NASA spots heavy rainfall in Tropical Storm Isaac

Posted By News On August 24, 2012 - 3:30pm
NASA spots heavy rainfall in Tropical Storm Isaac

NASA's Tropical Rainfall Measuring Mission satellite, known as TRMM has been monitoring the rainfall rates within Tropical Storm Isaac as the storm entered the eastern Caribbean Sea.

After becoming a tropical storm in the central Atlantic on August 21, Isaac continued tracking westward and entered the eastern Caribbean early on the evening of Aug. 22 with the ill-defined center passing just south of Guadeloupe in the Leeward Islands. Since becoming a tropical storm, Isaac has shown little change in intensity, but the National Hurricane Center expects that to change over the weekend of Aug. 25-26, 2012.

NASA's TRMM Satellite Sees Heavy Rainfall

NASA's TRMM satellite saw Isaac just after the storm passed the Leeward Islands and entered the eastern Caribbean. TRMM captured an image of Isaac's rainfall at 21:20 UTC (5:20 p.m. EDT) August 22, 2012. Although there were areas of moderate to heavy rain, they were mainly located southwest of the overall center. Isaac still showed no sign of an eye with very little rain near the overall center, which was located near 16 North latitude and 61.2 West longitude. There was also not much banding (curvature) in the rain features. Overall, those characteristics indicated that Isaac is still not well organized. At the time TRMM passed over Isaac, it was still a weak tropical storm with sustained winds estimated at 40 knots (~46 mph) and was moving due west at 22 mph (35.4 kmh). TRMM is a joint mission between NASA and the Japanese space agency JAXA.

On Aug. 23, 2012 as 1:40 pm EDT NASA's Aqua Satellite flew over Tropical Storm Isaac the MODIS instrument captured this visible image of the storm as it continues moving through the eastern Caribbean Sea.

(Photo Credit: : NASA Goddard MODIS Rapid Response Team)

NASA's Aqua Satellite Sees Isaac's Large Reach

On Aug. 23, 2012 as 1:40 p.m. EDT NASA's Aqua Satellite flew over Tropical Storm Isaac the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image of the storm as it continued moving through the eastern Caribbean Sea. The visible image showed the large extent of Tropical Storm Isaac. Isaac's tropical storm-force winds extend 185 miles (297.7 km) from the center, making the storm about 370 miles (595.5. km) in diameter. For a high resolution image from MODIS, go to:

Watches and Warnings

On Aug. 24, NOAA's National Hurricane Center (NHC) many watches and warnings were in effect as Isaac continued to slowly build up steam. A Hurricane Watch is in effect for Haiti. A Tropical Storm Warning is in effect for Dominican Republic, Haiti, and the Cuban Provinces of Camaguey, Las Tunas, Granma, Holguin, Santiago De Cuba, and Guantanamo. The Tropical Storm Warning is also in effect for the southeastern Bahamas including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands, and the Turks and Caicos Islands.

A Tropical Storm Watch is in effect for the Cuban Provinces of Ciego De Avila, Sancti Spiritus, and Villa Clara, Andros Island and the Central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay, San Salvador and Jamaica.

On Aug. 24 at 8 a.m. EDT (1200 UTC) Tropical Storm Isaac's maximum sustained winds were near 50 mph (80 Kmh) with higher gusts. Additional strengthening is forecast while Isaac's center remains over water, according to NHC forecasters. Issac was about 175 miles (280 km) south-southwest of Santo Domingo, Dominican Republic, and about 220 miles (355 km) southeast of Port au Prince, Haiti. That puts Isaac's center near latitude 16.0 north and longitude 70.3 west. Isaac is moving toward the west near 15 mph (24 kmh) and the NHC expects Isaac to turn west-northwest, then north. According to NHC forecasters, Isaac's center will move near or over Hispaniola today, Aug. 24 and near or over southeastern Cuba on Saturday, Aug. 25.

The heavy rainfall that the TRMM satellite observed is expected to be problematic for Hispaniola and Cuba. The NHC expects extreme rainfall totals of between 8 and 12 inches, with isolated amounts to 20 inches. The potential for flash-flooding and mudslides is present. Eastern Cuba and Jamaica may receive between 4 and 8 inches with isolated totals of 12 inches, while Puerto Rico and the Virgin Islands may get between 2 and 4 inches of rainfall, with isolated totals to 6 inches. Tropical storm-force winds, heavy surf and storm surges are also expected in those areas as Isaac continues on its track. For a full forecast, go to NHC's web page:

NASA's TRMM satellite saw Isaac just after it passed the Leeward Islands and entered the eastern Caribbean. This image was taken at 5:20 pm EDT on Aug. 22, 2012. Although there are areas of moderate (shown in green) to heavy rain (shown in red), these are mainly located southwest of the overall center.

(Photo Credit: : SSAI/NASA, Hal Pierce)

An animation of satellite observations from August 21-24, 2012, shows Tropical Storm Isaac moving through the eastern Caribbean Sea and over Puerto Rico and Hispaniola. This visualization was created by the NASA GOES Project at NASA Goddard Space Flight Center, Greenbelt, Md., using observations from NOAA's GOES-13 satellite.

(Photo Credit: : NASA/NOAA GOES Project)

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