLAND–(ENEWSPF)–August 26, 2017

Update

Satellites have been providing forecasters with valuable information as Harvey intensified to a Category 4 hurricane before making landfall in southeastern Texas. NASA’s GPM satellite and NOAA’s GOES-East satellite provided a look at Harvey’s heavy rainfall, cloud heights, temperatures and extent of the storm.

At 6 pm CDT on Aug 25, the National Hurricane Center noted that Harvey had strengthened to a Category 4 Hurricane on the Saffir-Simpson Hurricane Wind Scale. Harvey’s winds had increased to 130 mph (215 kph).

At 8:55 p.m. EDT when Harvey’s large eye was at the coast between Port Aransas and Port O’Connor, NOAA’s GOES East satellite provided an infrared picture of the massive storm. The eye appeared clear in the image created at NASA/NOAA GOES Project at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

Harvey’s eye made landfall around 10 p.m. CDT (11 p.m. EDT) on Friday, Aug 25 as a Category 4 hurricane between Port Aransas and Port O’Connor, Texas. The NHC said Harvey’s landfall was over the northern end of San Jose Island about 4 miles (6 km) east of Rockport.

Harvey is the first Category 4 hurricane to make landfall in Texas since Carla in 1961.

Measurements of Winds and Pressure Just After Landfall

At 11 p.m. CDT (12 a.m. EDT) a station at Aransas Pass run by the Texas Coastal Observing Network reported a sustained wind of 102 mph (165 kph) with a gust to 132 mph (213 kph). A station at Rockport, Texas, reported a pressure of 945 millibars on the western side of the eye.

At 12 a.m. CDT (1 a.m. EDT) on Aug. 26, a station at Copano Bay, Texas, reported a sustained wind of 74 mph (118 kph) with a gust to 110 mph (178 kph) in the northern eyewall. A station at Aransas Wildlife Refuge run by the Texas Coastal Observing Network recently reported a sustained wind of 78 mph (126 kph) with a gust to 105 mph (170 kph). A station at Rockport, Texas, reported a minimum pressure of 942 millibars in the eye.

NASA Measures Harvey’s Rainfall

The Global Precipitation Measurement (GPM) mission core observatory satellite had another look at Hurricane Harvey on Aug. 25, at 7:50 a.m. CDT (1150 UTC) as it was menacing the Texas gulf coast. GPM’s Dual-Frequency Precipitation Radar (DPR) instrument scanned precipitation within powerful storms wrapping around the eastern side of the hurricane. DPR found that intense storms in that area were dropping rain at a rate greater than 3.2 inches (82 mm) per hour.

Harvey Rainfall amounts
The GPM satellite measured rainfall in Hurricane Harvey on Aug. 25, at 7:50 a.m. CDT (1150 UTC) and found that intense storms in the eastern side were dropping rain at a rate greater than 3.2 inches (82 mm) per hour. Credits: NASA/JAXA, Hal Pierce

GPM’s Radar (DPR Ku Band) also was used to examine the 3-D configuration of precipitation within the storms on hurricane Harvey’s eastern side. DPR showed that storm tops there reached altitudes above 9.2 miles (14.8 km). GPM’s radar found the tallest of these powerful storms in a band of precipitation that was approaching the coastline near the Texas and Louisiana borders. These storms were measured by GPM’s radar reaching an altitude of over 10.3 miles (16.6 km).

GPM is co-managed by NASA and the Japan Aerospace Exploration Agency, JAXA.

On Saturday, Aug. 26, almost 10 inches of rain have already been reported at a few locations in southeastern Texas as of 4 a.m. CDT (5 a.m. EDT).

Warnings and Watches on Saturday, August 26

At 4 a.m. CDT (5 a.m. EDT) on Saturday, August 26, 2017 the warnings continued as Harvey moved slowly inland. A Storm Surge Warning is in effect for Baffin Bay to High Island, Texas. A Hurricane Warning is in effect for Baffin Bay to Port O’Connor,  Texas and a Tropical Storm Warning is in effect from north of Port O’Connor to High Island, Texas.

Harvey’s Status at 5 a.m. EDT on August 26

At 4 a.m. CDT (5 a.m. EDT) the National Hurricane Center (NHC) the eye of Hurricane Harvey was located by NOAA Doppler radar near 28.5 degrees north latitude and 97.2 degrees west longitude. That’s about 30 miles (50 km) southwest of Victoria, Texas.

Harvey was moving toward the northwest near 6 mph (9 kph). NHC said Harvey is expected to slow down through the day and meander over southeastern Texas through the middle of next week. Doppler radar data indicate that maximum sustained winds have decreased to near 100 mph (155 kph) with higher gusts. Additional weakening is forecast, and Harvey is likely to become a tropical storm later today.

