After crossing western Cuba, Tropical Storm Laura emerged into the Gulf of Mexico where warm water, low wind shear and a moist environment made conditions ideal for intensification.  As it made its way through the Gulf of Mexico Laura strengthened - from a category 1 hurricane with sustained winds of 75 mph on the morning of Tuesday August 25th, to a powerful category 4 storm, with sustained winds of 150 mph on the evening of Wednesday August 26th -  an increase of 75 mph in just 36 hours.  At this point Laura was nearing the coast of western Louisiana, and made landfall near Cameron, Louisiana at around 1:00 a.m. CDT at the same 150 mph intensity.  As it moved inland heading north over western Louisiana, Laura was overflown by the NASA / JAXA GPM Core Observatory satellite at 10:00 p.m. CDT on Wednesday August 26th, shortly before the storm made landfall, then again at 8:11 a.m. CDT on Thursday August 27th, about 7 hours after making landfall, as shown in the animation below.

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Rainfall rates derived directly from the GPM Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR) instruments show heavy rain (in red) pushing up into northern Louisiana and southern Arkansas as strong southerly winds drew moisture from the Gulf of Mexico on the eastern side of the storm’s strong cyclonic circulation.  With its ability to penetrate through the clouds using active radar, the DPR also provided a detailed look at Laura’s structure.  Precipitation cloud-top heights from the DPR (highlighted in blue, indicating frozen precipitation) show Laura still had the overall structure of a powerful hurricane, as evidenced by both the symmetry of the outer rainbands that still wrap completely around the storm, as well as the residual structure of a strong core near the center containing elements of very heavy rain (shown in pink).  At the time of this GPM overpass, Laura’s maximum sustained winds were still reported at 100 mph by the National Hurricane Center, the equivalent of a category 2 hurricane.

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The Integrated Multi-satellitE Retrievals for GPM (IMERG) data product was also used to estimate rain rates and total rainfall accumulation for Hurricane Laura from August 24th through August 28th, by which time Laura had weakened to a tropical depression. In this animation, blue and yellow shading show IMERG precipitation rates and green shading shows the rainfall accumulation starting from the beginning of the movie, when the remnants of Tropical Storm Marco were still delivering rain to the Florida Panhandle. The multi-colored line shows Laura's track and intensity based on advisories posted by the National Hurricane Center, smoothed for the animation, while the gray/white shading shows infrared observations from NOAA geosynchronous satellites, indicating cloudiness. The IMERG algorithm estimated that, by 0300 UTC on August 28, Hurricane Laura had dumped over 10 inches of precipitation in some patches of the Gulf of Mexico (dark green in the animation), up to 8 inches in some parts of Louisiana, and 4 inches in southeastern Arkansas.

Credits:

Text by Steve Lang, Jacob Reed (NASA Goddard Space Flight Center)
GPM overpass visualization by Alex Kekesi (NASA Goddard Scientific Visualization Studio)
IMERG rainfall visualization by Jason West (NASA Precipitation Processing System)