mardi 29 août 2017

NASA's GPM & IMERG Shows Rainfall Accumulation Along Harvey's Track













NASA & JAXA - Global Precipitation Measurement (GPM) patch.

Aug. 29, 2017

Harvey (was TD 09 - Atlantic Ocean)

As Harvey continues to dump catastrophic rains over southeastern Texas and southwestern Louisiana, NASA has been tallying rainfall accumulations in the storm's wake.


Image above: IMERG data for Harvey were compiled for the period from August 23 to 29, 2017 as it moved through the Gulf of Mexico and stalled over Texas. The IMERG totals showed over 30 inches of rainfall had occurred in the Houston metro area and part of the western Gulf of Mexico. Image Credits: NASA JAXA, Hal Pierce.

Total rainfall estimates from NASA's Integrated Multi-satellitE Retrievals for GPM (IMERG) data were compiled for the period from August 23 to 29, 2017. During this period Harvey dropped heavy rainfall as it moved through the Gulf of Mexico and stalled over Texas. The IMERG totals showed over 30 inches of rainfall had occurred in the Houston metro area and part of the western Gulf of Mexico.

It has been reported that Harvey dropped over 40 inches (1016 mm) of rain over southeastern Texas during this period. IMERG Data are produced at NASA's Goddard Space Flight Center in Greenbelt, Maryland, using data from the satellites in the Global Precipitation Measurement mission or GPM Constellation, and is calibrated with measurements from the GPM Core Observatory as well as rain gauge networks around the world. 

The National Weather Service reported at 1 p.m. CDT on Aug. 29 "A preliminary report from one Texas rain gauge has broken the Texas tropical cyclone rainfall record. Southeast of Houston, Mary's Creek at Winding Road reported 49.32 inches as of 9 a.m. CDT. This total is higher than the previous record of 48 inches set during tropical cyclone Amelia of 1978 at Medina, Texas."

The National Hurricane Center (NHC) indicates that Harvey continues to drop heavy rain over southeastern Texas and southern Louisiana as it moves toward the north-northeast. 

Warnings and Watches in Effect as of 1 p.m. CDT, Aug. 29

The NHC said a Tropical Storm Warning is in effect from nNorth of Port O'Connor, Texas to Morgan City, Louisiana. A Tropical Storm Watch is in effect from east of Morgan City to Grand Isle, Louisiana. A Storm Surge Watch is in effect from Port Bolivar, Texas to Morgan City.

IMERG Data on Rainfall From Harvey

Video above: This animation of IMERG data for Harvey were compiled for the period from August 23 to 29, 2017 as it moved through the Gulf of Mexico and stalled over Texas. The IMERG totals showed over 30 inches of rainfall had occurred in the Houston metro area and part of the western Gulf of Mexico. Video Credits: NASA JAXA, Hal Pierce.

More Heavy Rainfall Expected

NHC forecasters noted that catastrophic and life-threatening flooding continues in southeastern Texas and portions of southwestern Louisiana. Harvey is expected to produce additional rainfall accumulations of 6 to 12 inches through Friday over parts of the upper Texas coast into southwestern Louisiana. 

Isolated storm totals may reach 50 inches over the upper Texas coast, including the Houston/Galveston metropolitan area.  These rains are currently producing catastrophic and life-threatening flooding over large portions of southeastern Texas and southwestern Louisiana.

Elsewhere, Harvey is expected to produce additional rainfall amounts of 5 to 10 inches across portions of southern Louisiana into coastal Mississippi and Alabama. Rainfall associated with Harvey will spread north by mid to late week, with rainfall amounts of 4 to 8 inches spreading into portions of Arkansas and the Tennessee Valley.

A list of rainfall observations compiled by the NOAA Weather Prediction Center can be found at: http://www.wpc.ncep.noaa.gov/discussions/nfdscc1.html

Winds, Storm Surge, Ocean Swells

Tropical storm conditions are occurring over portions of the warning area along the coast and are likely to persist during the next day or so.

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...

San Luis Pass to Morgan City including Galveston Bay...1 to 3 ft

The deepest water will occur along the immediate coast near the area of onshore winds.  Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

Swells generated by Harvey are still affecting the coasts of Texas and Louisiana.  These swells are likely to cause life-threatening surf and rip current conditions.

Harvey's Location at 1 p.m. CDT, Aug. 29

At 1 p.m. CDT (1800 UTC), the center of Tropical Storm Harvey was located near 28.8 degrees north latitude and 94.3 degrees west longitude. That's about 80 miles (130 km) south-southwest of Port Arthur, Texas and about 95 miles (155 km) southwest of Cameron, Louisiana. Harvey was moving a little faster toward the north-northeast near 8 mph (13 kph), and this general motion is expected to continue today and tomorrow, Aug. 30. On the forecast track, the center of Harvey is expected to move inland over the northwestern Gulf within the tropical storm warning area later tonight or early Wednesday.

Maximum sustained winds remain near 45 mph (75 kph) with higher gusts. NHC said no significant change in strength is expected before the center moves inland. A gradual weakening should begin thereafter. The estimated minimum central pressure is 997 millibars.

(Update #2) Harvey's Rainfall and Structure Seen by GPM

The Global Precipitation Mission (GPM) Core Observatory captured these images of Hurricane Harvey at 7:45 a.m. EDT (11:45 UTC) and 5:25 p.m. EDT (21:25 UTC) on the August 27, 2017 nearly two days after the storm made landfall as it was meandering slowly southeast at just 2 mph (~4 kph) near Victoria, Texas west of Houston.

GPM Video of Harvey's Rainfall

Video Credits: NASA's Scientific Visualization Studio. GPM data provided by the joint NASA/JAXA GPM mission.