Hurricane-force winds extend outward up to 35 miles (55 km) from the center, and tropical-storm-force winds extend outward up to 140 miles (220 km). The estimated minimum central pressure is 963 millibars.

GOES East Satellite View of Harvey at 7 a.m. EDT on Aug. 26

At 6 a.m. CDT (7 a.m. EDT) as Harvey’s center continued to slowly meander over land, NOAA’s GOES East satellite provided an infrared picture of the massive storm. Harvey’s eye was still apparent in the image created at NASA/NOAA GOES Project at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

NHC Forecast: Hazards Affecting Land

Rainfall:  Harvey is expected to produce total rain accumulations of 15 to 30 inches and isolated maximum amounts of 40 inches over the middle and upper Texas coast through next Wednesday. During the same time period Harvey is expected to produce total rain accumulations of 5 to 15 inches in far south Texas and the Texas Hill Country over through southwest and central Louisiana. Rainfall of this magnitude will cause catastrophic and life-threatening flooding.

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 is expected to reach the following heights above ground if the peak surge occurs at the time of high tide…

Port Aransas to Port O’Connor…6 to 12 ft
Port O’Connor to Sargent…6 to 9 ft
Sargent to Jamaica Beach…4 to 6 ft
Baffin Bay to Port Aransas…3 to 6 ft
Jamaica Beach to High Island…2 to 4 ft
Mouth of the Rio Grande to Port Mansfield…1 to 3 ft
High Island to Morgan City…1 to 3 ft

The deepest water will occur along the immediate coast near and to the northeast of the landfall location, where the surge will be accompanied by large and destructive waves.  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 occurring inland from the coast within Harvey’s eyewall, and hurricane-force winds, especially in gusts, are still possible near the middle Texas coast for the next several hours.  Tropical storm conditions are occurring in other portions of the hurricane and tropical storm warning areas.  Tropical storm conditions are likely to persist along portions of the coast through at least Sunday.

Surf:  Swells generated by Harvey are affecting the Texas, Louisiana, and northeast Mexico coasts.  These swells are likely to cause life-threatening surf and rip current conditions.

Tornadoes:  Tornadoes are possible today and tonight near the middle and upper Texas coast into far southwest Louisiana.

For forecast updates, visit: www.nhc.noaa.gov

NASA Gets an In-Depth Look at Intensifying Hurricane Harvey, August 25, 2017

Hurricane Harvey
Hurricane Harvey at 8 a.m. EDT, Aug. 25, 2017 (Source: NASA.gov)

MARYLAND–(ENEWSPF)–August 25, 2017 — 8 a.m. EDT

As Hurricane Harvey continued to strengthen, NASA analyzed the storm’s rainfall, cloud heights and cloud top temperatures. NASA’s GPM and Aqua satellite provided information while an animation of GOES-East satellite imagery showed Harvey’s progression toward the Texas coast.

Hurricane Harvey
This visible image of Hurricane Harvey taken from NOAA’s GOES East satellite on Aug. 25 at 10:07 a.m. EDT (1407 UTC) clearly showed the storm’s eye as the storm nears landfall in the southeastern coast of Texas. Credits: NASA/NOAA GOES Project

Harvey’s intensification has been aided by movement through an environment that includes low vertical wind shear and the warm waters in the Gulf of Mexico.

Analyzing Harvey’s Rainfall

The Global Precipitation Mission (GPM) core observatory satellite flew almost directly above intensifying Hurricane Harvey on August 24, 2017 at 6:30 p.m. EDT (2230 UTC) when maximum sustained winds had increased to about 86 mph (75 knots). GPM’s Microwave Imager (GMI) instrument peered through dense storm clouds to reveal the location of intense rainfall bands near the center of the hurricane. The Goddard Profiling Algorithm (GPROF), using GMI data, indicated that powerful storms in the hurricane were dropping rain at a rate of over 2.1 inches (54 mm) per hour. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency, JAXA.

Hurricane Harvey
The GPM satellite flew almost directly above intensifying Hurricane Harvey on August 24, 2017 at 6:30 p.m. EDT and indicated that powerful storms in the hurricane were dropping rain at a rate of over 2.1 inches (54 mm) per hour. Credits: NASA /JAXA, Hal Pierce

Animating Harvey’s Track and Development

An animation of NOAA’s GOES-East satellite infrared and visible imagery from August 23 to August 25 showed the redevelopment and movement of Hurricane Harvey in the western Gulf of Mexico. By today, Aug. 25, Harvey had moved along the coast of southeastern Texas.

