The Tropical Rainfall Measuring Mission (TRMM) satellite twice flew directly above Hurricane Isaac as it was starting to pound Louisiana with strong winds and heavy rainfall. TRMM is a joint mission between NASA and the Japanese space agency JAXA.
NASA Measures Isaac's Heavy Rainfall Rates
TRMM's first orbit was on August 28, 2012 at 2212 UTC (5:12 p.m. CDT) and the second time was on August 29, 2012 at 0307 UTC (August 28, 2012 at 10:07 p.m. CDT). Isaac had just made landfall over the Mississippi delta when data used in the first image was captured and was making another Louisiana landfall at the time TRMM flew over Isaac again. An analysis of rainfall done at NASA's Goddard Space Flight Center in Greenbelt, Md. using data from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments showed that intense bands of rain around Isaac were occasionally dropping rain at a rate of over 70 mm/hour (~2.75 inches).
Due to Isaac's slow movement and intense rainfall, the National Hurricane Center (NHC) expects a prolonged period of flooding in the affected area. The NHC expects Isaac to produce total rainfall amounts of 7 to 14 inches with possible isolated maximum amounts of 25 inches over much of Louisiana., Mississippi, southwest Alabama, and Arkansas through Friday, Aug. 30.
Storm Surges Happening on Aug. 30
According to gauges from the National Ocean Service on Aug. 30 at 8.a.m EDT at New Canal Station, Louisiana a storm surge of near 6 feet was still occurring on the southern shore of Lake Pontchartrain and a storm surge near 5 feet was occurring at Waveland, Mississippi.
Isaac in 3-D Shows Powerful, Towering ThunderstormsA three-dimensional view of rainfall within then Hurricane Isaac was made at NASA Goddard using TRMM's Precipitation Radar (PR) data. The 3-D image showed a few very powerful thunderstorms near Isaac's eye were reaching heights of almost 17km (~10.6 miles). Those tall thunderstorms near a hurricane's center release heat and can help a hurricane become more powerful. NHC reported at 10 p.m. CDT (close to the time of the first TRMM image) that Isaac's central pressure had fallen to its lowest value of 968 millibars (~28.58 inches of mercury).
Where is Isaac on Aug. 30?
The National Hurricane Center (NHC) bulletin at 8 a.m. EDT on Aug. 30 noted that Isaac had weakened to a tropical storm with maximum sustained winds near 45 mph (75 kmh). Tropical-storm-force winds extend outward up to 175 miles (280 km) mainly east through south of the center. NHC forecasters noted that the strongest winds were occurring over water near the coast during the morning hours on Aug. 30.
Isaac hasn't moved much over the last two days, and continues a slow crawl to the north at 8 mph (13 kmh). At 8 a.m. EDT Isaac was located about 35 miles (60 km) southeast of Alexandria, La. or 125 miles (205 km) northwest of New Orleans, La. near latitude 31.1 north and longitude 91.8 west. NHC forecasters expect Isaac to continue a northerly track and weaken to a tropical depression late on Aug. 30, Thursday.
In addition to the heavy rains, storm surge and tropical-storm-force winds, isolated tornadoes are possible along the central Gulf Coast region and parts of the lower Mississippi River Valley through the day on Aug. 30. According to NHC, on the forecast track, the center of Isaac will continue to move over Louisiana today, over Arkansas on Friday, Aug. 31 and over southern Missouri Friday night.
Rob Gutro | EurekAlert!
Further reports about: > 3-D image > Goddard Space Flight Center > Gulf of Maine region > Hurricane > Hurricane Center > Hurricane Katrina > NASA > NHC > National Hurricane Center > Precipitation Radar > Radar > Rift Valley Fever > River > TRMM satellite > UTC > heavy rain > rainfall > tropical diseases > tropical storm
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