The animation shows rain rates derived from GPM's GMI microwave imager (outer swath) and dual-frequency precipitation radar or DPR (inner swath) overlaid on enhanced infrared data from the GOES-East satellite.

Harvey's cyclonic circulation is still quite evident in the infrared clouds, but GPM shows that the rainfall pattern is highly asymmetric with the bulk of the rain located north or east of the center. A broad area of moderate rain can be seen stretching from near Galveston Bay to north of Houston and back well to the west. Within this are embedded areas of heavy rain (red areas); the peak estimated rain rate from GPM during these overpasses was 96 mm/hr (~3.77 inches per hour). The animation was created at the NASA's Scientific Visualization Studio, at NASA's Goddard Space Flight Center, Greenbelt, Md.

With Harvey's circulation still reaching out over the Gulf of Mexico the storm is able to draw in a continuous supply of warm moist air to sustain the large amount of rain it is producing.

(Update #1)  NASA Watching Harvey from Satellites and the International Space Station

NASA has a lot of resources providing information on Tropical Storm Harvey as it continues to drop tremendous, flooding rainfall on Texas and Louisiana. Satellites like NASA's Aqua satellite and platforms like aircraft and the International Space Station continue to provide various kinds of data on the storm.

"NASA focuses on developing new research capabilities that can be used by our partners in the operational and response communities," said Dalia Kirschbaum, Research Physical Scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "While we continue to innovate in the type of information from satellites, models, and airborne platforms, the main focus is to ensure that the partners that are responding operationally to this event have the information in the format that they need to make effective decisions on emergency response. We continually and actively engage to ensure that the data pipeline is as effective and useful as possible."

NASA Resources in Action


Image above: Astronaut Randy Bresnik took this photo of Tropical Storm Harvey from the International Space Station on Aug. 28 at 1:27 p.m. CDT. Image Credit: NASA.

The International Space Station has provided a view of Harvey from its orbit in space. On Aug. 28 at 1:27 p.m. CDT Astronaut Randy Bresnik took a photo of Tropical Storm Harvey 

An infrared image taken at 2:29 p.m. CDT (19:29 UTC) on Aug. 28, 2017 from NASA's Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aqua satellite illustrated the growing flood threat from Tropical Storm Harvey.  The data showed a large area of coldest cloud top temperatures and strongest thunderstorms centered along the southeastern Texas coast. A second area of intense precipitation was visible over southeastern Louisiana.


Image above: This false-colored infrared image acquired from the AIRS instrument aboard NASA's Aqua satellite at 2:29 p.m. CDT (19:29 UTC) on Aug. 28, shows a large area of coldest cloud top temperatures and strongest thunderstorms (dark blue and purple) centered along the southeastern Texas coast. A second area of intense precipitation is visible over southeastern Louisiana. Image Credits: NASA JPL/Ed Olsen.

Harvey has reemerged over the Gulf of Mexico, but the National Hurricane Center forecasts only a small amount of strengthening before the storm moves slowly north and inland again.

National Hurricane Center Warnings and Watches

On Aug. 29 at 7 a.m. CDT, the National Hurricane Center (NHC) warned "Catastrophic and life-threatening flooding continues and continued heavy rainfall today is expected to worsen the flood situation in southeastern Texas and southwestern Louisiana." A Tropical Storm Warning is in effect from Mesquite Bay, Texas to Intracoastal City, Louisiana. A Storm Surge Watch is in effect from Port Bolivar, Texas to Morgan City, Louisiana.

There are also many flood warnings in effect throughout southeastern Texas and southwestern Louisiana. For specific forecasts, visit: http://www.weather.gov/.

More Rainfall Expected Today, August 29, 2017

NHC forecasters said "Harvey is expected to produce additional rainfall accumulations of 7 to 13 inches through Friday over parts of the upper Texas coast into southwestern Louisiana.  Isolated storm totals may reach 50 inches over the upper Texas coast, including the Houston/Galveston metropolitan area. Elsewhere, Harvey is expected to produce total rain accumulations of 5 to 15 inches farther east across south-central Louisiana. Rainfall amounts of 5 to 10 inches are expected in southeast Louisiana and coastal Mississippi and Alabama."

Harvey's Location at 7 a.m. CDT, August 29, 2017

At 7 a.m. CDT (1200 UTC), the center of Tropical Storm Harvey was estimated near 28.2 degrees north and 94.6 degrees west longitude. Harvey's center of circulation was about 90 miles (145 km) east-southeast of Port O'Connor, Texas. Harvey is moving toward the east-northeast near 3 mph (6 kph), and this motion is expected to continue through this morning.

Maximum sustained winds remain near 45 mph (75 kph) with higher gusts. Little change in strength is forecast during the next 48 hours. Tropical-storm-force winds extend outward up to 175 miles (280 km) from the center. The estimated minimum central pressure is 997 millibars.

A turn toward the northeast is expected later today and tonight, followed by a turn toward the north-northeast on Wednesday, Aug. 30. On the forecast track, the center of Harvey is expected to be just offshore of the middle and upper coasts of Texas through tonight, then move inland over the northwestern Gulf coast on Wednesday, Aug. 30.

A list of rainfall observations compiled by the NOAA Weather Prediction Center can be found at: http://www.wpc.ncep.noaa.gov/discussions/nfdscc1.html

For downloadable video, visit: https://svs.gsfc.nasa.gov/4458

GPM (Global Precipitation Measurement): http://www.nasa.gov/mission_pages/GPM/main/index.html and http://www.eorc.jaxa.jp/GPM/index_e.htm

For updated forecasts and warnings, visit: http://www.nhc.noaa.gov.

For local warnings and watches, visit: http://www.weather.gov/

Images (mentioned), Videos (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Rob Gutro/JPL/Alan Buis.

Greetings, Orbiter.ch

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