Infrared Data Shows Location of Powerful Storms

The Atmospheric Infrared Sounder or AIRS instrument that flies aboard NASA’s Aqua satellite analyzed Harvey in infrared light on Aug. 25 at 3:59 a.m. EDT (0759 UTC). AIRS data showed Harvey had a strong circular area of powerful thunderstorms around the center of circulation. A thick band of powerful thunderstorms were located north to east of the center.

Hurricane Harvey
The AIRS instrument that flies aboard NASA’s Aqua satellite analyzed Harvey in infrared light on Aug. 25 at 3:59 a.m. EDT (0759 UTC). AIRS data showed Harvey had a strong circular area of powerful thunderstorms (purple) around the center of circulation. A thick band of powerful thunderstorms were located north to east of the center. Credits: NASA JPL/Ed Olsen

In both the center and the band, AIRS detected strong thunderstorms high into the troposphere with very cold cloud top temperatures. Some of the coldest cloud top temperatures exceeded minus 81 degrees Fahrenheit (minus 63 degrees Celsius). Storms with temperatures that cold are high in the troposphere and NASA research has shown they have the ability to generate heavy rain. That heavy rain is in the forecast for Texas and Louisiana, according to the National Hurricane Center (NHC).

National Hurricane Center: Harvey’s Location and Status

At 8 a.m. EDT (1200 UTC) on Aug. 25, the National Hurricane Center (NHC) noted the eye of Hurricane Harvey was located by Air Force Reserve reconnaissance aircraft and NOAA Doppler radar near 26.3 degrees north latitude and 95.8 degrees west longitude.

Harvey is moving toward the northwest near 10 mph (17 km/h), but its forward speed is expected to decrease significantly during the next couple of days. Maximum sustained winds are near 110 mph (175 kph) with higher gusts.  Some strengthening is possible, and Harvey is expected to become a major hurricane before it reaches the middle Texas coast. Hurricane-force winds extend outward up to 35 miles (55 km) from the center, and tropical-storm-force winds extend outward up to 140 miles (220 km).The minimum central pressure reported by the Air Force plane was 950 millibars.

NHC Forecast: Rainfall, Storm Surge, Wind, Surf and Isolated Tornadoes

The National Hurricane Center forecast at 8 a.m. EDT on Aug. 25 outlined the threats of rainfall, storm surge, wind, surf and isolated tornadoes:

Rainfall

Harvey is expected to produce total rain accumulations of 15 to 25 inches and isolated maximum amounts of 35 inches over the middle and upper Texas coast through next Wednesday.  During the same time period Harvey is expected to produce total rain accumulations of 7 to 15 inches in far south Texas and the Texas Hill Country eastward through central and southwest Louisiana, with accumulations of up to 7 inches extending into other parts of Texas and the lower Mississippi Valley. Rainfall from Harvey will cause devastating and life-threatening flooding.

Storm Surge

NHC said, 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 is expected to reach the following heights above ground if the peak surge occurs at the time of high tide…

  • N Entrance Padre Island Natl Seashore to Sargent…6 to 12 ft
  • Sargent to Jamaica Beach…5 to 8 ft
  • Port Mansfield to N Entrance Padre Island Natl Seashore…5 to 7 ft
  • Jamaica Beach to High Island…2 to 4 ft
  • Mouth of the Rio Grande to Port Mansfield…2 to 4 ft
  • High Island to Morgan City…1 to 3 ft

The deepest water will occur along the immediate coast near and to the northeast of the landfall location, where the surge will be accompanied by large and destructive waves.  Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

Winds, Hurricane Conditions

Hurricane conditions are likely within the hurricane warning area later on Aug.25 (today and tonight), with tropical storm conditions expected to first reach the coast in the hurricane warning area later in the morning.  These conditions are likely to persist into Saturday in portions of the hurricane and tropical storm warning area.

Surf, Dangerous Swells, Rip Currents

Swells generated by Harvey will begin to affect the Texas, Louisiana, and northeast Mexico coasts later this morning. These swells are likely to cause life-threatening surf and rip current conditions

Isolated Tornadoes

Isolated tornadoes are possible across portions of the middle and upper Texas coast today.

On the forecast track, Harvey will make landfall on the middle Texas coast tonight or early Saturday.  Harvey is then likely to meander near or just inland of the middle Texas coast through the weekend.

For updated forecasts, visit the NHC website: www.nhc.noaa.gov.

Top image caption:  The Copernicus Sentinel-3A satellite saw the temperature at the top of Hurricane Harvey on 25 August 2017 at 04:06 GMT as the storm approached the US state of Texas.  The brightness temperature of the clouds at the top of the storm, some 12–15 km above the ocean, range from about –80°C near the eye of the storm to about 20°C at the edges.  Credit:  Copernicus Sentinel 3-A satellite, processed by ESA.

Source: NASA’s Goddard Space Flight Center

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